CCSP 4.1 January 15, 2009

1 of 784 Final Report 

## U.S. Climate Change Science Program

Synthesis and Assessment Product 4.1 Coastal Sensitivity to Sea Level Rise: A Focus on the Mid-Atlantic Region

Lead Agency: U.S. Environmental Protection Agency

Other Key Participating Agencies: U.S. Geological Survey National Oceanic and Atmospheric Administration Contributing Agencies: Department of TransportationCCSP 4.1 January 15, 2009

2 of 784 Final Report P.1 SCOPE AND APPROACH OF THIS PRODUCT ....................................................................... 11 P.2 FUTURE SEA-LEVEL SCENARIO S ADDRESSED IN THIS PRODUCT ............................. 14 P.3 PRODUCT ORGANIZATION ...................................................................................................... 16 EXECUTIVE SUMM ARY ............................................................................................................. ........... 19 ES.1 WHY IS SEA LEVEL RISING? HOW MUCH WILL IT RISE? ........................................... 20 ES.2 WHAT ARE THE EFFECTS OF SEA-LEVEL RISE? ............................................................ 21 ES.2.1 Sea-Level Rise and the Physical Environment ...................................................................... 22 ES.2.2 Societal Impa cts and Implications ......................................................................................... 27 ES.3 HOW CAN PEOPLE PREPARE FOR SEA-LEVEL RISE? ................................................... 28 ES.3.1 Options for Adaptin g to Sea-l evel Rise ................................................................................. ... 28 ES.3.2 Adapting to Sea-level Rise ............................................................................................. .......... 28 ES.4 HOW CAN SCIENCE IMPROVE UNDERSTANDING AND PREPAREDNESS FOR FUTURE SEA-LEVEL RISE? ............................................................................................................. 30 ES.4.1 Enhance Understanding .................................................................................................. ........ 32 ES.4.2 Enhance Decision Support ............................................................................................... ....... 33 PART I OVERVIEW. THE PHYSICAL ENVIRONMENT ................................................................. 34 CHAPTER 1: SEA-LEVEL RISE AND ITS EFFECTS ON THE COAST .......................................... 38 KEY POINTS

.............................................................................................................................. ........... 38 1.1 INTRODUCTION ............................................................................................................................ 4 0 1.1.1 Climate Change Basis for this Product .................................................................................... 45 1.2 WHY IS GLOBAL SEA LEVEL RISING? ................................................................................... 47 1.3 RELATIVE SEA-LEVEL RISE AROUND THE UNITED STATES ........................................ 52 1.4 IMPACTS OF SEA-LEVEL RI SE FOR THE UNITED STATES ............................................. 59 1.4.1 Coastal Vulnerability for the United States .............................................................................. 59 1.4.2 Climate Change, Se a-Level Rise and Storms ........................................................................... 61 1.4.3 Shoreline Change and Coastal Erosion ................................................................................... 62 1.4.4 Managing the Coastal Zone as Sea Level Rises ....................................................................... 64 CHAPTER 1 REFERENCES ............................................................................................................... 67 CHAPTER 2. COASTAL ELEVATIONS ............................................................................................... 7 7 KEY FINDINGS

.............................................................................................................................. ...... 77 2.1 INTRODUCTION ............................................................................................................................ 7 9 2.2 ELEVATION DATA ....................................................................................................................... 86 2.2.1 Topographic Maps, Digital Elevation Models, and Accuracy Standards ............................... 86 2.2.2 Lidar Elevation Data ................................................................................................................. 89 2.2.3 Tides, Sea Level, and Reference Datums ................................................................................. 91 2.2.4 Topographic/Bathymetric/Water Level Data Integration ........................................................ 95 2.3 VULNERABILTY MAPS AND ASSESSMENTS ......................................................................... 96 2.3.1 Large-Area Studies (Global and United States) ....................................................................... 98 2.3.2 Mid-Atlantic Region, States, and Localities ............................................................................101 2.3.3 Other Reports ...........................................................................................................................103 2.3.4 Limitations of Previous Studies ...............................................................................................104 2.4 FUTURE VULNERABILITY ASSESSMENTS ..........................................................................112 2.5 SUMMARY, CONCLUSIONS, AND FUTURE DIRECTIONS .................................................121 CHAPTER 2 REFERENCES ..............................................................................................................127 CHAPTER 3. OC EAN COASTS ....................................................................................................... ......141 KEY FINDINGS

.............................................................................................................................. .....141 3.1 INTRODUCTION ...........................................................................................................................141 3.2 ASSESSING THE POTENTIAL IMPACT OF SEA-LEVEL RISE ON THE OCEAN COASTS OF THE MID-ATLANTIC ..................................................................................................................145CCSP 4.1 January 15, 2009

3 of 784 Final Report 3.3 GEOLOGICAL CHARACTER OF THE MID-ATLANTIC COAST .......................................148 3.4 IMPORTANT FACTORS FOR MID-ATLANTIC SHORELINE CHANGE ...........................149 3.4.1 Geologic Framework ................................................................................................................150 3.4.2 Physical Processes ....................................................................................................................152 3.4.3 Sediment Supply .......................................................................................................................154 3.4.4 Human Impacts ........................................................................................................................156 3.5 COASTAL LANDFORMS OF THE MID-ATLANTIC ..............................................................157 3.5.1 Spits

.............................................................................................................................. ............158 3.5.2 Headlands

.............................................................................................................................. ...159 3.5.3 Wave-Dominated Barrier Islands ............................................................................................159 3.5.4 Mixed-Energy Barrier Islands .................................................................................................161 3.6 POTENTIAL RESPONSES TO FUTURE SEA-LEVEL RISE ..................................................162 3.6.1 Bluff and Upland Erosion .......................................................................................................162 3.6.2 Overwash, Inlet Processes, and Barrier Island Morphologic Changes .................................162 3.6.3 Threshold Behavior ..................................................................................................................164 3.7 POTENTIAL CHANGES TO THE MID-ATLANTIC OCEAN COAST DUE TO SEA-LEVEL RISE

.............................................................................................................................. .........................170 3.7.1 Spits

.............................................................................................................................. ............171 3.7.2 Headlands

.............................................................................................................................. ...171 3.7.3 Wave-Dominated Barrier Islands ............................................................................................171 3.7.4 Mixed-Energy Barrier Islands .................................................................................................174 CHAPTER 3 REFERENCES ..............................................................................................................176 CHAPTER 4. COASTAL WETL AND SUSTAINABILITY .................................................................189 KEY FINDINGS

.............................................................................................................................. .....189 4.1 INTRODUCTION ...........................................................................................................................191 4.2 WETLAND SETTINGS OF THE MID-ATLANTIC REGION ..................................................193 4.3 VERTICAL DEVELOPMENT AND ELEVATION CHANGE .................................................194 4.3.1 Wetland Vertical Development ................................................................................................195 4.3.2 Influence of Clim ate Change on Wetland Vertical Development ..........................................200 4.4 HORIZONTAL MIGRATION ......................................................................................................202 4.5 VULNERABILITY OF WETLANDS TO TWENTIETH CENTURY SEA-LEVEL RISE .....204 4.5.1 Sudden Marsh Dieback ............................................................................................................205 4.6 PREDICTING FUTURE WETLAND SUSTAINABILITY ........................................................206 4.6.1 Case Study: Mid-Atlantic Regional Assessment, New York to Virginia ................................210 4.6.2 Case Study: Albemarle–Pamlic o Sound Wetlands and Sea-Level Rise .................................221 4.7 DATA NEEDS

.............................................................................................................................. ...228 CHAPTER 4 REFERENCES ..............................................................................................................230 CHAPTER 5. VULNERABLE SPECIES: THE E FFECTS OF SEA-LEVEL RISE ON COASTAL HABITATS ...................................................................................................................... ..........................238 KEY FINDINGS

.............................................................................................................................. .....238 5.1 INTRODUCTION ...........................................................................................................................239 5.2 TIDAL MARSHES .........................................................................................................................243 5.3 FRESHWATER FORESTED WETLANDS ................................................................................252 5.4 SEA-LEVEL FENS .........................................................................................................................254 5.5 SUBMERGED AQUATIC VEGETATION .................................................................................254 5.6 TIDAL FLATS

.............................................................................................................................. ..257 5.7 ESTUARINE BEACHES ...............................................................................................................259 5.8 CLIFFS

.............................................................................................................................. ..............262 5.9 SUMMARY OF IMPACTS TO WETLAND-DEPENDENT SPECIES .....................................264 CHAPTER 5 REFERENCES ..............................................................................................................266 ZEDLER, J.B. AND J.C. CALLAWAY, 1999: TRACKING WETLAND RESTORATION: DO MITIGATION SITES FOLLOW DESIRED TRAJECTORIES? RESTORATION ECOLOGY, 7(1), 69-73. ........................................................................................................................ ...................................275CCSP 4.1 January 15, 2009

4 of 784 Final Report PART II OVERVIEW. SOCIETAL IM PACTS AND IMPLICATIONS ............................................276 CHAPTER 6. SHORE PROTEC TION AND RE TREAT .....................................................................281 KEY FINDINGS

.............................................................................................................................. .....281 6.1 TECHNIQUES FOR SHORE PROTECTION AND RETREAT ..............................................282 6.1.1 Shore Protection .......................................................................................................................282 6.1.2 Retreat

.............................................................................................................................. ........295 6.1.3 Combinations of Shore Protection and Retreat ......................................................................301 6.2 WHAT FACTORS INFLUENCE THE DECISION WHETHER TO PROTECT OR RETEAT?

.............................................................................................................................. ..................................303 6.2.1 Site-Specific Factors ................................................................................................................303 6.2.2 Regional Scale Factors ............................................................................................................305 6.2.3 Mutual Reinforcement Between Co astal Development and Shore Protection .......................307 6.3 WHAT ARE THE ENVIRONMENTAL CONSEQUENCES OF RETREAT AND SHORE PROTECTION?

.............................................................................................................................. .....308 6.4 WHAT ARE THE SOCIETAL CONSEQUE NCES OF SHORE PROTECTION AND RETREAT AS SEA LEVEL RISES? .................................................................................................313 6.4.1 Short-Term Consequences .......................................................................................................313 6.4.2 Long-Term Consequences .......................................................................................................314 6.5 HOW SUSTAINABLE ARE SHORE PROTECTION AND RETREAT? ...............................315 6.5.1 Is “Business as Usual” Sh ore Protection Su stainable? ............................................................317 6.5.2 Sustainable Shore Protection May Require Regional Coordination ......................................318 6.5.3 Either Shore Protection or a Failure to Plan can Limit the Flexibility of Future Generations

.............................................................................................................................. .............................320 CHAPTER 6 REFERENCES ..............................................................................................................321 CHAPTER 7. POPULATION, LAND USE, AND INFRASTRUCTURE ...........................................332 KEY FINDINGS

.............................................................................................................................. .....332 7.1 INTRODUCTION ...........................................................................................................................333 7.2 POPULATION STUDY ASSESSMENT .......................................................................................333 7.3 MID-ATLANTIC POPULATION ANALYSIS ............................................................................338 7.3.1 Example Population Analysis Results .....................................................................................346 7.4 LAND USE

.............................................................................................................................. .........352 7.5 TRANSPORTATION INFRASTRUCTURE ...............................................................................355 7.5.1 General Considerations ...........................................................................................................355 7.5.2 Recent U.S. Department of Transportation Studies ................................................................357 CHAPTER 7 REFERENCES ..............................................................................................................364 CHAPTER 8. PU BLIC ACCESS ...................................................................................................... .......368 KEY FINDINGS

.............................................................................................................................. .....368 8.1 INTRODUCTION ...........................................................................................................................369 8.2 EXISTING PUBLIC ACCESS AND THE PUBLIC TRUST DOCTRINE ................................369 8.3 IMPACT OF SHORE EROSION ON PUBLIC ACCESS ...........................................................375 8.4 IMPACT OF RESPONSES TO SEA-LEVEL RISE ON PUBLIC ACCESS .............................379 CHAPTER 8 REFERENCES ..............................................................................................................383 CHAPTER 9. COASTAL FLOODING, FLOODPLAINS AND COASTAL ZONE MANAGEMENT ISSUES ........................................................................................................................ ...............................386 KEY FINDINGS

.............................................................................................................................. .....386 9.1 INTRODUCTION ...........................................................................................................................387 9.2 PHYSICAL CHARACTERISTICS ..............................................................................................388 9.2.1 Floodplain

.............................................................................................................................. ..388 9.3 POTENTIAL IMPACTS OF SEA-LEVEL RISE ON COASTAL FLOODPLAINS ................390 9.4 POTENTIAL EFFECTS OF SEA-LEVEL RISE ON THE IMPACTS OF COASTAL STORMS

.............................................................................................................................. ..................................392 9.4.1 Historical Comparison at Tide Stations ..................................................................................393CCSP 4.1 January 15, 2009

5 of 784 Final Report 9.4.2 Typical 100-Year Storm Surge Elevations Relative to Mean Higher High Water within the Mid-Atlantic Region ..........................................................................................................................397 9.5 FLOODPLAIN MAPPING AND SEA-LEVEL RISE .................................................................400 9.6 STUDIES OF FUTURE COASTAL CONDITIONS AND FLOODPLAIN MAPPING ..........402 9.6.1 FEMA Coastal Studies .............................................................................................................402 9.6.2 Mapping Potential Impacts of Sea-Level Rise on Coastal Floodplains .................................405 9.7 HOW COASTAL RESOURCE MANAGERS COPE WITH SEA-LEVEL RISE AND ISSUES THEY FACE

.............................................................................................................................. ...........406 9.7.1 Studies by the Association of State Floodplain Managers ......................................................406 9.7.2 The Response through Floodproofing .....................................................................................407 9.7.3 Coastal Zone Management Act ................................................................................................409 9.7.4 The Coastal Zone Manageme nt Act and Sea-Level Rise Issues .............................................410 9.7.5 The Coastal Zone Enhancement Program ..............................................................................411 9.7.6 Coastal States Strategies ..........................................................................................................413 PART III OVERVIEW. PREPARING FOR SEA-LEV EL RISE ........................................................423 CHAPTER 10. IMPLICATIO NS FOR DECISIONS ............................................................................427 KEY FINDINGS

.............................................................................................................................. .....427 10.1 INTRODUCTION .........................................................................................................................428 10.2 DECISIONS WHERE PREPARING FOR SEA-LEVEL RISE IS WORTHWHILE .............431 10.2.1 Decisions that Address Large Near-Term Impacts ...............................................................434 10.2.2 Decisions Where Preparing Now Costs Little .......................................................................435 10.2.3 Options That Reallocate or Clarify Risks from Sea-Level Rise ............................................437 10.3 PROTECTING COASTAL WETLANDS ..................................................................................441 10.4 SHORE PROTECTION ...............................................................................................................447 10.5 LONG-LIVED STRUCTURES: SHOULD WE PLAN NOW OR LATER? ...........................448 10.6 DECISIONS BY COASTAL PROPERTY OWNERS ON ELEVATING HOMES ................452 10.7 FLOODPLAIN MANAGEMENT ...............................................................................................453 10.7.1 Floodplain Regulations ..........................................................................................................454 10.7.2 Floodplain Mapping ...............................................................................................................454 10.7.3 Federal Flood Insurance Rates .............................................................................................455 10.7.4 Post-Disaster Hazard Mitigation ...........................................................................................466 10.8 CONCLUSIONS ...........................................................................................................................466 CHAPTER 10 REFERENCES ............................................................................................................470 CHAPTER 11. ONGOIN G ADAPTATION ...........................................................................................480 KEY FINDINGS

.............................................................................................................................. .....480 11.1 INTRODUCTION .........................................................................................................................480 11.2 ADAPTATION FOR ENVIRONMENTAL PURPOSES ..........................................................481 11.2.1 Environmental Regulators .....................................................................................................481 11.2.2 Environmental Land Managers .............................................................................................482 11.3 OTHER ADAPTATION OPTIONS BEING CONSIDERED BY FEDERAL, STATE, AND LOCAL GOVERNMENTS ..................................................................................................................485 11.3.1 Federal Government ..............................................................................................................485 11.3.2 State Government ...................................................................................................................487 11.3.3 Local Government ..................................................................................................................488 CHAPTER 11 REFERENCES ............................................................................................................491 CHAPTER 12. INSTITUT IONAL BARRI ERS .....................................................................................495 KEY FINDINGS

.............................................................................................................................. .....495 12.1 INTRODUCTION .........................................................................................................................495 12.2 SOME SPECIFIC INSTITUTIONAL BARRIERS AND BIASES ...........................................499 12.2.1 Shore Protec tion versus Retreat ............................................................................................499 12.2.2 Shoreline Armoring versus Living Shorelines ......................................................................508 12.2.3 Coastal Development .................................................................................................... ..........511CCSP 4.1 January 15, 2009

6 of 784 Final Report 12.3 INTERDEPENDENCE: A BARRIER OR A SUPPORT NETWORK? ...................................515 12.3.1 Three Fundamental Pathways: Armor, Elevate, or Retreat .................................................516 12.3.2 Decisions That Cannot Be Made Until the Pathway Is Chosen ...........................................519 12.3.3 Opportunities for Deciding on the Pathway ..........................................................................525 CHAPTER 12 REFERENCES ............................................................................................................526 PART IV OVERVIEW. NATIONAL IMPLICATIONS AND A SCIENCE STRATEGY FOR THE WAY FORWARD ................................................................................................................... ..................534 CHAPTER 13. IMPLICATIONS OF SE A-LEVEL RISE TO THE NATI ON ...................................536 KEY FINDINGS

.............................................................................................................................. .....536 13.1 INTRODUCTION .........................................................................................................................538 13.2 TYPES OF COASTS ....................................................................................................................540 13.2.1 Cliff and Bluff Shorelines ......................................................................................................540 13.2.2 Sandy Shores, Pocket Beaches, Barrier Beaches, Spits, and Dunes ....................................541 13.2.3 Coastal Marshes, Mangroves, and Mud Flat Shorelines ......................................................542 13.2.4 Tropical Coral Reef Coasts ....................................................................................................543 13.3 P OTENTIAL FOR F UTURE S HORELINE C HANGE ............................................................................544 13.4 CONCLUSIONS ...........................................................................................................................548 CHAPTER 13 REFERENCES ............................................................................................................549CHAPTER 14. A SCIENCE STRATEGY FOR IMPROVING THE UNDERSTANDING OF SEALEVEL RISE AND ITS IMPACT S ON U.S. COASTS .........................................................................556 KEY FINDINGS

.............................................................................................................................. .....556 14.1 INTRODUCTION .........................................................................................................................557 14.2 A SCIENCE STRATEGY TO ADDRESS SEA-LEVEL RISE .................................................558 14.2.1 Learn From the Historic and Recent Geologic Past .............................................................560 14.2.2 Monitor Modern Coastal Conditions .....................................................................................563 14.2.3 Predict Future Coastal Conditions ........................................................................................570 14.2.4 Improve Understanding of Societal Impacts .........................................................................572 14.2.5 Develop Coastal Decision Support Systems for Planni ng and Policy Making ....................573 CHAPTER 14 REFERENCES ............................................................................................................577 APPENDIX 1. STATE AND LOCAL INFORM ATION ON VULNERABLE SPECIES AND COASTAL POLICIES IN THE MID-ATLANTIC ...............................................................................584 OVERVIEW ...................................................................................................................... .....................584 A1.A. L ONG I SLAND

.............................................................................................................................. .586 A1.A.1 Environmental Implications .................................................................................................587 A1.A.2 Development, Shore Prot ection, and Coastal Policies .........................................................592 A1.B. N EW Y ORK M ETROPOLITAN A REA ............................................................................................598 A1.C. N EW J ERSEY S HORE ......................................................................................................................605 A1.C.1 Environmental Implications .................................................................................................606 A1.C.2 Development, Shore Prot ection, and Coastal Policies .........................................................614 A1.D. D ELAWARE E STUARY ..................................................................................................................619 A1.D.1 Environmenal Implications ..................................................................................................619 A1.D.2 Development, Shore Protection, and Coastal Policies .........................................................624 A1.E. T HE A TLANTIC C OAST OF V IRGINIA , M ARYLAND , AND D ELAWARE ( INCLUDING COASTAL BAYS )

.............................................................................................................................. ........................634 A1.E.1 Environmental Implications .................................................................................................635 A1.E.2 Development, Shore Prot ection, and Coastal Policies .........................................................640 A1.F C HESAPEAKE B AY .........................................................................................................................645 A1.F.1 Inundation, Develop ment and Shore Protection, and Vulnerable Habitat .........................646 A1.F.2 Baywide Policy Context ........................................................................................................674 A1.G N ORTH C AROINA ...........................................................................................................................686 A1.G.1 Introduction ..........................................................................................................................686 A1.G.2 Shore Processes ....................................................................................................................691CCSP 4.1 January 15, 2009

7 of 784 Final Report A1.G.3 Vulnerable Habitats and Species .........................................................................................694 A1.G.4 Development, Shore Protection, and Coastal Policies .........................................................700 APPENDIX 1 REFERENCES .............................................................................................................710 APPENDIX 2. BASIC APPROACHES FOR SHORELINE CHANGE PROJECTIONS .................749 APPENDIX 2 REFERENCES .............................................................................................................759 GLOSSARY ...................................................................................................................... .........................766 SCIENTIFIC NAMES—CH APTER 5 SP ECIES ..................................................................................781 ACRONYMS AND ABBREVIATIONS ..................................................................................................78 3CCSP 4.1 January 15, 2009

8 of 784 Final Report ACKNOWLEDGEMENTS Throughout the process of preparing SAP 4.1, the authors were advised by a Federal Advisory Committee chosen for their diverse perspectives and technical expertise. The Coastal Elevations and Sea-Level Rise A dvisory Committee (CESLAC) consisted of: Margaret Davidson (Chairperson), NOAA ; Re becca Beavers, National Park Service; Alan Belensz, New York State Office of th e Attorney General; Mark Crowell, Federal Emergency Management Agency; Andrew Garcia , U.S. Army Corps of Engineers; Carl Hershner, Virginia Institute of Marine Science; Julie Hunkins, North Carolina Department of Transportation; Mark Mauriello, New Jersey Department of Environmental Protection; Mark Monmoni er, Syracuse University; William S. Nechamen, Association of St ate Floodplain Managers; Sam Pearsall, Environmental Defense Fund; Anthony Pratt, Coastal States Organization; Greg Rudolph, American Shore and Beach Preservation Association; Harvey Ryland, Institute for Business and Home Safety; Gwynne Schultz, Maryland De partment of Natural Resources. Jack Fitzgerald of EPA was the Designated Federa l Official for the CESLAC, with support provided by Stratus Consulting. Technical expert review was provided by: Fred Anders, New York Department of State; Mark Davis, Tulane University; Lesley Ewing, California Coastal Commission; Janet Freedman, Rhode Island Coastal Resources Council; Vivien Gornitz, NASA; Ellen Hartig, New York City Department of Pa rks & Recreation; Maria Honeycutt, AGI Congressional Fellow; Kurt Kalb, New Jersey Department of Environmental Protection; Stephen Leatherman, Florida International Un iversity; Ken Miller, Maryland Department of Natural Resources; Jim O’Connell, Univer sity of Hawaii, Sea Grant; Richard Osman, Smithsonian Institution; Marc Perry, U.S. Census Bureau; Chris Spaur, U.S. Army Corps of Engineers; John Teal, Teal Partners; John Thayer, North Carolina Department of Environment and Natural Resources; Dan Tres cott, Southwest Flor ida Regional Planning Council; John Whitehead, Appalachian Stat e University; Rob Young, Western Carolina University. An expert review of an early draft of Chapter 2 was also provided by an interagency geospatial team consisting of Eric Constance, USGS; Todd Davison, NOAA; Dean Gesch, USGS; and Jerry Johnston, EPA. This report relied heavily on stakeholder i nvolvement that was implemented through a series of three meetings held in the Mi d-Atlantic Region (Easton, Maryland; Red Bank, New Jersey; and Plymouth, North Carolina). Many of the comments received and discussion initiated at these meetings helped to define some of the issues addressed in this report. Linda Hamalak of NOAA organized th ese public meetings and the subsequent author meetings. The author meetings were hosted by the Blackwater National Wildlife Refuge in Maryland; the NOAA National Mari ne Fisheries Service in Sandy Hook, New Jersey; and the Partnership for the Sounds in Columbia, North Carolina The authors were also assisted by several of their colleagues at EPA, NOAA, and USGS. The interagency management team of Rona Birnbaum, EPA; Patricia Jellison, USGS; and Michael Szabados, NOAA, were instrumental in advising the authors during the final stages of the report. Rebecca Feldman of NOAA provided key l ogistical support inCCSP 4.1 January 15, 2009

9 of 784 Final Report addition to her contributions as an author. Karen Scott of EPA managed the expert review process, supported by Perrin Quarles Associates. The USGS authors thank several colleague s for their reviews, discussions, and contributions to Chapters 1, 3, 4, 13, and 14, as well as other portions of the report. These include: Mark Brinson, East Carolina University; Tom Cronin, USGS; Duncan FitzGerald, Boston University; Virginia Burk ett, USGS; Curt Larsen, USGS, (retired); Laura Moore, University of Virginia; Elizabeth Pendleton, USGS; Shea Penland (deceased), University of New Orleans; and Asbury Sallenger, USGS. Russ Jones of Stratus Consulting coordina ted technical and GI S support for several chapters in this report, with support fr om Jue Wang, Pyramid Systems Inc.; Richard Streeter and Tom Hodgson, St ratus Consulting; and John Herter and Gaurav Sinha, Industrial Economics. Christina Thomas (contra ctor to Stratus Consulting) edited the expert review draft. Chapter 3 includes results of a panel assessm ent. The authors of Chapter 3 thank the panelists for their contributions: Fred Anders, New York State, Dept. of State; K. Eric Anderson, USGS; Mark Byrnes, Applied Coasta l Research and Engineering; Donald R. Cahoon, USGS; Stewart Farrell, Ri chard Stockton College; Du ncan FitzGerald, Boston University, Massachusetts; Paul Gayes, Coastal Carolina Univ ersity; Carl Hobbs, Virginia Institute of Marine Science; Ra ndy McBride, George Mason University; Jesse McNinch, Virginia Institute of Marine Scie nce; Stan Riggs, East Carolina University; Antonio Rodriguez, University North Carolin a; Jay Tanski, New Yo rk Sea Grant; Art Trembanis, University of Delaware. Chapter 4 includes results based on a panel as sessment. The panel consisted of: Denise Reed, University of New Orleans; Dana Bishara, USGS; Jeffrey Donnelly, Woods Hole Oceanographic Institution; Mich ael Kearney, University of Maryland; Alexander Kolker, Louisiana Universities Marine Consortium; Lynn Leonard, University of North CarolinaWilmington; Richard Orson, Orson Environm ental Consulting, J. Court Stevenson, University of Maryland. The panel was conducte d under contract to EPA, with James G. Titus as the project officer. Je ff DeBlieux of The Nature Cons ervancy also contributed to portions of Chapter 4. The review process for SAP 4.1 included a public review of the Second draft. We thank the individuals who commented on this draft. The author team caref ully considered all comments submitted, and many resulted in improvements to this Product. We also thank the team of editors that wo rked closely with authors to produce this product. This includes Anne Waple, CCSP/ STG Inc., and the gra phics team at the National Climatic Data Center. Finally, we are especially grat eful to Alan Cohn of EPA fo r his management of the dayto-day process of developing and pro ducing this report, and providing overall coordination for this effort.CCSP 4.1 January 15, 2009

10 of 784 Final Report 

## Preface

The U.S. Climate Change Science Program (CCSP) was launched in February 2002 as a collaborative federal interagency program , under a new cabinet-level organization designed to improve the government-wide ma nagement and dissemination of climate change science and related technology development. The mission of the CCSP is to “facilitate the cr eation and application of knowledge of the Earth’s global environment through research, observations, decision suppor t, and communication”. This Product is one of 21 synthesis and assessment pr oducts (SAPs) identified in the 2003 Strategic Plan for the U.S. Climate Change Science Program , written to help ach ieve this mission. The SAPs are intended to support informed di scussion and decisions by policymakers, resource managers, stakeholde rs, the media, and the general public. The products help meet the requirements of the Global Ch ange Research Act of 1990, which directs agencies to “produce information readily usab le by policymakers attempting to formulate effective strategies for preventing, mitiga ting, and adapting to the effects of global change” and to undertake period ic scientific assessments.

One of the major goals within the mission is to understand the sensitivity and adaptability of different natural and managed ecosystems and human systems to climate and related global changes. This SAP (4.1), Coastal Sensitivity to Sea- Level Rise: A Focus on the Mid-Atlantic Region , addresses this goal by providing a detailed assessment of the effects of sea-level rise on coastal e nvironments and presenting some of the challenges that need to be addressed in order to adapt to sea-level rise while protecting environmental resources and sustaining economic growth. It is intended to provide the most currentCCSP 4.1 January 15, 2009

11 of 784 Final Report knowledge regarding the implications of risi ng sea level and possibl e adaptive responses, particularly in the mid-Atlantic region of the United States.

P.1 SCOPE AND APPROACH OF THIS PRODUCT The focus of this Product is to identify and review the potential impacts of future sealevel rise based on present scientific unde rstanding. To do so, this Product evaluates several aspects of sea-level rise impacts to the natural environment and examines the impact to human land development along the coas t. In addition, the Product addresses the connection between sea-level rise impacts and current adaptation strategies, and assesses the role of the existing coastal management policies in identifying and responding to potential challenges.

As with other SAPs, the first step in the pr ocess of preparing this Product was to publish a draft prospectus listing the que stions that the product would s eek to answer at the local and mid-Atlantic scale. After public comment , the final prospectus listed ten questions. This Product addresses those ten questions, a nd answers most of th em with specificity. Nevertheless, development of this Product has also highlighted current data and analytical capacity limitations . The analytical presentati on in this Product focuses on what characterizations can be provided with sufficient accuracy to be meaningful. For a few questions, the published literature was insu fficient to answer the question with great specificity. Nevertheless, the effort to answer the question has identified what information is needed or desirable, and curre nt limitations with regard to available data and tools.CCSP 4.1 January 15, 2009

12 of 784 Final Report This Product focuses on the U.S. mid-Atlantic coast, which includes the eight states from New York to North Carolina. The Mid-Atlan tic is a region where high population density and extensive coastal development is likely to be at increased risk due to sea-level rise. Other coastal regions in the United States, su ch as the Gulf of Me xico and the Florida coast, are potentially more vulnerable to sea- level rise and have been the focus of other research and assessments, but are ou tside the scope of this Product.

During the preparation of this Product, three regional meetings were held between the author team and representative s from relevant local, county, state, and federal agencies, as well non-governmental organizations. Many of the questions posed in the prospectus for SAP 4.1 were discussed in detail and the feedback has been incorporated into the Product. However, the available data are insuffici ent to answer all of the questions at both the local and regional scale. Therefore, the re sults of this Product are best used as a “starting point” for audiences seeking informa tion about sensitivity to and implications of sea-level rise.

Many of the findings included in this Produc t are expressed using common terms of likelihood ( e.g. , very likely, unlikely), sim ilar to those used in the 2007 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report, Climate Change 2007: The Physical Science Basis . The likelihood determinations used in this Product were established by the authors and modeled after other CCSP SAPs such as CCSP SAP 1.1, Temperature Trends in the Lower Atmosphere: Steps for UnderstandingCCSP 4.1 January 15, 2009

13 of 784 Final Report and Reconciling Differences. However, characterizations of likelihood in this Product arelargely based on the judgment of the authors and uncertainties from published peerreviewed literature (Figure P.1). Data on how coastal ecosystems and specific species may respond to climate change is limited to a small number of site-specific studies, often carried out for purposes unrelated to efforts to evaluate the potential impact of sea-level rise. Nevertheless, being able to characterize current understanding

― and the uncertainty associated with that information

― is important. In the main body of this Product, any use of the terms in Figure P.1 refl ect qualitative assessment of potential changes based on the authors’ review and understanding of availabl e published coastal scie nce literature and of governmental policies (the appendices do not contain findings). Statements that do not use these likelihood terms either have an insufficient basis for assessing likelihood or present information provided in the referen ced literature which was not accompanied by assessments of likelihood.

Figure P.1 Likelihood terms and related probabilities used for this Product (with the exception of Appendix 1).
The International System of Un its (SI) have been used in this Product; with English units often provided in parentheses. Where convers ions are not provided, some readers may wish to convert from SI to Englis h units using the following table:CCSP 4.1 January 15, 2009

14 of 784 Final Report Table P.1 Conversion from the Internationa l System of Units (SI) to English units Multiply By To obtain Length centimeter (cm) 0.3937 inch (in) millimeter (mm) 0.0394 inch (in) meter (m) 3.2808 foot (ft) kilometer (km) 0.6214 mile (mi) meter (m) 1.0936 yard (yd) Area square meter (sq m) 0.000247 acres hectare (ha) 2.47 acres square kilometer (sq km) 247 acres square meter (sq m) 10.7639 square foot (sq ft) hectare (ha) 0.00386 square mile (sq mi) square kilometer (sq km) 0.3861 square mile (sq mi) Rate of Change meters per year (m per year) 3.28084 foot per year (ft per year) millimeters per year (mm per year) 0. 03937 inch per year (in per year) meters per second (m per sec) 1.943 knots

P.2 FUTURE SEA-LEVEL SCENARIOS ADDRESSED IN THIS PRODUCT In this Product, the term “sea level” refers to mean sea level or the average level of tidal waters, generally measured over a 20-year period. These measurements generally indicate the water level relative to the land, and thus incorporate chan ges in the elevation of the land ( i.e ., subsidence or uplift) as well as absolute changes in sea level ( i.e. , rise in sea level caused by increasing its volume or addi ng water). For clarity, scientists often use two different terms:

 “Global sea-level rise” is th e average increase in the level of the world’s oceans that occurs due to a variety of fact ors, the most significant being thermalCCSP 4.1 January 15, 2009

15 of 784 Final Report expansion of the oceans and the additi on of water by melting of land-based ice sheets, ice caps, and glaciers.

 “Relative sea-level rise” refe rs to the change in sea level relative to the elevation of the adjacent land, which can also subs ide or rise due to natural and humaninduced factors. Relative sea-level change s include both global sea-level rise and changes in the vertical elevation of the land surface.

In this Product, both terms are used. Global se a-level rise is used when referring to the worldwide average increase in sea level. Rela tive sea-level rise, or simply sea-level rise, is used when referring to the scenarios us ed in this Product and effects on the coast.

This Product does not provide a forecast of fu ture rates of sea-level rise. Rather, it evaluates the implications of three relative sea-level rise scenarios over the next century developed from a combination of the twentieth century relative sea- level rise rate and either a 2 or 7 millimeter per year increase in global sea level:

 Scenario 1: the twentieth century rate, which is generally 3 to 4 millimeters per year in the mid-Atlantic region (30 to 40 centimeters total by the year 2100);

 Scenario 2: the twentieth century rate pl us 2 millimeters per year acceleration (up to 50 centimeters total by 2100);

 Scenario 3: the twentieth century rate pl us 7 millimeters per year acceleration (up to 100 centimeters total by 2100).CCSP 4.1 January 15, 2009

16 of 784 Final Report The twentieth century rate of sea-level rise re fers to the local long-term rate of relative sea-level rise that has been observed at NOAA National Ocean Service (NOS) tide gauges in the mid-Atlantic st udy region. Scenario 1 assesses the impacts if future sealevel rise occurs at the same rate as was observed over the tw entieth century at a particular location. Scenarios 1 and 2 are within the range of those report ed in the recent IPCC Report Climate Change 2007: The Ph ysical Science Basis, specifically in the chapter Observations: Oceanic Climate Change and Sea Level , while Scenario 3 exceeds the IPCC scenario range by up to 40 centimet ers by 2100. Higher estimates, as suggested by some recent publications, are the basis fo r Scenario 3. In addition to these three scenarios, some chapters refer to even hi gher sea-level rise scenarios, such as a 200 centimeter rise over the next few hundred years (a high but plausible estimate if ice sheet melting on Greenland and West Antarcti ca exceeds IPCC model estimates).

P.3 PRODUCT ORGANIZATION This Product is divided into four parts:

Part I first provides context and addresses th e effects of sea-level rise on the physical environment. Chapter 1 provides the context fo r sea-level rise and its effects. Chapter 2 discusses the current knowledge and limitations in coastal elevation mapping. Chapter 3 describes the physical changes at the coast that will result in changes to coastal landforms ( e.g. , barrier islands) and shoreline position in response to sea-level rise. Chapter 4 considers the ability of wetla nds to accumulate sediments and survive in response toCCSP 4.1 January 15, 2009

17 of 784 Final Report rising sea level. Chapter 5 exam ines the habitats and species that will be vulnerable to sea-level rise related impacts.

Part II describes the societal impacts and implications of sea-level rise. Chapter 6 provides a framework for assessing shoreline pr otection options in response to sea-level rise. Chapter 7 discusses the extent of vulnerable population and infrastructure, and Chapter 8 addresses the implications for public access to the shore. Chapter 9 reviews the impact of sea-level rise to flood hazards.

Part III examines strategies for coping with sea-level rise. Chapter 10 outlines key considerations when making decisions to reduc e vulnerability. Chapte r 11 discusses what organizations are currently doing to ad apt to sea-level rise, and Chapter 12 examines possible institutional barriers to adaptation.

Part IV examines national implications and a science strategy for moving forward. Chapter 13 discusses sea-level rise impacts and implications at a national scale and highlights how coasts in other parts of the Un ited States are vulnerable to sea-level rise. Chapter 14 presents opportunities for future e fforts to reduce uncerta inty and close gaps in scientific knowledge and understanding.

Finally, this Product also includes two appe ndices: Appendix 1 di scusses many of the species that depend on potentially vulnerable habitat in specific estuaries, providing local elaboration of the general issues examined in Chapter 5. The Appendi x also describe keyCCSP 4.1 January 15, 2009

18 of 784 Final Report statutes, regulations, and ot her policies that currently define how state and local governments are responding to sea-level ri se, providing support for some of the observations made in Part III. This Appe ndix is provided as background information and does not include findings or an inde pendent assessment of likelihood.

Appendix 2 reviews some of the basic appr oaches that have been used to conduct shoreline change or land loss assessments in th e context of sea-level rise and some of the difficulties that arise in using these methods.

Technical and scientific terms are used throughout this Pr oduct. To aid readers with these terms, a Glossary and a list of Acronyms a nd Abbreviations are incl uded at the end of the Product.CCSP 4.1 January 15, 2009

19 of 784 Final Report 

## Executive Summary

Authors: K. Eric Anderson, USGS; Donald R. Cahoon, USGS; Stephen K. Gill, NOAA; Benjamin T. Gutierrez, USGS; E. Robert Thieler, USGS; James G. Titus, U.S. EPA; S. Jeffress Williams, USGS (lead authors arranged in al phabetical order).

Global sea level is rising, and there is evid ence that the rate is accelerating. Increasing atmospheric concentrations of greenhouse gase s, primarily from human contributions, are very likely warming the atmosphere and ocean s. The warmer temperatures raise sea level by expanding ocean water, melting glaciers, a nd possibly increasing the rate at which ice sheets discharge ice and water into the ocean s. Rising sea level and the potential for stronger storms pose an increasing threat to coastal cities, residential communities, infrastructure, beaches, wetlands, and ecosystems. The potential impacts to the United States extend across the entire country: por ts provide gateways for transport of goods domestically and abroad; coas tal resorts and beac hes are central to the U.S. economy; wetlands provide valuable ecosystem services such as water filtering and spawning grounds for commercially important fisheries. How people respond to s ea-level rise in the coastal zone will have potentially la rge economic and environmental costs.

This Synthesis and Assessment Product examines the implications of rising sea level, with a focus on the mid-Atlantic region of the United States, where rate s of sea-level rise are moderately high, storm impacts occur, and th ere is a large extent of critical habitatCCSP 4.1 January 15, 2009

20 of 784 Final Report (marshes), high population densities, and in frastructure in low- lying areas. Although these issues apply to coastal regions acro ss the country, the mid- Atlantic region was selected as a focus area to explore how addr essing both sensitive ecosystems and impacts to humans will be a challenge. Using current scientific literature and expert panel assessments, this Product examines potential ri sks, possible responses, and decisions that may be sensitive to sea-level rise.

The information, data, and tools needed to inform decision-making with regard to sealevel rise are evolving, but insuffi cient to assess the implications at scales of interest to all stakeholders. Accordingly, this Product can only provide a starti ng point to discuss impacts and examine possible responses at the regional scale. The Product briefly summarizes national scale implications a nd outlines the steps involved in providing information at multiple scales ( e.g ., local).

ES.1 WHY IS SEA LEVEL RISING ? HOW MUCH WILL IT RISE? During periods of climate warming, two majo r processes cause gl obal mean sea-level rise: (1) as the ocean warms, the water e xpands and increases its volume and (2) land reservoirs of ice and water, including glaci ers and ice sheets, contribute water to the oceans. In addition, the land in many coas tal regions is subsiding, adding to the vulnerability to the effects of sea-level rise.

Recent U.S. and international assess ments of climate change show that global average sea level rose approximately 1.7 millimeters per year through the twentie th century, after aCCSP 4.1 January 15, 2009

21 of 784 Final Report period of little change during the previous two thousand years. Observations suggest that the rate of global sea-level rise may be accelerating. In 2007, the Intergovernmental Panel on Climate Change (IPCC) projected that global sea level will likely rise between 19 and 59 centimeters (7 and 23 inches) by the end of the century (2090 to 2099), relative to the base period (1980 to 1999), excluding any rapi d changes in ice flow from Greenland and Antarctica. According to the IPCC, the averag e rate of global sea- level rise during the twenty-first century is very likely to exceed the average rate over the last four decades. Recently observed accelerated ice flow a nd melting in some Greenland outlet glaciers and West Antarctic ice streams could substant ially increase the contribution from the ice sheets to rates of global sea-level rise. U nderstanding of the magnitude and timing of these processes is limited and, thus, there is currently no consensus on the upper bound of global sea-level rise. Recent st udies suggest the potential fo r a meter or more of global sea-level rise by the year 2100, and possibly several meters within the next several centuries.

In the mid-Atlantic region from New York to North Carolina, tid e-gauge observations indicate that relative sea-level rise (the combination of global sea-level rise and land subsidence) rates were higher than the global mean and ge nerally ranged between 2.4 and 4.4 millimeters per year, or about 0.3 meters (1 foot) over the twentieth century.

ES.2 WHAT ARE THE EFFECTS OF SEA-LEVEL RISE? Coastal environments such as beaches, barrier islands, wetlands, and estuarine systems are closely linked to sea level. Many of thes e environments adjust to increasing waterCCSP 4.1 January 15, 2009

22 of 784 Final Report level by growing vertically, migrating inland, or expanding laterally. If the rate of sealevel rise accelerates signif icantly, coastal environments and human populations will be affected. In some cases, the effects will be limited in scope and similar to those observed during the last century. In other cases, thresholds may be crossed, beyond which the impacts would be much greater. If the sea rise s more rapidly than the rate with which a particular coastal syst em can keep pace, it could fundame ntally change the state of the coast. For example, rapid sea-level rise can cause rapid landward migration or segmentation of some barrier island s, or disintegration of wetlands.

Today, rising sea levels are submerging low-lying lands, eroding beaches, converting wetlands to open water, exacerbating coasta l flooding, and increasing the salinity of estuaries and freshwater aquifers. Other imp acts of climate change, coastal development, and natural coastal processes al so contribute to these impacts. In undeveloped or lessdeveloped coastal areas where human influe nce is minimal, ecosystems and geological systems can sometimes shift upward and landw ard with the rising water levels. Coastal development, including buildings, roads, and other infrastructure, are less mobile and more vulnerable. Vulnerability to an accelera ting rate of sea-leve l rise is compounded by the high population density along the coast, th e possibility of other effects of climate change, and the susceptibility of coastal regions to storms and environmental stressors, such as drought or invasive species.

ES.2.1 Sea-Level Rise and th e Physical EnvironmentCCSP 4.1 January 15, 2009

23 of 784 Final Report The coastal zone is dynamic and the response of coastal areas to sea- level rise is more complex than simple inundation. Erosion is a natural process from waves and currents and can cause land to be lost even with a st able sea level. Sea-le vel rise can exacerbate coastal change due to erosion and accreti on. While some wetlands can keep pace with sea-level rise due to sediment inputs, those that cannot keep pace will gradually degrade and become submerged. Shore protection and en gineering efforts also affect how coasts are able to respond to sea-level rise.

For coastal areas that are vulnerable to inundati on by sea-level rise, elevation is generally the most critical factor in assessing pote ntial impacts. The exte nt of inundation is controlled largely by the slope of the land, with a greater ar ea of inundation occurring in locations with more gentle grad ients. Most of the currently available el evation data do not provide the degree of confiden ce that is needed for making quantitative assessments of the effects of sea-level rise for local planning and decision making. However, systematic collection of high-qualit y elevation data ( i.e ., lidar) will improve the ability to conduct detailed assessments (Chapter 2).

Nationally, coastal erosion will probably increas e as sea-level rises at rates higher than those that have been observed over the past century. The exact manner and rates at which these changes are likely to occur will depe nd on the character of coastal landforms ( e.g ., barrier islands, cliffs) and physical proce sses (Part I). Particularly in sandy shore environments which comprise the entire mi d-Atlantic ocean coast (Figure ES.1), it is virtually certain that coastal headlands, spits, and barrier islands will erode at a fasterCCSP 4.1 January 15, 2009

24 of 784 Final Report pace in response to future sea-level rise. Fo r sea-level rise scenarios greater than 7 millimeters per year, it is likely that some barrier islands in this region will cross a threshold where rapid barrier island migrati on or segmentation will occur (Chapter 3).

Figure ES.1 Potential mid-Atlantic coastal landform res ponses to three sea-level rise scenarios. Most coastal areas are currently experiencing erosion, which is expected to incr ease with future sea-level rise. In addition to undergoing erosion, coastal segments de noted with a “T” may also cross a threshold where rapid barrier island migration or segmentation will occur.

Tidal wetlands in the United States, such as the Mississippi River De lta in Louisiana and Blackwater River marshes in Maryland, ar e already experiencing submergence by relative sea-level rise and associ ated high rates of wetland loss.CCSP 4.1 January 15, 2009

25 of 784 Final Report For the mid-Atlantic region (Figure ES.2), acce leration in sea-level rise by 2 millimeters per year will cause many wetlands to become stressed; it is likely that most wetlands will not survive acceleration in sea- level rise by 7 millimeters per year. Wetlands may expand inland where low-lying land is available but, if existing wetlands cannot keep pace with sea-level rise, the result will be an overall loss of wetland area in the Mid-Atlantic. The loss of associated wetland ecosystem functions ( e.g. , providing flood control, acting as a storm surge buffer, protecting water quality buffer, and serving as a nursery area) can have important societal cons equences, such as was seen with the storm surge impacts associated with Hurricanes Katrina and R ita in southern Louisiana, including New Orleans, in 2005. Nationally, tidal wetlands already experiencing submergence by sealevel rise and associated land loss ( e.g ., Mississippi River delta in Louisiana, and Blackwater River marshes in Maryland) will cont inue to lose area in response to future accelerated rates of sea-level rise and changes in other climate and environmental drivers.CCSP 4.1 January 15, 2009

26 of 784 Final Report Figure ES.2 Areas where wetlands would be marginal or lost ( i.e ., converted to open water) under three sea-level rise scenarios.
Terrestrial and aquatic plants and animals th at rely on coastal habitat are likely to be stressed and adversely affected as sea le vel rises. The qualit y, quantity, and spatial distribution of coastal habitats will change as a result of erosion, salinity changes, and wetland loss. Depending on local conditions, habitat may be lo st or migrate inland in response to sea-level rise. Loss of tidal marshes would seriously threaten coastal ecosystems, causing fish and birds to move or produce fewer offspring. Many estuarine beaches may also be lost, threaten ing numerous species (Chapter 5).CCSP 4.1 January 15, 2009

27 of 784 Final Report Sea-level rise is just one of many factors affecting coas tal habitats: sediment input, nutrient runoff, fisheries management, and othe r factors are also im portant. Under natural conditions, habitats are continually shifting, an d species generally have some flexibility to adapt to varied geography and/or habitat type. Future habitat and species loss will be determined by factors that include rates of wetland submergence, coastal erosion, and whether coastal landforms and present-day ha bitats have space to migrate inland. As coastal development continues, the ability fo r habitats to change and migrate inland along the rest of the coast will not onl y be a function of the attribut es of the natural system, but also of the coastal management policie s for developed and undeveloped areas.

ES.2.2 Societal Impacts and Implications Increasing population, development, and suppor ting infrastructure in the coastal zone often compete with the desire to maintain the benefits that natural ecosystems ( e.g ., beaches, barrier islands, and wetlands) provide to humans. Increasing sea level will put additional stress on the ability to manage thes e competing interests effectively (Chapter 7). In the Mid-Atlantic, for ex ample, movement to the coast and development continues, despite the growing vulnerability to coastal hazards.

Rising sea level increases the vulnerability of development on coastal floodplains. Higher sea level provides an elevated base for stor m surges to build upon and diminishes the rate at which low-lying areas drai n, thereby increasing the risk of flooding from rainstorms. Increases in shore erosion also contri bute to greater flood damages by removingCCSP 4.1 January 15, 2009

28 of 784 Final Report protective dunes, beaches, and wetlands and by leaving some properties closer to the water's edge (Chapter 9).

ES.3 HOW CAN PEOPLE PREPARE FOR SEA-LEVEL RISE?
ES.3.1 Options for Adapting to Sea-level Rise At the current rate of sea-level rise, co astal residents and businesses have been responding by rebuilding at the same location, relocating, hold ing back the sea by coastal engineering, or some combination of these a pproaches. With a substantial acceleration of sea-level rise, traditional coastal e ngineering may not be economically or environmentally sustainable in some areas (Chapter 6).

Nationally, most current coastal policies do no t accommodate accelerations in sea-level rise. Floodplain maps, which are used to gui de development and building practices in hazardous areas, are generally based upon recen t observations of topographic elevation and local mean sea-level. However, these ma ps often do not take into account accelerated sea-level rise or possible changes in storm intensity (Chapter 9). As a result, most shore protection structures are designe d for current sea level, and de velopment policies that rely on setting development back from the coast are designed for current rates of coastal erosion, not taking into a ccount sea level rise.

ES.3.2 Adapting to Sea-level Rise The prospect of accelerated sea-level rise underscores the need to rigorously assess vulnerability and examine the costs and bene fits of taking adaptive actions. DeterminingCCSP 4.1 January 15, 2009

29 of 784 Final Report whether, what, and when specific actions are ju stified is not simple, due to uncertainty in the timing and magnitude of impacts, and di fficulties in quantifying projected costs and benefits. Key opportunities for preparing fo r sea-level rise include: provisions for preserving public access along th e shore (Chapter 8); land-us e planning to ensure that wetlands, beaches, and associated coastal ecosyst em services are preserved (Chapter 10); siting and design decisions such as retrofitting ( e.g. , elevating buildings and homes) (Chapter 10); and examining whether and how changing risk due to sea-level rise is reflected in flood insurance rates (Chapter 10).

However, the time, and often cultural shift, requi red to make change in federal, state, and local policies is sometimes a barrier to change. In the mid-Atlantic coastal zone, for example, although the management community recognizes sea-level rise as a coastal flooding hazard and state governments are starting to face the issue of sea-level rise, only a limited number of analyses and resulting stat ewide policy revisions to address rising sea level have been undertaken (Chapters 9, 11). Current policies in some areas are now being adapted to include the effects of se a-level rise on coastal environments and infrastructure. Responding to sea-level rise requires careful consideration regarding whether and how particular areas will be protected with structures, elevated above the tides, relocated landward, or left alone and potentially given up to the rising sea (Chapter 12).

Many coastal management decisions made toda y have implications for sea-level rise adaptation. Existing state policies that restri ct development along the shore to mitigateCCSP 4.1 January 15, 2009

30 of 784 Final Report hazards or protect water quality (Appendix 1) could preserve open space that may also help coastal ecosystems adapt to rising sea le vel. On the other hand, efforts to fortify coastal development can make it less likely that such an area would be abandoned as sea level rises (Chapter 6). A prim e opportunity for adapting to sea-level rise in developed areas may be in the aftermath of a severe storm (Chapter 9).

ES.4 HOW CAN SCIENCE IMPROVE UNDERSTANDING AND PREPAREDNESS FOR FUTURE SEA-LEVEL RISE? This Product broadly synthesizes physical, bi ological, social, and institutional topics involved in assessing the potenti al vulnerability of the mid-A tlantic United States to sealevel rise. This includes the potential for lands cape changes and associated geological and biological processes; and the ability of society and its institutions to adapt to change. Current limitations in the ability to quantitati vely assess these topics at local, regional, and national scales may affect whether, wh en, and how some decisions will be made.

Scientific syntheses and assessments such as this have different types and levels of uncertainty. Part I of this Product describes the physical settings and processes in the Mid-Atlantic and how they may be impacted by sea-level rise. There is uncertainty regarding coastal elevations and the extent to which some areas will be inundated. In some areas, coastal elevations have been mappe d with great detail and accuracy, and thus the data have the requisite high degree of certainty for local decision making by coastal managers. In many other areas, the coarser reso lution and limited vertic al accuracy of the available elevation data preclude their use in detailed assessments, but the uncertainty canCCSP 4.1 January 15, 2009

31 of 784 Final Report be explicitly quantified (Cha pter 2). The range of physic al and biological processes associated with coastal change is poorly understood at some of the time and space scales required for decision making. For example, a lthough the scope and general nature of the changes that can occur on ocean coasts in response to sea-level rise are widely recognized, how these changes occur in response to a specific rise in sea level is difficult to predict (Chapter 3). Sim ilarly, current model projections of wetland vulnerability on regional and national scales are uncertain due to the coarse level of resolution of landscape-scale models. While site-specific model projections are quite good where local information has been acquired on factors that control local accretionary processes in specific wetland settings, such pr ojections cannot presently be generalized so as to apply to larger regional or national scales with high confidence (Chapter 4). The cumulative impacts of physical and biological change due to sea-level rise on the quality and quantity of coastal habitats are not well understood.

Like the uncertainties associated with the physical settings, the potential human responses to future sea-level rise desc ribed in Part II of this Pr oduct are also uncertain. Society generally responds to changes as they emerge . The decisions that people make to respond to sea-level rise could be influenced by the physical sett ing, the properties of the built environment, social values, the constraints of regulations and economics, as well as the level of uncertainty in the form and magnitude of futu re coastal change. This Product examines some of the available options a nd assesses actions that federal and state governments and coastal communities could ta ke in response to sea-level rise. For example, as rising sea level impacts coastal lands, a funda mental choice is whether toCCSP 4.1 January 15, 2009

32 of 784 Final Report attempt to hold back the sea or allow natu re to takes its course. Both choices have important costs and uncertainties (Chapter 6).

Part III of this Product focuses on what might be done to prepare for sea-level rise. As discussed above, the rate, timing, and impacts of future sea-level rise are uncertain, with important implications for decision-making. For example, planning for sea-level rise requires examining the benefits and costs of such issues as coastal wetland protection, existing and planned coastal infrastructure, a nd management of floodplains in the context of temporal and spatial uncertainty (Chapter 10). In addition, inst itutional barriers can make it difficult to incorporate the potential im pacts of future sea-level rise into coastal planning (Chapter 12).

ES.4.1 Enhance Understanding An integrated scientific program of sea- level studies would reduce gaps in current knowledge and the uncertainty about the pot ential responses of coasts, estuaries, wetlands, and human populations to sea-le vel rise. This program should focus on expanded efforts to monitor ongoing physical and environmental changes, using new technologies and higher resolution elevation data as available. Insights from the historic and geologic past also provide important perspectives. A ke y area of uncertainty is the vulnerability of coasta l landforms and wetlands to sea-leve l rise; therefore, it is important to understand the dynamics of barrier island processes and wetland accretion, wetland migration, and the effects of land-use change as sea-level rise con tinues. Understanding, predicting, and responding to the environmental and societal effects of sea-level riseCCSP 4.1 January 15, 2009

33 of 784 Final Report would require an integrated program of research that in cludes both natural and social sciences. Social science resear ch is a necessary component as sea-level rise vulnerability, sea-level rise impacts, and the success of many adaptation strategies will depend on characterizing the social, economic, and pol itical contexts in which management decisions are made (Chapter 14).

ES.4.2 Enhance Decision Support Decision making on regional and local levels in the coastal zone can be supported by improved understanding of vulnera bilities and risks of sea-level rise impacts. Developing tools, datasets, and other coastal manageme nt information is key to supporting and promoting sound coastal planning, policy making, and decisions. This includes providing easy access to data and information resour ces and applying this information in an integrated framework using such tools as geographic information systems. Integrated assessments linking physical vulnerability w ith economic analyses and planning options will be valuable, as will efforts to assemble and assess coastal zone planning adaptation options for federal, state, and local decisi on makers. Stakeholder participation in every phase of this process is impor tant, so that decision makers and the public have access to the information that they need and can make well-informed choices regarding sea-level rise and the consequences of different management decisions. Coastal planning and policies that are consistent with the realit y of a rising sea could enable U.S. coastal communities to avoid or adapt to its potenti al environmental, societal, and economic impacts.CCSP 4.1 January 15, 2009

34 of 784 Final Report 

## Part I Overview. The Physical Environment

Authors: Donald R. Cahoon, USGS; S. Jeffress Williams, USGS; Benjamin T. Gutierrez, USGS; K. Eric Anderson, USGS; E. Robert Thieler, USGS; Dean B. Gesch;
USGS

The first part of this Product examines th e potential physical and environmental impacts of sea-level rise on the coasta l environments of the mid-A tlantic region. Rising sea level over the next century will have a range of effects on coastal regi ons, including land loss and shoreline retreat from erosion and inundati on, an increase in th e frequency of stormrelated flooding, and intrusion of salt water into coastal freshwater aquifers. The sensitivity of a coastal region to sea-leve l rise depends both on the physical aspects (shape and composition) of a coastal landscape and its ecological sett ing. One of the most obvious impacts is that there will be land lo ss as coastal areas ar e inundated and eroded. Rising sea level will not only i nundate the landscape but will al so be a driver of change for the coastal landscape. These impacts will have large effects on natural environments such as coastal wetland ecosystems, as well as effects on human development in coastal regions (see Part II of this Product). Making long-term projec tions of coastal change is difficult because of the multiple, interacting f actors that contribute to that change. Given the large potential impacts to human and natura l environments, there is a need to improve our ability to conduct long-term projections.CCSP 4.1 January 15, 2009

35 of 784 Final Report Part I describes the physical se ttings of the mid-Atlantic co ast as well as the processes that influence shoreline change and land loss in response to sea-level rise. Part I also provides an assessment of coastal changes th at may occur over the twenty-first century, as well as the consequences of those changes for coastal hab itats and the flora and fauna they support.

Chapter 1 provides an overview of the current un derstanding of climate change and sealevel rise and their potential effects on both natural environments and society, and summarizes the background information that was used to develop this Product. Sea-level rise will have a range of impacts to both natural systems and human development and infrastructure in coastal regions. A major challenge is to understand the extent of these impacts and how to develop planning and adaption strategies that address both the quality of the natural environmen t and human interests.

Chapter 2 highlights the important issues in an alysis of sea-level rise vulnerability based on coastal elevation data. Elevation is a critic al factor in determining vulnerability to inundation, which will be the primary response to sea-level rise for only some locations in the mid-Atlantic region. Because sea-le vel rise impact assessments often rely on elevation data, it is important to understand the inherent accuracy of the underlying data and its effects on the uncertainty of any re sulting vulnerability maps and statistical summaries. The existing studies of sea-level rise vulnerability in the Mid-Atlantic based on currently available elevation data do not provide the level of confidence that is optimal for local decision making. However, recent re search using newer high-resolution, highCCSP 4.1 January 15, 2009

36 of 784 Final Report accuracy elevation data is leading toward development of improved capabilities for vulnerability assessments.

Chapter 3 summarizes the factors and processe s controlling the dynamics of ocean coasts. The major factor affecting the location and sh ape of coasts at cente nnial and longer time scales is global sea-level change, which is linked to the Earth’s climate. These close linkages are well documented in th e scientific literature from field studies conducted over the past few decades. The details of the pro cess-response relationships, however, are the subject of active, ongoing rese arch. The general characteristics and shape of the coast (coastal morphology) reflects complex and ongoi ng interactions between changes in sea level, the physical processes that act on the coast (hydrodynamic regime, e.g. , waves and tidal characteristics), the availa bility of sediment (sedimen t supply) transported by waves and tidal currents at the shore, and underl ying geology (the structure and composition of the landscape which is often referred to as the geologic framework). Variations in these three factors are responsible for the diffe rent coastal landforms and environments occurring in the coastal regions of the Unite d States. Chapter 2 presents a synthesis and assessment of the potential changes that can be expected for the mid-Atlantic shores of the United States which are primarily co mprised of beaches and barrier islands.

Chapter 4 describes the vulner ability of coastal wetlands in the mid-Atlantic region to current and future sea-level rise. The fate of coastal wetlands is determined in large part by the way in which wetland vertical developmen t processes change with climate drivers. In addition, the processes by which wetlands build vertically vary by geomorphic setting.CCSP 4.1 January 15, 2009

37 of 784 Final Report Chapter 3 identifies those important climate drivers affecting wetland vertical development in the geomorphic settings of the mid-Atlantic region. The information on climate drivers, wetland vertical developmen t, geomorphic settings, and local sea-level rise trends was synthesized and assessed us ing an expert decision process to determine wetland vulnerability for each geomorphic settin g in each subregion of the mid-Atlantic region.

Chapter 5 summarizes the potential impacts to bi ota as a result of ha bitat change or loss driven by sea-level rise. Habitat quality, exte nt, and spatial distribu tion will change as a result of shore erosion, wetla nd loss, and shifts in estuar ine salinity gradients. Of particular concern is the lo ss of wetland habitats and the important ecosystem functions they provide, which include critical habitat for wildlife , the trapping of sediments, nutrients, and pollutants, the cycling of nutrients and mine rals, the buffering of storm impacts on coastal environments, and the exchange of materi als with adjacent ecosystems.CCSP 4.1 January 15, 2009

38 of 784 Final Report 

## Chapter 1: Sea-Level Rise and its Effects on the Coast

Lead Authors: S. Jeffress Williams, USGS; Benjamin T. Gutierrez, USGS; James G. Titus, U.S. EPA; Stephen K. Gill, NOAA; Donald R. Cahoon, USGS; E. Robert Thieler, USGS; K. Eric Anderson, USGS (retired) Contributing Authors: Duncan FitzGerald, Boston University; Virginia Burkett, USGS; Jason Samenow, U.S. EPA

KEY POINTS

 Consensus in the climate science community is that the global climate is changing, mostly due to mankind’s increas ed emissions of greenhouse gases (25 percent increase in the last century), such as carbon dioxide, methane, and nitrous oxide from burning of fossil fuels and la nd-use change. Warming of the climate system is unequivocal, but the effects of climate change are highly variable across regions and difficult to predict w ith high confidence based on limited observations over time and space. Two eff ects of atmospheric warming on coasts on regional, national, and gl obal scales are sea-level ri se and increase in major cyclone intensity.

 Global sea level has risen about 120 meters at highly variable rates due to natural processes since the end of the Last Glacial Maximum (i .e., last Ice Age). More recently, the sea-level rise rate has increas ed over natural rise due to increase in the burning of fossil fuels. In some regions, such as the mid-Atlantic region andCCSP 4.1 January 15, 2009

39 of 784 Final Report much of the Gulf of Mexico, sea-level rise is significantly greater than the observed global sea-level rise due to sinki ng of the land as a result of sediment compaction processes.

 Instrumental observations over the past 15 years show that global mean sea level has been highly variable at regional s cales around the world and, on average, the rate of rise appears to have accelerated over twentieth century rates, possibly due to atmospheric warming causing expansion of ocean water and ice-sheet melting.

 Results of climate model studies suggest se a-level rise in the twenty-first century will significantly exceed rates over the pa st century. Rates and the magnitude of rise could be much greater if warming affects dynamical processes that determine ice flow and losses in Greenland and Antarctica.

 Beyond the scope of this Product but impor tant to consider, global sea-level elevations at the peak of the last intergl acial warm cycle were 4 to 6 meters (13 to 20 feet) above present, and could be r ealized within the next several hundred years if warming and glacier and ice-sheet melting continue.

 Coastal regions are characterized by dyna mic landforms and processes because they are the juncture between the land, o ceans, and atmosphere. Features such as barrier islands, bluffs, dunes, and wetla nds constantly undergo change due to driving processes such as storms, sedi ment supply, and sea-level change. Based on surveys over the past century, all U.S. coastal states are experiencing overall erosion at highly variable rates. Sea- level rise will have profound effects by increasing flooding frequency and inundating low-lying coastal areas, but otherCCSP 4.1 January 15, 2009

40 of 784 Final Report processes such as erosion and accretion will have cumulative effects that are profound but not yet predictable with hi gh reliability. There is some recent scientific opinion that coastal landforms such as barrier islands and wetlands may have thresholds or tipping points with s ea-level rise and storms, leading to rapid and irreversible change.

 Nearly one-half of the 6.7 billion people around the world live near the coast and are highly vulnerable to storms and sea- level rise. In the United States, coastal populations have doubled over the past 50 ye ars, greatly increasing exposure to risk from storms and sea-level rise. C ontinued population growth in low-lying coastal regions worldwide and in the Un ited States will increase vulnerability to these hazards as the effects of c limate change become more pronounced.

 Most coastal regions are currently manage d under the premise that sea-level rise is not significant and that shorelines are static or can be fixed in place by engineering structures. The new reality of sea-level ri se due to climate change requires new considerations in managing areas to protect re sources and reduce risk to humans. Long-term climate change impact data are essential for adaptation plans to climate change and coastal zone plans are most useful if they have the premise that coasts are dynamic and highly variable.

1.1 INTRODUCTION The main objective of this Product is to re view and assess the poten tial impacts of sealevel rise on U.S.coastal regions. Careful re view and critique of sea-level and climate change science is beyond the sc ope of this Product; however, that information is centralCCSP 4.1 January 15, 2009

41 of 784 Final Report in assessing coastal impacts. Climate and co astal scientific disciplines are relatively recent, and while uncertainty exists in pred icting quantitatively th e magnitude and rates of change in sea level, a solid body of scien tific evidence exists th at sea level has risen over the recent geologic past, is currently rising and contribu ting to various effects such as coastal erosion, and has the potential to ri se at an accelerated rate this century and beyond. Worldwide data also show that rates of globa l sea-level rise are consistent with increasing greenhouse gas concentrati ons and global warming (IPCC, 2001, 2007;
Hansen et al ., 2007; Broecker and Kunzig, 2008). Global climate change is already having significant and wide ranging eff ects on the Earth’s ecosystems and human populations (Nicholls et al. , 2007).

In recognition of the influence of humans on the Earth, including the global climate, the time period since the nineteenth century is being referred to by scientists as the Anthropocene Era (Pearce, 2007; Zalasiewicz , 2008). Changes to the global climate have been dramatic and the rapid rate of climate change observed over the past two decades is an increasing challenge for adaptation, by humans and animals and plants alike.

Effects from climate change are not uniform, but vary considerably from region to region and over a range of time scales (Nicholls et al. , 2007). These variations occur due to regional and local differences in atmospheric, terrestrial, and o ceanographic processes. The processes driving climate change are co mplex and so-called feedback interactions between the processes can bot h enhance and diminish sea-level rise impacts, making prediction of long-term effects difficult. Acce lerated global sea-level rise, a likely majorCCSP 4.1 January 15, 2009

42 of 784 Final Report long-term outcome of climate change, will have increasingly far-reaching impacts on coastal regions of the United Stat es and around the world (Nicholls et al ., 2007). Relative sea-level rise impacts are already evident for many coastal regions and will increase significantly during this cen tury and beyond (FitzGerald et al , 2008; IPCC, 2007; Nicholls et al ., 2007). Sea-level rise will cause signifi cant and often dramatic changes to coastal landforms ( e.g. , barrier islands, beaches, dunes, marshes), as well as ecosystems, estuaries, waterways, and human populations and development in the coastal zone (Nicholls et al. , 2007; Rosenzweig et al. , 2008; FitzGerald et al. , 2008). Low-lying coastal plain regions, particularly those that are densely populated ( e.g .,the Mid-Atlantic, the north central Gulf of Mexi co), are especially vulnerabl e to sea-level rise and land subsidence and their combined impacts to th e coast and to development in the coastal zone ( e.g. , McGranahan et al. , 2007; Day et al ., 2007a).

The effects of sea-level rise are not necessarily obvious in th e short term, but are evident over the longer term in many ways. Arguably, th e most visible effect is seen in changing coastal landscapes, which ar e altered through more frequent flooding, inundation, and coastal erosion as barrier islands, beache s, and sand dunes change shape and move landward in concert with sea-le vel rise and storm effects. In addition, the alteration or loss of coastal habitats such as wetlands, bays, and estuaries has negative impacts on many animal and plant species that depend on these coastal ecosystems.

Understanding how sea-level rise is likely to affect coastal regions and, consequently, how society will choose to address this issue in the short term in ways that are sustainableCCSP 4.1 January 15, 2009

43 of 784 Final Report for the long term, is a major challenge for bot h scientists and coastal policy makers and managers. While human populations in high-risk coastal areas continue to expand rapidly, the analyses of long-term sea-level measurements show that sea level rose on average 19 centimeters (cm) (7.5 inches [i n]) globally during th e twentieth century (Jevrejeva et al., 2008). In addition, satellite data show global sea-level rise has accelerated over the past 15 years, but at highly variable rates on regional scales. Analyses indicate that the magnitude and rate of sea-level rise for this century and beyond is likely to exceed that of the past century (Meehl et al. , 2007; Rahmstorf, 2007; Jevrejeva et al. , 2008).

Over the last century, humans have gene rally responded to eroding shorelines and flooding landscapes by using engineering measur es to protect threat ened property or by relocating development inland to higher ground. In the future, these responses will become more widespread and more expensiv e for society as sea-level rise accelerates (Nicholls et al. , 2007). Currently the world populati on is 6.7 billion people and is predicted to expand to 9.1 billion by the year 2042 (UN, 2005). Globally, 44 percent of the world’s population lives with in 150 kilometers (km) (93 miles [mi]) of the ocean (<http://www.oceansatlas.org/index.jsp>) and more than 600 million people live in low elevation coastal zone areas th at are less than 10 meters (m) (33 feet [ft]) above sea level (McGranahan et al. , 2007), putting them at significant risk to the effects of sea-level rise. The 10 m elevation was chosen as a benchm ark for providing populat ion statistics to meet data resolution and quality needs b ecause that elevation is a commonly used reference elevation for coastal plain regions vu lnerable to coastal hazards such as storm-CCSP 4.1 January 15, 2009

44 of 784 Final Report surge flooding and sea-level rise. Eight of the 10 largest cities in the world are sited on the ocean coast. In the United States, 14 of th e 20 largest urban centers are located within 100 km of the coast and less th an 10 m above sea level. Us ing the year 2000 census data for U.S. coastal counties as defined by the National Oceanic and Atmospheric Administration (NOAA) and excl uding the Great Lakes states, approximately 126 million people resided in coastal areas (Crossett et al. , 2004). The Federal Emergency Management Agency (FEMA), using the same 2000 census data but diffe rent criteria for defining coastal counties, estimated the coastal population to be 86 million people (Crowell, et al., 2007). Regardless, U.S. coastal popul ations have expanded greatly over the past 50 years, increasing exposure to risk from storms and sea- level rise. Continued population growth in low-lying coastal regions worldwide and in the United States will increase vulnerability to these hazards.

Modern societies around the world have deve loped and populations have expanded over the past several thousand years under a rela tively mild and stable world climate and relatively stable sea level (S tanley and Warne, 2003; Day et al ., 2007b). However, with continued population growth, pa rticularly in coastal area s, and the probability of accelerated sea-level rise and increased stor miness, adaptation to expected changes will become increasingly challenging.

This Product reviews availabl e scientific litera ture through late 2008 and assesses the likely effects of sea-level rise on the coast of the United States, with a focus on the midAtlantic region. An important point to emphasize is that sea-level rise impacts will be far-CCSP 4.1 January 15, 2009

45 of 784 Final Report reaching. Coastal lands will not simply be flood ed by rising seas, but will be modified by a variety of processes ( e.g. , erosion, accretion) whose im pacts will vary greatly by location and geologic setting. For example, the frequency and magnitude of flooding may change and sea-level rise can alsoaffect wa ter table elevations, impacting fresh water supplies. These changes will have a broad ra nge of human and environmental impacts. To effectively cope with sea-level rise a nd its impacts, current policies and economic considerations should be examined, and possible options for changing planning and management activities are warranted so that society and the envir onment are better able to adapt to potential accelera ted rise in sea level. This Product examines the potential coastal impacts for three different plausible s cenarios of future sea-level rise, and focuses on the potential effects to the year 2100. The effects, of course, will extend well beyond 2100, but detailed discussion of effects farther in to the future is outside the scope of this Product.

1.1.1 Climate Change Basis for this Product The scientific study of climate change and asso ciated global sea-leve l rise is complicated due to differences in observations, data quality, cumulative effects, and many other factors. Both direct and i ndirect methods are useful fo r studying past climate change. Instrument records and historical documents ar e most accurate, but are limited to the past 100 to 150 years in the United States. Geol ogical information from analyses of continuous cores sampled from ice sheets and glaciers, sea and lake sediments, and sea corals provide useful proxies that have a llowed researchers to decipher past climate conditions and a record of climate and sea-le vel changes stretching ba ck millions of yearsCCSP 4.1 January 15, 2009

46 of 784 Final Report before recorded history (Miller et al ., 2005; Jansen et al. , 2007). The most precise methods have provided accurate hi gh-resolution data on the climate ( e.g ., global temperature, atmospheric composition) dating back more than 400,000 years.

The Intergovernmental Panel on Climate Change (IPCC) 2007 Fourth Assessment Report provides a comprehensive review and asse ssment of global climate change trends, expected changes over the next century, and the impacts and challenges that both humans and the natural world are likely to be conf ronted with during the next century (IPCC, 2007). Some key findings from this repor t are summarized in Box 1.1. A 2008 U.S. Climate Change Science Program (CCSP) repor t provides a general assessment of current scientific understandi ng of climate change impacts to the United States (CENR, 2008) and the recent CCSP Synthe sis and Assessment (SAP) 3.4 report on Abrupt Climate Change discusses the effects of complex cha nges in ice sheets and glaciers on sea level (Steffen et al., 2008). CCSP SAP 4.1 provides more sp ecific information and scientific consensus on the likely effects and implications of future sea-level rise on coasts and wetlands of the United States and also in cludes a science strategy for improving the understanding of sea-level rise , documenting its effects, and devising robust models and methods for reliably predicting future changes and impacts to coastal regions.

BOX 1.1 SELECTED FINDINGS OF THE INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE (IPCC) (2007A AND B) ON CLIMATE AND GLOBAL SEA-LEVEL RISE Recent Global Climate Change: Note: The likelihood scale, established by the IPCC and used throughout SAP 4.1, is described in the Preface. The terms used in that scale will be it alicized when used as such in this Product Warming of the climate system is une quivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.CCSP 4.1 January 15, 2009

47 of 784 Final Report Human-induced increase in atmospheric carbon dioxide is the most important factor affecting the warming of the Earth’s climate since the start of the Industria l Era. The atmospheric con centration of carbon dioxide in 2005 exceeds by far the natural range over the last 650,000 years. Most of the observed increase in global average temperatures si nce the mid-twentieth century is very likely due to the observed increase in human-caused greenhouse gas concentrations. Discernible human influences now extend to other aspects of climat e, including ocean warming, continental-average temperatures, temperature extremes, and wind patterns. Recent Global Sea-Level Rise Observations since 1961 show that the average temperature of the gl obal ocean has increased to depths of at least 3,000 meters (m) and that the ocean has been absorbing more than 80 percent of the heat added to the climate system. Such warming causes seawater to expand, contributing to global sea-level rise. Mountain glaciers and snow cover have declined on average in both hemispheres. Widespread decreases in glaciers and ice caps have contributed to global sea-level rise. New data show that losses from the ice sh eets of Greenland and Antarctica have very likely contributed to global sea-level rise between 1993 and 2003. Global average sea level rose at an average rate of 1. 8 (1.3 to 2.3) millimeters (mm) per year between 1961 and 2003. The rate was faster between 1993 and 2003: about 3.1 (2.4 to 3.8) mm per year. Whether the faster rate for 1993 to 2 003 reflects decadal variability or an increase in the long er term trend is unclear (see Figure 1.3). Global average sea level in the last intergl acial period (about 125,000 years ago) was likely 4 to 6 m higher than during the twentieth century, mainly due to the retreat of polar ice. Ice core data indicate that average polar temperatures at that time were 3 to 5°C higher than present, because of differences in the Earth’s orbit. The Greenland ice sheet and other arctic ice fields likely contributed no more than 4 m of the observed global sea-level rise. There may also have been contributions from Antarctica ice sheet melting. Projections of the Future: Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the twenty-first century that would very likely be larger than those observed during the twentieth century. Based on a range of possible greenhouse gas emissi on scenarios for the next century, the IPCC estimates the global increase in temperature will likely be between 1.1 and 6.4oC. Estimates of sea-level rise for the same scenarios are 0.18 m to 0.59 m, excluding the contribution from accelerated ice discharges from the Greenland and Antarctica ice sheets. Extrapolating the recent acceleration of ice discharges from the polar i ce sheets would imply an additional contribution up to 0.20 m. If melting of these ice caps increases, larger values of sea-level rise cannot be excluded. In addition to global sea-level rise, the storms that lead to coastal storm surges could become more intense. The IPCC indicates that, based on a range of computer models, it is likely that hurricanes will become more intense, with larger peak wind speeds and more h eavy precipitation associated with ongoing increases of tropical sea surface temperatures, wh ile the tracks of “winter” or extr atropical cyclones are projected to shift towards the poles along with some indications of an increase in intensity in the North Atlantic.
-end-text box1.2 WHY IS GLOBAL SEA LEVEL RISING?CCSP 4.1 January 15, 2009

48 of 784 Final Report The elevation of global sea le vel is determined by the dynamic balance between the mass of ice on land (in glaciers and ice sheets) and the mass of water in oc ean basins. Both of these factors are highly influenced by the Earth’s atmospheric temperature. During the last 800,000 years, global sea level has rise n and fallen about 120 m (400 ft) in response to the alternating accumulation and decline of large continental ice sheets about 2 to 3 km (1 to 2 mi) thick as climate warmed and cooled in naturally occurring 100,000 year astronomical cycles (Imbrie and Imbrie, 1986; Lambeck et al., 2002). Figure 1.1 shows a record of large global sea-le vel change over the past 400,000 years during the last four cycles, consisting of glacial maximums with lo w sea levels and interglacial warm periods with high sea levels. The last interglacial period, about 125,0 00 years ago, lasted about 10,000 to 12,000 years, with averag e temperatures warmer than today but close to those predicted for the next century, and global sea level was 4 to 6 m (13 to 20 ft) higher than present (Imbrie and Imbrie, 1986). Following th e peak of the last Ice Age about 21,000 years ago, the Earth entered the present inte rglacial warm period. Global sea level rose very rapidly at average rates of 10 to 20 mm per year punctuated with periodic large “meltwater pulses” with rates of more than 50 mm per year from about 21,000 to 6,000 years ago. Sea-level rise then slowed to a rate of about 0.5 mm per year from 6,000 to 3,000 years ago (Fairbanks, 1989; Rohling et al., 2008). During the past 2,000 to 3,000 years the rate slowed to approximately 0.2 mm per year until an acce leration occurred in the late nineteenth century (IPCC 2001).

There is growing scientific evidence that, at the onset of the present interglacial warm period, the Earth underwent abrupt changes wh en the climate system crossed severalCCSP 4.1 January 15, 2009

49 of 784 Final Report thresholds or tipping points (points or levels in the evolution of the Earth's climate leading to irreversible change) that tri ggered dramatic changes in temperature, precipitation, ice cover, and sea level. These changes are thought to have occurred over a few decades to a century and the cause s are not well understood (NRC, 2002; Alley et al. , 2003). One cause is thought to be disruption of major ocean currents by influxes of fresh water from glacial melt. It is not known with any confid ence how anthropogenic climate change might alter the natural glacial-interglaci al cycle or the forcings that drive abrupt change in the Earth’s climate system. Imbrie and Imbrie (1986) surmise that the world might experience a “super-inter glacial” period with mean temperatures higher than past warm periods.

Figure 1.1 Plot of large variations in global sea level elevation over the last 400,000 years resulting from four natural glacial and interglacial cycles. Evidence suggests that sea level was about 4 to 6 meters (m) higher than present during the last interglacial warm period 125,000 years ago and 120 m lower during the last Ice Age, about 21,000 ye ars ago (see reviews in Muhs et al ., 2004 and Overpeck et al ., 2006). (Reprinted from Quaternary Scien ce Reviews, 21/1-3, Phillippe Huybrec hts, Sea-level changes at the LGM from ice-dynamic reconstructions of the Greenland and Antarctic ice sheets during the glacial cycles, 203- 231, Copyright [2002], with permission from Elsevier.)CCSP 4.1 January 15, 2009

50 of 784 Final Report At the peak of the last Ice Age, sea level was approximately 120 m lower than today and the shoreline was far seaward of its present location, at th e margins of the continental shelf (Figure 1.2). As the climate warmed and ice sheets melted, sea level rose rapidly but at highly variable rates, eroding and submergi ng the coastal plain to create the continental shelves, drowning ancestral river valleys, and creating major estuaries such as Long Island Sound, Delaware Bay, Chesapeake Bay, Tampa Bay, Galveston Bay, and San Francisco Bay.

Figure 1.2 Generalized plot of the rise in global sea level at variable rates over the last 18,000 years as the Earth moved from a glacial period to the present interglacial warm period. This curve is reconstructed from geologic samples, shown as data points. Rise was rapid but highly variable for much of the time and slowed about 3,000 years ago. Recent acceleration is not shown at this scale. Reprinted by permission from Macmillan Publishers Ltd: Nature (Fairbanks, R.G., A 17,000-year glacio-eustatic sea levelCCSP 4.1 January 15, 2009

51 of 784 Final Report record

― influence of glacial melting rates on the Younger Dryas event and deep-sea circulation, 349[6250], 637-642), ©1989.

Global sea level was relatively stable with rate s of rise averaging 0 to 0.2 mm per year until rates increased in the late nineteen th and early twentieth centuries (Bindoff et al., 2007; Lambeck et al., 2004; Gehrels et al. , 2008). Some studies indi cate that acceleration in sea-level rise may have begun earlier, in the late eighteenth century (Jevrejeva et al., 2008). Analyses of tide-gauge data indicate that the twentieth century rate of sea-level rise averaged 1.7 mm per year on a global scale (Fi gure 1.3) (Bindoff et al. , 2007), but that the rate fluctuated over decadal pe riods throughout the century (Church and White, 2006; Jevrejeva et al ., 2006, 2008). Between 1993 and 2003, both satellite altimeter and tide-gauge observations indicate that the rate of sea-level rise in creased to 3.1 mm per year (Bindoff et al ., 2007); however, with such a short record, it is not yet possible to determine with certainty whether this is a natural decadal varia tion or due to humaninduced climate warming (Bindoff et al ., 2007).CCSP 4.1 January 15, 2009

52 of 784 Final Report Figure 1.3 Annual averages of global mean sea level in millimeters from IPCC (2007). The red curve shows sea-level fields since 1870 (updated from Church and White, 20 06); the blue curve displays tide gauge data from Holgate and Woodworth (2004), and the black curve is based on satellite observations from Leuliette et al. (2004). The red and blue curves are deviations from their averages for 1961 to 1990, and the black curve is the deviation from the average of the red curve for the period 1993 to 2001. Vertical error bars show 90 percent confidence inte rvals for the data points. Adapted from Climate Change 2007: The Physical Science Basis . Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Figure 5.13. Cambridge University Press.

Box 1.2 Relative Sea Level “Global sea-level rise” results mainly from the worldwid e increase in the volume of the world’s oceans that occurs as a result of thermal expansion of warming ocean water and the addition of water to the ocean from melting ice sheets and glaciers (ice masses on land). “R elative sea-level rise” is measured directly by coastal tide gauges, which record both the movement of the land to which they are attached and changes in global sea level. Global sea-level rise can be estimated from tide gauge data by subtracting the landelevation change component. Thus, tide gauges are important observation instruments for measuring sealevel change trends. However, because variations in climate and ocean circulation can cause fluctuations over 10-year time periods, the most reliable sea level da ta are from tide gauges having records 50 years or longer and for which the rates have been adjusted using a global isostatic adjustment model (Douglas et al ., 2001) At regional and local scales along the coast, verti cal movements of the land surface can also contribute significantly to sea-level change and the combination of global sea-level and land-level change is referred to as “relative sea level” (Douglas, 2001).Thus, “rela tive sea-level rise” refers to the change in sea level relative to the elevation of the land, which includes both global sea-level rise and vertical movements of the land. Both terms, global sea level and relative sea level, are used throughout this Product. Vertical changes of the land surface result from many factors including tectonic processes and subsidence (sinking of the land) due to compact ion of sediments and extr action of subsurface fluids such as oil, gas, and water. A principal contributor to this change alon g the Atlantic Coast of North America is the vertical relaxation adjustments of the Earth’s crust to reduced ice loading due to climate warming since the last Ice Age. In addition to glacial adjustments, sediment loadin g also contributes to regional subsidence of the land surface. Subsidence contributes to high rates of relativ e sea-level rise (9.9 millimeters per year) in the Mississippi River delta where thick sediments have accumulated and are compacting. Likewise, fluid withdrawal from coastal aquifers causes the sediment s to compact locally as the water is extracted. In Louisiana, Texas, and Southern California, oil, gas and ground-water extraction have contributed markedly to subsidence and relative sea-level rise (Gornitz and Lebedeff, 1987; Emery and Aubrey, 1991; Nicholls and Leatherman, 1996; Galloway et al. , 1999; Morton et al. , 2004). In locations where the land surface is subsiding, rates of relative sea-level rise exceed the average rate of global rise ( e.g. , the north central Gulf of Mexico Coast and mid-Atlantic coast).
--End Text Box—

1.3 RELATIVE SEA-LEVEL RISE AROUND THE UNITED STATES Geologic data from radiocarbon age-dating orga nic sediments in cores and coral reefs are indirect methods used for determining sea-leve l elevations over the past 40,000 years, butCCSP 4.1 January 15, 2009

53 of 784 Final Report the records from long-term (more than 50 y ears) tide-gauge sta tions have been the primary direct measurements of relative s ea-level trends over th e past century (Douglas , 2001). Figure 1.4 shows the large va riations in relative sea level for U.S. coastal regions. The majority of the Atlantic Coast and Gulf of Mexico Coast experience higher rates of sea-level rise (2 to 4 mm per year and 2 to 10 mm per year, respectively) than the current global average (1.7 mm per year).

Figure 1.4 Map of twentieth century annual relative sea-level rise rates around the U.S. coast. The higher rates for Louisiana (9.85 millimeters [mm] per year) and the mid-Atlantic region (1.75 to 4.42 mm per year) are due to land subsidence. Sea level is stab le or dropping relative to the land in the Pacific Northwest, as indicated by the negative values, where the land is tectonically active or rebounding upward in response to the melting of ice sheets sin ce the last Ice Age (data from Zervas, 2001).
There are large variations for relative sea- level rise (and fall) around the United States, ranging from a fall of 16.68 mm per year at Skag way in southeast Alaska due to tectonicCCSP 4.1 January 15, 2009

54 of 784 Final Report processes and land rebound upward as a result of glacier melti ng (Zervas, 2001), to a rise of 9.85 mm per year at Grand Isle, Louisiana, due to la nd subsidence downward from natural causes and possibly oil and gas extraction.

The rate of relative sea-leve l rise (see Box 1.2 for definiti on) measured by tide gauges at specific locations along the Atlantic coast of the United States varies from 1.75 mm to as much as 4.42 mm per year (Table 1.1; Figure 1.4; Zervas, 2001). The lower rates, which occur along New England and from Georgia to northern Florida, are close to the global rate of 1.7 ±0.5 mm per year (Bindoff et al. , 2007). The highest rates are in the midAtlantic region between northern New Jersey and southern Virginia. Figure 1.5 is an example of the monthly average (mean) sea- level record and the observed relative sealevel rise trend at Baltimore, Maryland. At this location, th e relative sea-level trend is 3.12 (±0.08) mm per year, almost twice the present rate of global sea-level rise. Subsidence of the land surface, at tributed mainly to adjustments of the Earth’s crust in response to the melting of the Laurentide ice sheet and to the compaction of sediments due to freshwater withdrawal from coastal aquifers, contributes to the high rates of relative sea-level rise observ ed in this region (Gornitz and Lebedeff, 1987; Emery and Aubrey, 1991; Kearney and Stevenson, 1991; Douglas, 2001; Peltier, 2001).CCSP 4.1 January 15, 2009

55 of 784 Final Report Figure 1.5 The monthly computed average sea-level reco rd (black line) from 1900 to 2000 from the Baltimore, Maryland tide gauge. Blue line is the observed data. The zero line is the latest 19-year National Tidal Datum Epoch mean value. The rate, 3.12 millimete rs (mm) per year, is nearly double the present rate (1.7 mm per year) of global sea-level rise due to land subsidence (based on Zervas, 2001).

Table 1.1 Rates of relative sea-level rise for select ed long-term tide gauges on the Atlantic coast of the United States (Zervas, 2001). Fo r comparison, the global average rate is 1.7 millimeters per year.

Station Rate of Sealevel rise (mm per

year) Time Span of Record Eastport, Maine 2.12 ±0.13 1929-1999 Portland, Maine 1.91 ±0.09 1912-1999 Seavey Island, Maine 1.75 ±0.17 1926-1999 Boston, Massachusetts 2.65 ±0.10 1921-1999 Woods Hole, Massachusetts 2.59 ±0.12 1932-1999

Providence, Rhode Island 1.88 ±0.17 1938-1999

Newport, Rhode Island 2.57 ±0.11 1930-1999 New London, Connecticut 2.13 ±0.15 1938-1999 Montauk, New York 2.58 ±0.19 1947-1999 Willets Point, New York 2.41 ±0.15 1931-1999 The Battery, New York 2.77 ±0.05 1905-1999 Sandy Hook, New Jersey 3.88 ±0.15 1932-1999 Atlantic City, New Jersey 3.98 ±0.11 1911-1999 Philadelphia, Pennsylvania 2.75 ±0.12 1900-1999 Lewes, Delaware 3.16 ±0.16 1919-1999 Baltimore, Maryland 3.12 ±0.08 1902-1999 Annapolis, Maryland 3.53 ±0.13 1928-1999CCSP 4.1 January 15, 2009

56 of 784 Final Report Solomons Island, Maryland 3.29 ±0.17 1937-1999 Washington, D.C. 3.13 ±0.21 1931-1999 Hampton Roads, Virginia 4.42 ±0.16 1927-1999

Portsmouth, Virginia 3.76 ±0.23 1935-1999 Wilmington, North Carolina 2.22 ±0.25 1935-1999 Charleston, South Carolina 3.28 ±0.14 1921-1999 Fort Pulaski, Georgia 3.05 ±0.20 1935-1999 Fernandina Beach, Florid a 2.04 ±0.12 1897-1999 Mayport, Florida 2.43 ±0.18 1928-1999 Miami, Florida 2.39 ±0.22 1931-1999 Key West, Florida 2.27 ±0.09 1913-1999

While measuring and dealing with longer term global averages of sea-level change is useful in understanding effect s on coasts, shorter term and regional-scale variations due primarily to warming and oceanographic proces ses can be quite different from long term averages, and equally important for manageme nt and planning. As shown in Figure 1.6 from Bindoff et al. (2007) based on a decade of data, some of the highest rates of rise are off the U.S. Mid-Atlantic and the western Pa cific, while an apparent drop occurred off the North and South American Pacific Coast.CCSP 4.1 January 15, 2009

57 of 784 Final Report Fi gur e 5. 15

Figure 1.6 (Top) Geographic distribution of short-term linear trends in mean sea level (millimeters [mm] per year) for 1993 to 2 003 based on TOPEX/Poseidon satellite altimetry (updated from Cazenave and Nerem, 2004) and (bottom) geographic distribution of linear trends in thermal expansion (mm per year) for 1993 to 2003 (based on temperature data down to 700 meters [from Ishii et al ., 2006]). Adapted from Climate Change 2007: The Physical Science Basis . Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Figure 5.15. Cambridge University Press.

Recently, the IPCC Fourth Assessment Report (IPCC, 2007) estimated that global sea level is likely to rise 18 to 59 cm (7 to 23 in) over the next century; however, possible increased melt water contributions from Gr eenland and Antarctic have been excluded (Meehl et al., 2007; IPCC, 2007). The IPCC projections (Figure 1.7) represent a “likely range” which inherently allows for the possibili ty that the actual rise may be higher or lower. Recent observations sugge st that sea-level rise rate s may already be approaching the higher end of the IP CC estimates (Rahmstorf et al. , 2007; Jevrejeva et al. , 2008). This is because potentially important meltwater contributions from Greenland and Antarctica were excluded due to limited data and an inab ility at that time to adequately model iceCCSP 4.1 January 15, 2009

58 of 784 Final Report flow processes. It has been suggested by Ra hmstorf (2007) and other climate scientists that a global sea-level rise of 1 m (3 ft) is plausible within this century if increased melting of ice sheets in Greenland and Antarctica is added to the factors included in the IPCC estimates. Therefore, thoughtful precaution s uggests that a global sea-level rise of 1 m to the year 2100 should be considered fo r future planning and policy discussions

Figure 1.7 Plot in centimeters rise over time of past sea- level observations and several future sea-level projections to the year 2100 based on various comput er models. The blue shaded area is the projection by Bindoff et al. (2007) and the basis for the IPCC (2007) estimates. The higher gray and dash line projections are from Rahmstorf (2007) considering the factors used in the IPCC estimates, and also potentially increased melting of ice sheets in Greenland and Antarctica. From: Rahm storf, S., 2007: A semi-empirical approach to projecting future sea-level rise. Science , 315(5810), 368-370.Reprinted with permission from AAAS.

This Product focuses on the effects of sea-leve l rise on U.S. coasts over the next century, but climate warming and its effects are like ly to continue well beyond that due to the amount of greenhouse gases already in the at mosphere. Currently, the amount of potential melting from land-based ice masses (primar ily Greenland and West Antarctica) is uncertain and is therefore not fully incorporated into all sea-level rise model projections.CCSP 4.1 January 15, 2009

59 of 784 Final Report Recent observations of changes in ice c over and glacial melting on Greenland, West Antarctica, and smaller glaciers and ice caps ar ound the world indicate that ice loss could be more rapid than the trends evaluated for the IPCC (2007) report (Chen et al. , 2006; Shepherd and Wingham, 2007; Meier et al. , 2007; Fettweis et al. , 2007). The science needed to assign probability to these high scenarios is not yet well established, but scientists agree th at this topic is worthy of continued study because of the grave implications for coastal areas in th e United States and around the world.

1.4 IMPACTS OF SEA-LEVEL RISE FOR THE UNITED STATES 1.4.1 Coastal Vulnerability for the United States Coastal communities and habitats will be increasingly stressed by climate change impacts due to sea-level rise and storms (Field et al. , 2007). To varying degrees over decades, rising sea level will affect entire coastal systems from the ocean shoreline well landward. The physical and ecological changes that occur in the near future will impact people and coastal development. Impacts from sea-level rise include: land lo ss through submergence and erosion of lands in coastal areas; mi gration of coastal landforms and habitats; increased frequency and extent of storm-re lated flooding; wetland lo sses; and increased salinity in estuaries and coastal freshwater aquifers. Each of these effects can have impacts on both natural ecosystems and human developments. Often the impacts act together and the effects are cumulative. Ot her impacts of climate change, such as increasingly severe droughts and storm intens ity—combined with c ontinued rapid coastal development—could increase the magnitude and extent of sea-level rise impacts (Nicholls, et al. , 2007). To deal with these impacts, new practices in managing coasts andCCSP 4.1 January 15, 2009

60 of 784 Final Report the combined impacts of mitigating changes to the physical system ( e.g., coastal erosion or migration, wetland losses) a nd impacts to human populations ( e.g., property losses, more frequent flood damage ) should be considered.

Global sea-level rise, in combination with th e factors above, is alre ady having significant effects on many U.S. coastal areas. Flooding of low-lying regions by storm surges and spring tides is becoming more frequent. In certain areas, wetland losses are occurring, fringe forests are dying and being converted to marsh, farmland and lawns are being converted to marsh ( e.g ., see Riggs and Ames, 2003; 2007), and some roads and urban centers in low elevation ar eas are more frequently fl ooded during spring high tides (Douglas, 2001). In addition, “ghost forests” of standing dead trees killed by salt water intrusion are becoming increasingly comm on in southern New Jersey, Maryland, Virginia, Louisiana, and North Carolina (Riggs and Ames, 2003). Rela tive sea level rise is causing salt water intrusion into estuaries a nd threatening freshwater resources in some parts of the mid-Atlantic region (Barlow, 2003).

Continued rapid coastal development exacerb ates both the environm ental and the human impact of rising sea level. Due to the incr eased human population in coastal areas, once sparsely developed coastal areas have b een transformed into high-density year-round urban complexes ( e.g. , Ocean City, Maryland; Virginia Beach, Virginia; Myrtle Beach, South Carolina). With accelerated rise in sea level and increased intensity of storms, the vulnerability of development at the coast a nd risks to people will increase dramaticallyCCSP 4.1 January 15, 2009

61 of 784 Final Report unless new and innovative coastal zone management and planning approaches are employed.

1.4.2 Climate Change, Sea-Le vel Rise and Storms Although storms occur episodically, they can have long-term impacts to the physical environment and human populations. Coupled with rise in sea level, the effects of storms could be more extensive in the future due to changes in storm character, such as intensity, frequency, and storm tracking. In addition to hi gher sea level, coastal storm surge from hurricanes could become higher and more inte nse rainfall could ra ise the potential for flooding from land runoff. Recent studies ( e.g. , Emanuel, et al. , 2004, 2008; Emanuel, 2005; Komar and Allen, 2008; Elsner et al ., 2008) have concluded th at there is evidence that hurricane intensity has increased during the past 30 years over the Atlantic Ocean; however, it is unknown whether these trends will continue. There is currently no scientific consensus on changes in th e frequency of major storms. Emanuel et al. (2008) suggest that increased wind shear from gl obal warming, which weakens hurricanes, may reduce the global frequency of hurricanes. This is in agreement with Gutowski et al

. (2008).
Land-falling Atlantic coast hurricanes can produc e storm surges of 5 m (16 ft) or more (Karl et al ., 2008). The power and frequency of Atlantic hurricanes has increased substantially in recent decades, though North American mainland land-falling hurricanes do not appear to have increased over the past century (Karl et al. , 2008). The IPCC (2007) and Karl et al. (2008) indicate that, based on computer models, it is likely that hurricanes will become more intense, with incr eases in tropical sea surface temperatures.CCSP 4.1 January 15, 2009

62 of 784 Final Report Although hurricane intensity is expected to increase on average, the effects on hurricane frequency in the Atlantic are still not certain and are the topic of c onsiderable scientific study (Elsner et al ., 2008; Emanuel et al ., 2008; see also review in Karl et al. , 2008 ).
Extratropical cyclones can also produce si gnificant storm surges. These storms have undergone a northward shift in tr ack over the last 50 years (Karl et al. , 2008). This has reduced storm frequencies and intensities in the mid-latitudes and increased storm frequencies and intensities at high latitudes (Gutowski et al. , 2008). Karl et al. (2008) conclude that future intense extratropical cyclones will become more frequent with stronger winds and more extreme wave heights though the overall numbe r of storms may decrease. So, while general storm projections are possible, specifi c projections for regional changes in extratropical cyclone activity, such as for the mid-Atlantic coast, are not yet available. Thus, while increased storm intensity is a serious risk in concert with sea-level rise, specific storm predictions are not so well established that planners can yet rely on them.

1.4.3 Shoreline Change and Coastal Erosion The diverse landforms comprising more than 152,750 km (95,471 mi) of U.S. tidal coastline (<http://shoreline.noaa.gov/faqs.html>) reflect a dynamic in teraction between: (1) natural factors and physical processes th at act on the coast ( e.g. , storms, waves, currents, sand sources and sinks, rela tive sea level), (2) human activity ( e.g. , dredging, dams, coastal engineering), and (3) the geologi cal character of the coast and nearshore. Variations of these physical processes in both location and time, and the local geologyCCSP 4.1 January 15, 2009

63 of 784 Final Report along the coast, result in the majority of the U.S. coastlin es undergoing overall long-term erosion at highly varying ra tes, as shown in Figure 1.7.

Figure 1.8 Shoreline change around the Unite d States based on surveys over the past century. All 30 coastal states are experiencing overall erosion at highly variable rates due to natural processes ( e.g. , storms, sea-level rise) and human activity (From USGS, 1985).
The complex interactions between these factor s make it difficult to relate sea-level rise and shoreline change and to reach agreement among coastal scientists on approaches to predict how shorelines will change in respons e to sea-level rise. The difficulty in linking sea-level rise to coastal change stems from th e fact that shoreline change is not driven solely by sea-level rise. Instead, coasts ar e in dynamic flux, responding to many driving forces, such as the underlying geological char acter, changes in tidal flow, and volume of sediment in the coastal system. For example, FitzGerald et al. (2008) discuss the dramatic effects that changes in tidal wetland area can have on entire coasta l systems by alteringCCSP 4.1 January 15, 2009

64 of 784 Final Report tidal flow, which in turn affects the size and shape of tidal inlets, ebb and flood tide deltas, and barrier islands. Consequently, whil e there is strong scientific consensus that climate change is accelerating sea-level rise and affecting coastal re gions, there are still considerable uncertainties predicting in any detail how the coast will respond to future sea-level rise in concert w ith other driving processes.

There is some scientific opini on that barrier islands, wetlands, and other parts of coastal systems might have tipping points or threshol ds, such that when limits are exceeded the landforms become unstable and undergo larg e irreversible changes (NRC, 2002; Riggs and Ames, 2003; Nicholls et al ., 2007). These changes are thought to occur rapidly and are thus far unpredictable. It is possible that this is happeni ng to barrier islands along the Louisiana coast that are subject to high rates of sea-level rise , frequent major storms over the past decade, and limited sediment supply (Sallenger et al ., 2007). Further deterioration of the barrier islands and wetlands may also occur in the near future along the North Carolina Outer Banks coast as a re sult of increased sea- level rise and storm activity (Culver et al. , 2007, 2008; Riggs and Ames, 2003).

1.4.4 Managing the Coastal Zone as Sea Level Rises A key issue for coastal zone management is how and where to adapt to the changes that will result from sea-level rise in ways that benefit or minimize impacts to both the natural environment and human populations. Shore prot ection policies have been developed in response to shoreline retreat problems that affect property or coastal wetland losses. While it is widely recognized th at sea-level rise is an underl ying cause of these changes,CCSP 4.1 January 15, 2009

65 of 784 Final Report there are few existing policies that explicitly address or incorporate sea-level rise into decision making. Many property owners and government programs engage in coastal engineering activities designed to protect property and beaches such as beach nourishment or seawall or breakwater construction. Some of the current practices affect the natural behavior of coastal landforms a nd disrupt coastal ecosystems. In the short term, an acceleration of sea-level rise may si mply increase the cost of current shore protection practices (Nordstrom, 2000). In th e long term, policy makers might evaluate whether current approaches and justificati ons for coastal development and protection need to be modified to reflect the increas ing vulnerability to accelerating rates of sealevel rise.

To facilitate these decisions, policy makers require credible scientific data and information. Predicting sea-level rise impacts such as shoreline changes or wetland losses with quantitative precision and certainty is of ten not possible. Related effects of climate change, including increased storms, precipita tion, runoff, drought, and sediment supply add to the difficulty of providing accurate re liable information. Predicting future effects is challenging because the abil ity to accurately map and qua ntify the physical response of the coast to sea-level rise, in combination wi th the wide variety of other processes and human engineering activities along the shoreline, has not yet been well developed.

United States coastal regions are generally managed under the premise that sea level is stable, shorelines are static, and storms are regular and predictable. This Product examines how sea-level rise and changes in storm intensity and frequency due to climateCCSP 4.1 January 15, 2009

66 of 784 Final Report change call for new considerations in mana ging areas to protect resources and reduce risk. This SAP 4.1 also examines possibl e strategies for coastal planning and management that will be effective as sea-le vel rise accelerates. For instance, broader recognition is needed that coastal sediments are a valuable resource, best conserved by implementing Best Coastal Sediment Management practices (see <http://www.wes.army.mil/rsm/>) on local, regi onal, and national levels in order to conserve sediment resources and maintain natural sediment transport processes.

This Product assesses the current scientif ic understanding of how sea-level rise can impact the tidal inundation of low-lying lands, ocean shoreline processe s, and the vertical accretion of tidal wetlands. It also discusse s the challenges that will be present in planning for future sea-level rise and adapti ng to these impacts. Th e SAP 4.1 is intended to provide information for coastal decision make rs at all levels of government and society so they can better understand this topic and incorporat e the effects of acc elerating rates of sea-level rise into long-term management and planning.CCSP 4.1 January 15, 2009

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Morton , R.A., T.L. Miller, and L.J. Moore, 2004: National Assessment of Shoreline Change: Part 1, Historical Shoreline C hanges and Associated Coastal Land Loss along the U.S. Gulf of Mexico. U.S. Geological Survey open file report 2004- 1043. U.S. Geological Survey, St. Petersburg, FL, 44 pp. <http://pubs.usgs .gov/of/2004/1043>CCSP 4.1 January 15, 2009

74 of 784 Final Report Muhs , D.R., J.F. Wehmiller, K.R. Simmons, an d L.L. York, 2004: Quaternary sealevel history of the United States. In: The Quaternary Period of the United States [Gillespie, A.R., S.C. Porter, and B.F. At water (eds.)]. Elsevier, Amsterdam, pp. 147-183.
Nicholls , R.J., P.P. Wong, V.R. Burkett, J.O. Codignotto, J.E. Hay, R.F. McLean, S. Ragoonaden, and C.D. Woodroffe, 2007: Co astal systems and low-lying areas. Climate Change 2007: Impacts, Adaptation and Vulnerability . Contribution of Working Group II to the Fourth Assessmen t Report of the Intergovernmental Panel on Climate Change [Parry, M.L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson (eds.)]. Cambri dge University Press, Cambridge, UK, and New York, pp. 315-356. Nordstrom, K.F., 2000: Beaches and Dunes of Developed Coasts . Cambridge University Press, New York, 338 pp.
NRC (National Research Council) 2002: Abrupt Climate Change: Inevitable Surprises

. National Academy Press, Washington, DC, 230 pp. Overpeck , J.T., B.L. Otto-Bliesner, G.H. Miller, D.R. Muhs, R.B. Alley, and J.T. Keihl, 2006: Paleo-climatic evidence for the futu re ice-sheet instability and rapid sea level rise. Science , 311(5768) , 1747-1750.

Pearce , F., 2007: With Speed and Violence: Why Scien tists Fear Tipping Points in Climate Change . Beacon Press, Boston, 278 pp.
Peltier , W.R., 2001: Global glacial isostatic adjust ment and modern instrumental records of relative sea level history. In: Sea Level Rise: History and Consequences [Douglas, B.C., M.S. Kearney, and S.P. Leatherman (eds.)]. International geophysics series v. 75. Academic Press, San Diego, pp. 65-95.
Rahmstorf , S., 2007: A semi-empirical approach to pr ojecting future sea-level rise. Science , 315(5810) , 368-370.CCSP 4.1 January 15, 2009

75 of 784 Final Report Rahmstorf , S., A. Cazenave, J.A. Church, J.E. Hansen, R.F. Keeling, D.E. Parker, and R.C.J. Somerville, 2007: Recent climate observations compared to projections. Science , 316(5825) , 709. Riggs , S.R. and D.V. Ames, 2003: Drowning of the North Carolina Coast: Sea-Level Rise and Estuarine Dynamics . Publication number UNC-SG-03-04. North Carolina Sea Grant, Raleigh, NC, 152 pp. Riggs , S.R. and D.V. Ames, 2007: Effect of Storms on Barrier Island Dynamics, Core Banks, Cape Lookout National Seashore, North Carolina, 1960-2001 . U.S. Geological Survey scientific investig ations report 2006-5309. U.S. Geological Survey, Reston, VA, 78 pp. Rohling , E.J., K. Grant, Ch. Hemleben, M. Siddall, B.A.A. Hoogakker, M. Bolshaw, and M. Kucera, 2008: High rates of sea-level ri se during the last interglacial period. Nature Geoscience , 1(1) , 38-42. Rosenzweig , C., D. Karoly, M. Vicarelli, P. Ne ofotis, Q. Wu, G. Casassa, A. Menzel, T.L. Root, N. Estrella, B. Seguin, P. Tr yjanowski, C. Liu, S. Rawlins, and A. Imeson, 2008: Attributing physical and biological impacts to anthropogenic climate change. Nature , 453(7193) , 353-358. Sallenger , A.S., C.W. Wright, and J. Lillycr op, 2007: Coastal-change impacts during Hurricane Katrina: an overview. In: Coastal Sediments ’07 , [Kraus, N.C. and J.D. Rosati (eds.)]. America Society of Civil Engineers, Reston, VA, pp. 888-896. Shepherd , A. and D. Wingham, 2007: Recent sea- level contributions of the Antarctic and Greenland ice sheets. Science , 315(5818) , 1529-1532. Stanley , D.J. and A.G. Warne, 1993: Nile delta : recent geological evolution and human impact. Science , 260(5108) , 628-634.
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76 of 784 Final Report Subcommittee on Global Change Researc h. U.S. Geological Survey, Reston, VA, pp 60-142.

UN (United Nations), 2005: World Population Prospects: The 2004 Revision . Volume III: Analytical Report. United Nation s Publication, Sales No. E.05.XIII.7, New York, 194 pp.
USGS (U.S. Geological Survey), 1985: National Atlas of the United States: Coastal Erosion and Accretion . U.S. Geological Surv ey, Reston, VA, 1 map. Zalasiewicz, J., M. Williams, A. Smith, T.L. Barry, A.L. Coe, P.R. Brown, P. Brenchley, D. Cantrill, A. Gale, P. Gibbard, F.J. Gregory, M.W. Hounsl ow, A.C. Kerr, P. Pearson, R. Knox, J. Powell, C. Waters, J. Marshall, M. Oates, P. Rawson, and P. Stone, 2008: Are we now living in the Anthropocene? GSA Today , 18(2) , 4-7.

Zervas , C., 2001: Sea Level Variations of the United States 1854-1999. NOAA technical report NOS CO-OPS 36. NOAA National O cean Service, Silver Spring, MD, 186 pp. <http://tidesandcurrents.noaa.gov /publications/techrpt36doc.pdf>CCSP 4.1 January 15, 2009

77 of 784 Final Report 

## Chapter 2. Coastal Elevations

Lead Author: Dean B. Gesch, USGS

Contributing Authors: Benjamin T. Gutierrez, USGS; Stephen K. Gill, NOAA

KEY FINDINGS

 Coastal changes are driven by complex and interrelated processes. Inundation will be the primary response to sea-level rise in some coastal locations ; yet there has been little recognition in previous studies that inundation is just one response out of a number of possible responses to sea-level rise. A challe nge remains to quantify the various effects of sea-level rise and to id entify the areas and settings along the coast where inundation will be the dominant coasta l change process in response to rising

seas.

 Sheltered, low-energy coastal areas, where sediment influx is minimal and wetlands are absent or are unable to build vertically in response to rising water levels, may be submerged. In these cases, the extent of i nundation is controlled largely by the slope of the land, with a greater degree of inundati on occurring in areas with more gentle gradients. In areas that ar e vulnerable to a simple inunda tion response to rising seas, elevation is a critical factor in assessing potential impacts.

 Accurate delineations of potential inu ndation zones are critical for meeting the challenge of fully determining the potential socioeconomic and environmental impacts of predicted sea-level rise.CCSP 4.1 January 15, 2009

78 of 784 Final Report  Coastal elevation data have been widely used to quantify the potential effects of predicted sea-level rise, esp ecially the area of land that could be inundated and the affected population. Because sea-level rise im pact assessments often rely on elevation data, it is critical to understand the inhere nt accuracy of the underlying data and its effects on the uncertainty of any resulting vulnerability maps and statistical summaries.

 The accuracy with which coastal elevations have been mapped directly affects the reliability and usefulness of sea-level rise impact assessments. Although previous studies have raised awaren ess of the problem of mapping and quantifying sea-level rise impacts, the usefulness and applicab ility of many results are hindered by the coarse resolution of available input data. In addition, the unc ertainty of elevation data is often neglected.

 Existing studies of sea-level rise vulnerab ility based on currently available elevation data do not provide the degr ee of confidence that is optimal for local decision making.

 There are important technical considerations that need to be incorporated to improve future sea-level rise impact assessments, especially those with a goal of producing vulnerability maps and statis tical summaries that rely on the analysis of elevation data. The primary aspect of these improvements focuses on using high-resolution, high-accuracy elevation da ta, and consideration and application of elevation uncertainty information in development of vulnerability maps and area statistics.CCSP 4.1 January 15, 2009

79 of 784 Final Report  Studies that use elevation data as an input for vulnerability maps and/or statistics need to have a clear statement of the absolute vertical accuracy. Ther e are existing national standards for quantifying and reporting elevation data accuracy.

 Currently best available elev ation data for the entire mid-Atlantic region do not support an assessment using a sea-level rise increment of 1 me ter or less, using national geospatial standards for accur acy assessment and reporting. This is particularly important because the 1-meter scenario is s lightly above the range of current sea-level rise estimates for the rema inder of this century and slightly above the highest scenario us ed in this report.

 High-quality lidar elevation data, such as that which could be obtained from a national lidar data collection program, would be necessary for the entire coastal zoneto complete a comprehensive assessment of sea-level rise vulnerability in the midAtlantic region. The availability of such el evation data will narrow the uncertainty range of elevation datasets, thus improving th e ability to conduct detailed assessments that can be used in local decision making.

2.1 INTRODUCTION Sea-level rise is a coastal hazard that can exacerbate the problems posed by waves, storm surges, shoreline erosion, wetland loss, and sa ltwater intrusion (NRC, 2004). The ability to identify low-lying lands is one of the key elements needed to assess the vulnerability of coastal regions to these impacts. For n early three decades, a number of large area sealevel rise vulnerability assessments have focused mainly on identifying land located below elevations that would be affected by a given sea-level rise s cenario (Schneider andCCSP 4.1 January 15, 2009

80 of 784 Final Report Chen, 1980; U.S. EPA, 1989; Najjar et al ., 2000; Titus and Richman, 2001; Ericson et al ., 2006; Rowley et al ., 2007). These analyses require use of elevation data from topographic maps or digital elevation models (DEMs) to identify low-lying land in coastal regions. Recent reports have stressed that sea-level rise impact assessments need to continue to include maps of these areas subject to inundation based on measurements of coastal elevations (Coastal States Organization, 2007; Seiden, 2008). Accurate mapping of the zones of potential inundation is critical for meeting the challenge of determining the potential soci oeconomic and environmental impacts of predicted sealevel rise (FitzGerald et al ., 2008).

Identification of the socioeconomic impacts of projected sea-leve l rise on vulnerable lands and populations is an important initial step for the nation in meeting the challenge of reducing the effects of natural disasters in the coastal zone (Subcommittee on Disaster Reduction, 2008). A number of st ate coastal programs are us ing sea-level rise inundation models (including linked storm surge/sea-level rise models) to provide a basis for coastal vulnerability and socioeconomic analyses (Coastal States Organization, 2007). State coastal managers are concerned that these research efforts and those of the federal government should be well coordinated, comp lementary, and not redundant. Despite the common usage of elevation datasets to invest igate sea-level rise vulnerability, there are limitations to elevation-based analyses. These limitations are related to the relevance of this approach in a variety of settings and to the data sources and methodologies used to conduct these analyses. Thus, an important objective of this Chapter is to review the available data and techniques, as well as th e suitability of elevation-based analyses forCCSP 4.1 January 15, 2009

81 of 784 Final Report informing sea-level rise assessments, to provi de guidance for both scientists and coastal
managers.

While elevation-based analyses are a critical component of sea-level rise assessments, this approach only addresses a portion of the vulnerability in coastal regions. Coastal changes are driven by complex and interrelat ed processes such as storms, biological processes, sea-level rise, and sediment tr ansport, which operate over a range of time scales (Carter and Woodroffe, 1994; Brinson et al ., 1995; Eisma, 1995; Pilkey and Cooper, 2004; FitzGerald et al ., 2008). The response of a coas tal region to sea-level rise can be characterized by one or more of th e processes in the following broad categories (Leatherman, 2001; Valiela, 2006; FitzGerald et al ., 2008):

 land loss by inundation of low-lying lands;

 land loss due to erosion (removal of mate rial from beaches, dunes, and cliffs);

 barrier island migration, breaching, and segmentation;

 wetland accretion and migration;

 wetland drowning (deterioration a nd conversion to open water);

 expansion of estuaries;

 salt water intrusion (into freshwater aquifers and surface waters); and

 increased frequency of storm flooding (e specially of uplands and developed coastal lands). Because large portions of the population (both in the United States and worldwide) are located in coastal regions, each of these impacts has consequences for the natural environment as well as human populations. Us ing elevation datase ts to identify andCCSP 4.1 January 15, 2009

82 of 784 Final Report quantify low-lying lands is only one of many asp ects that need to be considered in these assessments. Nonetheless, analyses based on us ing elevation data to identify low-lying lands provide an important foundation for sea-level rise impact studies.

There is a large body of literatur e on coastal processes and their role in both shoreline and environmental change in coastal regi ons (Johnson, 1919; Curray, 1964; Komar, 1983; Swift et al ., 1985; Leatherman, 1990; Carter and Woodroffe, 1994; Brinson, 1995; Eisma, 1995; Wright, 1995; Komar, 1998; D ean and Dalrymple, 2002; FitzGerald et al ., 2008). However, there is generally little discussion of the su itability of using elevation data to identify the vulnerability of coastal regions to sea-level rise. While it is straightforward to reason that low-lying la nds occurring below a future sea-level rise scenario are vulnerable, it is often generall y assumed that these lands will be inundated. Instead, inundation is likely only one part of the response out of a number of possible sea-level rise impacts. Despite this, some assessments have opted for inundation-based assessments due to the lack of any clear a lternatives and the difficulty in accounting for complex processes such as sedimentation (Najjar et al ., 2000). It is plausible that extreme rates of sea-level rise ( e.g. , 1 meter or more in a single ye ar) could result in widespread simple coastal inundation. However, in the more common and likely case of much lower sea-level rise rates, the physical proce sses are more complex and rising seas do not simply flood the coastal landscape below a gi ven elevation contour (Pilkey and Thieler, 1992). Instead, waves and currents will modify the landscape as sea level rises (Bird, 1995; Wells, 1995). Still, inundation is an important component of coastal change (Leatherman, 2001), especially in very low gr adient regions such as North Carolina.CCSP 4.1 January 15, 2009

83 of 784 Final Report However, due to the complexity of the inte rrelated processes of erosion and sediment redistribution, it is difficult to distinguish a nd quantify the individual contributions from inundation and erosion (Pilkey and Cooper, 2004).

Inundation will be the primary response to sea- level rise only in some coastal locations. In many other coastal settings , long-term erosion of beaches and cliffs or wetland deterioration will alter the coastal landscape l eading to land loss. To distinguish the term inundation from other processes, especially erosion, Leatherman (2001) offered the following important distinction:

 erosion involves the physical remova l of sedimentary material

 inundation involves the permanent submergence of land. Another term that can confuse the discussion of sea-level rise and submergence is the

term flooding (Wells, 1995; Najjar et al ., 2000), which in some cases has been used interchangeably with inundation

. Flooding often connotes tem porary, irregular highwater conditions. The term inundation is used in this Chap ter (but not throughout the entire Product) to refer to the perman ent submergence of land by rising seas.

It is unclear whether simply modeling the inundation of the land surface provides a useful approximation of potential land areas at risk from sea-level rise. In many settings, the presence of beaches, barrier islands, or we tlands indicates that sedimentary processes (erosion, transport, or accumulation of material ) are active in both the formation of and/or retreat of the coastal landscape. Sheltere d, low-energy coastal areas, where sediment influx is minimal and wetlands are absent or ar e unable to build vertically in response toCCSP 4.1 January 15, 2009

84 of 784 Final Report rising water levels, may be submerged. In th ese cases, the extent of inundation is controlled by the slope of the land, with a greater degree of inunda tion occurring in the areas with more gentle gradients (Leather man, 2001). In addition, inundation is a likely response in heavily developed regions with hardened shores. The construction of extensive seawalls, bulkheads, and revetments to armor the shores of developed coasts and waterways have formed nearly immovabl e shorelines that may become submerged. However, the challenge remains to quantify th e various effects of sea-level rise and to identify the areas and settings along the coast where inundation will be the dominant coastal change process from sea-level rise.

Despite several decades of research, previ ous studies do not provide the full answers about sea-level rise impacts for the mid-A tlantic region with th e degree of confidence that is optimal for local decision making. Although these studies have illuminated the challenges of mapping and quantifying sea-le vel rise impacts, the usefulness and applicability of many results ar e hindered by the qua lity of the availa ble input data. In addition, many of these studies have not ad equately reported the uncertainty in the underlying elevation data and how that uncertain ty affects the derived vulnerability maps and statistics. The accuracy with which coasta l elevations have been mapped directly affects the reliability and us efulness of sea-level rise impact assessments. Elevation datasets often incorporate a ra nge of data sources, and some studies have had to rely on elevation datasets that ar e poorly suited for detailed inundation mapping in coastal regions, many of which are gently sloping landscapes (Ericson et al ., 2006; Rowley et al ., 2007; McGranahan et al ., 2007). In addition to the limited spatial detail, these datasetsCCSP 4.1 January 15, 2009

85 of 784 Final Report have elevation values quantized only to whole meter intervals, and their overall vertical accuracy is poor when compared to the interval s of predicted sea-level rise over the next century. These limitations can undermine attempts to achieve high-quality assessments of land areas below a given sea-level rise s cenario and, consequently, all subsequent analyses that rely on this foundation.

Due to numerous studies that used elevation da ta, but have lacked general recognition of data and methodology constraints, this Chapte r provides a review of data sources and methodologies that have been used to conduc t sea-level rise vuln erability assessments. New high-resolution, high-accuracy elevation da ta, especially lidar (light detection and ranging) data, are becoming more readily availa ble and are being integrated into national datasets (Gesch, 2007) as well as being used in sea-level rise applica tions (Coastal States Organization, 2007). Research is also progressing on how to take advantage of the increased spatial resolution a nd vertical accuracy of the new data (Poulter and Halpin, 2007; Gesch, 2009). Still, there is a critical need to thor oughly evaluate the elevation data, determine how to appropria tely utilize the data to deliv er well-founded results, and accurately communicate the associated uncertainty.

The widespread use of vulnerability assessments , and the attention they receive, is likely an indication of the broad pub lic interest in sea-level ri se issues. Because of this extensive exposure, it is important for the co astal science community to be fully engaged in the technical development of elevation-ba sed analyses. Many recent reports have been motivated and pursued from an economic or public policy context rather than aCCSP 4.1 January 15, 2009

86 of 784 Final Report geosciences perspective. It is important for scientists to communicate and collaborate with coastal managers to actively identify a nd explain the applicati ons and limitations of sea-level rise impact assessments. Arguably, sea- level rise is one of the most visible and understandable consequences of climate cha nge for the general public, and the coastal science community needs to ensure that appr opriate methodologies ar e developed to meet the needs for reliable information. This Chapte r reviews the various da ta sources that are available to support inundation vulnerability assessments. In addition, it outlines what is needed to conduct and appropriately report re sults from elevation-based sea-level rise vulnerability analyses and di scusses the context in which these analyses need to be applied.

2.2 ELEVATION DATA Measurement and representation of coastal t opography in the form of elevation data provide critical information for research on se a-level rise impacts. Elevation data in its various forms have been used extensively for sea-level rise studies. This section reviews elevation data sources in order to prov ide a technical basis for understanding the limitations of past sea-level rise impact analys es that have relied on elevation data. While use of coastal elevation data is relatively st raightforward, there are technical aspects that are important considerations for c onducting valid quantitative analyses.

2.2.1 Topographic Maps, Digital Elevation Models, and Accuracy Standards Topographic maps with elevation contours ar e perhaps the most recognized form of elevation information. The U.S. Geological Surv ey (USGS) has been a primary source ofCCSP 4.1 January 15, 2009

87 of 784 Final Report topographic maps for well over a century. The base topographic map series for the United States (except Alaska) is published at a s cale of 1:24,000, and the elevation information on the maps is available in digital form as digital elevation m odels. The USGS began production of DEMs matching the 1:24,000-scal e quadrangle maps in the mid-1970s using a variety of image-based (photogrammetric) and cartographic techniques (Osborn et al ., 2001). Coverage of the conterminous United States with 30-meter (m) (98-foot [ft]) horizontal resolution DEMs was completed in 19 99, with most of the individual elevation models being derived from the elevation co ntours and spot heights on the corresponding topographic maps. Most of these maps have a 5-ft, 10-ft, 20-ft, or 40-ft contour interval, with 5-ft being the contour interval used in many low relief areas along the coast. About the time 30-m DEM coverage was completed, the USGS began development of a new seamless raster (gridded) elevation database known as the National Elevation Dataset (NED) (Gesch et al ., 2002). As the primary eleva tion data product produced and distributed by the USGS, the NED includes many USGS DEMs as well as other sources of elevation data. The diverse source datase ts are processed to a specification with a consistent resolution, coordina te system, elevation units, and horizontal and vertical datums to provide the user with an elevati on product that represents the best publicly available data (Gesch, 2007). DEMs are also pr oduced and distributed in various formats by many other organizations, and they are us ed extensively for mapping, engineering, and earth science applications (Maune, 2007; Maune et al ., 2007a).

Because sea-level rise impact assessments often rely on elevation data, it is important to understand the inherent accuracy of the underlyi ng data and its effects on the uncertaintyCCSP 4.1 January 15, 2009

88 of 784 Final Report of any resulting maps and statistical su mmaries from the assessments. For proper quantitative use of elevation da ta, it is important to identify and understand the vertical accuracy of the data. Vertical accuracy is an expression of the overall quality of the elevations contained in the dataset in co mparison to the true ground elevations at corresponding locations. Accuracy standard s and guidelines exist, in general for geospatial data, and specifically for eleva tion data. For topographic maps, the National Map Accuracy Standards (NMA S) issued in 1947 are the most commonly used; they state that “vertical accuracy, as applied to c ontour maps on all publication scales, shall be such that not more than 10 pe rcent of the elevations tested shall be in error by more than one-half the contour interval” (USGS, 1999). An alternative way to state the NMAS vertical accuracy standard is that an elev ation obtained from the topographic map will be accurate to within one-half of the contour interval 90 percent of the time. This has also been referred to as “linear error at 90 percent confidence” (LE90) (Greenwalt and Shultz, 1962). For example, on a topographic map with a 10-ft contour interval that meets NMAS, 90 percent of the elevations will be accura te to within 5 ft, or stated alternatively, any elevation taken from the map will be with in 5 ft of the actual elevation with a 90- percent confidence level. Ev en though the NMAS was developed for printed topographic maps and it predates the existence of DEMs, it is important to understand its application because many DEMs are derived from topographic maps.

As the production and use of digital geospa tial data became commonplace in the 1990s, the Federal Geographic Data Committee (F GDC) developed and published geospatial positioning accuracy standards in support of th e National Spatial Data InfrastructureCCSP 4.1 January 15, 2009

89 of 784 Final Report (Maune et al ., 2007b). The FGDC standard for testi ng and reporting the vertical accuracy of elevation data, termed the National Sta ndard for Spatial Data Accuracy (NSSDA), states that the “reporting standa rd in the vertical component is a linear uncer tainty value, such that the true or theoretical location of the point falls within +/- of that linear uncertainty value 95 percent of the time” (F ederal Geographic Data Committee, 1998). In practice, the vertical accuracy of DEMs is often reported as the root mean square error (RMSE). The NSSDA provides the method for translating a reported RMSE to a linear error at the 95-percent confidence level. Maune et al . (2007b) provide a useful comparison of NMAS and NSSDA vertical accuracy measures for common contour intervals (Table 2.1) and methods to conve rt between the repor ting standards. The NSSDA, and in some cases even the older NM AS, provides a useful approach for testing and reporting the important ver tical accuracy information for elevation data used in sealevel rise assessments.

Table 2.1 Comparison of National Map Accuracy Standards and National Standard for Spatial Data Accuracy vertical accuracy values with the equivalent common contour intervals (Maune et al ., 2007b). NMAS Equivalent contour interval NMAS 90-percent confidence level (LE90) NSSDA RMSE NSSDA 95-percent confidence level 1 ft 0.5 ft 0.30 ft (9.25 cm) 0.60 ft (18.2 cm) 2 ft 1 ft 0.61 ft (18.5 cm) 1.19 ft (36.3 cm) 5 ft 2.5 ft 1.52 ft (46.3 cm) 2.98 ft (90.8 cm) 10 ft 5 ft 3.04 ft (92.7 cm) 5.96 ft (1.816 m) 20 ft 10 ft 6.08 ft (1.853 m) 11.92 ft (3.632 m)

2.2.2 Lidar Elevation Data Currently, the highest resolution elevation datasets are those derived from lidar surveys. Collected and post-processed unde r industry-standard best pract ices, lidar elevation data routinely achieve vertical accuracies on the order of 15 centimeters (cm) (RMSE). SuchCCSP 4.1 January 15, 2009

90 of 784 Final Report accuracies are well suited for analyses of impacts of sea-level rise in sub-meter increments (Leatherman, 2001). Using the conversion methods between accuracy standards documented by Maune et al . (2007b), it can be shown that lidar elevation data with an accuracy of equal to or better th an 18.5 cm (RMSE) is equivalent to a 2-ft contour interval map meeting NMAS.

Lidar is a relatively recent remote sensi ng technology that has advanced significantly over the last 10 years to the point where it is now a standard survey tool used by government agencies and the mapping industry to collect very detailed, high-accuracy elevation measurements, both on land and in shallow water coastal areas. The discussion of lidar in this Chapter is limited to topographic lidar us ed to map land areas. Lidar measurements are acquired using laser technol ogy to precisely measure distances, most often from an aircraft, that are then converted to elevati on data and integrated with Global Positioning System (GPS) information (Fowler et al ., 2007). Because of their high vertical accuracy and spatial resolution, elev ation data derived from lidar surveys are especially useful for applications in lo w relief coastal environments. The technical advantages of lidar in dynamic coastal sett ings, including the ability to perform repeat high-precision surveys, have f acilitated successful use of th e data in studies of coastal changes due to stor m impacts (Brock et al ., 2002; Sallenger et al ., 2003; Stockdon et al ., 2007). Numerous organizations, including ma ny state programs, have recognized the advantages of lidar for use in mapping the co astal zone. As an example, the Atlantic states of Maine, Connecticut, New Jerse y, Delaware, Maryland, North Carolina, andCCSP 4.1 January 15, 2009

91 of 784 Final Report Florida have invested in lidar surveys for us e in their coastal programs (Coastal States Organization, 2007; Rubinoff, et al ., 2008).

2.2.3 Tides, Sea Level, and Reference Datums Sea-level rise assessments typically focus on understanding potential changes in sea level, but elevation datasets are often referenced to a “vertical datum,” or reference point, that may differ from sea level at any specifi c location. In any work dealing with coastal elevations, water depths, or wa ter levels, the reference to which measurements are made must be carefully addressed and thoroughly documented. All elevations, water depths, and sea-level data are referenced to a define d vertical datum, but different datums are used depending on the data types and the original purpose of the measurements. A detailed treatment of the theory behind the development of vertical reference systems is beyond the scope of this Product. However, a basic understanding of vertical datums is necessary for fully appreciating the important issues in using coasta l elevation data to assess sea-level rise vulnerabi lity. Zilkoski (2007), Maune et al . (2007a), and NOAA (2001) provide detailed explan ations of vertical datums and tides, and the brief introduction here is based largely on those sources.

Land elevations are most often referenced to an orthometric (sea-level referenced) datum, which is based on a network of surveyed (o r “leveled”) vertical control benchmarks. These benchmarks are related to local mean sea level at specific tide stations along the coast. The elevations on many topographic maps, and thus DEMs derived from those maps, are referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29),CCSP 4.1 January 15, 2009

92 of 784 Final Report which uses mean sea level at 26 tide gauge sites (21 in the United States and 5 in Canada). Advances in surveying techniques and the advent of computers for performing complex calculations allowed the development of a new vertical datum, the North American Vertical Datum of 1988 (NAVD 88). Development of NAVD 88 provided an improved datum that allowed for the correction of errors that had been introduced into the national vertical control ne twork because of crustal motion and ground subsidence. In contrast to NGVD 29, NAVD 88 is tied to mean sea level at onl y one tide station, located at Father Point/Rimouski, Quebec, Canada. Orthometric datums such as NGVD 29 and NAVD 88 are referenced to tide gauges, so they are sometimes informally referred to as “sea level” datums because they are inherently tied to some form of mean sea level. NAVD 88 is the official verti cal datum of the United States, as stated in the Federal Register in 1993, and as such, it should serve as the reference for all products using land elevation data.

Water depths (bathymetry data) are usually refe renced vertically to a tidal datum, which is defined by a specific phase of the tides . Unlike orthometric datums such as NGVD 29 and NAVD 88, which have national or internatio nal coverage, tidally referenced datums are local datums because they are relative to nearby tide sta tions. Determination of tidal datums in the United States is based on obs ervations of water levels over a 19-year period, or tidal epoch. The current official tidal epoch in use is the 1983-2001 National Tidal Datum Epoch (NTDE). Averaging over th is period is necessary to remove random and periodic variations caused by seasonal differences and the nearly 19-year cycle of theCCSP 4.1 January 15, 2009

93 of 784 Final Report lunar orbit. NTDEs are updated approximately every 25 years to acc ount for relative sealevel change (NOAA, 2001). The following ar e the most commonly used tidal datums:

 Mean higher high water (MHHW): the aver age of the higher high water levels observed over a 19-year tidal epoch (only the higher water level of the pair of high waters in a tidal day is used);

 Mean high water (MHW): the average of the high water levels observed over a 19-year tidal epoch;

 Local mean sea level (LMSL): the average of hourly water levels observed over a 19-year tidal epoch;

 Mean low water (MLW): the average of the low water levels observed over a 19- year tidal epoch; and

 Mean lower low water (MLLW): the average of the lower low water levels observed over a 19-year tidal epoch (only th e lower water level of the pair of low waters in a tidal day is used). MLLW is the reference chart datum used for NOAA nautical chart products.

As an illustration, Figure 2.1 depicts the rela tionship among vertical datums for a point located on the shore at Gibson Island, Chesapea ke Bay. These elevations were calculated with use of the “VDatum” vertical datum transformation tool (Parker et al ., 2003; Myers, 2005), described in the following s ection. Sea-level rise trends at specific tide stations are generally calculated based on observed monthly mean sea level values to filter out the high frequency fluctuations in tide levels.CCSP 4.1 January 15, 2009

94 of 784 Final Report Figure 2.1 Diagram of the VDatum derived relationship among vertical datums for a point on the shore at Gibson Island, Chesapeake Bay. The point is located between the tide stations at Baltimore and Annapolis, Maryland where datum relationships are based on observations. The numbers represent the vertical difference above or below NAVD 88. For instance, at this location in the Chesapeake Bay the estimated MLLW reference is more than 20 centimeters below th e NAVD 88 zero reference, whereas local mean sea level is only about 1 centimeter below NAVD zero.
Based on surveys at tide stations, NAVD 88 ranges from 15 cm below to 15 cm above LMSL in the mid-Atlantic region. Due to slop es in the local sea surface from changes in tidal hydrodynamics, LMSL generally increa ses in elevation relative to NAVD 88 for locations increasingly farther up estuaries a nd tidal rivers. For smaller scale topographic maps and coarser resolution DEMs, the tw o datums are often reported as being equivalent, when in reality they are not. The di fferences should be reported as part of the uncertainty analyses. Differences between NAVD 88 and LMSL on the U.S. West Coast often exceed 100 cm and must be taken into account in any inundation mapping application. Similarly, but more importantl y, many coastal projects still inappropriately use NGVD 29 as a proxy for local mean sea level in planning, designing, and reference mapping. In the Mid-Atlantic, due to relativ e sea level change si nce 1929, the elevation of NGVD 29 ranges from 15 cm to more th an 50 cm below the elevation of LMSL Relationship of vertical datums for Gibson Island, Chesapeake Bay



### MLLW MLW LMSL NAVD 88 MHW MHHW

-0.80 ft -0.75 ft -0.53 ft -0.04 ft 0.00 ft 0.44 ft 0.72 ft

0.000 m -0.012 m -0.163 m -0.229 m -0.244 m 0.219 m 0.134 m

NGVD 29CCSP 4.1 January 15, 2009

95 of 784 Final Report (1983-2001 NTDE). This elevation difference must be taken into account in any type of inundation mapping. Again, because LMSL is a sloped surface relative to orthometric datums due to the complexity of tides in estuaries and inland waterways, the elevation separation between LMSL and NGVD 29 increases for locations farther up estuaries and tidal rivers.

2.2.4 Topographic/Bathymetric/Water Level Data Integration High-resolution datasets that effectively depict elevations across the land-sea boundary from land into shallow water are useful for many coastal applications (NRC, 2004), although they are not readily available for ma ny areas. Sea-level rise studies can benefit from the use of integrated topographic/bathymetric models because the dynamic land/water interface area, including the intertidal zone, is properly treated as one seamless entity. In addition, other coastal research topics rely on elevat ion data that represent nearshore topography and bathymetry (water dept hs), but because existing topographic, bathymetric, and water level data have b een collected independently for different purposes, they are difficult to use together . The USGS and the National Oceanic and Atmospheric Administration ( NOAA) have worked collaboratively to address the difficulties in using disparate elevation and depth information, initially in the Tampa Bay region in Florida (Gesch a nd Wilson, 2002). The key to su ccessful integration of topographic, bathymetric, and water level data is to place them in a consistent vertical reference frame, which is generally not the case with terrestrial and marine data. A vertical datum transformation tool calle d VDatum developed by NOAA’s National Ocean Service provides the capability to convert topographic, bath ymetric and water level dataCCSP 4.1 January 15, 2009

96 of 784 Final Report to a common vertical datum (Parker et al ., 2003; Myers, 2005). Work was completed in mid-2008 on providing VDatum coverage for th e mid-Atlantic region. VDatum uses tidal datum surfaces, derived from hydrodynamic mode ls corrected to match observations at tide stations, to interpolate the elevati on differences between LMSL and NAVD 88. An integrated uncertainty analysis fo r VDatum is currently underway by NOAA.

The National Research Council (NRC, 2004) ha s recognized the advantages of seamless data across the land/water in terface and has recommended a national implementation of VDatum and establishment of protocols for merged topographic/bathymetric datasets (NOAA, 2008a). Work has continued on producti on of other such merged datasets for coastal locations, including North Caro lina and the Florid a panhandle (Feyen et al ., 2005, 2008). Integrated topographic/ba thymetric lidar (Nayegandhi et al ., 2006; Guenther, 2007) has been identified as a valuable techno logy for filling critical data gaps at the land/water interface, which would facilitate development of more high quality datasets (NRC, 2004).

2.3 VULNERABILTY MAPS AND ASSESSMENTS Maps that depict coastal areas at risk of potential inundation or other adverse effects of sea-level rise are appealing to planners and land managers that are charged with communicating, adapting to, and reducing the risks (Coastal States Organization, 2007). Likewise, map-based analyses of sea-level rise vulnerability often include statistical summaries of population, infrastructure, a nd economic activity in the mapped impact zone, as this information is critical for risk management and mitigation efforts. ManyCCSP 4.1 January 15, 2009

97 of 784 Final Report studies have relied on elevation data to de lineate potential imp act zones and quantify effects. During the last 15 years, this appro ach has also been facilitated by the increasing availability of spatially ex tensive elevation, demographic, land use/land cover, and economic data and advanced geographic info rmation system (GIS) tools. These tools have improved access to data and have provide d the analytical software capability for producing map-based analyses and statistic al summaries. The body of peer reviewed scientific literature cited in this Chapter includes numerous studies that have focused on mapping and quantifying potential sea-level rise impacts.

A number of terms are used in the literature to describe the adverse effects of sea-level rise, including inundation , flooding , submergence , and land loss . Likewise, multiple terms are used to refer to what this Chapter has called vulnerability, including at risk , subject to , impacted by , and affected by . Many reports do not dis tinguish among the range of responses to sea-level rise , as described in Section 2.1. Instead, simple inundation, as a function of increased water levels projected onto the land surface, is assumed to reflect the vulnerability.

Monmonier (2008) has recognized the dual nature of sea-level rise vulnerability maps as both tools for planning and as cartographic instruments to illustrate the potential catastrophic impacts of climat e change. Monmonier cites repo rts that depict inundation areas due to very large increases in global sea-level. Frequently, however, the sea-level rise map depictions have no time scales and no indication of uncertainty or data limitations. Presumably, these broad-scale maps are in the illustration category, and onlyCCSP 4.1 January 15, 2009

98 of 784 Final Report site-specific, local scale produc ts are true planning tools, but therein is the difficulty. With many studies it is not clear if the maps (and associated statistical summaries) are intended simply to raise awaren ess of potential broad impacts or if they are intended to be used in decision making for specific locations.

2.3.1 Large-Area Studies (Global and United States) Sea-level rise as a consequence of climate cha nge is a global concern, and this is reflected in the variety of studies conducted for locati ons around the world as well as within the United States. Table 2.2 summarizes the characteristics of a nu mber of the sea-level rise assessments conducted over broad areas, with some of the studies discussed in more detail below.
Table 2.2 Characteristics of some sea-level rise asse ssments conducted over broad areas. GTOPO30 is a global raster DEM with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). SRTM is the Shuttle Radar Topogr aphy Mission data. NED is the National Elevation Dataset.
Study Study area Elevation data Sea-level rise scenario Elevation accuracy reported? Maps published?

Schneider and Chen (1980) Conterminous United States 15- and 25- foot contours from USGS 1:24,000-scale maps 4.6 and 7.6 m No Yes

U.S. EPA

(1989) Conterminous United States Contours from USGS maps 0.5, 1, and 2 m No No

Titus et al

.

(1991) Conterminous United States Contours from USGS maps, wetland delineations, and tide data 0.5, 1, and 2 m No No

FEMA (1991) United States Coastal floodplain

maps 1 ft and 3 ft No No

Small and Nicholls

(2003) Global GTOPO30 5-m land elevation increments Estimated a 5- meter uncertainty for elevation data (no error

metric specified) NoCCSP 4.1 January 15, 2009

99 of 784 Final Report Ericson et al

. (2006) 40 deltas distributed worldwide GTOPO30 0.5-12.5 mm per year for years 2000- 2050 No No Rowley et al

. (2007) Global GLOBE (GTOPO30) 1, 2, 3, 4, 5, and 6 m No Yes

McGranahan et al . (2007) Global SRTM Land elevations 0 to 10 m (to define the “low elevation coastal zone”) No, although 10-meter elevation increment was used in recognition of data limitations Yes

Demirkesen et

al . (2007) Izmir, Turkey SRTM 2 and 5 m Yes, but no error metric

specified Yes

Demirkesen et

al . (2008) Turkey SRTM 1, 2, and 3 m Yes, but no error metric

specified Yes Marfai and King (2008) Semarang, Indonesia Local survey data 1.2 and 1.8 m No Yes Kafalenos et

al . (2008) U.S. Gulf Coast NED 2 and 4 ft No Yes

Schneider and Chen (1980) presented one of th e early reports on potential sea-level rise impacts along U.S. coastlines. They used the 15-ft and 25-ft contours from USGS 1:24,000-scale maps to “derive approximate ar eas flooded within i ndividual counties” along the coast. As with many of the vulnerability studies, Schneider and Chen also combined their estimates of submerged area s with population and property value data to estimate socioeconomic impacts, in this case on a state-by-state basis.

Reports to Congress by the U.S. Environmental Protection Agency (EPA) and the Federal Emergency Management Agency (FEMA) cont ributed to the collection of broad area assessments for the United States. Th e EPA report (U.S. EPA, 1989; Titus et al ., 1991) examined several different global sea-level rise scenarios in the range of 0.5 to 2 m (1.6 to 6.6 ft), and also discussed impacts on wetlands under varying shoreline protectionCCSP 4.1 January 15, 2009

100 of 784 Final Report scenarios. For elevation information, the study used contours from USGS topographic maps supplemented with wetland delineations from Landsat satellite imagery and tide gauge data. The study found that the availabl e data were inadequate for production of detailed maps. The FEMA (1991) report estimat ed the increase of land in the 100-year floodplain from sea-level rises of 1 ft (0.3 m) and 3 ft (0.9 m). FEMA also estimated the increase in annual flood damages to insu red properties by the year 2100, given the assumption that the trends of development would continue.

Elevation datasets with global or near-global extent have been used for vulnerability studies across broad areas. For their studies of the global popul ation at risk from coastal hazards, Small and Nicholls (2003) and Ericson et al . (2006) used GTOPO30, a global 30-arc-second (about 1-kilometer [km]) eleva tion dataset produced by the USGS (Gesch et al ., 1999). Rowley et al . (2007) used the GLOBE 30-arc-second DEM (Hastings and Dunbar, 1998), which is derived mostly fr om GTOPO30. As with many vulnerability studies, these investigations used the delinea tions of low-lying lands from the elevation model to quantify the population at risk from sea-leve l rise, in one instance using increments as small as 1 m (Rowley et al ., 2007).

Elevation data from the Shuttle Radar Topography Mission (SRTM) (Farr et al ., 2007) are available at a 3-arc-second (about 90-m) resolution with n ear-global coverage. Because of their broad area coverage a nd improved resolution over GTOPO30, SRTM data have been used in several studies of the land area and populat ion potentially at risk from sea-level rise (McGranahan et al ., 2007; Demirkesen et al ., 2007, 2008). Similar toCCSP 4.1 January 15, 2009

101 of 784 Final Report other studies, McGranahan et al . (2007) present estimates of the population at risk, while Demirkesen et al . (2007) document the dominant land use/land cover classes in the delineated vulnerable areas.

2.3.2 Mid-Atlantic Region, States, and Localities A number of sea-level rise vul nerability studies have been published for sites in the midAtlantic region, the focus area for this Produc t. Table 2.3 summarizes the characteristics for these reports, and important information from some of the studies is highlighted.

Table 2.3 Characteristics of some sea-level rise vulnerability studies conducte d over mid-Atlantic locations. GTOPO30 is a global raster DEM with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). SRTM is the Shuttl e Radar Topography Mission data. NED is the National Elevation Dataset.
Study Study area Elevation data Sea-level rise scenarios Elevation accuracy reported? Maps published? Titus and Richman

(2001) U.S. Atlantic and Gulf

coasts USGS DEMs derived from

1:250,000- scale maps 1.5- and 3.5-m land elevation

increments No Yes Najjar et al

. (2000) Delaware 30-meter USGS DEMs 2 ft No Yes Kleinosky et

al . (2007) Hampton Roads, Virginia 10-meter and 30-meter USGS DEMs 30, 60, and 90 cm No Yes

Wu et al

.

(2002) Cape May County, New Jersey 30-meter USGS DEMs 60 cm No Yes

Gornitz et al

. (2002) New York City area 30-meter USGS DEMs 5-ft land elevation increments No, although only qualitative results were

reported Yes

Titus and Wang (2008) Mid-Atlantic states Contours from USGS 1:24,000-scale

maps, lidar,

local data 0.5-m land elevation increments Yes, RMSE vs. lidar for a portion of the

study area Yes

Larsen et al

. (2004) Blackwater Natio nal Wildlife Refuge, Maryland Lidar 30-cm land elevation increments No YesCCSP 4.1 January 15, 2009

102 of 784 Final Report Gesch, (2009) North Carolina GTOPO30, SRTM, NED, lidar 1 m Yes, with NSSDA error metric (95% confidence) Yes

A study by Titus and Richman (2001) is often re ferred to in discussions of the land in the United States that is subject to the effects of sea-level ri se. The methods used to produce the maps in that report are clearly documente d. However, because they used very coarse elevation data (derived from USGS 1: 250,000-scale topographic ma ps), the resulting products are general and limited in their ap plicability. The authors acknowledge the limitations of their results because of the source data they used, and clearly list the caveats for proper use of the maps. As such, these maps are useful in depicting broad implications of sea-level rise, but are not appropriate for site-specific decision making.

Numerous studies have used the NED, or the underlying USGS DEMs from which much of the NED is derived, as the i nput elevation information. Najjar et al . (2000) show an example of using USGS 30-m DEMs for a simp le inundation model of Delaware for a 2- ft (0.6-m) sea-level rise . In another study, Kleinosky et al . (2007) used elevation information from USGS 10-m and 30-m DEMs to depict vulnerability of the Hampton Roads, Virginia area to storm surge flooding in addition to sea-level rise. Storm surge heights were first determined by modeling, th en 30-, 60-, and 90-cm increments of sealevel rise were added to project the expansi on of flood risk zones onto the land surface. In addition, Wu et al . (2002) conducted a study for Cape May County, New Jersey using an approach similar to Kleinosky et al . (2007), where they added 60 cm to modeled storm surge heights to account for sea-level rise.CCSP 4.1 January 15, 2009

103 of 784 Final Report More recently, Titus and Wang (2008) conducted a study of the mid-Atlantic states (New York to North Carolina) using a variety of elevation data sources including USGS 1:24,000-scale topographic maps (mostly with 5- or 10-ft contour in tervals), lidar data, and some local data provided by state agenci es, counties, and municipalities. They used an approach similar to that described in Titus and Richman (2001) in which tidal wetland delineations are employed in an effort to es timate additional elevation information below the first topographic map contour.

2.3.3 Other Reports In addition to reports by federal government agencies and studies published in the peerreviewed scientific literature, there have been numerous assessment reports issued by various non-governmental organizations, univers ities, state and local agencies, and other private groups ( e.g. , Anthoff et al ., 2006; Dasgupta et al ., 2007; Stanton and Ackerman, 2007; US DOT, 2008; Mazria and Kershner, 2007; Glick et al ., 2008; Cooper et al ., 2005; Lathrop and Love, 2007; Johnson et al ., 2006; Bin et al ., 2007; Slovinsky and Dickson, 2006). While it may be difficult to judg e the technical veracity of the results in these reports, they do share common characteris tics with the studies reviewed in Sections 2.3.1 and 2.3.2. Namely, they make use of th e same elevation datasets (GTOPO30, SRTM, NED, and lidar) to proj ect inundation from sea-level ri se onto the land surface to quantify vulnerable areas, and they present st atistical summaries of impacted population and other socioeconomic variables. Many of these reports include detailed maps and graphics of areas at risk. Although some are also availabl e in printed formats, all of theCCSP 4.1 January 15, 2009

104 of 784 Final Report reports listed above are available onlin e (see Chapter 2 References for website information).

This category of reports is hi ghlighted because some of the reports have gained wide public exposure through press releases and subs equent coverage in the popular press and on Internet news sites. For example, the repo rt by Stanton and Ackerman (2007) has been cited at least eight times by the mainstream media (see: <http://ase.tufts.edu/gdae/Pubs/rp/FloridaClima te.html>). The existence of this type of report, and the attention it has r eceived, is likely an indicatio n of the broad public interest in sea-level rise issues. Thes e reports are often written from an economic or public policy context rather than from a geosciences perspe ctive. Nevertheless, it is important for the coastal science community to be cognizant of them because the reports often cite journal papers and they serve as a conduit for co mmunicating recent sea-level rise research results to less technical audiences . It is interesting to note that all of the reports listed here were produced over the last three years, thus, it is likely that that this type of outlet will continue to be used to discu ss sea-level rise issues as globa l climate change continues to garner more public attention. Arguably, sea- level rise is among the most visible and understandable consequences of climate cha nge for the general public, and they will continue to seek information about it from th e popular press, Internet sites, and reports such as those described here.

2.3.4 Limitations of Previous StudiesCCSP 4.1 January 15, 2009

105 of 784 Final Report It is clear from the literature review ed in Sections 2.3.1, 2.3.2, and 2.3.3 that the development of sea-level rise impact assessments has been an active research topic for the past 25 years. However, there is still significant progress to be made in improving the physical science-based information needed for decision making by planners and land and resource managers in the coastal zone. Although previous studies have brought ample attention to the problem of mapping and quantif ying sea-level rise impacts, the quality of the available input data and the common te ndency to overlook the consequences of coarse data resolution and large uncertainty ranges hinder the usefulness and applicability of many results. Specifically, fo r this Product, none of the previous studies covering the mid-Atlantic region can be used to fully an swer with high confid ence the Synthesis and Assessment Product (SAP) 4.1 prospectus question (CCSP, 2006) that re lates directly to coastal elevations: “Which lands are currently at an elevation that could lead them to be inundated by the tides without shore protec tion measures?” The collective limitations of previous studies are described in this Section, while the “les sons learned”, or recommendations for required qualities of futu re vulnerability assessments, are discussed in Section 2.4.

Overall, there has been little recognition in previous studies that inundation is only one response out of a number of possible responses to sea-level rise (see Section 2.1). Some studies do mention the various types of co astal impacts (erosion, saltwater intrusion, more extreme storm surge flooding) (Najjar et al ., 2000; Gornitz et al ., 2002), and some studies that focus on wetland impacts do cons ider more than just inundation (U.S.EPA, 1989; Larsen et al ., 2004). However, in general, many vulnerability maps (andCCSP 4.1 January 15, 2009

106 of 784 Final Report corresponding statistical summaries) imply th at a simple inundation scenario is an adequate representation of the impacts of ri sing seas (Schneider and Chen, 1980; Rowley et al ., 2007; Demirkesen et al ., 2008; Najjar et al ., 2000).

Based on the review of the studies cite d in Sections 2.3.1, 2.3.2, and 2.3.3, these general limitations have been identified:
1. Use of lower resolution elevation data with poor vertical accuracy. Some studies have had to rely on elevation datasets th at are poorly suited for detailed inundation mapping ( e.g. , GTOPO30 and SRTM). While these gl obal datasets may be useful for general depictions of low el evation zones, their relativ ely coarse spatial detail precludes their use for production of detailed vulnerability maps. In addition to the limited spatial detail, these datasets have elevation values quan tized only to whole meter intervals, and their overall vertical accuracy is poor when compared to the intervals of predicted sea-level rise over the next century. The need for better elevation information in sea-level rise assessments has been broadly recognized (Leatherman, 2001; Marbaix, and Nicholls, 2007; Jacob et al ., 2007), especially for large-scale planning maps (Monmonier, 2008) and detailed quantitative assessments (Gornitz et al ., 2002).

2. Lack of consideration of uncerta inty of input elevation data. A few studies generally discuss the limitati ons of the elevation data us ed in terms of accuracy (Small and Nicholls, 2003; McGranahan et al ., 2007; Titus and Wang, 2008). However, none of these studies exhibit rigorous accuracy testing and reportingCCSP 4.1 January 15, 2009

107 of 784 Final Report according to accepted national standards (NSSDA and NMAS). Every elevation dataset has some vertical error, which can be tested and measured, and described by accuracy statements. The overall vertical error is a measure of the uncertainty of the elevation information, and that uncertainty is propagated to any derived maps and statistical summaries. Gesch (2009) demonstr ates why it is important to account for vertical uncertainty in sea- level rise vulnerability maps and area sta tistics derived from elevation data (see Box 2.1).

3. Elevation intervals or sea-le vel rise increments not s upported by vertical accuracy of input elevation data. Most elevation datasets, with the exception of lidar, have vertical accuracies of several meters or even tens of meters (at the 95 percent confidence level). Figure 2.2 shows a graphi cal representation of DEM vertical accuracy using error bars around a specified elevation. In this case, a lidar-derived DEM locates the 1-meter elevation to with in ±0.3 m at 95-percent confidence. (In other words, the true elevation at that lo cation falls within a range of 0.7 to 1.3 m.) A less accurate topographic map- derived DEM locates the 1-m elevation to within ±2.2 m at 95-percent confidence, which means the true land elevation at that location falls within a range of 0 (assuming sea level was delineated accurately on the original topographic map) to 3.2 m. Many of the stud ies reviewed in this Chapter use land elevation intervals or sea-level rise increm ents that are 1 m or less. Mapping of submeter increments of sea-level rise is highly questionable if the elevation data used have a vertical accuracy of a meter or mo re (at the 95-percent confidence level) (Gesch, 2009). For example, by definition a topographic map with a 5-ft contourCCSP 4.1 January 15, 2009

108 of 784 Final Report interval that meets NMAS has an absolute vertical accuracy (which accounts for all effects of systematic and random errors) of 90.8 cm at the 95-percent confidence level (Maune, et al ., 2007b). Likewise, a 10-ft contour interv al map has an absolute vertical accuracy of 181.6 cm (1.816 m) at the 95-percen t confidence level. If such maps were used to delineate the inundation zone from a 50-cm s ea-level rise, the results would be uncertain because the vertical incremen t of rise is well within the bounds of statistical uncertainty of the elevation data.

Figure 2.2 Diagram of how a sea-level rise of 1 meter is mapped onto the land surface using two digital elevation models with differing vertical accuracies. The more accurat e lidar-derived DEM (±0.3 m at 95-percent confidence) results in a delineation of the inundation zone with much less uncertainty than when the less accurate topographic map-derived DEM (±2.2 m at 95-percent confidence) is used (Gesch, 2009).

4. Maps without symbology or caveats concer ning the inherent vertic al uncertainty of input elevation data. Some studies have addressed limitations of their maps and statistics (Titus and Richman, 2001; Najjar et al ., 2000), but most reports presentCCSP 4.1 January 15, 2009

109 of 784 Final Report maps without any indication of the error a ssociated with the unde rlying elevation data (see number 3 above). Gesch (2009) presents one method of spa tially portraying the inherent uncertainty of a mapped sea- level rise inundation zone (see Box 2.1).

5. Inundated area and impacted population esti mates reported without a range of values that reflect the in herent vertical uncertainty of input elevation data. Many studies use the mapped inundation zone to calc ulate the at-risk area, and then overlay that delineation with spatially distributed population data or other socioeconomic variables to estimate impacts. If a spa tial expression of the uncertainty of the inundation zone (due to the vertical error in the elevation data) is not included, then only one total can be reported. More comp lete and credible information would be provided if a second total wa s calculated by including the variable (area, population, or economic parameter) that falls within an additional delineation that accounts for elevation uncertainty. A range of values can then be reported, which reflects the uncertainty of the mapped inundation zone.

6. Lack of recognition of differences among reference orthometric datums, tidal datums, and spatial variations in sea-level datums. The vertical reference frame of the data used in a particular study needs to be specified, especially for local studies that produce detailed maps, since there can be significant differences between an orthometric datum zero reference and mean sea level (Figure 2.1; see also Section 2.2.3). As described earlier, there are im portant distinctions between vertical reference systems that are used for land elev ation datasets and those that are used toCCSP 4.1 January 15, 2009

110 of 784 Final Report establish the elevations of sea level. Most of the reviewed st udies did not specify which vertical reference frame was used. Often, it was probably an orthometric datum because most elevation datasets are in reference to such datums. Ideally, a tool such as VDatum will be available so that data may be easily transformed into a number vertical reference frames at the discretion of the user.

Start box***** Text Box 2.1: A Case Study Using Lidar Elevation Data To illustrate the application of elevation uncertainty information and the advantages of lidar elevation data for sea-level rise assessment, a case study for Nort h Carolina (Gesch, 2009) is presented and summarized here. North Carolina has a broad expanse of low-lying land (Titus and Richman, 2001), and as such is a good site for a mapping comparison. Lidar data at 1/9-arc-second (about 3 meters [m]) grid spacing were analyzed and compared to 1-arc-second (about 30 m) DEMs derived from 1:24,000-scale topographic maps. The potential inundation zone from a 1-m sea-level rise was mapped from both elevation datasets, and the corresponding areas were compared. The anal ysis produced maps and statistics in which the elevation uncertainty was considered . Each elevation dataset was “floode d” by identifying the grid cells that have an elevation at or below 1 m and are conn ected hydrologically to the ocean through a continuous path of adjacent inundated grid cells. For each datase t, additional areas were de lineated to show a spatial representation of the uncertainty of the projected inundation area. This was accomplished by adding the linear error at 95-percent confidence to the 1-m sea-level increase an d extracting the area at or below that elevation using the same flooding algorithm. The lidar data exhibited ±0.27 m error at 95-percent confidence based on accuracy reports from the data producer, while the topogr aphic map-derived DEMs had ±2.21 m error at 95-percent confidence based on an accuracy assessment w ith high-quality surveyed control points. Box Figure 2.1 and Box Table 2.1 show the results of the North Carolina mapping comparison. In Box Figure 2.1 the darker blue tint represents the area at or below 1-m in elevation, and the lighter blue tint represents the additional area in th e vulnerable zone given the vertical uncertainty of the input elevation datasets. The more accurate lidar data for delineation of the vulnerable zone results in a more certain delineation (Box Figure 2.1B), or in other words the zone of uncertainty is small. Box Table 2.1 compares the vulnerable areas as delineated fr om the two elevation datasets. The delineation of the 1-m zone from the topographic map-derived DEMs more than doubles wh en the elevation uncertain ty is considered, which calls into question the reliability of any conclusions drawn from the delineation. It is apparent that for this site the map-derived DEMs do not have the vertical accuracy required to reliably delineate a 1-m sea-level rise inundation zone. Lidar is the appropriate eleva tion dataset for answering the question about how much land in the study site is vulnerable to a 1-m sea-level ri se, for which the answer is: “4,195 to 4,783 square kilometers (sq km) at a 95-percent confidence level” . This case study emphasizes why a range of values should be given when reporting the size of the inundation area for a given sea-level rise scenario, especially for sites where high-accuracy lidar data are not availa ble Without such a range being reported, users of an assessment report may not understand the amount of uncertainty associated with area delineations from less accurate data and the implications for any subsequent decisions based on the reported statistics. Box Table 2.1 The area of land vulnerable to a 1-meter sea-level rise as calculated from two elevation datasets (see Box Figure 2.1), as well as the area of vulnerability when the uncertainty of the elevation data is considered (Gesch, 2009).CCSP 4.1 January 15, 2009

111 of 784 Final Report Elevation dataset Area less than or equal to 1 meter in elevation (sq km) Area less than or equal to 1 meter in elevation at 95 percent confidence

(sq km) Percent increase in vulnerable area when elevation uncertainty is included 1-arc-second (30-m) DEMs derived from 1:24,000-scale

topographic maps 4,014 8,578 114%

1/9-arc-second (3-m) lidar elevation grid 4,195 4,783 14%CCSP 4.1 January 15, 2009

112 of 784 Final Report Box Figure 2.1 Lands vulnerable to a 1-meter sea-level rise, developed from topographic map-derived DEMs (A), and lidar elevation data (B) (Gesch, 2009) . The background is a recent true color orthoimage.

End Box 2.1****

2.4 FUTURE VULNERABILITY ASSESSMENTSCCSP 4.1 January 15, 2009

113 of 784 Final Report To fully answer the relevant elevation ques tion from the prospectus for this SAP 4.1 (see Section 2.3.4), there are important technical considera tions that need to be incorporated to improve future sea-level rise impact as sessments, especially those with a goal of producing vulnerability maps a nd statistical summaries of im pacts. These considerations are important for both the researchers who de velop impact assessments, as well as the users of those assessments who must understand the technical issues to properly apply the information. The recommendations for impr ovements described below are based on the review of the previous st udies cited in Sections 2.3.1, 2.3.2, 2.3.3, and other recent research:

1. Determine where inundation will be th e primary response to sea-level rise. Inundation (submergence of the uplands) is only one of a number of possible responses to sea-level rise (Leathe rman, 2001; Valiela, 2006; FitzGerald et al ., 2008). If the complex nature of coastal change is not recognized up front in sea-level rise assessment reports, a reader may mistakenly a ssume that all stretches of the coast that are deemed vulnerable will experience the same “flooding” impact, as numerous reports have called it. For the coastal settings in wh ich inundation is the primary vulnerability, elevation data sets should be analyzed as detailed below to produce comprehensive maps and statistics.

2. Use lidar elevation data (or other hi gh-resolution, high-accuracy elevation source). To meet the need for more accurate, detailed, and up-to-date sea-level rise vulnerability assessments, new studies s hould be based on recently collected high-CCSP 4.1 January 15, 2009

114 of 784 Final Report resolution, high-accuracy, lidar elevation data. Other mapping approaches, including photogrammetry and ground surveys, can pr oduce high-quality eleva tion data suitable for detailed assessments, but lidar is the preferred approach for cost-effective data collection over broad coastal areas. Lidar has the added ad vantage that, in addition to high-accuracy measurements of ground el evation, it also can be used to produce information on buildings, infrastructure, a nd vegetation, which may be important for sea-level rise impact assessments. As L eatherman (2001) points out, inundation is a function of slope. The ability of lidar to measure elevations very precisely facilitates the accurate determination of even small sl opes, thus it is quite useful for mapping low relief coastal landforms. The numerous advantages of lidar elevation mapping in the coastal zone have been widely re cognized (Leatherman, 2001; Coastal States Organization, 2007; Monmonier, 2008; S ubcommittee on Disaster Reduction, 2008; Feyen et al ., 2008; Gesch, 2009). A recent study by the National Research Council (NRC, 2007) concluded that FEMA’s requi rements for floodplain mapping would be met in all areas by elevation data with 1-ft to 2-ft equivalent contour accuracy, and that a national lidar program called “Eleva tion for the Nation” should be carried out to create a new national DEM. Elevation da ta meeting 1-ft contour interval accuracy (NMAS) would allow effective sea-level ri se inundation modeling for increments in the 0.35 m range, while data with 2-ft contou r interval accuracy would be suitable for increments of about 0.7 m.

3. Test and report absolute vertical accuracy as a measure of elevation uncertainty. Any studies that use elevation data as an input for vulnerabi lity maps and/or statisticsCCSP 4.1 January 15, 2009

115 of 784 Final Report need to have a clear statemen t of the absolute vertical accuracy (in reference to true ground elevations). The NSSDA vertical accuracy testing and reporting methodology (Federal Geographic Data Committee, 1998), wh ich uses a metric of linear error at 95-percent confidence, is the preferred approach. Vertical accuracy may be reported with other metrics in cluding RMSE, standard deviati on (one sigma error), LE90, or three sigma error. Maune et al . (2007b) and Greenwalt a nd Shultz (1962) provide methods to translate among the different erro r metrics. In any case, the error metric must be identified because quoting an accuracy figure without specifying the metric is meaningless. For lidar elevation data, a sp ecific testing and repor ting procedure that conforms to the NSSDA has been deve loped by the National Digital Elevation Program (NDEP) (2004). The NDEP guidelines are useful because they provide methods for accuracy assessment in “open terrain” versus other land cover categories such as forest or urban areas where the lidar sensor may not have detected ground level. NDEP also provides guidance on accuracy testing and reporting when the measured elevation model errors are from a non-Gaussian (non-normal) distribution.

4. Apply elevation uncertainty information in development of vulnerability maps and
area statistics. Knowledge of the uncertainty of input elevation data should be incorporated into the devel opment of sea-level rise impact assessment products. In this case, the uncertainty is expressed in the verti cal error determined through accuracy testing, as described above. Other hydrologic applications of elevation data, including rainfall runoff modeling (Wu et al ., 2008) and riverine flood inundation modeling (Yilmaz et al ., 2004, 2005), have benefitted from the incorporation ofCCSP 4.1 January 15, 2009

116 of 784 Final Report elevation uncertainty. For s ea-level rise inunda tion modeling, the error associated with the input elevation dataset is used to include a zone of uncertainty in the delineation of vulnerable land at or below a specific elevation. For example, assume a map of lands vulnerable to a 1-m sea-level ri se is to be developed using a DEM. That DEM, similar to all elevation datasets, has an overall vertical e rror. The challenge, then, is how to account for the elevation uncer tainty (vertical error) in the mapping of the vulnerable area. Figure 2.2 (Gesch, 2009) shows how the elevation uncertainty associated with the 1-m level, as expre ssed by the absolute vertical accuracy, is projected onto the land surface. The topogra phic profile diagram shows two different elevation datasets with differing vertical ac curacies depicted as error bars around the 1-m elevation. One dataset has a vertical accuracy of ±0.3 m at the 95-percent confidence level, while the other has an accuracy of ±2.2 m at the 95-percent confidence level. By adding the error to the projected 1-m sea-leve l rise, more area is added to the inundation zone delineation, and this a dditional area is a spatial representation of the uncertainty. The additi onal area is interpreted as the region in which the 1-m elevation may actually fall, given the statistical uncertainty of the
DEMs.

Recognizing that elevation data inherently have vertical unce rtainty, vulnerability maps derived from them should include so me type of indication of the area of uncertainty. This could be provided as a caveat in the map legend or margin, but a spatial portrayal with map symbolo gy may be more effective. Merwade et al . (2008) have demonstrated this approach for floodplain mapping where the modeledCCSP 4.1 January 15, 2009

117 of 784 Final Report inundation area has a surrounding uncertainty zone depicted as a buffer around the flood boundary. Gesch (2009) used a similar approach to show a spatial representation of the uncertainty of the pr ojected inundation area fr om a 1-m sea-level rise, with one color for the area below 1- m in elevation and another color for the adjacent uncertainty zone (see Box 2.1).

As with vulnerability maps derived from elevation data, statistical summaries of affected land area, population, land use/la nd cover types, number of buildings, infrastructure extent, and other socioeconom ic variables should include recognition of the vertical uncertainty of the underlying data. In many studies, the delineated inundation zone is intersected with geospa tial representations of demographic or economic variables in order to summarize th e quantity of those va riables within the potential impact zone. Such overlay and summarizing operations should also include the area of uncertainty associated with th e inundation zone, and t hus ranges of the variables should be reported. The range for a particular va riable would increase from the total for just the proj ected inundation zone up to the combined total for the inundation zone plus the adjacent uncerta inty zone. Additionally, because the combined area of the inundation zone and its adjacent uncertainty zone has a known confidence level, the range can be reported wi th that same confidence level. Merwade et al . (2008) have recommended such an appr oach for floodplain mapping when they state that the flood inundation extent should be reported as being “in the range from x units to y units with a z -% confidence level”.CCSP 4.1 January 15, 2009

118 of 784 Final Report An important use of elevation data accuracy information in an assessment study is to guide the selection of land elevation interv als or sea-level rise increments that are appropriate for the available data. Inundati on modeling is usually a simple process wherein sea level is effectively raised by delineating the area at and below a specified land elevation to create the inundation z one. This procedure is effectively a contouring process, so the vertical accur acy of a DEM must be known to determine the contour interval that is supported. DE Ms can be contoured at any interval, but, just by doing so, it does not mean that the contours meet published accuracy standards. Likewise, studies can use sma ll intervals of sea-level rise, but the underlying elevation data must have the ver tical accuracy to suppor t those intervals. The intervals must not be so small that th ey are within the bounds of the statistical uncertainty of the elevation data.

5. Produce spatially explicit maps and detailed statistics that can be used in local decision making. The ultimate use of a sea-level ri se assessment is as a planning and decision-making tool. Some assessments cove r broad areas and are useful for scoping the general extent of the ar ea of concern for sea-level rise impacts. However, the smaller-scale maps and corresponding statis tics from these broad area assessments cannot be used for local decision making, wh ich require large-scale map products and site specific information. Such spatiall y explicit planning maps require highresolution, high-accuracy input data as source information. Monmonier (2008) emphasizes that “reliable large-scale planni ng maps call for markedly better elevation data than found on conventional topographi c maps”. Even with source data thatCCSP 4.1 January 15, 2009

119 of 784 Final Report supports local mapping, it is importa nt to remember, as Frumhoff et al . (2007) point out, due to the complex nature of coastal dynamics that “projecting the impacts of rising sea level on specific locations is not as simple as mapping which low-lying areas will eventually be inundated”.

Proper treatment of elevation uncertainty is especially important for development of large-scale maps that will be used for pl anning and resource management decisions. Several states have realized the advantages of using high-accuracy lidar data to reduce uncertainty in sea-level rise studies and development of local map products (Rubinoff, et al ., 2008). Accurate local-scale maps can also be generalized to smaller-scale maps for assessments over larger areas. Such aggregation of detailed information benefits broad area studies by incorporating the best av ailable, most detailed information.

Development of large-scale spatially explicit maps presents a new set of challenges. At scales useful for local decision making, th e hydrological connectivity of the ocean to vulnerable lands must be mapped and considered . In some vulnerable areas, the drainage network has been artificially modified with di tches, canals, dikes, levees, and seawalls that affect the hydrologic pa ths rising water can traver se (Poulter and Halpin, 2007; Poulter et al ., 2008). Fortunately, lidar data often in clude these important features, which are important for improving large-scal e inundation modeling (Coastal States Organization, 2007). Older, lowe r resolution elevation data often do not include these fine-scale manmade features, which is anot her limitation of these data for large-scale
maps.CCSP 4.1 January 15, 2009

120 of 784 Final Report Other site-specific data shoul d be included in impact assessments for local decision making, including knowledge of local sea-level rise trends and the differences among the zero reference for elevation data (often an orthometric datum), local mean sea level, and high water (Marbaix, and Nic holls, 2007; Poulter and Halpin , 2007). The high water level is useful for inundation mapping because it distinguishes the area of periodic submergence by tides from those areas that may become inundated as sea-level rises (Leatherman, 2001). The importance of knowing the local relationships of water level and land vertical reference systems emphasizes the need for a national implementation of VDatum (Parker et al ., 2003; Myers, 2005) so that accurate information on tidal dynamics can be incorporated into local sea-level rise assessments.

Another useful advance for detailed sea-level rise assessments can be realized by better overlay analysis of a delineated vulnerability zone and local popul ation data. Population data are aggregated and reported in census bl ocks and tracts, and ar e often represented in area-based statistical thematic maps, also known as choropleth maps. However, such maps usually do not represent actual populat ion density and distribution across the landscape because census units include both inhabited and uninhabited land. Dasymetric mapping (Mennis, 2003) is a technique that is used to disaggregate population density data into a more realistic spatial distri bution based on ancillary land use/land cover information or remote sensing images (Sleeter and Gould, 2008; Chen, 2002). This technique holds promise for better analysis of population, or other socioeconomic data, to report statistical summaries of sea-level rise impacts within vulnerable zones.CCSP 4.1 January 15, 2009

121 of 784 Final Report 2.5 SUMMARY, CONCLUSIONS, AND FUTURE DIRECTIONS The topic of coastal elevations is most relevant to the fi rst SAP 4.1 prospectus question (CCSP, 2006): “Which lands are currently at an elevation that coul d lead them to be inundated by the tides without shore protec tion measures?” The difficulty in directly answering this question for the mid-Atlantic region with a high degree of confidence was recognized. Collectively, the av ailable previous studies do no t provide the full answer for this region with the degree of confidence th at is optimal for local decision making. Fortunately, new elevation data, especially lidar, are becoming available and are being integrated into the USGS NED (Gesch, 2007) as well as being used in sea-level rise applications (Coastal States Organization, 2007). Also, resear ch is progressing on how to take advantage of the increased spatial resolution and vertical accuracy of new data (Poulter and Halpin, 2007; Gesch, 2009).

Using national geospatial standards for accu racy assessment and reporting, the currently best available elevation data for the entir e mid-Atlantic region do not support an assessment using a sea-level rise increment of 1-m or less, which is slightly above the range of current estimates for the remainder of this century and the high scenario used in this Product. Where lidar data meeting cu rrent industry standards for accuracy are available, the land area below the 1-m contour (simulating a 1-m sea-level rise) can be estimated for those sites along the coast at which inundation will be the primary response. The current USGS holdings of the best availa ble elevation data include lidar for North Carolina, parts of Maryland, and parts of New Jersey (Figure 2.3). Lidar data for portionsCCSP 4.1 January 15, 2009

122 of 784 Final Report of Delaware and more of New Jersey and Maryland will be integrated into the NED in 2009. However, it may be some time before the full extent of the mid-Atlantic region has sufficient coverage of elevation data that are suitable for detailed assessments of submeter increments of sea-level rise and deve lopment of spatially explicit local planning
maps.

Figure 2.3 The current best available elevation source data (as of August 2008) for the National Elevation Dataset over the mid-Atlantic region.

Given the current status of th e NED for the mid-Atlantic re gion (Figure 2.3), the finest increment of sea-level rise that is supporte d by the underlying eleva tion data varies across the area (Table 2.4 and Figure 2.4). At a minimu m, a sea-level rise increment used for inundation modeling should not be smaller than the range of st atistical uncertainty of the elevation data. For instance, if an elevation da taset has a vertical accuracy of ±1 m at 95- percent confidence, the smallest sea-level rise increment that should be considered is 1 m.CCSP 4.1 January 15, 2009

123 of 784 Final Report Even then, the reliability of the vulnerable area delineation would not be high because the modeled sea-level rise increment is the same as the inherent verti cal uncertainty of the elevation data. Thus, the reliability of a delin eation of a given sea-level rise scenario will be better if the inherent vert ical uncertainty of the elevati on data is much less than the modeled water level rise For example, a sea-le vel rise of 0.5 m is reliably modeled with elevation data having a verti cal accuracy of ±0.25 m at 95-percent confidence. This guideline, with the eleva tion data being at least twice as accurate as the modeled sea-level rise, was applied to derive the numbers in Table 2.4.
Table 2.4 Minimum sea-level rise scenarios for vulnerability assessments supported by elevation datasets of varying vertical accuracy.

Elevation data source Vertical accuracy: RMSE Vertical accuracy: linear error at 95-percent confidence Minimum sea-level rise increment for inundation modeling 1-foot contour interval map 9.3 cm 18.2 cm 36.4 cm

Lidar 15.0 cm 29.4 cm 58.8 cm

2-foot contour interval map 18.5 cm 36.3 cm 72.6 cm

1-meter contour interval map 30.4 cm 59.6 cm 1.19 m

5-foot contour interval map 46.3 cm 90.7 cm 1.82 m

10-foot contour interval map 92.7 cm 1.82 m 3.64 m

20-foot contour interval map 1.85 m 3.63 m 7.26 mCCSP 4.1 January 15, 2009

124 of 784 Final Report Figure 2.4 The estimated minimum sea-level rise scenarios for inundation modeling in the mid-Atlantic region given the current best available elevation data.
High-quality lidar elevation data, such as that which could be collect ed in a national lidar survey, would be necessary for the entire co astal zone to complete a comprehensive assessment of sea-level rise vu lnerability in the mid-Atlantic region. Lidar remote sensing has been recognized as a means to provide highly detailed and accurate data for numerous applications, and ther e is significant interest from the geospatial community in developing an initiative for a national lidar collection for the United States (Stoker et al ., 2007, 2008). If such an initiative is successful , then a truly national assessment of potential sea-level rise impacts could be realized. A U.S. national lidar dataset would facilitate consistent assessment of vulnerab ility across state or jurisdictional boundaries, an approach for which coastal states ha ve voiced strong advocacy (Coastal StatesCCSP 4.1 January 15, 2009

125 of 784 Final Report Organization, 2007). Even with the current investment in lidar by several states, there is a clear federal role in the development of a national lidar program (NRC, 2007; Monmonier, 2008; Stoker et al ., 2008).

Use of recent, high-accuracy lidar elevation da ta, especially with full consideration of elevation uncertainty as described in S ection 2.4, will result in a new class of vulnerability maps and statis tical summaries of impacts. These new assessment products will include a specific level of confidence, with ranges of variables reported. The level of statistical confidence could even be user selectable if asse ssment reports publish results at several confidence levels.

It is clear that improved elevation data and analysis techniques will lead to better sealevel rise impact assessments. However, ne w assessments must include recognition that inundation, defined as submergence of the uplan ds, is the primary response to rising seas in only some areas. In other areas, the response may be dominated by more complex responses such as those involving shoreline erosion, wetland accretion, or barrier island migration. These assessments should first consider the geological setting and the dominant local physical proce sses at work to determine where inundation might be the primary response. Analysis of lidar elevation data, as outlined above, should then be conducted in those areas.

Investigators conducting sea-level rise impact studies should strive to use approaches that generally follow the guidelines above so that results can be consiste nt across larger areasCCSP 4.1 January 15, 2009

126 of 784 Final Report and subsequent use of the maps and data can reference a common baseline. Assessment results, ideally with spatially explicit vulnera bility maps and summar y statistics having all the qualities described in Section 2.4, should be published in peer-reviewed journals so that decision makers can be confident of a sound scientific base for their decisions made on the basis of the findings. If necessar y, assessment results can be reformatted into products that are more easily used by lo cal planners and decision makers, but the scientific validity of the information remains.CCSP 4.1 January 15, 2009

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141 of 784 Final Report 

## Chapter 3. Ocean Coasts

Authors: Benjamin T. Gutierrez, USGS; S. Jeffress Williams, USGS; E. Robert Thieler,
USGS

KEY FINDINGS

 Along the ocean shores of the Mid-Atlant ic, which are comprised of headlands, barrier islands, and spits, it is virtually certain that erosion will dominate changes in shoreline position in response to sea- level rise and storms over the next century.

 It is very likely that landforms along the mid-Atla ntic coast of the United States will undergo large changes if the higher sea-level rise scenarios occur. The response will vary depending on the type of coastal landforms and the local geologic and oceanographic conditions, and could be more variable than the changes observed over the last century.

 For higher sea-level rise scenarios, it is very likely that some barrier island coasts will cross a threshold and undergo signifi cant changes. These changes include more rapid landward migration or segm entation of some barrier islands.

3.1 INTRODUCTION The general characteristics of the coas t, such as the presence of beaches versus cliffs, reflects a complex and dynamic inter action between physical processes ( e.g., waves and tidal currents) that act on the coast, availa bility of sediment tr ansported by waves andCCSP 4.1 January 15, 2009

142 of 784 Final Report tidal currents, underlying geology, and changes in sea level (see review in Carter and Woodroffe, 1994a). Variations in these f actors from one region to the next are responsible for the different coastal landforms, such as beaches, barrier islands, and cliffs that are observed along the coast today. Base d on studies of the ge ologic record, the scope and general nature of the changes that can occur in response to sea-level rise are widely recognized (Curray, 1964; Carter and Woodroffe, 1994a; FitzGerald et al. , 2008). On the other hand, determining precisely how these changes occur in response to a specific rise in sea level has been difficult. Part of the complication arises due to the range of physical processes and factors that m odify the coast and operate over a range of time periods ( e.g., from weeks to centuries to thous ands of years) (Cowell and Thom, 1994; Stive et al. , 2002; Nicholls et al. , 2007). Because of the complex interactions between these factors and the difficulty in de termining their exact influence, it has been difficult to resolve a quantitative relationship between sea-level rise and shoreline change ( e.g. , Zhang et al. , 2004; Stive, 2004). Consequently, it has been difficult to reach a consensus among coastal scientists as to whether or not sea-level rise can be quantitatively related to obser ved shoreline changes and de termined using quantitative models (Dubois, 2002; Stive, 2004; Pilkey and Cooper, 2004; Cowell et al. , 2006).

Along many U.S. shores, shoreline changes are related to changes in the shape of the landscape at the water’s edge ( e.g. , the shape of the beach). Changes in beach dimensions, and the resulting shoreline changes, do not occur directly as the result of sealevel rise but are in an almost continual state of change in response to waves and currents as well as the availability of sediment to the coastal system (see overviews in Carter andCCSP 4.1 January 15, 2009

143 of 784 Final Report Woodroffe, 1994b; Stive et al. , 2002; Nicholls et al. , 2007). This is especially true for shoreline changes observed over the past century, when the increase in sea level has been relatively small (about 30 to 40 centimeters, or 12 to16 inches, along the mid-Atlantic coast). During this time, large storms, varia tions in sediment supply to the coast, and human activity have had a more obvious infl uence on shoreline changes. Large storms can cause changes in shoreline position that persist for weeks to a decade or more (Morton et al. , 1994; Zhang et al. , 2002, 2004; List et al. , 2006; Riggs and Ames, 2007). Complex interactions with nearshore sa nd bodies and/or underlying geology (the geologic framework), the mechanics of wh ich are not yet clearly understood, also influence the behavior of beach morphology over a range of time periods (Riggs et al. , 1995; Honeycutt and Krantz, 2003; Schupp et al. , 2006; Miselis and McNinch, 2006). In addition, human actions to control changes to the shore and coastal waterways have altered the behavior of some portio ns of the coast considerably ( e.g. , Assateague Island, Maryland, Dean and Perlin, 1977; Leatherma n, 1984; also see reviews in Nordstrom, 1994, 2000; Nicholls et al. , 2007).

It is even more difficult to develop quantitati ve predictions of how shorelines may change in the future (Stive, 2004; P ilkey and Cooper, 2004; Cowell et al. , 2006). The most easily applied models incorporate relatively few pr ocesses and rely on assumptions that do not always apply to real-world settings (Thieler et al. , 2000; Cooper and Pilkey, 2004). In addition, model assumptions often apply best to present conditions, but not necessarily to future conditions. Models that incorporate more factors are applied at specific locations and require precise knowledge regarding the underlying geology or sediment budgetCCSP 4.1 January 15, 2009

144 of 784 Final Report ( e.g ., GEOMBEST, Stolper et al. , 2005), and it is therefore difficult to apply these models over larger coastal regions. Appendix 2 presents brief summaries of a few basic methods that have been used to predict the potential for shoreline ch anges in response to sea-level rise.

As discussed in Chapter 2, recent and ongoing assessments of sea-level rise impacts commonly examine the vulnerability of coasta l lands to inundation by specific sea-level rise scenarios ( e.g., Najjar et al. , 2000; Titus and Richman, 2001; Rowley et al. , 2007). This approach provides an estimate of the land area that may be vulnerable, but it does not incorporate the processes ( e.g. , barrier island migration) nor the environmental changes ( e.g ., salt marsh deterioration) that may occu r as sea level rises. Because of these complexities, inundation can be used as a basi c approach to approximate the extent of land areas that could be affected by changing s ea level. Because the majority of the U.S. coasts, including those along the Mid-Atlantic , consist of sandy s hores, inundation alone is unlikely to reflect the poten tial consequences of sea-le vel rise. Instead, long-term shoreline changes will involve contri butions from both i nundation and erosion (Leatherman, 1990, 2001) as well as changes to other coastal environments such as wetland losses.

Most portions of the open coast of the United St ates will be subject to significant physical changes and erosion over the next century because the majority of coastlines consist of sandy beaches which are highly mobile and in a continual state of change. This Chapter presents an overview and assessment of the im portant factors and processes that influenceCCSP 4.1 January 15, 2009

145 of 784 Final Report potential changes to the mid-Atlantic ocean coast due to sea-level rise expected by the end of this century. This overview is based in part on a panel assessment ( i.e ., expert judgement) that was undertaken to addre ss this topic for th is Product (Gutierrez et al., 2007). The panel assessment process is desc ribed in Section 3.2 and Box 3.1. Section 3.3 reviews the geological characte ristics of the mid-Atlanic co ast. Section 3.4 provides an overview of the basic factors that influen ce sea-level rise-driven shoreline changes. Sections 3.5 and 3.6 describe the coastal la ndforms of the mid-A tlantic coast of the United States and what is known regarding how these landforms respond to changes in sea-level based on a literature review included as part of the panel assessment (Gutierrez et al. , 2007). The potential responses of mid-Atlantic coastal la ndforms to sea-level rise, which were defined in the panel assessm ent, are presented in Section 3.7 and communicated using the likelihood terms speci fied in the Preface (see Figure P.1).

3.2 ASSESSING THE POTENTIAL IMPACT OF SEA-LEVEL RISE ON THE OCEAN COASTS OF THE MID-ATLANTIC Lacking a single agreed-upon method or scie ntific consensus vi ew about shoreline changes in response to sea-leve l rise at a regional scale, a panel was consulted to address the key question that guide d this Chapter (Gutierrez et al. , 2007). The panel consisted of coastal scientists whose research experien ces have focused on the mid-Atlantic region and have been involved with coastal ma nagement in the mid-Atlantic region 1 . The panel

1 Fred Anders (New York State, Dept. of State, Albany, NY), Eric Anderson (USGS, NOAA Coastal Services Center, Charleston, SC), Mark Byrnes (A pplied Coastal Research and Engineering, Mashpee, MA), Donald Cahoon (USGS, Beltsv ille, MD), Stewart Farrell (Richard Stockton College, Pomona, NJ), Duncan FitzGerald (Boston University, Boston, MA), Paul Gayes (Coastal Carolina University, Conway, SC), Benjamin Gutierrez (USGS, Woods Hole, MA), Ca rl Hobbs (Virginia Institute of Marine Science, Gloucester Pt., VA), Randy McBride (George Mason Un iversity, Fairfax, VA), Jesse McNinch (Virginia Institute of Marine Science, Gloucester Pt., VA), Stan Riggs (East Carolina University, Greenville, NC),CCSP 4.1 January 15, 2009

146 of 784 Final Report discussed the changes that might be expected to occur to the ocean shores of the U.S. mid-Atlantic coast in response to predicted accelerations in sea-level rise over the next century, and considered the important ge ologic, oceanographic, and anthropogenic factors that contribute to shor eline changes in this region. The assessment presented here is based on the professional judgment of th e panel. This qualita tive assessment of potential changes that was developed by the panel is based on an understanding of both coastal science literature and their personal field observations.

This assessment focuses on four sea-level rise scenarios. As define d in the Preface and Chapter 1, the first three sea-level rise scenarios (Scenarios 1 through 3) assume that: (1) the sea-level rise rate observed during th e twentieth century wi ll persist through the twenty-first century; (2) the twentieth century rate will in crease by 2 millimeters (mm) per year, and (3) the twentieth century ra te will increase by 7 mm per year. Lastly, a fourth scenario is discussed, which consider s a 2-meter (6.6-foot) rise over the next few hundred years. In the following discussions, se a-level change refers to the relative sealevel change, which is the combination of gl obal sea-level change and local change in land elevation. Using thes e scenarios, this asse ssment focuses on:

 Identifying important factors and processe s contributing to shoreline change over the next century;

 Identifying key geomorphic settings along th e coast of the mid-Atlantic region;

 Defining potential responses of shor elines to sea-level rise; and

Antonio Rodriguez (University of North Carolina, Morehead City, NC), Jay Tanski (New York Sea Grant, Stony Brook, NY), E. Robert Thieler (USGS, Woods Hole, MA), Art Trembanis (University of Delaware, Newark, DE), S. Jeffress Willia ms (USGS, Woods Hole, MA).CCSP 4.1 January 15, 2009

147 of 784 Final Report  Assessing the likelihood of these responses.

Box 3.1: The Panel Assessment Pro cess Used in SAP 4.1, Chapter 3 As described in this Product, there is currently a lack of scientific cons ensus regarding local-, regional-, and national-scale coastal changes in response to sea-leve l rise, due to limited elevation and observational data and lack of adequate scientific unde rstanding of the complex processes that contribute to coastal change. To address the question of potential future changes to th e mid-Atlantic coast posed in the SAP 4.1 Prospectus, the authors assembled 13 coastal scientists for a meeti ng to evaluate the potential outcomes of the sea-level rise scenarios used in this Product. These scientists we re chosen on the basis of their technical expertise and experience in the coastal research community, and also their involvement with coastal management issues in the mid-Atlantic region. Prior to the meeting, the scie ntists were provided with documents describing the Climate Change Science Program, and the Prospectus for this Product. The Prospectus included key questions and topics that the panel was charged to address. The panel was also provided a draft version of the report by Reed et al. (2008), which documented a similar panel-assessment approach used in developing Chapter 4 of this Product. The sea-level rise impact assessment effort was conducted as an open discussion facilitated by the USGS authors over a two-day period. The main topics that the panel discussed were: 1) approaches that can be used to conduct long-term assessments of coastal change; 2) key geomorphic environments in the mid-Atlantic region from Long Island, NY to North Carolina; 3) potential responses of these environments to sea-level rise based on an understanding of important factors and processes contributing to coastal change; and 4) the likelihood of these responses to the sea-level rise scenarios used in this Product (see Section 3.7). The qualitative, consensus-based assessment of poten tial changes and their likelihood developed by the panel was based on their review and understanding of peer reviewed published coastal science literature, as well as field observations drawn from other studies conducted in the mid-Atlantic region. The likelihood statements reported in Section 3.7 were determined based on the results of the discussion during the two-day meeting and revised according comments from panelists during the drafting of a summary report. The USGS report (Gutierrez et al. , 2007) summarizing the process used, the basis in the published literature, and a synthesis of the resulting assessment was produced based on results of the meeting, reviewed as part of the USGS peer review process, and approved by members of the panel.CCSP 4.1 January 15, 2009

148 of 784 Final Report 3.3 GEOLOGICAL CHARACTER OF THE MID-ATLANTIC COAST The mid-Atlantic margin of the United States is a gently sloping coastal plain that has accumulated over millions of years in response to the gradual erosion of the Appalachian mountain chain. The resulting sedimentation ha s constructed a broad coastal plain and a continental shelf that extends almost 300 k ilometers (approximately 185 miles) seaward of the present coast (Colquhoun et al. , 1991). The current morphology of this coastal plain has resulted from the incision of rivers that drain the region a nd the construction of barrier islands along the mainland occurring be tween the river systems. Repeated ice ages, which have resulted in sea-level fluctuations up to 140 meters (460 feet) (Muhs et al. , 2004), caused these rivers to erode large va lleys during periods of low sea level that then flooded and filled with sediments when sea levels rose. The northern extent of the mid-Atlantic region considered in this Pr oduct, Long Island, New York, was also shaped by the deposition of glacial outwash plains and moraines that accumulated from the retreat of the Laurentide ice sheet, whic h reached its maximum extent approximately 21,000 years ago. This sloping landscape that char acterizes entire mid-Atlantic margin, in combination with slow rates of sea-level ri se over the past 5,000 years and sufficient sand supply, is also thought to have enabled the form ation of the barrier islands that comprise the majority of the Atlant ic Coast (Walker and Colema n, 1987; Psuty and Ofiara, 2002).

The mid-Atlantic coast is generally describe d as a sediment-starved coast (Wright, 1995). Presently, sediments from the river systems of the region are tra pped in estuaries and only minor amounts of sediment are deliver ed to the open ocean coast (Meade, 1969, 1972). In addition, these estuaries trap sandy se diment from the continental shelf (Meade,CCSP 4.1 January 15, 2009

149 of 784 Final Report 1969). Consequently, the sediments that form the mainland beach and barrier beach environments are thought to be derived main ly from the wave-driven erosion of the mainland substrate and sediments from the s eafloor of the continental shelf (Niedoroda et al. , 1985; Swift et al. , 1985; Wright, 1995). Since the largest waves and associated currents occur during storms along the Atlantic Coast, storms are often thought to be significant contributors to coastal changes (Niedoroda et al. , 1985; Swift et al. , 1985; Morton and Sallenger, 2003).

The majority of the open coasts along the mid-Atlantic region are sandy shores that include the beach and barrier environments . Although barriers comprise only 15 percent of the world coastline (Glaes er, 1978), they are the dominant shoreline type along the Atlantic Coast. Along the portion of the mid-A tlantic coast examined here, which ranges between Montauk, New York and Cape Lookout , North Carolina, barriers line the majority of the open coast. Consequently, sc ientific investigati ons exploring coastal geology of this portion of North America have focused on understanding barrier island systems (Fisher, 1962, 1968; Pierce and Colquhoun, 1970; Kraft, 1971; Leatherman, 1979; Moslow and Heron, 1979, 1994; Swift, 1975; Nummedal, 1983; Oertel, 1985; Belknap and Kraft, 1985; Hine and Snyder, 1985; Davis, 1994).

3.4 IMPORTANT FACTORS FOR MID- ATLANTIC SHORELINE CHANGE Several important factors influe nce the evolution of the mid-A tlantic coast in response to sea-level rise including: (1 ) the geologic framework, (2) physical proce sses, (3) the sediment supply, and (4) human activity. Each of these factors influences the response ofCCSP 4.1 January 15, 2009

150 of 784 Final Report coastal landforms to changes in sea level. In addition, these factors contribute to the local and regional variations of sea-level rise impacts that are difficult to capture using quantitative prediction methods.

3.4.1 Geologic Framework An important factor influencing coastal morphology and behavior is the underlying geology of a setting, which is also referred to as the geological framework (Belknap and Kraft, 1985; Demarest and Leatherman, 1985; Schwab et al. , 2000). On a large scale, an example of this is the contrast in th e characteristics of the Pacific Coast versus the Atlantic Coast of the United States. The co llision of tectonic pl ates along the Pacific margin has contributed to the development of a steep coast where cliffs line much of the shoreline (Inman and Nordstrom, 1971; Muhs et al. , 1987; Dingler and Clifton, 1994; Griggs and Patsch, 2004; Hapke et al. , 2006; Hapke and Reid, 2007). While common, sandy barriers and beaches along the Pacific ma rgin are confined to river mouths and low-lying coastal plains that stretch between rock outcrops and coas tal headlands. On the other hand, the Gulf of Mexico and Atlantic coasts of the Un ited States are situated on a passive margin where tectonic activity is mi nor (Walker and Coleman, 1987). As a result, these coasts are composed of wide coastal plains and wide contin ental shelves extending far offshore. The majority of these coasts are lined with barrier beaches and lagoons, large estuaries, isolated coastal capes, and ma inland beaches that abut high grounds in the surrounding landscape.CCSP 4.1 January 15, 2009

151 of 784 Final Report From a smaller-scale perspective focused on th e mid-Atlantic region, the influence of the geological framework involves more subtle details of the regional geology. More specifically, the distribution, st ructure, and orientation of different rock and sediment units, as well as the presence of features such as river and creek va lleys eroded into these units, provides a structural cont rol on a coastal environment ( e.g ., Kraft, 1971; Belknap and Kraft, 1985; Demarest and Leatherman, 1985; Fletcher et al. , 1990; Riggs et al. , 1995; Schwab et al. , 2000; Honeycutt and Krantz, 2003). Moreover, the framework geology can control (1) the locati on of features, such as inle ts, capes, or sand-ridges, (2) the erodibility of sediments, and (3) the t ype and abundance of sediment available to beach and barrier island settings. In the mid- Atlantic region, the position of tidal inlets, estuaries, and shallow water embayments can be related to the existence of river and creek valleys that were present in the lands cape during periods of lower sea level in a number of cases ( e.g ., Kraft, 1971; Belknap and Kraft, 1985; Fletcher et al. , 1990). Elevated regions of the landscape, which can often be identified by areas where the mainland borders the ocean coast, form coasta l headlands. The erosion of these features supplies sand to the nearshore system. Differences in sediment composition ( e.g. , sediment size or density), can sometimes be related to differences in shoreline retreat rates ( e.g. , Honeycutt and Krantz, 2003). In ad dition, the distribution of underlying geological units (rock outcrops, hard-grounds, or sedimentary strata ) in shallow regions offshore of the coast can modify waves and cu rrents and influencing patterns of sediment erosion, transport, and deposition on the adjacent shores (Riggs et al. , 1995; Schwab et al. , 2000). These complex interactions with nearshore sand bodies and/or underlying geology can also influence the behavior of beach morphology over a range of time scalesCCSP 4.1 January 15, 2009

152 of 784 Final Report (Riggs et al. , 1995; Honeycutt and Krantz, 2003; Schupp et al. , 2006; Miselis and McNinch, 2006).

3.4.2 Physical Processes The physical processes acting on the coast are a principal factor shaping coastal landforms and consequently changes in shor eline position (see reviews in Davis, 1987; Komar, 1998). Winds, waves, and tidal cu rrents continually er ode, rework, winnow, redistribute, and shape the sediments that make up these landforms. As a result, these forces also have a controlling influence on the composition and morphology of coastal landforms such as beaches and barrier islands.

Winds have a range of effects on coastal area s. They are the main cause of waves and also generate currents that transport sediments in shallow waters. In addition, winds are a significant mechanism transporting sand along b eaches and barrier islands that generate and sustain coastal dunes.

Waves are either generated by local winds or result from far-away disturbances such as large storms out at sea. As waves propagate into shallow water, their energy decreases but they are also increasingl y capable of moving the sedime nt on the seabed. Close to shore each passing wave or breaking wave suspends sediments off the seabed. Once suspended above the bottom, these sediments can be carried by wave- or tide-generated

currents.CCSP 4.1 January 15, 2009

153 of 784 Final Report Wave-generated currents are important agents of change on sandy shores. The main currents that waves generate are longshore currents, ri p currents, and onshore and offshore directed currents that accompany the surge and retreat of breaking waves. Longshore currents are typically the most importa nt for sediment transport that influences changes in shoreline position. Where waves a pproach the coast at an angle, longshore currents are generated. The speed of these cu rrents varies, depending on the wave climate ( e.g., average wave height and direction) and more specifically, on the power and angle of approach of the waves ( e.g. , high waves during storms , low waves during fair weather). These currents provide a mechanism for sand transport along the coast, referred to as littoral transport, longshore drift, or longshore transport. During storms, high incoming waves can generate longshore curren ts exceeding 1 meter (3 feet) per second and storm waves can transport thousands of cubic meters of sand in a relatively short time period, from hours to days. During calm c onditions, waves are weaker but can still gradually transport large volumes of sand ove r longer time periods, ranging from weeks to months. Where there are changes in coas tal orientation, the angle at which waves approach the coast changes and can lead to local reversals in longshore sediment transport. These variations can result in the creation of abundances or deficits of longshore sediment transport and contribute to the seaward growth or landward retreat of the shoreline at a pa rticular location ( e.g ., Cape Lookout, North Carolina, McNinch and Wells [1999]).

The effect of tidal currents on shores is more subtle except for region s near the mouths of inlets, bays, or areas where there is a change in the orientation of th e shore. The rise andCCSP 4.1 January 15, 2009

154 of 784 Final Report fall of the water level caused by tides moves the boundary be tween the land and sea (the shoreline), causing the level that waves act on a shore to move as well. In addition, this controls the depth of water which influences the strength of breaki ng waves. In regions where there is a large tidal range, there is a greater area over wh ich waves can act on a shore. The rise and fall of the water level al so generates tidal currents. Near the shore, tidal currents are small in comparison to wave-driven currents. Near tidal inlets and the mouths of bays or estuaries, tidal currents are strong due to the large volumes of water that are transported through th ese conduits in response to ch anging water levels. In these settings, tidal currents transport sediment fr om ocean shores to back-barrier wetlands, inland waterways on flood tides and vice versa on ebb tides. Aside from these settings, tidal currents are generally small along the mid-Atlantic region except near changes in shoreline orientation or sand banks ( e.g. , North Carolina Capes, Cape Henlopen, Delaware). In these settings, the strong cu rrents generated can significantly influence sediment transport pathways and the behavior of adjacent shores.

3.4.3 Sediment Supply The availability of sediments to a coastal region also has important effects on coastal landforms and their behavior (Curray, 1964). In general, assuming a relatively stable sea level, an abundance of sediment along the coas t can cause the coast to build seaward over the long term if the rate of supply exceeds the rate at which sediments are eroded and transported by nearshore currents. Conversely, th e coast can retreat la ndward if the rate of erosion exceeds the rate at which sediment is supplied to a coastal region. One way to evaluate the role of sediment supply in a region or specific location is to examine theCCSP 4.1 January 15, 2009

155 of 784 Final Report amount of sediment being gained or lost along the shore. This is often referred to as the sediment budget (Komar, 1996; List, 2005; Rosa ti, 2005). Whether or not there is an overall sediment gain or loss from a coasta l setting is a critical determinant of the potential response to changes in sea level; however, it is diffi cult if to quan tify with high confidence the sediment budget over time periods as long as a century or its precise role in influencing shoreline changes.

The recent Intergovernmental Panel on C limate Change (IPCC) chapter on coastal systems and low-lying regions noted that the availability of sediment to coastal regions will be a key factor in future shoreline changes (Nicholls et al. , 2007). In particular, the deposition of sediments in coastal embayments ( e.g. , estuaries and lagoons) may be a significant sink for sediments as they deepen in response to sea-level rise and are able to accommodate sediments from coastal river sy stems and adjacent open ocean coasts. For this reason, it is expected that the potential for erosion and sh oreline retreat will increase, especially in the vicinity of tidal inlets (see Nicholls et al. , 2007). In addition, others have noted an important link between changes in the dimension of coastal embayments, the sediment budget, and the potential for shoreline changes (FitzGerald et al. , 2006, 2008). In the mid-Atlantic region, coastal sediment s generally come from erosion of both the underlying coastal landscape and th e continental shelf (Swift et al. , 1985; Niedoroda et al. , 1985). Sediments delivered through coastal rivers in the mid-Atlantic region, are generally captured in estu aries contributing minor amounts of sediments to the openocean coast (Meade, 1969).CCSP 4.1 January 15, 2009

156 of 784 Final Report 3.4.4 Human Impacts The human impact on the coast is another important factor a ffecting shoreline changes. A variety of erosion control pr actices have been undertaken over the last century along much of the mid-Atlantic region, particular ly during the la tter half of the twentieth century (see reviews in Nordstrom, 1994; 2000). As discussed later in Chapter 6, shoreline engineering structures such as s eawalls, revetments, groins, and jetties have significantly altered sediment transport processes, and conseque ntly affect the availability of sediment ( e.g. , sediment budget) to sustain beache s and barriers and the potential to exacerbate erosion on a local level (see disc ussion on Assateague Island in Box 3.2). Beach nourishment, a commonly used approach, has been used on many beaches to temporarily mitigate erosion and provide st orm protection by adding to the sediment budget.

The management of tidal inlets by dredging has had a large impact to the sediment budget particularly at local le vels (see review in Nordstrom, 1994; 2000). In the past, sand removed from inlet shoals has been tran sferred out to sea, thereby depleting the amount of sand available to sustain portions of the longshore transport system and, consequently, adjacent shores (Marino a nd Mehta, 1988; Dean, 1988). More recently, inlet management efforts have attempted to re tain this material by returning it to adjacent shores or other shores where sand is needed.

A major concern to coastal scientists a nd managers is whether or not erosion management practices are sustainable for the long term, and whether or how theseCCSP 4.1 January 15, 2009

157 of 784 Final Report shoreline protection measures might impede the ability of natural pro cesses to respond to future sea-level rise, especially at accelerated rates. It is also uncertain whether beach nourishment will be continued into the futu re due to economic constraints and often limited supplies of suitable sand resources. Ch apter 6 describes some of these erosion control practices and their management and policy implications further. In addition, Chapter 6 also describes the important c oncept of “Regional Sediment Management” which is used to guide the management of sediment in inlet dredging, beach nourishment, or other erosion control activities.

3.5 COASTAL LANDFORMS OF THE MID-ATLANTIC For this assessment, the coastal landforms al ong the shores of the mid-Atlantic region are classified using the criteria developed by Fisher (1967; 1982), Hayes (1979), and Davis and Hayes (1984). Four distinct geomorphi c settings, including spits, headlands, and wave-dominated and mixed-energy barrier isla nds, occur in the mid-Atlantic region, as shown in Figure 3.1 and described below.CCSP 4.1 January 15, 2009

158 of 784 Final Report Figure 3.1 Map of the mid-Atlantic coast of the United Stat es showing the occurrence of the four coastal landform types (geomorphic settings) . Numbers on the map designate distinct portions of the coast divided by landform type and refer to the discussions in Sections 3.5 and 3.7. Numbers on the photographs refer to specific sections of the coast that are depicted on the map. Images from Google Earth. (Gutierrez et. al. , 2007).
3.5.1 Spits The accumulation of sand from longshore transp ort has formed large spits that extend from adjacent headlands into the mouths of large coastal embayments (Figure 3.1, Sections 4, 9, and 15). Outstanding examples of these occur at the entrances of Raritan Bay (Sandy Hook, New Jersey) and Delaware Bay (Cape Henlopen, Delaware). The evolution and existence of these spits resu lts from the interac tion between alongshore transport driven by incoming waves and the tidal flow through the large embayments. Morphologically, these areas can evolve rapidl y. For example, since 1842 Cape Henlopen (Figure 3.1, Section 9) has extend ed almost 1.5 kilometers (0.9 miles) to the north intoCCSP 4.1 January 15, 2009

159 of 784 Final Report the mouth of Delaware Bay as the northe rn Delaware shoreline has retreated and sediment has been transported north by longshore currents (Kraft, 1971; Kraft et al. , 1978; Ramsey et al. , 2001).

3.5.2 Headlands Along the shores of the mid- Atlantic region, coas tal headlands typically occur where elevated regions of the landscape intersect the coast. These regions are often formed where drainage divides that separate creeks and rivers fr om one another occur in the landscape, or where glacial deposits create high grounds (Taney, 1961; Kraft, 1971; Nordstrom et al. , 1977). The erosion of headlands provi des a source of sediment that is incorporated into the longshore transport system that supplies and maintains adjacent beaches and barriers. Coastal headlands are present on Long Island, New York (see Figure 3.1), from Southampton to Montauk (S ection 1), in northern New Jersey from Monmouth to Point Pleasant (Section 5; Oertel and Kraft, 1994), in southern New Jersey at Cape May (Section 8), on Delaware north and south of Indian River and Rehoboth Bays (Sections 10 and 12; Kraft, 1971; Oertel and Kraft, 1994; Ramsey et al. , 2001), and on the Virginia Coast, from Cape Henry to Sandbridge (Section 16).

3.5.3 Wave-Dominated Barrier Islands Wave-dominated barrier islands occur as relatively long and thin stretches of sand fronting shallow estuaries, lagoons, or embayments that are bisected by widely-spaced tidal inlets (Figure 3.1, Sections 2, 6, 10, 13, and 17). These barriers are present in regions where wave energy is large relative to tidal energy, such as in the mid-AtlanticCCSP 4.1 January 15, 2009

160 of 784 Final Report region (Hayes, 1979; Davis and Hayes, 1984). Li mited tidal ranges result in flow-through tidal inlets that are marginally sufficient to flush the sediments that accumulate from longshore sediment transport. In some cases, th is causes the inlet to migrate over time in response to a changing balance between tidal flow through the inlet and wave-driven longshore transport. Inlets on wa ve-dominated coasts often ex hibit large flood-tidal deltas and small ebb-tidal deltas as tidal currents are often str onger during the flooding stage of the tide.

In addition, inlets on wave-dom inated barriers are often te mporary features. They open intermittently in response to storm-genera ted overwash and migrate laterally in the overall direction of longshore transport. In many cases, these inlets are prone to filling with sands from alongshore sediment transport ( e.g ., McBride, 1999).

Overwash produced by storms is co mmon on wave-dominated barriers ( e.g ., Morton and Sallenger, 2003; Riggs and Ames, 2007). Ov erwash erodes low-lying dunes into the island interior. Sediment deposition from overwash adds to the island’s elevation. Overwash deposits (washover fans) that exte nd into the back-barrier waterways form substrates for back-barrier marshe s and submerged aquatic vegetation.

The process of overwash is an important mechanism by which some types of barriers migrate landward and upward over time. This process of landward migration has been referred to as “roll-over” (Dillon, 1970; Godfrey and Godf rey, 1976; Fisher, 1982; Riggs and Ames, 2007). Over decades to centuries, the intermittent proce sses of overwash andCCSP 4.1 January 15, 2009

161 of 784 Final Report inlet formation enable the barrier to mi grate over and erode into back-barrier environments such as marshes as relative sea- level rise occurs over time. As this occurs, back-barrier environments such as marshe s are eroded and buried by barrier beach and dune sands.

3.5.4 Mixed-Energy Barrier Islands The other types of barrier islands present al ong the U.S. Atlantic coast are mixed-energy barrier islands, which are shorter and wide r than their wave-dom inated counterparts (Hayes, 1979; Figure 3.1, Sections 3, 4, 7, and 14) . The term “mixed-energy” refers to the fact that both waves and tidal currents ar e important factors influencing the morphology of these systems. Due to the larger tidal range and conseque ntly stronger tidal currents, mixed energy barriers are shorter in length a nd well-developed tidal inlets are moreabundant than for wave-dominated barriers. Some authors have referred to the mixedenergy barriers as tide-domina ted barriers along the New Jersey and Virginia coasts ( e.g ., Oertel and Kraft, 1994).

The large sediment transport capacity of the tidal currents within the inlets of these systems maintains large ebb-tidal deltas s eaward of the inlet m outh. The shoals that comprise ebb-tidal deltas cau se incoming waves to refr act around the large sand body that forms the delta such that local re versals of alongshore currents and sediment transport occur downdrift of the inlet. As a result, portions of the barrier downdrift of inlets accumulate sediment which form recurv ed sand ridges and give the barrier islands a ‘drumstick’-like shape (Hayes 1979; Davis, 1994).CCSP 4.1 January 15, 2009

162 of 784 Final Report 3.6 POTENTIAL RESPONSES TO FUTURE SEA-LEVEL RISE Based on current understanding of the four la ndforms discussed in the previous section, three potential responses coul d occur along the mid-Atlantic coast in response to sealevel rise over the next century.

3.6.1 Bluff and Upland Erosion Shorelines along headland regions of the coast will retreat landward with rising sea level. As sea level rises over time, uplands will be eroded and the sediments incorporated into the beach and dune systems along these shores. Along coastal headlands, bluff and upland erosion will persist under all four of the sea-level rise scenarios considered in this Product. A possible management reaction to bluff erosion is shore armoring ( e.g. Nordstrom, 2000; Psuty and Ofiara, 2002; see Chapter 6). This may reduce bluff erosion in the short term but could increase long-te rm erosion of the ad jacent coast by reducing sediment supplies to the littoral system.

3.6.2 Overwash, Inlet Processes, and Barrier Island Morphologic Changes For barrier islands, three main processes are agents of change as sea level rises. First, with higher sea level, storm overwash may o ccur more frequently. This is especially critical if the sand availabl e to the barrier, such as from longshore transport, is insufficient to allow the barrier to maintain it s width and/or build vertically over time in response to rising water levels. If sediment s upplies or the timing of the barrier recovery are insufficient, storm surges coupled with breaking waves will affect increasingly higherCCSP 4.1 January 15, 2009

163 of 784 Final Report elevations of the barrier systems as mean sea level increases, possibly causing more extensive erosion and overwash. In addition, it is possible that future hurricanes may become more intense, possibly increasing the potential for episodic overwash, inlet formation, and shoreline retreat. The topic of recent and future storm trends has been debated in the scientific comm unity, with some researchers suggesting that other climate change impacts such as strengthening wind shear may lead to a decrease in future hurricane frequency (see Chap ter 1 and reviews in Meehl et al. , 2007; Karl et al. , 2008; Gutowski et al. , 2008). It is also expected that extrat ropical storms will be more frequent and intense in the future, but these effects wi ll be more pronounced at high latitudes (60° to 90°N) and possibly decreased at midlatitudes (30° to 60°N) (Meehl et al. , 2007; Karl et al. , 2008; and Gutowski et al. , 2008).

Second, tidal inlet formation and migration will contribute to important changes in future shoreline positions. Storm surges coupled with high waves can cause not only barrier island overwash but also breach the barrier s and create new inlets. In some cases, breaches can be large enough to form inlets that persist for some time until the inlet channels fill with sediments accumulated from longshore transport. Numerous deposits have been found along the shores of the mi d-Atlantic region, indicating former inlet positions (North Carolina: Moslow and Heron, 1979 and Everts et al. , 1983; Fire Island, New York: Leatherman, 1985). Several inlets al ong the mid-Atlantic coast were formed by the storm surges and breaches from an unnamed 1933 hurricane, including Shackleford Inlet in North Caro lina; Ocean City inlet in Mary land; Indian River Inlet in Delaware; and Moriches Inlet in New York. Recently, tidal inlets were formed in theCCSP 4.1 January 15, 2009

164 of 784 Final Report North Carolina Outer Banks in response to Hurricane Isabel in 2003. While episodic inlet formation and migration are na tural processes and can occur independently of long-term sea-level rise, a long-term increase in sea le vel coupled with limited sediment supply and increases in storm frequency a nd/or intensity could increase th e likelihood for future inlet breaching.

Third, the combined effect of rising sea leve l and stronger storms could accelerate barrier island shoreline changes. These will involve both changes to the seaward facing and landward facing shores of some barrier islands. Assessmen ts of shoreline change on barrier islands indicate that barriers have thinned in some areas over the last century (Leatherman, 1979; Jarrett, 1983; Everts et al. , 1983; Penland et al. , 2005). Evidence of barrier migration is not widespread on the mid-Atlantic coast (Morton et al. , 2003), but is documented at northern Assateague Island in Maryland (Leatherman, 1979) and Core Banks, North Carolina (Riggs and Ames, 2007).

3.6.3 Threshold Behavior Barrier islands are dynamic environments that are sensitive to a range of physical and environmental factors. Some evidence suggest s that changes in some or all of these factors can lead to conditions where a barr ier system becomes less stable and crosses a geomorphic threshold. Once a threshold is crossed, the potential for significant and irreversible changes to the barrier island is high. These changes can involve landward migration or changes to the barrier island di mensions such as reduction in size or anCCSP 4.1 January 15, 2009

165 of 784 Final Report increased presence of tidal in lets. Although it is difficult to precisely define an unstable barrier, indications include:

 Rapid landward migration of the barrier;

 Decreased barrier width and height, due to a loss of sand eroded from beaches and dunes;

 Increased frequency of overwash during storms;

 Increased frequency of barrier br eaching and inlet formation; and

 Segmentation of the barrier.

Given the unstable state of so me barrier islands under current rates of sea-level rise and climate trends, it is very likely that conditi ons will worsen under accelerated sea-level rise rates. The unfavorable conditions for ba rrier maintenance could result in significant changes, for example, to barrier islands as observed in coastal Louisiana (further discussed in Box 3.2; McBride et al. , 1995; McBride and Byrnes, 1997; Penland et al. , 2005; Day et al. , 2007; Sallenger et al. , 2007; FitzGerald et al. , 2008). In one case, recent observations indicate that the Chandeleur Islands are undergoing a significant land loss due to several factors which include: (1) limited sediment supply by longshore or crossshore transport, (2) accelerat ed rates of sea-level rise, and (3) permanent sand removal from the barrier system by storms such as Hurricanes Camille, Georges, and Katrina. Likewise, a similar trend has been observed for Isle Dernieres, also on the Louisiana coast (see review in FitzGerald et al. , 2008). In addition, recent studies from the North Carolina Outer Banks indicate that there have been at least two pe riods during the past several thousand years where fully open-ocean conditions have occurred in AlbemarleCCSP 4.1 January 15, 2009

166 of 784 Final Report and Pamlico Sounds, which are estuaries front ed by barrier islands at the present time (Mallinson et al. , 2005; Culver et al. , 2008). This indicates that portions of the North Carolina barrier island system may have segm ented or become less continuous than the present time for periods of a few hundred years, and later reformed. Given future increases in sea level and/or storm activity, the potential for a threshold crossing exists, and portions of these barrier islands could once again become segmented.

Changes in sea level coupled with change s in the hydrodynamic climate and sediment supply in the broader coasta l environment contribute to the development of unstable barrier island behavior. The threshold behavior of unstable barriers could result in: barrier segmentation, barrier disintegra tion, or landward migration an d roll-over. If the barrier were to disintegrate, portions of the ocean shoreline could migrate or back-step toward and/or merge with the mainland.

The mid-Atlantic coastal regions most vulnera ble to threshold behavi or can be estimated based on their physical dimensions. During storms, large portions of low-elevation, narrow barriers can be inundated under hi gh waves and storm surge. Narrow, lowelevation barrier islands, such as the norther n portion of Assateague Island, Maryland are most susceptible to storm overwash, which can lead to landward migration and the formation of new tidal inlets ( e.g ., Leatherman, 1979; see also Box 3.2).

The future evolution of some low-elevation, narrow barriers could de pend in part on the ability of salt marshes in b ack-barrier lagoons and estuaries to keep pace with sea-levelCCSP 4.1 January 15, 2009

167 of 784 Final Report rise (FitzGerald et al. , 2006, 2008; Reed et al. , 2008). A reduction of salt marsh in backbarrier regions could increase the volume of water exchanged with the tides ( e.g., the tidal prism) of back-barrier systems, alte ring local sediment budgets and leading to a reduction in sandy materials available to sustain barrier systems (FitzGerald et al. , 2006, 2008).
BOX 3.2: Evidence for Threshold Cr ossing of Coasta l Barrier Landforms Barrier islands change and evolve in subtle and somewhat predictable ways over time in response to storms, changing sediment supply, an d changes in sea level. Recent fiel d observations suggest that some barrier islands can reach a “thres hold” condition: that is , a point where they become unstable and disintegrate. Two sites where barrier island disintegration is occurring and may continue to occur are along the 72 kilometers (about 45 miles) long Chandeleur Islands in Louisiana, east of the Mississippi River Delta, due to impacts of Hurricane Katrina in September 2005; and the northern 10 kilometers (6 miles) of Assateague Island National Seashore, Maryland due to 70 years of sediment starvation caused by the construction of jetties to maintain Ocean City Inlet. Chandeleur Islands, Louisiana In the Chandeleur Islands, the high storm surge (abou t 4 meters or 13 feet) an d waves associated with Hurricane Katrina in 2005 completely submerged the is lands and eroded about 85 percent of the sand from the beaches and dunes (Sallenger et al. , 2007). Box Figure 3.2a (UTM Northing) shows the configuration of the barriers in 2002, and in 2005 after Katr ina’s passage. Follow-up aer ial surveys by the U.S. Geological Survey indicate that erosion has continued since that time. When the Chandeleur Islands were last mapped in the late 1980s and erosion rates were calculated from the 1850s, it was estimated that the Chandeleurs would last approxim ately 250 to 300 years (Williams et al. , 1992). The results from postKatrina studies suggest that a threshold has been crossed such that conditions have changed and natural processes may not contribute to the rebuilding of the barrier in the future. Assateague Island National Seashore, Maryland An example of one shoreline setting where human activity has increased the vulnerability of the shore to sea-level rise is Assateague Island, Maryland. Pr ior to a hurricane in 1933, Assateague Island was a continuous, straight barrier connected to Fenwick Island (Dolan et al. , 1980). An inlet that formed during the storm separated the island into two sections at the southern end of Ocean City, Maryland. Subsequent construction of two stone jetties to maintain the inlet for navigation interrupted the longshore transport of sand to the south. Since then, the jetties have trapped sand, building the Ocean City shores seaward by 250 meters (820 feet) by the mid-1970s (Dean and Perlin, 1977). In addition, the development of sand shoals (ebb tidal deltas) around the inlet mouth has sequ estered large volumes of sand from the longshore transport system (Dean and Perlin, 1977; FitzGerald, 19 88). South of the inlet, the opposite has occurred. The sand starvation on the northern portion of Assateague Island has caused the shore to migrate almost 700 meters (2,300 feet) landward and transformed the barrier into a low-relief, overwash-dominated barrier (Leatherman, 1979; 1984). This extrem e change in barrier island sediment supply has caused a previously stable segment of the barrier island to migrate. To mitigate the effects of the jetties, and to restore the southward sediment transport that was present prior to the existence of Ocean C ity inlet, the U.S. Army Corps of Engineers and National Park Service mechani cally transfer sand from the inlet and the ebb and flood tidal deltas, where the sand is now trapped, to the shallow nearshore regions along the north end of the island. Annual surveys indicate that waves successfully transport the sediment alongshore and have slowed the high shoreline retreat rates present before the project began (Schupp et al. , 2007). Current plans call for continued biannual transfer of sand from the tidal deltas to Assateague Island to mitigate the continued sediment starvation by the Ocean City inlet jetties.CCSP 4.1 January 15, 2009

168 of 784 Final Report Box Figure 3.2a Maps showing the extent of the Chandeleur Islands in 2002, three years before Hurricane Katrina and in 2005, after Hurricane Katrina. Land area above mean high water. Source: A. Sallenger, USGS.

Box Figure 3.2b Aerial Photo of northern Assateague Island and Ocean City, Maryland showing former barrier positions. Note that in 1850, a single barrie r island, shown in outlined in yellow, occupied this stretch of coast. In 1933, Ocean City inlet was created by a hurricane . The inlet improv ed accessibility to the ocean and was stabilized by jetties soon after. By 1942, the barrier south of the inlet had migratedCCSP 4.1 January 15, 2009

169 of 784 Final Report landward (shown as a green shaded region). Shore lines acquired from the State of Maryland Geological Survey. Photo source: NPS.

Box Figure 3.2c North oblique photographs of northern Assateague Island in 1998 after a severe winter storm. The left photo of Assateague Island barrier shows clear evidence of overwash. The right 2006 photo shows a more robust barrier that had been augmented by recent beach nourishment. The white circles in the photos specify identical locations on the barrier. The offset between Fenwick Island (north) and Assateague Island due to Ocean City inlet and jetties can be seen at the top of the photo. Sources: a) National Park Service, b) Jane Thomas, IAN Photo and Video Library. END BOX****CCSP 4.1 January 15, 2009

170 of 784 Final Report 3.7 POTENTIAL CHANGES TO THE MI D-ATLANTIC OCEAN COAST DUE 388 TO SEA-LEVEL RISE 389 In this Section, the responses to the four sea-level rise sc enarios considered in this 390 Chapter are described according to coastal landform types (Figure 3.2). The first three 391 sea-level rise scenarios (Scenarios 1 through 3) are: (1) a continua tion of the twentieth 392 century rate, (2) the twentieth century rate plus 2 mm per year, and (3) the twentieth 393 century rate plus 7 mm per year. Scenario 4 specifies a 2-meter rise (6.6-foot) over the 394 next few hundred years. Because humans ha ve a significant impact on portions of the 395 mid-Atlantic coast, this assessment focuses on assessing the vulnerability of the coastal 396 system as it currently exists (see discussion in Section 3.4). However, there are a few 397 caveats to this approach: 398

 This is a regional-scale assessment a nd there are local exceptions to these 399 geomorphic classifications and potential outcomes; 400

 Given that some portions of the mid-A tlantic coast are heavily influenced by 401 development and erosion mitigation practi ces, it cannot be assumed that current 402 practices will continue into the future given uncertainties rega rding the decision403 making process that occurs when these practices are pursued; but, 404

 At the same time, there are locations wh ere some members of the panel believe 405 that erosion mitigation will be implemented regardless of cost. 406 To express the likelihood of a given outcome fo r a particular sea-level rise scenario, the 407 terminology advocated by ongoing CCSP assessments was used (see Preface, Figure P.1; 408 CCSP, 2006). This terminology is used to quantify and communicate the degree of 409 likelihood of a given outcome specified by the assessment. These terms should not be 410CCSP 4.1 January 15, 2009

171 of 784 Final Report construed to represent a qua ntitative relationship between a specific sea-level rise 411 scenario and a specific dimension of coastal ch ange, or rate at which a specific process 412 operates on a coastal geomorphic compartment. The potential coastal responses to the 413 sea-level rise scenarios are described below according to the coastal landforms defined in 414 Section 3.5. 415
416 3.7.1 Spits 417 418 For sea-level rise Scenarios 1 through 3, it is virtually certain that the coastal spits along 419 the mid-Atlantic coast will be subject to increased storm overwash, erosion, and 420 deposition over the next century (s ee Figure 3.2, Sections 4, 9, 15). It is virtually certain 421 that some of these coastal spits will c ontinue to grow though the accumulation of 422 sediments from longshore transport as the erosion of updrift coastal compartments 423 occurs. For Scenario 4, it is likely that threshold behavior coul d occur for this type of 424 coastal landform (rapid landward and/or alongshore migration). 425
426 3.7.2 Headlands 427 Over the next century, it is virtually certain that these headlands along the mid-Atlantic 428 coast will be subject to increased erosion for all four sea-level rise scenarios (see Figure 429 3.2, Sections 1, 5, 8, 10, 12, and 16). It is very likely that shoreline and upland (bluff) 430 erosion will accelerate in response to projected increases in sea level. 431
432 3.7.3 Wave-Dominated Barrier Islands 433 Potential sea-level rise impacts on wave-dominat ed barriers in the Mid-Atlantic vary by 434 location and depend on the sea-level rise s cenario (see Figure 3.2, Sections 2, 6, 11, 13, 435CCSP 4.1 January 15, 2009

172 of 784 Final Report 17). For Scenario 1, it is virtually certain that the majority of the wave-dominated barrier 436 islands along the mid-Atlantic coast will co ntinue to experience morphological changes 437 through erosion, overwash, and inlet formation as they have over the last several 438 centuries, except for the northern portion of Assateague Island (Section 13 ). In this area, 439 the shoreline exhibits high rates of erosi on and large portions of this barrier are 440 submerged during moderate storms. In the past, large storms have breached and 441 segmented portions of northern Assateague Island (Morton et al. , 2003). Therefore, it is 442 possible that these portions of the coast are already at a geomorphic threshold. With any 443 increase in the rate of sea-level rise, it is virtually certain that this barrier island will 444 exhibit large changes in morphology, ultimately leading to the degrad ation of the island. 445 At this site, however, periodic tr ansfer of sand from the shoals of Ocean City Inlet appear 446 to be reducing erosion and shoreline retreat in Section13 (see Box 3.2). Portions of the 447 North Carolina Outer Banks (Figure 3.2) may similarly be nearing a geomorphic 448 threshold. 449 450 For Scenario 2, it is virtually certain that the majority of the wave-dominated barrier 451 islands in the mid-Atlantic region will c ontinue to experience morphological changes 452 through overwash, erosion, and inlet formati on as they have over the last several 453 centuries. It is also about as likely as not that a geomorphic threshold will be reached in a 454 few locations, resulting in rapid morphologica l changes in these barrier systems. Along 455 the shores of northern Assateague Island (Sect ion 13) and a substantia l portion of Section 456 17 it is very likely that the barrier isla nds could exhibit threshold behavior (barrier 457 segmentation). For this scenario, the ability of wetlands to maintain their elevation 458 through accretion at higher rates of sea-level rise may be reduced (Reed et al. , 2008). It is 459CCSP 4.1 January 15, 2009

173 of 784 Final Report about as likely as not that the loss of back -barrier marshes will lead to changes in 460 hydrodynamic conditions between tidal inlets an d back-barrier lagoons, thus affecting the 461 evolution of barrier islands ( e.g ., FitzGerald et al. , 2006; FitzGerald et al., 2008). 462
463 For Scenario 3, it is very likely that the potential for threshold behavior will increase 464 along many of the mid-Atlantic barrier islands. It is virtually certain that a 2-meter (6.6- 465 foot) sea-level rise will lead to threshold behavior (segme ntation or disintegration) for 466 this landform type. 467
468CCSP 4.1 January 15, 2009

174 of 784 Final Report 469 Figure 3.2 Map showing the potential sea-level rise re sponses for each coastal compartment. Colored 470 portions of the coastline indicates th e potential response for a given sea-level rise scenario according to the 471 inset table (Gutierrez et. al. , 2007). The color scheme was created using ColorBrewer by Cindy Brewer and 472 Mark Harrower. 473 474 3.7.4 Mixed-Energy Barrier Islands 475 476 The response of mixed-energy barrier islands will vary (see Figure 3.2, Sections 3, 7, 14). 477 For Scenarios 1 and 2, the mixed-energy barrie r islands along the mid-Atlantic will be 478 subject to processes much as have occurred ov er the last century such as storm overwash 479 and shoreline erosion. Given the degree to whic h these barriers have been developed, it is 480 difficult to determine the likelihood of future inlet breaches, or whether these would be 481CCSP 4.1 January 15, 2009

175 of 784 Final Report allowed to persist due to common management decisions to repair breaches when they 482 occur. In addition, changes to the back-barrier shores are uncertain due to the extent of 483 coastal development. 484 485 It is about as likely as not that four of the barrier is lands along the Virginia Coast 486 (Wallops, Assawoman, Metompkin, and Cedar Islands) are presently at a geomorphic 487 threshold. Thus, it, it is very likely that further sea-level rise will contribute to significant 488 changes resulting in the segmentation, disi ntegration and/or more rapid landward 489 migration of these barrier islands. 490 491 For the higher sea-level rise scen arios (Scenarios 3 and 4), it is about as likely as not that 492 these barriers could reach a geomorphic th reshold. This threshold is dependent on the 493 availability of sand from the longshore transport system to supply the barrier. It is 494 virtually certain that a 2-meter (6.6-foot) sea-level ri se will have severe consequences 495 along the shores of this porti on of the coast, including one or more of the extreme 496 responses described above. For Scenario 4, th e ability of wetlands to maintain their 497 elevation through accretion at higher rates of sea-level rise may be reduced (Reed et al. , 498 2008). It is about as likely as not that the loss of back-barri er marshes could lead to 499 changes in the hydrodynamic conditions between tidal inlets and back-barrier lagoons, 500 affecting the evolution of barrier islands (FitzGerald et al. , 2006, 2008). 501 502CCSP 4.1 January 15, 2009

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Muhs , D.R., R.M. Thorson, J.J. Clague, W.H. Mathews, P.F. McDowell, and H.M. 718 Kelsey, 1987: Pacific coast and mountain system. In: Geomorphic Systems of 719 North America [Graf, W.L. (ed.)]. Geological Society of America, Boulder CO, 720 pp. 517-582. 721

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Nicholls , R.J., P.P. Wong, V.R. Burkett, J.O. Codignotto, J.E. Hay, R.F. McLean, S. 731 Ragoonaden, and C.D. Woodroffe, 2007: Coas tal systems and low-lying areas. In: 732 Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of 733 Working Group II to the Fourth Assessmen t Report of the Intergovernmental 734 Panel on Climate Change [Parry, M.L., O.F. Canziani, J.P. Palutikof, P.J. van der 735 Linden, and C.E. Hanson (eds.)]. Cambri dge University Press, Cambridge, UK, 736 and New York, pp. 315-356. 737
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185 of 784 Final Report Nordstrom , K.F., 1994: Developed coasts. In: Coastal Evolution: Late Quaternary 741 Shoreline Morphodynamics [Carter, R.W.G. and C. D. Woodroffe (eds.)]. 742 Cambridge University Press, Cambridge, UK, pp. 477-510. 743 Nordstrom, K.F., 2000: Beaches and Dunes of Developed Coasts . Cambridge University 744 Press, New York, 338pp. 745

Nordstrom , K., S. Fisher, M. Burr, E. Franke l, T. Buckalew, and G. Kucma, 1977: 746 Coastal Geomorphology of New Jersey, Volumes I and II . Tech report 77-1. 747 Center for Coastal and Environmental Studies, Rutgers University, New 748 Brunswick, NJ. 749

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Penland , S., P.F. Connor, A. Beall, S. Fearnl ey, and S.J. Williams, 2005: Changes in 756 Louisiana’s shoreline: 1855-2002. Journal of Coastal Research , Special Issue 44 , 757 7-39. 758
Pierce , J.W. and D.J. Colquhoun, 1970: Holocene evolution of a portion of the North 759 Carolina coast. Geological Society of America Bulletin , 81(12) , 3697-3714. 760 Pilkey , O.H. and J.A.G Cooper, 2004: Society and sea-level rise. Science , 303(5665) , 761 1781-1782. 762 Psuty , N.P. and D.D. Ofiara, 2002: Coastal Hazard Management: Lessons and Future 763 Directions from New Jersey. Rutgers University Press, New Brunswick, NJ, 429 764 pp. 765CCSP 4.1 January 15, 2009

186 of 784 Final Report Ramsey , K.W., W.S. Schenck, and L.T. Wang, 2001: Physiographic Regions of the 766 Delaware Atlantic Coast . Delaware Geological Surv ey special publication 25. 767 University of Delaware, Lewes, 1 map. 768

Reed , D.J., D. Bishara, D. Cahoon, J. Donnell y, M. Kearney, A. Kolker, L. Leonard, 769 R.A. Orson, and J.C. Stevenson, 2008: Site-specific scenarios for wetlands 770 accretion as sea level rises in the mid-Atlantic region. Section 2.1 in: Background 771 Documents Supporting Climate Change Science Program Synthesis and 772 Assessment Product 4.1: Coastal Elevati ons and Sensitivity to Sea Level Rise 773 [Titus, J.G. and E.M. Strange (eds .)]. EPA 430R07004. U.S. Environmental 774 Protection Agency, Washington, DC, pp. 134-174. 775 <http://epa.gov/climatechange/e ffects/coastal/background.html> 776 Riggs , S.R. and D.V. Ames, 2007: Effect of Storms on Barrier Island Dynamics, Core 777 Banks, Cape Lookout National Seashore, North Carolina, 1960-2001 . U.S. 778 Geological Survey scientific investig ations report 2006-5309. U.S. Geological 779 Survey, Reston, VA, 78 pp. 780 Riggs , S.R., W.J. Cleary, and S.W. Snyder, 1995: Influence of inherited geologic 781 framework upon barrier beach morphology and shoreface dynamics. Marine 782 Geology , 126(1-4) , 213-234. 783
Rosati , J.D., 2005: Concepts in sediment budgets. Journal of Coastal Research , 21(2) , 784 307-322. 785 Rowley , R.J., J.C. Kostelnick, D. Braaten, X. Li , and J. Meisel, 2007: Risk of rising sea 786 level to population and land area. EOS, Transactions of the American 787 Geophysical Union , 88(9) , 105, 107. 788 Sallenger , A.S., C.W. Wright, and J. Lillycr op, 2007: Coastal-change impacts during 789 Hurricane Katrina: an overview. In: Coastal Sediments '07 [Kraus, N.C. and J.D. 790 Rosati (eds.)]. America Society of Civil Engineers, Reston, VA, pp. 888-896. 791CCSP 4.1 January 15, 2009

187 of 784 Final Report Schupp , C.A., J.E. McNinch, and J.H. List, 2006: Shore-oblique bars, gravel outcrops 792 and correlation to shoreline hotspots. Marine Geology , 233(1-4) , 63-79. 793 Schupp , C.A., G.P. Bass, and W.G. Gross kopf, 2007: Sand bypassing restores natural 794 processes to Assatea gue Island, Maryland. In: Coastal Sediments '07 [Kraus, N.C. 795 and J.D. Rosati (eds.)]. America Soci ety of Civil Engineers, Reston, VA, pp. 796 1340-1353. 797
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Stive , M.J.F., 2004: How important is global warm ing for coastal erosion? An editorial 802 comment. Climatic Change , 64(1-2) , 27-39. 803
Stive , M.J.F., S.G.J. Aarninkhof, L. Hamm, H. Hanson, M. Larson, K.M. Wijnberg, R.J. 804 Nicholls, and M. Capohianco, 2002: Variabil ity of shore and shoreline evolution. 805 Coastal Engineering , 47(2) , 211-235. 806 Stolper , D., J.H. List, and E.R. Thieler, 2005: Simulating the evolution of coastal 807 morphology and stratigraphy with a ne w morphological-behavior model 808 (GEOMBEST). Marine Geology , 218(1-4) , 17-36. 809
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188 of 784 Final Report Thieler , E.R., O.H. Pilkey, R.S. Young, D.M. Bush, and F. Chai, 2000: The use of 818 mathematical models to predict beach beha vior for coastal engineering: a critical 819 review. Journal of Coastal Research , 16(1) , 48-70. 820
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Walker , H.J. and J.M. Coleman, 1987: Atla ntic and Gulf Coast province. In: 824 Geomorphic Systems of North America [Graf, W.L. (ed.)]: Geological Society of 825 America, Boulder CO, pp. 51-110. 826
Williams , S.J., S. Penland, and A.H. Sallenger, 1992: Atlas of Shoreline Changes in 827 Louisiana from 1853 to 1989 . U.S. Geological Survey mi scellaneous investigation 828 series I-2150-A; Louisiana Barrier Is land Erosion Study. U.S.Geological Survey, 829 Reston, VA and Louisiana Geologi cal Survey, Baton Rouge, 107 pp. 830 Wright , L.D., 1995: Morphodynamics of Inner Continental Shelves . CRC Press, Boca 831 Raton, FL, 241 pp. 832 Zhang , K., B.C. Douglas, and S.P. Leatherma n, 2002: Do storms cause long-term beach 833 erosion along the U.S. east barrier coast? Journal of Geology , 110(4) , 493-502. 834 Zhang , K., B.C. Douglas, and S.P. Leathe rman, 2004: Global warming and coastal 835 erosion. Climatic Change , 64(1-2) , 41-58. 836

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## Chapter 4. Coastal Wetland Sustainability 838

839 Lead Authors: Donald R. Cahoon, USGS; Denise J. R eed, University of New Orleans; 840 Alexander S. Kolker, Louisian a Universities Marine Consorti um; Mark M. Brinson, East 841 Carolina University 842
843 Contributing Authors: J. Court Stevenson, University of Maryland; Stanley Riggs, East 844 Carolina University; Robert Christian, East Carolina University; Enrique Reyes, East 845 Carolina University; Christine Voss, East Carolina University; David Kunz, East 846 Carolina University 847
848 KEY FINDINGS 849

 It is virtually certain that tidal wetlands already experiencing submergence by sea850 level rise and associat ed high rates of loss ( e.g. , Mississippi River Delta in 851 Louisiana, Blackwater River marshes in Ma ryland) will continue to lose area in 852 response to future accelerated rates of s ea-level rise and changes in other climate 853 and environmental drivers (factors that cause measurable changes). 854

 It is very unlikely that there will be an overall increase in tidal wetland area in the 855 United States over the next 100 years, given current wetland loss rates and the 856 relatively minor accounts of ne w tidal wetland development ( e.g. , Atchafalaya Delta 857 in Louisiana). 858

 Current model projections of wetland vulnera bility on regional and national scales 859 are uncertain due to the coar se level of resolution of landscape-scale models. In 860CCSP 4.1 January 15, 2009

190 of 784 Final Report contrast, site-specific model projections are quite good where local information has 861 been acquired on factors that control local accretionary processe s in specific wetland 862 settings. However, the authors have lo w confidence that site-specific model 863 simulations can be successfully generalized so as to apply to larger regional or 864 national scales. 865

 An assessment of the mid-Atla ntic region based on an opini on approach by scientists 866 with expert knowledge of wetland accreti onary dynamics projects with a moderate 867 level of confidence that thos e wetlands keeping pace with twentieth century rates of 868 sea-level rise (Scenario 1) would survive a 2 millimeter per year acceleration of sea869 level rise (Scenario 2) only under optimal hydrology and sediment supply 870 conditions, and would not survive a 7 millimet er per year acceleration of sea-level 871 rise (Scenario 3). There may be localized exceptions in regions where sediment 872 supplies are abundant, such as at river m ouths and in areas where storm overwash 873 events are frequent. 874

 The mid-Atlantic regional assessment re vealed a wide variability in wetland 875 responses to sea-level rise, both within a nd among subregions and for a variety of 876 wetland geomorphic settings. This underscores both the influence of local processes 877 on wetland elevation and the difficulty of ge neralizing from regional/national scale 878 projections of wetland sustainability to the local scale in the absence of local 879 accretionary data. Thus, regiona l or national scale assessments should not be used to 880 develop local management plans where lo cal accretionary dyn amics may override 881 regional controls on wetland vertical development. 882CCSP 4.1 January 15, 2009

191 of 784 Final Report  Several key uncertainties need to be addr essed in order to improve confidence in 883 projecting wetland vulnerability to sea-le vel rise, including: a better understanding 884 of maximum rates at which wetland vertical accretion can be sustained; interactions 885 and feedbacks among wetland elevation, floodi ng, and soil organic matter accretion; 886 broad-scale, spatial variabili ty in accretionary dynamic s; land use change effects 887 ( e.g. , freshwater runoff, sediment supply, barr iers to wetland migration) on tidal 888 wetland accretionary processes; and lo cal and regional sediment supplies, 889 particularly fine-grain cohesive se diments needed for wetland formation. 890 891 4.1 INTRODUCTION 892 Given an expected increase in the rate of sea-level rise in the next century, effective 893 management of highly valuable coastal wetl and habitats and resources in the United 894 States will be improved by an in-depth assess ment of the effects of accelerated sea-level 895 rise on wetland vertical development ( i.e. , vertical accretion), the horizontal processes of 896 shore erosion and landward migration affec ting wetland area, and the expected changes 897 in species composition of plant a nd animal communities (Nicholls et al. , 2007). This 898 Chapter assesses current and projected future rates of vertical bu ildup of coastal wetland 899 surfaces and wetland sustainability during the ne xt century under the three sea-level rise 900 scenarios, as described briefly above, and in greater detail in Chapter 1. 901 902 Many factors must be considered in such an assessment, including: the interactive effects 903 of sea-level rise and othe r environmental drivers, ( e.g., changes in sediment supplies 904 related to altered river flows and storms); lo cal processes controlli ng wetland vertical and 905CCSP 4.1 January 15, 2009

192 of 784 Final Report horizontal development and the interaction of these processes with the array of 906 environmental drivers; geomorphic setti ng; and limited opportunities for landward 907 migration ( e.g. , human development on the coast, or steep slopes) (Figures 4.1 and 4.2). 908 Consequently, there is no simple, direct answ er on national or regional scales to the key 909 question facing coastal wetland managers to day, namely, “Are wetlands building 910 vertically at a pace equal to current sea-level rise, and will they build vertically at a pace 911 equal to future sea-level rise?” This is a difficult question to answer because of the 912 various combinations of local drivers and processes controlling wetland elevation across 913 the many tidal wetland settings found in Nort h America, and also due to the lack of 914 available data on the critical drivers and lo cal processes across these larger landscape 915 scales. 916

917 Figure 4.1 Climate and environmental drivers influencing vertical and horizontal wetland development. 918 919CCSP 4.1 January 15, 2009

193 of 784 Final Report The capacity of wetlands to keep pace with sea-level rise can be more confidently 920 addressed at the scale of indi vidual sites where data are av ailable on the critical drivers 921 and local processes. However, scaling up from the local to the national perspective is 922 difficult, and is rarely done, because of data constraints and because of variations in 923 climate, geology, species composition, and human-induced stressors that become 924 influential at larger scales. Better estimates of coastal wetland sust ainability under rising 925 sea levels and the factors influencing future sustainability are needed to inform coastal 926 management decision making. This Chapter provides an overview of the factors 927 influencing wetland sustainability ( e.g. , environmental drivers, accretionary processes, 928 and geomorphic settings), the state of knowledge of current and future wetland 929 sustainability, including a region al case study analysis of th e mid-Atlantic coast of the 930 United States, and information needed to improve projections of future wetland 931 sustainability at continental, regional, and local scales. 932 933 4.2 WETLAND SETTINGS OF THE MID-ATLANTIC REGION 934 Coastal wetlands in the continental United Stat es occur in a variety of physical settings 935 (Table 4.1). The geomorphic classification sc heme presented in Table 4.1, developed by 936 Reed et al . (2008) (based on Woodroffe, 2002 and Cahoon et al ., 2006), provides a useful 937 way of examining and comparing coasta l wetlands on a regional scale. Of the 938 geomorphic settings described in Table 4.1, saline fringe marsh, back-barrier lagoon 939 marsh, estuarine brackish marsh, tidal fresh ma rsh, and tidal fresh fo rest are found in the 940 mid-Atlantic region of the United States. Back-barrier lagoon salt marshes are either 941 attached to the backside of th e barrier island, or are islands ei ther landward of a tidal inlet 942 or behind the barrier island. Sa line fringe marshes are located on the landward side of 943CCSP 4.1 January 15, 2009

194 of 784 Final Report lagoons where they may be able to migrate ups lope in response to sea-level rise (see 944 Section 4.3 for a description of the wetland migration process). Estuarine marshes are 945 brackish (a mixture of fresh and salt water) and occur along channels rather than open 946 coasts, either bordering tidal ri vers or embayments; or as is lands within tidal channels. 947 Tidal fresh marshes and tidal fresh forests occur along river channels, usually above the 948 influence of salinity but not of tides. These wetlands can be distinguished based on 949 vegetative type (species composition; herbaceous versus forested) and the salinity of the 950 area. Given the differing hydrodynamics, sedime nt sources, and vegetative community 951 characteristics of these geomorphic settings, the relationship between sea-level rise and 952 wetland response will also differ. 953

954 4.3 VERTICAL DEVELOPMENT AND ELEVATION CHANGE 955 A coastal marsh will survive if it builds vertically at a rate equal to the rise in sea level; 956 that is, if it maintains its elevation relative to sea level. It is well established that marsh 957 surface elevation changes in response to sea-level rise. Tidal wetland surfaces are 958 frequently considered to be closely coupled with local mean sea level ( e.g. , Pethick, 959 1981; Allen, 1990). If a marsh builds vertically at a slower rate than the sea rises, 960 however, then a marsh area cannot maintain its elevation relative to sea level. In such a 961 case, a marsh will gradually become submerged a nd convert to an intertidal mudflat or to 962 open water over a period of many decades (Morris et al ., 2002). 963 964 The processes contributing to the capacity of a coastal wetland to maintain a stable 965 relationship with changing sea levels are complex and often nonlinear (Cahoon et al ., 966CCSP 4.1 January 15, 2009

195 of 784 Final Report 2006). For example, the response of tidal wetl ands to future sea-level rise will be 967 influenced not only by local site characteris tics, such as slope and soil erodibility 968 influences on sediment flux, but also by change s in drivers of verti cal accretion, some of 969 which are themselves influenced by climate chan ge (Figure 4.1). In a ddition to the rate of 970 sea-level rise, vertical accretion dynamics ar e sensitive to changes in a suite of human 971 and climate-related drivers, in cluding alterations in river and sediment discharge from 972 changes in precipitation patte rns and in discharge and runoff related to dams and 973 increases in impervious surfaces, increased frequency and intensity of hurricanes, and 974 increased atmospheric temperatures and carbon dioxide concentrations . Vertical accretion 975 is also affected by local environmental drivers such as shallow (local) and deep (regional) 976 subsidence and direct altera tions by human activities ( e.g. , dredging, diking). The relative 977 roles of these drivers of wetland vertical development vary with geomorphic setting. 978
979 4.3.1 Wetland Vertical Development 980 Projecting future wetland sustainability is made more difficult by the complex interaction 981 of processes by which wetlands build vertical ly (Figure 4.2) and vary across geomorphic 982 settings (Table 4.1). Figure 4.2 shows how e nvironmental drivers, mineral and organic 983 soil development processes, and wetland el evation interact. Tidal wetlands build 984 vertically through the accumulation of mi neral sediments and plant organic matter 985 (primarily plant roots). The suite of proce sses shown in Figure 4.2 c ontrols the rates of 986 mineral sediment deposition and accumulation of plant organic matter in the soil, and 987 ultimately elevation change. Overall minera l sedimentation represents the balance 988 between sediment import and export, which is influenced by sediment supply and the 989CCSP 4.1 January 15, 2009

196 of 784 Final Report relative abundance of various particle sizes, and varies am ong geomorphic settings and 990 different tidal and wave energy regimes. Sedi ment deposition occurs when the surface of 991 a tidal wetland is flooded. Thus, flooding dept h and duration are important controls on 992 deposition. The source of sediment may be s upplied from within the local estuary (Reed, 993 1989), and by transport from riverine and o ceanic sources. Sediments are remobilized by 994 storms, tides, and, in higher latitudes, ice rafting. 995
996

997 Figure 4.2 A conceptual diagram illustrating how environm ental drivers (white boxes) and accretionary 998 processes (grey boxes) influence vertical wetland development. 999 1000 The formation of organic-rich wetland soils is an important contribut or to elevation in 1001 both mineral sediment rich and mineral se diment poor wetlands (see review by Nyman et 1002 al. , 2006). Organic matter accumulation represents the balance betw een plant production 1003CCSP 4.1 January 15, 2009

197 of 784 Final Report (especially by roots and rhizomes) and decom position and export of plant organic matter 1004 (Figure 4.2). Accumulation co mes from root and rhizome growth, which contributes 1005 mass, volume, and structure to the sediments. The relativ e importance of mineral and 1006 organic matter accumulation can vary dependi ng on local factors such as rates of 1007 subsidence and salinity regimes. 1008 Table 4.1 Wetland types and their characteristics as they are distributed within geomorphic settings 1009 in the continental United States. 1010 1011 Geomorphic Setting Description Subsettings Dominant accretion processes Example Site Dominant vegetation Open Coast Areas sheltered from waves and currents due to coastal topography or bathymetry Storm sedimentation Peat accumulation Appalachee Bay, Florida smooth cordgrass (Spartina alterniflora) black needlerush (Juncus roemerianus) spike grass (Distichlis spicata) salt hay (Spartina patens) glasswort (Salicornia spp.) saltwort (Batis maritima) Back-Barrier Lagoon Marsh (BB) Occupies fill within transgressive back-barrier lagoons Back-barrier Active flood

tide delta Lagoonal fill Storm sedimentation (including barrier overwash) Peat accumulation Oceanic inputs via inlets Great South Bay, New York; Chincoteague Bay, Maryland, Virginia smooth cordgrass (Spartina alterniflora) black needlerush ( Juncus roemerianus) spike grass (Distichlis spicata) salt hay (Spartina patens) glasswort (Salicornia spp.) saltwort (Batis maritima) Estuarine Embayment Shallow coastal embayments with some river discharge, frequently drowned river valleys Chesapeake Bay,Maryland, Virginia; Delaware Bay, New Jersey, Pennsylvania, Delaware, Estuarine Embayment a. Saline Fringe Marsh (SF) Transgressive marshes bordering uplands at the lower end of estuaries (can also be found in back-barrier Storm sedimentation Peat accumulation Peconic Bay, New York; Western Pamlico Sound, North Carolina smooth cordgrass (Spartina alterniflora) black needlerush (Juncus roemerianus) spike grassCCSP 4.1 January 15, 2009

198 of 784 Final Report Geomorphic Setting Description Subsettings Dominant accretion processes Example Site Dominant vegetation lagoons) (Distichlis spicata) salt hay (Spartina patens) glasswort (Salicornia spp.) saltwort (Batis maritima) Estuarine Embayment b. Stream Channel Wetlands Occupy estuarine/alluvial channels rather than open coast Dennis Creek, New Jersey; Lower Nanticoke River, Maryland
Estuarine Brackish Marshes (ES) Located in vicinity of turbidity maxima zone Meander Fringing Island Alluvial and tidal inputs Peat accumulation Lower James River, Virginia; Lower Nanticoke River, Maryland; Neuse River Estuary, North Carolina smooth cordgrass (Spartina alterniflora) salt hay (Spartina patens) spike grass (Distichlis spicata) black grass (Juncus gerardi) black needlerush (Juncus roemerianus) sedges (Scirpus olneyi) cattails (Typha spp.) big cordgrass (Spartina cynosuroides) pickerelweed (Pontederis cordata) Tidal Fresh Marsh (FM) Located above turbidity maxima zone; develop in drowned river valleys as filled with sediment Alluvial and tidal inputs Peat accumulation Upper Nanticoke River, Maryland; Anacostia River, Washington, DC arrow arum (Peltandra virginica) pickerelweed (Pontederis cordata) arrowhead (Sagitarria spp.) bur-marigold (Bidens laevis) halberdleaf tearthumb (Polygonum arifolium)scarlet rosemallow (Hibiscus coccineus) wild-rice (Zizannia aquatica) cattails (Typha spp.)CCSP 4.1 January 15, 2009

199 of 784 Final Report Geomorphic Setting Description Subsettings Dominant accretion processes Example Site Dominant vegetation giant cut grass (Zizaniopsis miliacea) big cordgrass (Spartina cynosuroides) Tidal Fresh Forests (FF) Develop in riparian zone along rivers and backwater areas beyond direct influence of seawater Deepwater Swamps (permanently flooded) Bottomland Hardwood Forests (seasonally flooded) Alluvial input Peat accumulation Upper Raritan Bay, New Jersey; Upper Hudson River, New York bald cypress (Taxodium distichum) blackgum (Nyssa sylvatica) oak (Quercus spp.) green ash (Fraxinus pennsylvanica) (var. lanceolata ) Nontidal Brackish Marsh Transgressive marshes bordering uplands in estuaries with restricted tidal signal Alluvial input Peat accumulation Pamlico Sound, North Carolina black needlerush (Juncus roemerianus) smooth cordgrass (Spartina alterniflora) spike grass (Distichlis spicata) salt hay (Spartina patens) big cordgrass (Spartina cynosuroides) Nontidal Forests Develop in riparian zone along rivers and backwater areas beyond direct influence of seawater in estuaries with restricted tidal signal Bottomland Hardwood Forests (seasonally flooded) Alluvial input Peat accumulation Roanoke River, North Carolina; Albemarle Sound, North Carolina bald cypress (Taxodium distichum) blackgum (Nyssa sylvatica) oak (Quercus spp.) Green ash, Fraxinus pennsylvanica 4. Delta Develop on riverine sediments in shallow open water during active deposition; reworked by marine processes after abandonment Alluvial input Peat accumulation Compaction/Subsidence Storm sedimentation Marine Processes Mississippi Delta, Louisiana smooth cordgrass (Spartina alterniflora) black needlerush (Juncus roemerianus) spike grass (Distichlis spicata) salt hay (Spartina patens) glasswort (Salicornia spp.) saltwort (Batis maritima) maidencan e (Panicum haemitomon) arrowhead (Sagitarria spp.)CCSP 4.1 January 15, 2009

200 of 784 Final Report 4.3.2 Influence of Climate Change on Wetland Vertical Development 1012 Projections of wetland sustainabi lity are further complicated by the fact that sea-level rise 1013 is not the only factor influe ncing accretionary dynamics and sustainability (Figure 4.1). 1014 The influence of sea-level rise and othe r human- and climate-related environmental 1015 drivers on mineral sediment delivery system s is complex. For example, the timing and 1016 amount of river flows are altered by changes in discharge related to both the effects of 1017 dams and impervious surfaces built by humans and to changes in precipitation patterns 1018 from changing climate. This results in a cha nge in the balance of forces between river 1019 discharge and the tides that control the phys ical processes of water circulation and 1020 mixing, which in turn determines the fate of sediment within an estuary. Where river 1021 discharge dominates, highly stratified es tuaries prevail, and where tidal motion 1022 dominates, well-mixed estuaries tend to develop (Dyer, 1995). Many mid-Atlantic 1023 estuaries are partially mixed systems because the influence of river discharge and tides 1024 are more balanced. 1025
1026 River discharge is affected by interannual and interseasonal variations and intensities of 1027 precipitation and evapotranspiration patte rns, and by alterations in land use ( e.g ., 1028 impervious surfaces and land cover types) and control over river flows ( e.g ., 1029 impoundments and withdrawals). Sea-level rise can further change the balance between 1030 river discharge and tides by its effect on tidal range (Dyer, 1995). An increase in tidal 1031 range would increase tidal velocities and, consequentl y, tidal mixing and sediment 1032 transport, as well as extend th e reach of the tide landward. In addition, sea-level rise can 1033 affect the degree of tidal asymmetry in an estuary ( i.e. , ebb versus flood dominance). In 1034CCSP 4.1 January 15, 2009

201 of 784 Final Report flood dominant estuaries, marine sediments ar e more likely to be imported to the estuary. 1035 However, an increase in sea level without a change in tidal range may cause a shift 1036 toward ebb dominance, thereby reducing th e input of marine sediments that might 1037 otherwise be deposited on intertidal flat s and marshes (Dyer, 1995). Estuaries with 1038 relatively small intertidal areas and small tidal amplitudes would be particularly 1039 susceptible to such changes. The current hydr odynamic status of es tuaries today is the 1040 result of thousands of years of interaction between rising sea level and coastal landforms. 1041
1042 The degree of influence of s ea-level rise on wetland floodi ng, sedimentation, erosion, and 1043 salinity is directly linked w ith the influence of altered river flows and storm impacts 1044 (Figure 4.2). Changes in fr eshwater inputs to the coas t can affect coastal wetland 1045 community structure and function (Sklar and Browder, 1998) through fluctuations in the 1046 salt balance up and down the estuary. Low- salinity and freshwater wetlands are 1047 particularly affected by increases in salinit y. In addition, the loca tion of the turbidity 1048 maximum zone (the region in many estuaries where suspended sediment concentrations 1049 are higher than in either the river or sea) can shift seaward with increases in river 1050 discharge, and the size of this zone will in crease with increasing tidal ranges (Dyer, 1051 1995). Heavy rains (freshwater) and tidal surges (salty water) from storms occur over 1052 shorter time periods than in terannual and interseasonal vari ation. This can exacerbate or 1053 alleviate (at least temporarily) salinity and inundation effect s of altered freshwater input 1054 and sea-level rise in all wetland types. The direction of elevation change depends on the 1055 storm characteristics, wetland type, and loca l conditions at the ar ea of storm landfall 1056 (Cahoon, 2006). Predicted increases in the magn itude of coastal storms from higher sea 1057CCSP 4.1 January 15, 2009

202 of 784 Final Report surface temperatures (Webster et al., 2005) will likely increase storm-induced wetland 1058 sedimentation in the mid-Atlantic regional wetlands. Increased storm intensity could 1059 increase the resuspension of nearshore sedi ments and the storm-related import of oceanic 1060 sediments into tidal marshes. 1061
1062 In addition to sediment supplies, accumula tion of plant organic matter is a primary 1063 process controlling wetland vertical deve lopment of soil. The production of organic 1064 matter is influenced by factors associated w ith climate change, including increases in 1065 atmospheric carbon dioxide concentrations, ri sing temperatures, more frequent and 1066 extensive droughts, higher nutrient loadi ng from floodwaters and ground waters, and 1067 increases in salinity of flood wa ters. Therefore, a critical que stion that scientists must 1068 address is: “How will these potential changes in plant growth affect wetland elevations 1069 and the capacity of the marsh to keep p ace with sea-level rise?” Some sites depend 1070 primarily on plant matter accumulation to build vertically. For example, many brackish 1071 marshes dominated by salt hay ( Spartina patens ) (McCaffrey and Thomson, 1980) and 1072 mangroves on oceanic islands with lo w mineral sediment inputs (McKee et al. , 2007), 1073 changes in root production (Cahoon et al. , 2003, 2006) and nutrient additions (McKee et 1074 al. , 2007) can significantly change root growth and wetland el evation trajectories. These 1075 changes and their interactions warrant further study. 1076
1077 4.4 HORIZONTAL MIGRATION 1078 Wetland vertical development can lead to horizontal expansion of wetland area (both 1079 landward and seaward; Redfield, 1972), dependi ng on factors such as slope, sediment 1080 supply, shoreline erosion rate, a nd rate of sea-level rise. As marshes build vertically, they 1081CCSP 4.1 January 15, 2009

203 of 784 Final Report can migrate inland onto dry upla nds, given that the slope is not too steep and there is no 1082 human-made barrier to migration (Figure 4.1). Some of the best examples of submerged 1083 upland types of wetlands in the mid-Atlantic region are found on the Eastern Shore of 1084 Chesapeake Bay, a drowned river valley estuary (Darmody and Foss, 1979). Given a 1085 setting with a low gradient slope, low wave energy, a nd high sediment supply ( e.g. , 1086 Barnstable Marsh on Cape Cod, Massachusetts ), a marsh can migrate both inland onto 1087 uplands and seaward onto sand flats as the sh allow lagoon fills with sediment (Redfield, 1088 1972). Most coasts, however, have enough wave energy to prevent seaward expansion of 1089 the wetlands. The more common alternative is erosion of the seaward boundary of the 1090 marsh and retreat. In these settings, as l ong as wetland vertical development keeps pace 1091 with sea-level rise, wetland area will expa nd where inland migration is greater than 1092 erosion of the seaward boundary, remain unc hanged where inland migration and erosion 1093 of the seaward boundary are equal, or declin e where erosion of the seaward boundary is 1094 greater than inland migration ( e.g. , Brinson et al. , 1995). If wetland vertical development 1095 lags behind sea-level rise ( i.e. , wetlands do not keep pace), the wetlands will eventually 1096 become submerged and deteriorate even as they migrate, resulting in an overall loss of 1097 wetland area, as is occurring at Blackwater National Wildlife Refuge in Dorchester 1098 County, Maryland (Stevenson et al. , 1985). Thus, wetland migration is dependent on 1099 vertical accretion, which is the key process for both wetland survival and expansion. If 1100 there is a physical obstruction preventing in land wetland migration, such as a road or a 1101 bulkhead, and the marsh is keeping pace with sea-level rise, then the marsh will not 1102 expand but will survive in place as long as there is no lateral erosion at its seaward edge. 1103 Otherwise, the wetland will become narrower as waves erode the shoreline. Thus, having 1104CCSP 4.1 January 15, 2009

204 of 784 Final Report space available with a low gradient slope for inland expansion is critical for maintaining 1105 wetland area in a setting where seawar d erosion of the marsh occurs. 1106
1107 4.5 VULNERABILITY OF WETLANDS TO TWENTIETH CENTURY SEA1108 LEVEL RISE 1109 A recent evaluation of accretion and elevation trends from 49 salt marshes located around 1110 the world, including sites from the Atlantic, Gu lf of Mexico, and Pacific coasts of the 1111 United States, provides insights into the mechanisms and variability of wetland responses 1112 to twentieth century trends of local sea-level rise (Cahoon et al., 2006). Globally, average 1113 wetland surface accretion rates were greater than and positively related to local relative 1114 sea-level rise, suggesting that the marsh su rface level was being maintained by surface 1115 accretion within the tidal range as sea level ro se. In contrast, average rates of elevation 1116 rise were not significantly related to sea-le vel rise and were significantly lower than 1117 average surface accretion rates, indicating that shallow soil subsidence occurs at many 1118 sites. Regardless, elevation changes at many s ites were greater than local sea-level rise 1119 (Cahoon et al., 2006). Hence, understanding elevation change, in addition to surface 1120 accretion, is important when determining wetla nd sustainability. Secondly, accretionary 1121 dynamics differed strongly among geomorphic settings, with deltas and embayments 1122 exhibiting high accretion and high shallow subsidence compared to back-barrier and 1123 estuarine settings (see Cahoon et al., 2006). Thirdly, strong re gional differences in 1124 accretion dynamics were observed for the No rth American salt marshes evaluated, with 1125 northeastern U.S. marshes exhibiting high ra tes of both accretion and elevation change, 1126 southeastern Atlantic and Gulf of Mexico salt marshes exhibiting high rates of accretion 1127CCSP 4.1 January 15, 2009

205 of 784 Final Report and low rates of elevation change, and Pacifi c salt marshes exhibiting low rates of both 1128 accretion and elevation change (see Cahoon et al., 2006). The marshes with low elevation 1129 change rates are likely vulnerable to current and future sea-level rise, with the exception 1130 of those in areas where the land surface is ri sing, such as on the Pacific Northwest Coast 1131 of the United States. 1132
1133 4.5.1 Sudden Marsh Dieback 1134 An increasing number of re ports available online (see e.g. , <http://wetlands.neers.org/>, 1135 <www.inlandbays.org>, <www.brownmarsh.ne t>, <www.lacoast.gov/watermarks/2004- 1136 04/3crms/index.htm>) of widespread “s udden marsh dieback” and “brown marsh 1137 dieback” from Maine to Louisiana, along w ith published studies documenting losses of 1138 marshes dominated by saltmarsh cordgrass ( Spartina alterniflora ) and other halophytes 1139 (plants that naturally grow in salty soils), s uggest that a wide variety of marshes may be 1140 approaching or have actually gone beyond thei r tipping point where th ey can continue to 1141 accrete enough inorganic materi al to survive (Delaune et al., 1983; Stevenson et al., 1142 1985; Kearney et al., 1988, 1994; Mendelssohn a nd McKee, 1988; Hartig et al., 2002; 1143
McKee et al., 2004; Turner et al., 2004). Sudden dieback was documented over 40 years 1144 ago by marsh ecologists (Goodman and W illiams, 1961). However, it is not known 1145 whether all recently identified events are the same phenomenon and caused by the same 1146 factors. There are biotic factors, in add ition to insufficient accretion, that have been 1147 suggested to contribute to sudden marsh dieback, including fungal diseases and 1148 overgrazing by animals such as waterfowl, nut ria, and snails. Interacting factors may 1149 cause marshes to decline even more rapidly th an scientists would predict from one driver, 1150CCSP 4.1 January 15, 2009

206 of 784 Final Report such as sea-level rise. There are few details about the onset of sudden dieback because 1151 most studies are done after it has already o ccurred (Ogburn and Alber, 2006). Thus, more 1152 research is needed to understand sudden marsh dieback. The apparent increased 1153 frequency of this phenomenon over the last se veral years suggests an additional risk 1154 factor for marsh survival over the next cen tury (Stevenson and K earney, in press). 1155 1156 4.6 PREDICTING FUTURE WETLAND SUSTAINABILITY 1157 Projections of future wetland su stainability on regional to na tional scales are constrained 1158 by the limitations of the two modeling appro aches used to evaluate the relationship 1159 between future sea-level rise and coastal wetland elevation: lands cape scale models and 1160 site-specific models. Large scale landscape models, such as the Sea Level Affecting 1161 Marshes Model (SLAMM) (Park et al. , 1989), simulate general tr ends over large areas, 1162 but typically at a very coar se resolution. These landscape mo dels do not mechanistically 1163 simulate the processes that contribute to wetland elevation; the processes are input as 1164 forcing functions and are not simulated within the model. Thus, this modeling approach 1165 does not account for infrequent events that influence wetland vertical development, such 1166 as storms and floods, or for fr equent elevation feedback m echanisms affecting processes 1167 (for example, elevation change alters floodi ng patterns that in turn affect sediment 1168 deposition, decomposition, and plant productio n). In addition, these models are not 1169 suitable for site-specific research and ma nagement problems because scaling down of 1170 results to the local level is not feasib le. Therefore, although landscape models can 1171 simulate wetland sustainability on broad spatia l scales, their coarse resolution limits their 1172 accuracy and usefulness to the local manager. 1173CCSP 4.1 January 15, 2009

207 of 784 Final Report 1174 On the other hand, process orie nted site-specific models ( e.g. , Morris et al. , 2002; 1175 Rybczyk and Cahoon, 2002) are more mechanistic than landscape models and are used to 1176 simulate responses for a specific site with a narrow range of conditions and settings. 1177 These site-specific models can account for accre tion events that occur infrequently, such 1178 as hurricanes and major river floods, and the feedback effects of elevation on inundation 1179 and sedimentation that influence accretionary processes over timeframes of a century. 1180 The use of site-specific conditions in a m odel makes it possible to predict long-term 1181 sustainability of an individual wetland in a particular geomorphic se tting. However, like 1182 the landscape models, site-specific models also have a scaling problem. Using results 1183 from an individual site to make long-term projections at larger spatial scales is 1184 problematic because accretionary and process data are not available for the variety of 1185 geomorphic settings across thes e larger-scale landscapes for calibrating and verifying 1186 models. Thus, although site-specific models provide high resolution simulations for a 1187 local site, at the present time future coasta l wetland response to sea- level rise over large 1188 areas can be predicted w ith only low confidence. 1189 1190 Recently, two different modeling approaches ha ve been used to provide regional scale 1191 assessments of wetland response to climate ch ange. In a hierarchical approach, detailed 1192 site-specific models were parameterized w ith long-term data to generalize landscape1193 level trends with moderate confidence fo r inland wetland sites in the Prairie Pothole 1194 Region of the Upper Midwest of the United States (Carroll et al. , 2005; Voldseth et al. , 1195 2007; Johnson et al. , 2005). The utility of this appro ach for coastal wetlands has not yet 1196CCSP 4.1 January 15, 2009

208 of 784 Final Report been evaluated. Alternatively, an approach was used to assess coastal wetland 1197 vulnerability at regional-to-gl obal scales from three broad en vironmental drivers: (1) ratio 1198 of relative sea-level rise to tidal range, (2) sedi ment supply, and (3) lateral 1199 accommodation space ( i.e. , barriers to wetland migration) (McFadden et al. , 2007). This 1200 model suggests that, from 2000 to 2080, there will be global wetland area losses of 33 1201 percent for a 36 centimeter (cm) rise in sea le vel and 44 percent for a 72 cm rise; and that 1202 regionally, losses on the Atlantic and Gulf of Mexico coasts of the United States will be 1203 among the most severe (Nicholls et al. , 2007). However, this model, called the Wetland 1204 Change Model, remains to be validated a nd faces similar challe nges when downscaling, 1205 as does the previously descri bed model when scaling up. 1206
1207 Taking into account the limitations of curre nt predictive modeling approaches, the 1208 following assessments can be made about futu re wetland sustainability at the national 1209 scale: 1210

 It is virtually certain that tidal wetlands already experiencing submergence by sea1211 level rise and associat ed high rates of loss ( e.g. , Mississippi River Delta in 1212 Louisiana, Blackwater National Wildlife Refuge marshes in Maryland) will continue 1213 to lose area under the influence of future accelerated rates of sea-level rise and 1214 changes in other climate a nd environmental drivers. 1215

 It is very unlikely that there will be an overall increase in tidal wetland area on a 1216 national scale over the next 100 years, gi ven current wetland loss rates and the 1217 relatively minor accounts of ne w tidal wetland development ( e.g. , Atchafalaya Delta 1218 in Louisiana). 1219CCSP 4.1 January 15, 2009

209 of 784 Final Report  Current model projections of wetland vulnera bility on regional and national scales 1220 are uncertain because of the coarse level of resolution of landscape scale models. In 1221 contrast, site-specific model projections are quite good where local information has 1222 been acquired on factors that control local accretionary processe s in specific wetland 1223 settings. However, the authors have lo w confidence that site-specific model 1224 simulations, as currently portrayed, can be successfully scaled up to provide realistic 1225 projections at regional or national scales. 1226
1227 The following information is needed to improve the confidence in projections of future 1228 coastal wetland sustainability on regional and continental scales: 1229

 Models and validation data . To scale up site-specific model outputs to regional 1230 and continental scales with high confidence, detailed data are needed on the 1231 various local drivers and pr ocesses controlling wetland elevation across all tidal 1232 geomorphic settings of the United States . Obtaining and evaluating the necessary 1233 data will be an enormous and expensive task, but not an impractical one. It will 1234 require substantial coordination w ith various private and government 1235 organizations in order to develop a large, searchable database. Until this type of 1236 database becomes a reality, current mode ling approaches need to improve or 1237 adapt such that they can be applied across a broad spatial scale with better 1238 confidence. For example, evaluating th e utility of applying the multi-tiered 1239 modeling approach used in the Prairie Po thole Region to coastal wetland systems 1240 and validating the broad scale Wetland Change Model for North American coastal 1241 wetlands will be important first steps. Sc ientists’ ability to predict coastal wetland 1242CCSP 4.1 January 15, 2009

210 of 784 Final Report sustainability will improve as specific ecological and geological processes 1243 controlling accretion and thei r interactions on local and regional scales are better 1244 understood. 1245

 Expert opinion . Although models driven by empiri cal data are preferable, given 1246 the modeling limitations described, an expert opinion ( i.e. , subjective) approach 1247 can be used to develop spatially explic it landscape-scale predictions of coastal 1248 wetland responses to future sea-level rise with a low-to-moderate level of 1249 confidence. This approach requires conve ning a group of scientists with expert 1250 knowledge of coastal wetland geomorphic pr ocesses, with conclusions based on 1251 an understanding of the processes driving marsh survival during sea-level rise and 1252 of how the magnitude and nature of these processes might change due to the 1253 effects of climate change and other factor s. Because of the enormous complexity 1254 of these issues at the continental scal e, the expert opinion approach would be 1255 applied with greater confidence at th e regional scale. Two case studies are 1256 presented in Sections 4.6.1 and 4.6.2; the fi rst, using the expe rt opinion approach 1257 applied to the mid-Atlantic region from Ne w York to Virginia, the second, using a 1258 description of North Carolina wetlands from the Albemarle–Pamlico Region and 1259 an evaluation of their potent ial response to sea-level rise, based on a review of the 1260 literature. 1261
1262 1263 4.6.1 Case Study: Mid-Atlantic Regional Assessment, New York to Virginia 1264 1265 A panel of scientists with diverse and expert knowledge of wetland accretionary 1266 processes was convened to develop spatially explicit landscape-scale predictions of 1267CCSP 4.1 January 15, 2009

211 of 784 Final Report coastal wetland response to the three scenarios of sea-level ri se assessed in this Product 1268 (see Chapter 1) for the mid-Atlantic region fr om New York to Virginia (see Text Box 1269 4.1). The results of the panel’s effort (Reed et al., 2008) inform this Product assessment 1270 of coastal elevations and sea-level rise. 1271 Begin text box 1272 1273 Text Box 4.1: The Wetland Assessment Process Used by a Panel of Scientists 1274 1275 As described in this Product, scientific consensus re garding regional-scale coastal changes in response to 1276 sea-level rise is currently lacking. To address the issue of future changes to mid-Atlantic coastal wetlands, 1277 Denise Reed, a wetlands specialist at the University of New Orleans, was contracted by the U.S.EPA to 1278 assemble a panel of coastal wetland scientists to eval uate the potential outcomes of the sea-level rise 1279 scenarios used in this Product. Denise Reed chose the 8 members of this panel on the basis of their 1280 technical expertise and experience in the coastal wetla nd research community, particularly with coastal 1281 wetland geomorphic processes, and also their involvement with coastal management issues in the mid1282 Atlantic region. The panel was charged to address the question, “To what extent can wetlands vertically 1283 accrete and thus keep pace with rising sea level, that is, will sea-level rise cause the area of wetlands to 1284 increase or decrease?”. 1285 1286 The sea-level rise impact assessment effort was conducted as an open discussion facilitated by Denise Reed 1287 over a two-day period. Deliberations were designed to ensure that conclusions were based on an 1288 understanding of the processes driving marsh survival as sea level rises and how the magnitude and nature 1289 of these processes might change in th e future in response to climate change and other factors. To ensure a 1290 systematic approach across regions within the mid-Atlantic region, the panel: 1291 1292 1) identified a range of geomorphic settings to assist in distinguishing among the different process 1293 regimes controlling coastal wetland accretion (see Figure 4.3 and Table 4.1); 1294 2) identified a suite of processes that contribute to marsh accretion (see Table 4.1) and outlined 1295 potential future changes in current pr ocess regimes caused by climate change; 1296 3) divided the mid-Atlantic into a series of regions based on similarity of process regime and current 1297 sea-level rise rates; and 1298 4) delineated geomorphic settings within each region on 1:250,000 scale maps, and agreed upon the 1299 fate of the wetlands within these settings under the three sea-level rise scenarios, with three 1300 potential outcomes: keeping pace, marg inal, and loss (see Figure 4.4). 1301 1302 The qualitative, consensus-based assessment of poten tial changes and their likelihood developed by the 1303 panel is based on their review and understanding of published coastal science literature ( e.g ., 88 published 1304 rates of wetland accretion from the mid-Atlantic region , and sea-level rise rates based on NOAA tide gauge 1305 data), as well as field observations drawn from other studies conducted in the mid-Atlantic region. A report 1306 (Reed et al ., 2008) summarizing the process used, basis in the published literature, and a synthesis of the 1307 resulting assessment was produced and approved by all members of the panel. 1308 1309 The report was peer reviewed by external subject-matte r experts in accordance with U.S. EPA peer review 1310 policies. Reviewers were asked to examine locality-s pecific maps for localities with which they were 1311 familiar, and the documentation for how the maps were created. They were then asked to evaluate the 1312 assumptions and accuracy of the maps, and errors or omissions in the text. The comments of all reviewers 1313 were carefully considered and inco rporated, wherever possible, throughout the report. The final report was 1314 published and made available online in February 2008 as a U.S. Environmental Protection Agency report: 1315 < http://epa.gov/climatechange/effects/downloads/section2_1.pdf >. 1316 1317CCSP 4.1 January 15, 2009

212 of 784 Final Report End text box 1318 1319 4.6.1.1 Panel Assessment Methods. 1320 The general approach used by the panel is summarized in Box 4.1. The panel recognized 1321 that accretionary processes differ among setti ngs and that these processes will change in 1322 magnitude and direction with future climate ch ange. For example, it is expected that the 1323 magnitude of coastal storms will increase as sea-surface temperatures increase (Webster 1324 et al. , 2005), likely resulting in an increase in storm sediment ation and oceanic sediment 1325 inputs. Also, the importance of peat accumulation to vertical accretion in freshwater 1326 systems (Neubauer 2008) is expected to incr ease in response to sea-level rise up to a 1327 threshold capacity, beyond which peat accumulation can no longer increase. However, if 1328 salinities also increase in freshwater systems, elevation gains from increased peat 1329 accumulation could be offset by increased decomposition from sulfate reduction. 1330 Enhanced microbial breakdown of organic-rich soils is likely to be most important in 1331 formerly fresh and brackish environments where the availability of sulfate, and not 1332 organic matter, generally limits sulfate-re duction rates (Goldhab er and Kaplan, 1974). 1333 Increases in air and soil temperatures are e xpected to diminish the importance of ice 1334 effects. Changes in precipitation and human la nd-use patterns will alter fluvial sediment 1335 inputs. 1336
1337 The fate of mid-Atlantic wetlands for the thr ee sea-level rise scenarios evaluated in this 1338 Product was determined by the panel through a consensus opinion af ter all information 1339 was considered (see Figure 4.4). The wetlands were classified as keeping pace, marginal, 1340 or loss (Reed et al., 2008): 1341CCSP 4.1 January 15, 2009

213 of 784 Final Report 1. Keeping pace : Wetlands will not be submerged by rising sea levels and will be 1342 able to maintain their relative elevation. 1343
2. Marginal : Wetlands will be able to maintain their elevation only under optimal 1344 conditions. Depending on the dominant accreti onary processes, this could include 1345 inputs of sediments from storms or floods, or the maintenance of hydrologic 1346 conditions conducive for optimal plant grow th. Given the complexity and inherent 1347 variability of climatic and other factor s influencing wetland accretion, the panel 1348 cannot predict the fate of these wetla nds. Under optimal conditions they are 1349 expected to survive. 1350
3. Loss : Wetlands will be subject to increased flooding beyond that normally 1351 tolerated by vegetative communities, leadi ng to deterioration and conversion to 1352 open water habitat. 1353 1354 1355 1356 1357 1358 1359
1360
1361CCSP 4.1 January 15, 2009

214 of 784 Final Report 1362 Figure 4.3 Geomorphic settings of mid-Atlantic tidal wetlands (data source: Reed et al., 2008; map 1363 source: Titus et al ., 2008). 1364 1365 The panel recognized that wetland s identified as marginal or loss will become so at an 1366 uneven rate and that the rate and spatial di stribution of change will vary within and 1367 among similarly designated areas. The panel fu rther recognized that wetland response to 1368 sea-level rise over the next century will de pend upon the rate of sea-level rise, existing 1369 wetland condition ( e.g. , elevation relative to sea level) , and local controls of accretion 1370 processes. In addition, changes in flooding and salinity patterns may re sult in a change of 1371 dominant species ( i.e. , less flood-tolerant high marsh species replaced by more flood1372 tolerant low marsh species), which could a ffect wetland sediment trapping and organic 1373CCSP 4.1 January 15, 2009

215 of 784 Final Report matter accumulation rates. A wetland is considered marginal when it becomes severely 1374 degraded (greater than 50 percent of vegetated area is converted to open water) but still 1375 supports ecosystem functions associated with that wetland type. A wetland is considered 1376 lost when its function shifts primarily to that of shallow open water habitat. 1377
1378 There are several caveats to th e expert panel approach, interp retations, and application of 1379 findings. First, regional scale assessments are intended to provide a landscape-scale 1380 projection of wetland vulnerabi lity to sea-level rise ( e.g. , likely trends, areas of major 1381 vulnerability) and not to repl ace assessments based on loca l process data. The authors 1382 recognize that local exceptions to the panel’ s regional scale assessment likely exist for 1383 some specific sites where detailed accretionary data are available. Second, the panel’s 1384 projections of back-barrier we tland sustainability assume th at protective barrier islands 1385 retain their integrity. Shoul d barrier islands collapse (see Section 3.7.3), the lagoonal 1386 marshes would be exposed to an increas ed wave energy environment and erosive 1387 processes, with massive marsh loss likely over a relatively short period of time. (In such a 1388 case, vulnerability to marsh loss would be only one of a host of environmental problems.) 1389 Third, the regional projections of wetland sustainability assume that the health of marsh 1390 vegetation is not adversely affected by local ou tbreaks of disease or other biotic factors 1391 ( e.g. , sudden marsh dieback). Fourth, the pane l considered the e ffects of a rate 1392 acceleration above current of 2 mm per year (Scenario 2) and 7 mm per year (Scenario 1393 3), but not rates in between. Determining wetl and sustainability at sea-level rise rates 1394 between Scenarios 2 and 3 requires greater understanding of the variations in the 1395 maximum accretion rate regionally and among vegetative communities (Reed et al., 1396CCSP 4.1 January 15, 2009

216 of 784 Final Report 2008). Currently, there are few estimates of th e maximum rate at which marsh vertical 1397 accretion can occur (Bricker-Urso et al., 1989; Morris et al., 2002) and no studies 1398 addressing the thresholds for organic matter accumulation in the marshes considered by 1399 the panel. Lastly, the panel recognized the serious limitations of scaling down their 1400 projections from the regional to local level and would place a low level of confidence on 1401 such projections in the absence of local accretionary and process data. Thus, findings 1402 from this regional scale approach should not be used for local pl anning activities where 1403 local effects on accretionary dynamics may override regi onal controls on accretionary 1404 dynamics. 1405
1406 4.6.1.2 Panel Findings. 1407 The panel developed an approach for predic ting wetland response to sea-level rise that 1408 was more constrained by available studies of accretion and accret ionary processes in 1409 some areas of the mid-Atlantic region ( e.g. , Lower Maryland Eastern Shore) than in other 1410 areas ( e.g. , Virginia Beach/Currituck Sound). Give n these inherent data and knowledge 1411 constraints, the authors classified the confidence level for all findings in Reed et al. 1412 (2008) as likely ( i.e. , greater than 0.66 but less than 0.90). 1413
1414 Figure 4.4 and Table 4.2 present the panel’s consensus findings on wetland vulnerability 1415 of the mid-Atlantic region. The panel determined that a majority of tidal wetlands settings 1416 in the mid-Atlantic region (with some loca l exceptions) are like ly keeping pace with 1417 Scenario 1, that is, continued sea-level rise at the twentieth centur y rate, 3 to 4 mm per 1418 year (Table 4.2, and areas depicted in brow n, beige, yellow, and green in Figure 4.4) 1419CCSP 4.1 January 15, 2009

217 of 784 Final Report through either mineral sediment deposition, organic matter accumulation, or both. 1420 However, under this scenario, extensive areas of estuarine marsh in Delaware Bay and 1421 Chesapeake Bay are marginal (areas depicted in red in Figure 4.4), with some areas 1422 currently being converted to subt idal habitat (areas depicted in blue in Figure 4.4). It is 1423 virtually certain that estuarine marshes curr ently so converted will not be rebuilt or 1424 replaced by natural processes. Human manipulation of hydrologic and sedimentary 1425 processes and the elimination of barriers to onshore wetland migration would be required 1426 to restore and sustain these de grading marsh systems. The rem oval of barriers to onshore 1427 migration invariably would result in land use changes th at have other societal 1428 consequences such as property loss. 1429
1430 Under accelerated rates of sea- level rise (Scenarios 2 and 3), the panel agreed that 1431 wetland survival would very likely depe nd on optimal hydrology and sediment supply 1432 conditions. Wetlands primarily dependent on mineral sediment accumulation for 1433 maintaining elevation would be very unlikely to survive Scenario 3, ( i.e. , at least 10 mm 1434 per year rate of sea-level rise when added to the twentieth century rate). Exceptions may 1435 occur locally where sediment inputs from inlets, overwash events, or rivers are 1436 substantial ( e.g. , back-barrier lagoon and lagoonal f ill marshes depicted in green on 1437 western Long Island, Figure 4.4). 1438 1439 Wetland responses to sea-level rise are typi cally complex. A close comparison of Figure 1440 4.3 and Figure 4.4 reveals that marshes from all geomorphic settings, except estuarine 1441 meander (which occurs in only one subregi on), responded differently to sea-level rise 1442CCSP 4.1 January 15, 2009

218 of 784 Final Report slr +2 +7 slr +2 +7 slr +2 +7 slr +2 +7 slr +2 +7 slr +2 +7 slr +2 +7 slr +2 +7 Back barrier lagoon, other K K,M K,L K M L K M L M M-L L

Back barrier lagoon, flood tide delta KKM KML K M L

Back barrier lagoon, lagoonal fill K,L M,L L K M L K M L

Estuarine marsh K M L K M L K,M M,L L K,M, L M-L L L,M L L K M L Estuarine fringe K M L KML M M-L L Estuarine meander K M L KML Saline fringe K K,L M K M L K M L K M L K,L M,L L Tidal fresh forest K K K M M-L Tidal fresh marsh K K K KML K K K K K K K K K K K K K = keeping pace, M = marginal, L = loss; multiple letters under a single slr scenario (e.g., K,M or K,M,L) indicate more than one response for that geomorphic setting; M-L indicates that the wetland would be either marginal or lost. Virginia Beach – Currituck Sound Table 3.2 The range of wetland responses to three sea level rise (slr) scenarios (20th Century rate, 20th Century rate + 2 mm/y r, and 20th Century rate + 7 mm/y) within and among geomorphic settings and subregions of the Mid-Atlantic Region from New York to Virginia Region

Delaware Bay Maryland - Virginia Chesapeake Bay Lower Maryland Eastern Shore Geomorphic Setting Long Island, NY Raritan Bay, NY New Jersey within and/or among subregions, underscoring why local processes and drivers must be 1443 taken into account. Given the variety of ma rsh responses to sea-level rise among and 1444 within subregions (Table 4.2), assessing the likelihood of survival for each wetland 1445 setting is best done by subregion, and w ithin subregion, by geomorphic setting. 1446
1447CCSP 4.1 January 15, 2009

219 of 784 Final Report The scientific panel determined that tidal fr esh marshes and forests in the upper reaches 1448 of rivers are likely to be sustainable ( i.e. , less vulnerable to future sea-level rise than most 1449 other wetland types) (Table 4.2), because they have higher accretion rates and accumulate 1450 more organic carbon than saline marshes (Cra ft, 2007). Tidal fresh marshes have access 1451 to reliable and often abundant sources of mine ral sediments, and their sediments typically 1452 have 20 to 50 percent organic matter content, indicating that large quantities of plant 1453 organic matter are also available. Assumi ng that salinities do not increase, a condition 1454 that may reduce soil organic matter accumula tion rates, and current mineral sediment 1455 supplies are maintained, the panel considered it likely that tidal fresh marshes and forests 1456 would survive under Scenario 3. Vertical deve lopment, response to accelerated sea-level 1457 rise, and movement into newly submerged ar eas are rapid for tidal fresh marshes (Orson, 1458 1996). For several tidal fresh marshes in the high sediment-load Delaware River Estuary 1459 vertical accretion through the accumulation of both mineral and plant matter ranged from 1460 7 mm per year to 17.4 mm per year from the 1930s to the 1980s as tidal influences 1461 became more dominant (Orson et al., 1992). Exceptions to the finding that fresh marshes 1462 and forests would survive under Scenario 3 ar e the New Jersey shore, where tidal fresh 1463 marsh is considered marginal under Scenario 2 and lost under Scenar io 3, and Virginia 1464 Beach–Currituck Sound where fresh forest is ma rginal under Scenario 1, marginal or lost 1465 under Scenario 2, and lost under Scenario 3. 1466
1467 Different marshes from the geomorphic settings back-barrier other, back-barrier lagoonal 1468 fill, estuarine marsh, and saline fringe setti ngs responded differently to sea-level rise 1469 within at least one subregion as well as among subregions (Table 4.2). For example, 1470CCSP 4.1 January 15, 2009

220 of 784 Final Report back-barrier lagoonal fi ll marshes on Long Island, New York were classified as either 1471 keeping pace or lost at the current rate of sea-level rise. Those marshes surviving under 1472 Scenario 1 were classified as either marginal (brown) or keeping up (beige and green) 1473 under Scenario 2 (Figure 4.4). Under Scenario 3, only the lagoonal fill marshes depicted 1474 in green in Figure 4.4 are expected to survive. 1475
1476 The management implications of these findings are important on several levels. The 1477 expert panel approach provides a regional assessment of future wetland resource 1478 conditions, defines likely trends in wetla nd change, and identifies areas of major 1479 vulnerability. However, the wide variability of wetland responses to sea-level rise within 1480 and among subregions for a variety of geomorphic settings underscores not only the 1481 influence of local processes on wetland eleva tion but also the difficulty of scaling down 1482 predictions of wetland sustainabi lity from the regional to the local scale in the absence of 1483 local accretion data. Most importantly for ma nagers, regional scale assessments such as 1484 this should not be used to develop local management plans becaus e local accretionary 1485 effects may override regional controls on wetland vertical development (McFadden et al., 1486 2007). Instead, local managers are encouraged to acquire data on the factors influencing 1487 the sustainability of their local wetla nd site, including envi ronmental stressors, 1488 accretionary processes, and geomorphic settings, as a basis for developing local 1489 management plans. 1490 1491CCSP 4.1 January 15, 2009

221 of 784 Final Report 1492 Figure 4.4 Wetland survival in response to three sea- level rise scenarios (data source: Reed et al., 2008; 1493 map source: Titus et al., 2008). 1494 1495 4.6.2 Case Study: Albemarle–Pamlico So und Wetlands and Sea-Level Rise 1496 The Albemarle–Pamlico (A–P) region of North Carolina is distinct in the manner and the 1497 extent to which rising sea level is expected to affect coastal wetlands. Regional wetlands 1498 influenced by sea level are among the most extensive on the U.S. East Coast because of 1499CCSP 4.1 January 15, 2009

222 of 784 Final Report large regions that are less than 3 meters (m) above sea level, as well as the flatness of the 1500 underlying surface. Further, the wetlands lack astronomic tides as a source of estuarine 1501 water to wetland surfaces in most of the A–P region. Instea d, wind-generated water level 1502 fluctuations in the sounds and precipitation are the principal sour ces of water. This 1503 “irregular flooding” is the hallmark of th e hydrology of these wetlands. Both forested 1504 wetlands and marshes can be found; variati ons in salinity of floodwater determine 1505 ecosystem type. This is in st riking contrast to most othe r fringe wetlands on the East 1506
Coast. 1507 1508 4.6.2.1 Distribution of Wetland Types 1509 Principal flows to Albemarle Sound are from the Chowan and Roanoke Rivers, and to 1510 Pamlico Sound from the Tar and Neuse Rivers. Hardwood forests occupy the floodplains 1511 of these major rivers. Only the lower reaches of these rivers are affected by rising sea 1512 level. Deposition of riverine sediments in the estuaries approximates the current rate of 1513 rising sea level (2 to 3 mm per year) (B enninger and Wells, 1993). These sediments 1514 generally do not reach coastal marshes, in pa rt because they are deposited in subtidal 1515 areas and in part because astronomic tides ar e lacking to carry them to wetland surfaces. 1516 Storms, which generate high water levels (esp ecially nor’easters a nd tropical cyclones), 1517 deposit sediments on shoreline storm levees an d to a lesser extent onto the surfaces of 1518 marshes and wetland forests. Blackwater str eams that drain pocosins (peaty, evergreen 1519 shrub and forested wetlands), as well as other tributaries that drain the coastal plain, are a 1520 minor supply of suspended sediment to the estuaries. 1521 1522CCSP 4.1 January 15, 2009

223 of 784 Final Report Most wetlands in the A–P region were fo rmed upon Pleistocene sediments deposited 1523 during multiple high stands of sea level. Inter-stream divides, typified by the Albemarle– 1524 Pamlico Peninsula, are flat and poorly drai ned, resulting in extensive developments of 1525 pocosin swamp forest habitats. The original accumulation of peat was not due to rising 1526 sea level but to poor drainage and climatic c ontrols. Basal peat ages of even the deepest 1527 deposits correspond to the last glacial peri od when sea level was over 100 m below its 1528 current position. Rising sea level has now intercepted some of these peatlands, 1529 particularly those at lower elevations on th e extreme eastern end of the A–P Peninsula. 1530 As a result, eroding peat shorelines are extens ive, with large volumes of peat occurring 1531 below sea level (Riggs and Ames, 2003). 1532 1533 Large areas of nontidal marshes and forested wetlands in this area are exposed to the 1534 influence of sea level. They can be classifi ed as fringe wetlands because they occur along 1535 the periphery of estuaries that flood them irregularly. Salinity, however, is the major 1536 control that determines the dominant vegetati on type. In the fresh-to-oligohaline (slightly 1537 brackish) Albemarle Sound region, forested a nd shrub-scrub wetlands dominate. As the 1538 shoreline erodes into the forested wetlands, bald cypress trees become stranded in the 1539 permanently flooded zone and eventually di e and fall down. This creates a zone of 1540 complex habitat structure of fallen trees a nd relic cypress knees in shallow water. 1541 Landward, a storm levee of coarse sand borders the swamp forest in areas exposed to 1542 waves (Riggs and Ames, 2003). 1543 1544CCSP 4.1 January 15, 2009

224 of 784 Final Report Trees are killed by exposure to extended pe riods of salinity above approximately one1545 quarter to one-third sea water, and most trees and shrubs have restricted growth and 1546 reproduction at much lower salinities (Conner et al., 1997). In brackish water areas, 1547 marshes consisting of halophytes replace fore sted wetlands. Marshes are largely absent 1548 from the shore of Albemarle Sound and mout hs of the Tar and Neuse Rivers where 1549 salinities are too low to affect vegetation. In Pamlico Sound, however, large areas consist 1550 of brackish marshes with few tidal creeks. Small tributaries of the Neuse and Pamlico 1551 River estuaries grade from brackish marsh at estuary mouths to forested wetlands in 1552 oligohaline regions further upstream (Brinson et al., 1985). 1553 1554 4.6.2.2 Future Sea-Level Rise Scenarios 1555 Three scenarios were used to frame projections of the effects of ri sing sea level over the 1556 next few decades in the North Carolina non-ti dal coastal wetlands. The first is a non1557 drowning scenario that assumes rising sea level will maintain its twentieth century, 1558 constant rate of 2 to 4 mm per year (Scenario 1). Predictions in this case can be inferred 1559 from wetland response to sea-level changes in the recent past (Spaur and Snyder, 1999; 1560
Horton et al. , 2006). Accelerated rates of sea-leve l rise (Scenarios 2 and 3), however, 1561 may lead to a drowning scenario. This is mo re realistic if IPCC predictions and other 1562 climate change models prove to be correct (Church and White, 2006), and the Scenario 1 1563 rates double or triple. An a dditional scenario possible in North Carolina involves the 1564 collapse of barrier islands, as hypothesized by Riggs and Ames (2003). This scenario is 1565 more daunting because it anticipates a shift fr om the current non-tidal regime to one in 1566 which tides would be present to initiate currents capable of transporting sediments 1567CCSP 4.1 January 15, 2009

225 of 784 Final Report without the need of storms and frequen tly possibly flooding wetland surfaces now only 1568 flooded irregularly. The underlying effects of these three scen arios and effects on coastal 1569 wetlands are summarized in Table 4.3. 1570 1571 Table 4.3 Comparison of three scenarios of rising sea level and their effects on coastal processes. Scenario Vertical accretion of wetland surface Shoreline erosion rate Sediment supply Non-drowning: historical exposure of wetlands (past hundreds to several thousand yrs) is predictive of future behavior. Vertical accretion will keep pace with rising sea level (~2-4 mm/yr) Keeps pace with rising sea level Recent historical patterns are maintained Low due to a lack of sources; vertical accretion mostly biogenic

Drowning: vertical accretion rates cannot accelerate to match rates of rising sea level; barrier islands remain intact Wetlands undergo collapse and marshes break up from within Rapid acceleration when erosion reaches collapsed regions Local increases of organic and inorganic suspended sediments as wetlands erode
Barrier islands breached: change to tidal regime throughout Pamlico Sound Biogenic accretion replaced by inorganic sediment supply Rapid erosion where high tides overtop wetland shorelines Major increase in sediments and their redistribution; tidal creeks develop along antecedent drainages mostly in former upland regions 1572 Under the non-drowning scenario, vertical accretion would keep pace with rising sea 1573 level as it has for millennia. Current rates (Cahoon, 2003) and those based on basal peats 1574 suggest that vertical accretion roughly matc hes the rate of rising sea level (Riggs et al., 1575 2000; Erlich, 1980; Whitehead and Oakes, 1979) . Sources of inorganic sediment to 1576 supplement vertical marsh accretion are neglig ible due to both the large distance between 1577 the mouths of piedmont-draining Neuse, Tar, Roanoke and Chowan Rivers and the 1578 absence of tidal currents and tidal creeks to transport sediments to marsh surfaces. 1579 1580 Under the drowning scenario, the uncertainty of the effects of accelerated rates lies in the 1581 untested capacity of marshes and swamp forest s to biogenically accrete organic matter at 1582 sea-level rise rates more rapid than experi enced currently. It has been suggested that 1583 brackish marshes of the Mississippi Delta cannot survive when subjected to relative rates 1584CCSP 4.1 January 15, 2009

226 of 784 Final Report of sea-level rise of 10 mm per year (Day et al., 2005), well over twice the rate currently 1585 experienced in Albemarle and Pamlico Sounds. As is the case for the Mississippi Delta 1586 (Reed et al., 2006), external sources of mineral sediments would be required to 1587 supplement or replace the process of organi c accumulation that now dominates wetlands 1588 of the A–P region. Where abundant supplies of sediment are available and tidal currents 1589 strong enough to transport them, as in North Inlet, South Carolina, Morris et al. (2002) 1590 reported that the high salt marsh (dwarf Spartina ) could withstand a 12 mm per year rate. 1591 In contrast to fringe wetlands, swamp fore sts along the piedmont-d raining rivers above 1592 the freshwater–seawater interface are likel y to sustain themselves under drowning 1593 scenario conditions because there is a general abundance of mineral sediments during 1594 flood stage. This applies to regions within the floodplain but not at river mouths where 1595 shoreline recession occurs in res ponse to more localized drowning. 1596 1597 Pocosin peatlands and swamp forest at higher el evations of the coastal plain will continue 1598 to grow vertically since they are both independent of sea- level rise. Under the drowning 1599 scenario, however, sea-level influenced wetla nds of the lower coasta l plain would convert 1600 to aquatic ecosystems, and the large, low, and flat pocosin areas identified by Poulter 1601 (2005) would transform to aquati c habitat. In areas of pocosin peatland, shrub and forest 1602 vegetation first would be kill ed by brackish water. It is unlikely that pocosins would 1603 undergo a transition to marsh for two reasons: (1) the pocosin root mat would collapse 1604 due to plant mortality and decomposition, causing a rapid subs idence of several 1605 centimeters, and resulting in a transition to ponds rather than marshes and (2) brackish 1606 water may accelerate decomposition of peat due to availability of sulfate to drive 1607CCSP 4.1 January 15, 2009

227 of 784 Final Report anaerobic decomposition. With the simu ltaneous death of woody vegetation and 1608 elimination of potential marsh plant establishment, organic-rich soils would be exposed 1609 directly to the effects of decomposition, erosion, suspensi on, and transport without the 1610 stabilizing propertie s of vegetation. 1611
1612 Under the collapsed barrier island scenario (see Section 3.7.3), the A–P regions would 1613 undergo a change from a non-tidal estuary to one dominated by astronomic tides due to 1614 the collapse of some portions of the barrier islands. A transition of this magnitude is 1615 difficult to predict in detail. However, P oulter (2005), using the ADCIRC-2DDI model of 1616 Luettich et al. (1992), estimated that conversion from a non-tidal to tidal estuary might 1617 flood hundreds of square kilometers. The effect is largely due to an increase in tidal 1618 amplitude that produces the flooding rather than a mean rise in sea level itself. While the 1619 mechanisms of change are speculative, it is doubtful that an intermediate stage of marsh 1620 colonization would occur on former pocosin and swamp forest areas because of the 1621 abruptness of change. Collapse of the barrier is lands in this scenario would be so severe 1622 due to the sediment-poor condition of many barrier segments that attempts to maintain 1623 and/or repair them would be extr emely difficult, or even futile. 1624 1625 The conversion of Pamlico Sound to a tidal system would likely re-establish tidal 1626 channels where ancestral streams are locat ed, as projected by Riggs and Ames (2003). 1627 The remobilization of sediments could then supply existing marshes with inorganic 1628 sediments. It is more likely, however, that marshes would become established landward 1629 on newly inundated mineral soils of low-lying uplands. Such a state change has not been 1630CCSP 4.1 January 15, 2009

228 of 784 Final Report observed elsewhere, and computer models are seldom robust enough to encompass such 1631 extreme hydrodynamic transitions. 1632
1633 4.7 DATA NEEDS 1634 A few key uncertainties must be addressed in order to increase confidence in the authors’ 1635 predictions of wetland vulnerability to sea-level rise. First, determining the fate of coastal 1636 wetlands over a range of accelerated sea-leve l rise rates requires more information on 1637 variations in the maximum accretion rate regionally, within geomorphic settings, and 1638 among vegetative communities. To date, few studies have specifi cally addressed the 1639 maximum rates at which marsh vertical accreti on can occur, particularly the thresholds 1640 for organic accumulation. Second, although the interactions among changes in wetland 1641 elevation, sea level, and we tland flooding patterns are be coming better understood, the 1642 interaction of these feedback controls between flooding a nd changes in other accretion 1643 drivers, such as nutrient s upply, sulfate respiration, and soil organic matter accumulation 1644 is less well understood. Third, scaling up from numerical model predictions of local 1645 wetland responses to sea-level rise to long-term projections at regional or continental 1646 scales is severely constrained by a lack of availabl e accretionary and process data at these 1647 larger landscape scales. Newly emerging num erical models used to predict wetland 1648 response to sea-level rise need to be applie d across the range of we tland settings. Fourth, 1649 scientists need to better understand the role of cha nging land use on tidal wetland 1650 processes, including space available for wetla nds to migrate landward and alteration in 1651 the amount and timing of freshwater runo ff and sediment suppl y. Finally, sediment 1652 supply is a critical factor in fluencing wetland vulnerability, but the amount and source of 1653CCSP 4.1 January 15, 2009

229 of 784 Final Report sediments available for wetland formation a nd development is often poorly understood. 1654 Coastal sediment budgets typically evaluate co arse-grain sediments needed for beach and 1655 barrier development. In contrast, fine-gra in cohesive sediments needed for wetland 1656 formation and development are typically not evaluated. Improving our understanding of 1657 each of these factors is critical for pr edicting the fate of tidal marshes. 1658 1659
1660CCSP 4.1 January 15, 2009

230 of 784 Final Report CHAPTER 4 REFERENCES 1661 * Indicates non-peer reviewed literature; available upon request 1662 1663 Allen , J.R.L., 1990: The formation of coastal pe at marshes under an upward tendency of 1664 relative sea level . Journal of the Geological Society , 147(5) , 743-745. 1665 Benninger , L.K. and J.T. Wells, 1993: Sources of sediment to the Neuse River estuary, 1666 North Carolina. Marine Chemistry , 43(1-4) , 137-156. 1667
Bricker-Urso , S., S.W. Nixon, J.K. Cochran, D.J. Hirschberg, and C. Hunt, 1989: 1668 Accretion rates and sediment accumulation in Rhode Island salt marshes. 1669 Estuaries , 12(4) , 300-317. 1670
Brinson , M.M., H.D. Bradshaw, and M.N. Jones, 1985: Transitions in forested wetlands 1671 along gradients of salinity and hydroperiod . Journal of the Elisha Mitchell 1672 Scientific Society , 101 , 76-94. 1673 Brinson, M.M., R.R. Christian, and L.K. Blum, 1995: Multiple states in the sea-level 1674 induced transition from terre strial forest to estuary. Estuaries, 18(4) , 648-659. 1675
Cahoon , D.R., 2003: Storms as agents of we tland elevation change: their impact on 1676 surface and subsurface sediment processes. Proceedings of the International 1677 Conference on Coastal Sediments 2003 , May 18-23, 2003, Clearwater Beach FL. 1678 World Scientific Publishing Cor poration, Corpus Christi, TX. 1679
Cahoon , D.R., 2006: A review of major storm impacts on coastal wetland elevation. 1680 Estuaries and Coasts , 29(6A) , 889-898. 1681
Cahoon , D.R., J.R. French, T. Spencer, D. Reed, and I. Moller, 2000: Vertical accretion 1682 versus elevational adjustment in UK sa ltmarshes: an evaluation of alternative 1683 methodologies. In: Coastal and Estuarine Environments: Sedimentology, 1684 Geomorphology and Geoarchaeology . [Pye, K. and J.R.L. Allen (eds.)]. 1685 Geological Society, London, pp. 223-238. 1686CCSP 4.1 January 15, 2009

231 of 784 Final Report Cahoon , D.R., P. Hensel, J. Rybczyk, K. McKee, C.E. Proffitt, and B. Perez, 2003: Mass 1687 tree mortality leads to mangrove peat co llapse at Bay Islands, Honduras after 1688 Hurricane Mitch. Journal of Ecology, 91 , 1093-1105. 1689
Cahoon , D.R., P.F. Hensel, T. Spencer, D.J. R eed, K.L. McKee, and N. Saintilan, 2006: 1690 Coastal wetland vulnerability to relative sea level rise: wetland elevation trends 1691 and process controls. In: Wetlands and Natural Resource Management 1692 [Verhoeven, J.T.A., B. Beltman, R. Bobbi nk, and D. Whigham (eds.)]. Ecological 1693 studies volume 190, Springer, Berlin and New York, pp. 271-292. 1694
Carroll , R., G. Pohll, J. Tracy, T. Winter, and R. Smith, 2005: Simulation of a 1695 semipermanent wetland basin in the Co ttonwood Lake area, ea st-central North 1696 Dakota. Journal of Hydrologic Engineering , 10(1) , 70-84. 1697
Church , J.A. and N.J. White, 2006: A 20th century acceleration in glob al sea level rise. 1698 Geophysical Research Letters , 33(1) , L01602, doi:10.1029/2005GL024826. 1699
Conner , W.H., K.W. McLeod, and J.K. McCarro n, 1997: Flooding and salinity effects 1700 on growth and survival of four common forested wetland species. Wetlands 1701 Ecology and Management , 5(2) , 99-109. 1702
Craft , C., 2007: Freshwater input structures soil propertie s, vertical accretion, and 1703 nutrient accumulation of Geor gia and U.S. tidal marshes. Limnology and 1704 Oceanography , 52(3) , 1220-1230. 1705 Darmody , R.G. and J.E. Foss, 1979: Soil-landscape relationships of the tidal marshes of 1706 Maryland. Soil Science Society of America Journal , 43(3) , 534-541. 1707 Day , J.W., Jr., J. Barras, E. Clairain, J. J ohnston, D. Justic, G.P. Kemp, J.-Y. Ko, R. 1708 Lane, W.J. Mitsch, G. Steyer, P. Temp let, and A. Yañez-Arancibia, 2005: 1709 Implications of global climatic change a nd energy cost and availability for the 1710 restoration of the Mississippi delta. Ecological Engineering , 24(4) , 253-265. 1711CCSP 4.1 January 15, 2009

232 of 784 Final Report DeLaune , R.D., R.H. Baumann, and J.G. Gosse link, 1983: Relationships among vertical 1712 accretion, coastal submergence, and erosion in a Louisiana Gulf Coast marsh. 1713 Journal of Sedimentary Petrology , 53(1) , 147-157. 1714 Dyer , K., 1995: Response of estuar ies to climate change. In: Climate Change: Impact on 1715 Coastal Habitation [Eisma, D. (ed.)]. Lewis Pu blishers, Boca Raton, FL, pp. 85- 1716 110. 1717

* Erlich , R.N., 1980: Early Holocene to Recent Development and Sedimentation of the 1718 Roanoke River Area, North Carolina . M.S. thesis, Department of Geology. 1719 University of North Carolina, Chapel Hill, 83 pp. 1720
Goldhaber , M.B. and I.R. Kaplan, 1974: The sulfur cycle. In: Marine Chemistry

. 1721 [Goldberg, E.D. (ed.)]. Wiley, New York, pp. 569-655. 1722
Goodman , P.J. and W.T. Williams, 1961: Inve stigations into ‘die-back’ of Spartina 1723 townsendii agg.: III. Physical co rrelates of ‘die-back’. Journal of Ecology , 49(2) , 1724 391-398. 1725 Hartig , E.K., V. Gornitz, A. Kolker, F. Muschacke, and D. Fallon, 2002: Anthropogenic 1726 and climate-change impacts on salt mars hes of Jamaica Bay, New York City. 1727 Wetlands , 22(1) , 71-89. 1728

Horton , B.P., R. Corbett, S. J. Culver, R. J. Edwards, C. Hillier, 2006: Modern salt 1729 marsh diatom distributions of the Outer Banks, North Carolina, and the 1730 development of a transfer function for high resolution reconstructi ons of sea level. 1731 Estuarine, Coastal and Shelf Science , 69(3-4) , 381-394. 1732

Johnson , W.C., B.V. Millett, T. Gilmanov, R.A. Voldseth, G.R. Guntenspergen, and 1733 D.E. Naugle, 2005: Vulnerability of north ern prairie wetlands to climate change. 1734 Bioscience , 55(10) , 863-872. 1735 Kearney , M.S., R.E. Grace, and J.C. Stevenson, 1988: Marsh loss in the Nanticoke 1736 Estuary, Chesapeake Bay. Geographical Review , 78 , 205-220. 1737CCSP 4.1 January 15, 2009

233 of 784 Final Report Kearney , M.S., J.C. Stevenson, and L.G. Ward, 1994: Spatial and temporal changes in 1738 marsh vertical accretion rates at Monie Bay: implications for sea level rise. 1739 Journal of Coastal Research , 10(4) , 1010-1020. 1740
Luettich , R.A., Jr., J.J. Westerink, and N.W. Scheffener, 1992: ADCIRC: An Advanced 1741 Three-dimensional Circula tion Model for Shelves, Coas ts, and Estuaries. Report 1742 1: Theory and Methodology of ADCIRC-2DDI and ADCIRC-3DL . Technical 1743 report DRP-92-6. U.S. Army Engineers Waterways Experiment Station, 1744 Vicksburg, MS, 141 pp. 1745 McCaffrey , R.J. and J. Thomson, 1980: A record of the accumulation of sediment and 1746 trace metals in a Connecticut salt marsh. In: Estuarine Physics and Chemistry: 1747 Studies in Long Island Sound. [Saltzman, B. and R.C. Aller (eds.)]. Advances in 1748 geophysics volume 22. Academic Press, New York, 424 pp. 1749

McFadden , L., T. Spencer, and R.J. Nicholls, 2007: Broad-scale modelling of coastal 1750 wetlands: what is required? Hydrobiologia , 577 , 5-15. 1751

McKee , K.L., I.A. Mendelssohn, and M.D. Matern e, 2004: Acute salt marsh dieback in 1752 the Mississippi deltaic plain: a drought induced phenomenon? Global Ecology 1753 and Biogeography , 13(1) , 65-73. 1754

McKee , K.L., D.R. Cahoon, and I.C. Feller, 200 7: Caribbean mangroves adjust to rising 1755 sea level through biotic controls on change in soil elevation. Global Ecology and 1756 Biogeography , 16(5) , 545-556. 1757

Mendelssohn , I.A. and K.L. McKee, 1988: Spartina alterniflora die-back in Louisiana: 1758 time-course investigation of soil waterlogging effects. Journal of Ecology , 76(2) , 1759 509-521. 1760
Morris , J.T., P.V. Sundareshwar, C.T. Niet ch, B. Kjerfve, and D.R. Cahoon, 2002: 1761 Responses of coastal wetla nds to rising sea level. Ecology , 83(10) , 2869-2877. 1762

Neubauer , S.C. 2008: Contributions of m inera l and organic components to tidal 1763 freshwater marsh accretion. Estuarine Coastal and Shelf Science , 78(1) , 78-88. 1764CCSP 4.1 January 15, 2009

234 of 784 Final Report Nicholls , R.J., P.P. Wong, V.R. Burkett, J.O. Codignotto, J.E. Hay, R.F. McLean, S. 1765 Ragoonaden, and C.D. Woodroffe, 2007. Coastal systems and low-lying areas. 1766 Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of 1767 Working Group II to the Fourth Assessmen t Report of the Intergovernmental 1768 Panel on Climate Change [Parry, M.L., O.F. Canziani, J.P. Palutikof, P.J. vaan der 1769 Linden, and C.E. Hanson (eds.)]. Cambri dge University Press, Cambridge, UK, 1770 and New York, pp. 315-356. 1771 Nyman , J.A., R.J. Walters, R.D. Delaune, and W.H. Patrick, Jr., 2006: Marsh vertical 1772 accretion via vegetative growth. Estuarine Coastal and Shelf Science , 69(3-4) , 1773 370-380. 1774 Ogburn , M.B. and M. Alber, 2006: An investiga tion of salt marsh dieback in Georgia 1775 using field transplants. Estuaries and Coasts , 29(1) , 54-62. 1776 Orson, R.A., 1996: Some applications of pale oecology to the management of tidal 1777 marshes. Estuaries, 19(2A) , 238-246. 1778
Orson , R.A., R.L. Simpson, and R.E. Good, 1992: A mechanism for the accumulation 1779 and retention of heavy metals in tidal freshwater marshes of the upper Delaware 1780 River estuary. Estuarine, Coastal and Shelf Science , 34(2) , 171-186. 1781

Park , R.A., M.S. Trehan, P.W. Mausel, and R. C. Howe, 1989: The effects of sea level 1782 rise on U.S. coastal wetlands. In: The Potential Effects of Global Climate Change 1783 on the United States. Appendix: B, Sea Level Rise . EPA 230-05-89-052. U.S. 1784 Environmental Protection Agenc y, Washington, DC, 1-1 to1-55. 1785 <http://epa.gov/climatechange/effects/coastal/appB.html> 1786
Pethick , J., 1981: Long-term accretion rates on tidal salt marshes. Journal of 1787 Sedimentary Petrology , 51 , 571-577. 1788

* Poulter , B., 2005: Interactions Between Landscape Disturbance and Gradual 1789 Environmental Change: Plant Community Migr ation in Response to Fire and Sea 1790CCSP 4.1 January 15, 2009

235 of 784 Final Report Level Rise . Ph.D. dissertation, Nicholas School of the Environment and Earth 1791 Sciences. Duke University, Durham, NC, 216 pp. 1792
Redfield , A.C., 1972: Development of a New England salt marsh. Ecological 1793 Monographs , 42 , 201-237. 1794

Reed , D.J., 1989: Patterns of sediment deposi tion in subsiding coas tal salt marshes, 1795 Terrebonne Bay, Louisiana: the role of winter storms. Estuaries , 12(4) , 222-227. 1796

Reed , D.J., M.S. Peterson, and B.J. Lezina, 2006: Reducing the effects of dredged 1797 material levees on coastal marsh fu nction: Sediment deposition and nekton 1798 utilization. Environmental Management , 37(5) , 671-685. 1799 Reed, D.J., D. Bishara, D. Cahoon, J. Donnell y, M. Kearney, A. Kolker, L. Leonard, 1800 R.A. Orson, and J.C. Stevenson, 2008: Site-specific sce narios for wetlands 1801 accretion as sea level rises in the mid-Atlantic region . Section 2.1 in: Background 1802 Documents Supporting Climate Change Science Program Synthesis and 1803 Assessment Product 4.1, J.G. Titus and E.M. Strange (eds.). EPA 430R07004. 1804 U.S. Environmental Protection Agency, Washington, DC. 1805 Riggs , S.R. and D.V. Ames, 2003: Drowning the North Carolina Coast: Sea-level Rise 1806 and Estuarine Dynamics . Publication no. UNC-SG-03-04, North Carolina Sea 1807 Grant, Raleigh, NC, 152 pp. 1808 Riggs , S.R., G.L. Rudolph, and D.V. Ames, 2000: Erosional Scour and Geologic 1809 Evolution of Croatan Sound, Northeastern North Carolina . Report nNo. 1810 FHWA/NC/2000-002. North Carolina Depart ment of Transportation, Raleigh, 1811 NC, 115 pp. 1812 Rybczyk , J.M. and D.R. Cahoon, 2002: Estimating the potential for s ubmergence for two 1813 subsiding wetlands in the Mississippi River delta. Estuaries , 25(5) , 985-998. 1814
Sklar , F.H. and J.A. Browder, 1998: Coastal environmental impacts brought about by 1815 alterations to freshwater fl ow in the Gulf of Mexico. Environmental Management , 1816 22(4) , 547-562. 1817CCSP 4.1 January 15, 2009

236 of 784 Final Report Spaur , C.C. and S.W. Snyder, 1999: Coastal wetl ands evolution at the leading edge of 1818 the marine transgression: Jarrett Bay, North Carolina. Journal of the Elisha 1819 Mitchell Scientific Society, 115 , 20-46. 1820
Stevenson , J.C. and M.S. Kearney, In press: Impact s of global change and sea level rise 1821 on tidal wetlands. In: Human Impacts on Marshes: A Global Perspective 1822 [Silliman. B.R., M.D. Bertness, and E. Gros holz (eds.)]. University of California 1823 Press, Berkeley, 49 pp. (expected June 2009). 1824
Stevenson , J.C., M.S. Kearney, and E. C. Pendl eton, 1985: Sedimentation and erosion in 1825 a Chesapeake Bay brackish marsh system. Marine Geology , 67(3-4) , 213-235. 1826
Titus , J. G., R. Jones, and R. Streeter, 2008: Maps depicting site-specific scenarios for 1827 wetlands accretion as sea level rises in the Mid-Atlantic region. Section 2.2 in: 1828 Background Documents Supporting Climate Change Science Program Synthesis 1829 and Assessment Product 4.1: Coastal Elevati ons and Sensitivity to Sea Level Rise 1830 [Titus, J.G. and E.M. Strange (eds .)]. EPA 430R07004. U.S. Environmental 1831 Protection Agency, Washington, DC, pp. 176-186. 1832 <http://epa.gov/climatechange/e ffects/coastal/background.html> 1833

Turner , R.E., E.M. Swenson, C.S. Milan, J.M. Lee, and T.A. Oswald, 2004: Below1834 ground biomass in healthy and impaired salt marshes. Ecological Research , 19(1) , 1835 29-35. 1836

Voldseth , R.A., W.C. Johnson, T. Gilmanov, G. R. Guntenspergen, and B.V. Millet, 1837 2007: Model estimation of land use effect s on water levels of northern prairie 1838 wetlands. Ecological Applications , 17(2) , 527-540. 1839

Webster , P.J., G.J. Holland, J.A. Curry, and H.R. Chang, 2005: Changes in tropical 1840 cyclone number, duration, and intens ity in a warming environment. Science , 1841 309(5742) , 1844-1846. 1842CCSP 4.1 January 15, 2009

237 of 784 Final Report Whitehead , D.R. and R.Q. Oaks, 1979: Developmenta l history of the Dismal Swamp. In: 1843 The Great Dismal Swamp [Kirk, P.W. (ed.)]. University Press of Virginia, 1844 Charlottesville, VA, pp. 25-43. 1845
Woodroffe , C.I., 2002: Coasts: Form, Process and Evolution . Cambridge University 1846 Press, Cambridge, UK, and New York, 623 pp. 1847

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## Chapter 5. Vulnerable Species: the Effects of Sea-Level 1849 

## Rise on Coastal Habitats 1850

1851 Authors: Ann Shellenbarger Jones, Industria l Economics, Inc.; Christina Bosch, 1852 Industrial Economics, Inc.; Elizabet h Strange, Stratus Consulting, Inc. 1853 1854 KEY FINDINGS 1855

 The quality, quantity, and spatia l distribution of coastal ha bitats continuously change 1856 as a result of shore erosion, salinity changes, and wetland dynamics; however, 1857 accelerated rates of sea-level rise will cha nge some of the major controls of coastal 1858 wetland maintenance. Shore protection and development now prevents migration of 1859 coastal habitats in many areas. Vulnerable species that rely on these habitats include 1860 an array of biota ranging from endangered be etles to commercially important fish and 1861 shellfish; and from migratory birds to marsh plants and aquatic vegetation. 1862

 Three key determinants of future tidal marsh acreage are: (1) the capacity of the 1863 marsh to raise its surface to match the rate of rising sea level, (2) th e rate of erosion of 1864 the seaward boundary of the marsh, and (3) th e availability of space for the marsh to 1865 migrate inland. Depending on local conditions, a tidal marsh may be lost or migrate 1866 landward in response to sea-level rise. 1867

 Where tidal marshes become submerged or are eroded, the expected overall loss of 1868 wetlands would cause wetland-dependent spec ies of fish and birds to have reduced 1869 population sizes. Tidal marshes and associat ed submerged aquatic plant beds are 1870CCSP 4.1 January 15, 2009

239 of 784 Final Report important spawning, nursery, and shelter areas for fish and shellfish, including 1871 commercially important speci es like the blue crab. 1872

 Many estuarine beaches may also be lost in areas with vertical shore protection and 1873 insufficient sediment supply. Endangered beetles, horseshoe crabs, the red knot 1874 shorebird, and diamondback terrapins are among many species that rely on sandy 1875 beach areas. 1876

 Loss of isolated marsh islands already undergoing submersion will reduce available 1877 nesting for bird species, especially those th at rely on island habitat for protection from 1878 predators. Additional temporary islands may be formed as tidal marshes are 1879 inundated, although research on th is possibility is limited. 1880

 Many of the freshwater tidal forest systems such as those found in the Mid-Atlantic 1881 are considered globally imperiled, and are at risk from sea-level rise among other 1882 threats. 1883

 Tidal flats, a rich source of invertebra te food for shorebirds, may be inundated, 1884 though new areas may be created as othe r shoreline habitats are submerged. 1885
1886 5.1 INTRODUCTION 1887 Coastal ecosystems consist of a variety of environments, including tidal marshes, tidal 1888 forests, aquatic vegetation beds, tidal flats, beaches, and cliffs. For tidal marshes, Table 1889 4.1 outlines the major marsh types, relevant accretionary processes, and the primary 1890 vegetation. These environments provide impor tant ecological and human use services, 1891 including habitat for endangered and thre atened species. The ecosystem services, 1892 described in detail within this Chapter, in clude not only those pro cesses that support the 1893CCSP 4.1 January 15, 2009

240 of 784 Final Report ecosystem itself, such as nutrient cycling, but also the human benefits derived from those 1894 processes, including fish pr oduction, water purification, wate r storage and delivery, and 1895 the provision of recreational opportunities th at help promote human well-being. The high 1896 value that humans place on these services has been demonstrated in a number of studies, 1897 particularly of coastal wetlands (NRC, 2005). 1898 1899 The services provided by coastal ecosystems could be affected in a number of ways by 1900 sea-level rise and coastal engi neering projects designed to pr otect coastal properties from 1901 erosion and inundation. As seas rise, coastal habitats are subject to inundation, storm 1902 surges, salt water intrusion, a nd erosion. In many cases, the pl acement of hard structures 1903 along the shore will reduce sediment inputs from upland sources and increase erosion 1904 rates in front of the structures (USGS, 2003). If less sediment is available, marshes that 1905 are seaward of such structures may have diffi culty maintaining appropriate elevations in 1906 the face of rising seas. Wetlands that are unable to accrete sufficient substrate as sea level 1907 rises will gradually convert to open water, ev en if there is space av ailable for them to 1908 migrate inland, thereby eliminating critical ha bitat for many coastal species. In addition, 1909 landward migration of wetland s may replace current upland habitats that are blocked 1910 from migration (NRC, 2007; MEA, 2005). Shal low water and shore habitats are also 1911 affected by shore responses. Table 6.1 provi des a preliminary overview of the expected 1912 environmental effects of human responses to sea-level rise. 1913 1914 Habitat changes in response to sea-level rise and related processes may include structural 1915 changes (such as shifts in vegetation zones or loss of vegetate d area) and functional 1916CCSP 4.1 January 15, 2009

241 of 784 Final Report changes (such as altered nutrient cycling). In turn, degraded ecosystem processes and 1917 habitat fragmentation and loss may not only alter species distri butions and relative 1918 abundances, but may ultimately reduce local populations of the species that depend on 1919 coastal habitats for feeding, nesting, spawni ng, nursery areas, protection from predators, 1920 and other activities that affect growth, survival, and reproductive success. 1921 1922 Habitat interactions are extremely complex. Each habitat supports adjacent systems—for 1923 example, the denitrifying effects of wetla nds aid adjacent submerged vegetation beds by 1924 reducing algal growth; the pr esence of nearshore oyster or mussel beds reduces wave 1925 energy which decreases erosion of marsh e dges; and primary productivity is exported 1926 from marsh to open waters (see Box 5.1). This Chapter presents simplifications of these 1927 interactions in order to iden tify primary potential effects of both increased rates of sea1928 level rise and likely shore protec tions on vulnerable species. In particular, sea-level rise is 1929 just one factor among many affecting coastal ar eas; sediment input, nutrient runoff, fish 1930 and shellfish management, and other factors al l contribute to the ec ological condition of 1931 the various habitats discussed in this Section. Sea-level rise may also exacerbate pollution 1932 through inundation of upland sources of cont amination such as landfills, industrial 1933 storage areas, or agricultural waste retention ponds. Under natural cond itions, habitats are 1934 also continually shifting; the focus of this Chapter is the effect that shoreline management 1935 will have on the ability for those shifts to occur ( e.g. , for marshes or barrier islands to 1936 migrate, for marsh to convert to tidal flat or vice versa) and any inte rruption to the natural 1937 shift. 1938 BOX 5.1: Finfish, Tidal Salt Marshes, and Habitat Interconnectedness 1939 1940CCSP 4.1 January 15, 2009

242 of 784 Final Report Tidal salt marshes are among the most productive habitats in the world (Teal, 1986). While this 1941 productivity is used within the marshes, marsh-associated organic matter is also exported to food webs 1942 supporting marine transient fish production in open wa ters. Marine transients are adapted to life on a 1943 “coastal conveyor belt”, often spawning far out on the continental shelf and producing estuarine-dependent 1944 young that are recruited into coas tal embayments year-round (Deegan et al. , 2000). These fish comprise 1945 more than 80 percent of species of commercial and recreational value that occupy inshore waters. 1946 1947 Tidal salt marshes serve two critical functions for young finfish (Boesch and Turner, 1984). First, abundant 1948 food and the warm shallow waters of the marsh are conducive to rapid growth of both resident and 1949 temporary inhabitants. Second, large predators are generally less abundant in subtidal marsh creeks; 1950 consequently marshes and their drainage systems may serve as a shelter from predators for the young fish. 1951 Protection, rapid growth, and the ability to deposit energy reserves from the rich marsh diet prepare young 1952 fish for the rigors of migration and/or overwintering (Weinstein et al. , 2005; Litvin and Weinstein, in 1953 press). 1954 1955 Effects of Sea-Level Rise 1956 Intertidal and shallow subtidal waters of estuarine wetlands are “epicenters” of material exchange, primary 1957 (plant) and secondary (animal) production, and are primary nurseries for the young of many fish and 1958 shellfish species (Childers et al. , 2000; Weinstein, 1979; Deegan et al. , 2000). The prospect of sea-level 1959 rise, sometimes concomitant with land subsidence, human habitation of the shore zone, and shore 1960 stabilization place these critical resources at risk. Such ecological hotspots could be lost as a result of sea1961 level rise because human presence in the landscape leaves tidal wetlands little or no room to migrate inland. 1962 Because of lack of a well-defined drainage system, small bands of in tertidal marsh located seaward of 1963 armored shorelines have little ecological value in the production of these finfish (Weinstein et al. , 2005; 1964 Weinstein, 1983). Due to its interconnectedness with adjacent habitats, loss of tidal salt marshes would 1965 significantly affect fish populations, both estuarine and marine, throughout the mid-Atlantic region. 1966 1967 While habitat migration, loss, and gain have all occurred thro ughout geological history, 1968 the presence of developed shorelines introduces a new barrier. Although the potential 1969 ecological effects are unders tood in general terms, few studies have sought to 1970 demonstrate or quantify how the interactions of sea-level rise and di fferent types of shore 1971 protections may affect the ecosystem serv ices provided by coastal habitats, and in 1972 particular the abundance and distribution of animal species (see Chapter 6 for discussion 1973 of shore protections). While some studies have examined impacts of either sea-level rise 1974 ( e.g. , Erwin et al. , 2006; Galbraith et al. , 2002) or shore protections ( e.g. , Seitz et al. , 1975 2006) on coastal fauna, minimal literature is av ailable on the combined effects of rising 1976 seas and shore protections. Nonetheless, it is possible in some cases to identify species 1977 most likely to be affected based on knowledge of species-habitat associations. Therefore, 1978CCSP 4.1 January 15, 2009

243 of 784 Final Report this Chapter draws upon the ecologi cal literature to describe the primary coastal habitats 1979 and species that are vulnerable to the inter active effects of sea-level rise and shore 1980 protection activities, and highlights those speci es that are of particular concern. While 1981 this Chapter provides a detailed discussion on a region-wide scale, Appendix 1 of this 1982 Product provides much more detailed discussi ons of specific local habitats and animal 1983 populations that may be at risk on a lo cal scale along the mid-Atlantic coast. 1984 1985 5.2 TIDAL MARSHES 1986 In addition to their dependence on tidal influe nce, tidal marshes are defined primarily in 1987 terms of their salinity: salt, brackish, and freshwater. Chap ter 4 describes the structure 1988 and flora of these marshes as well as their likely responses to se a-level rise. Table 5.1 1989 presents a general overview of the habitat type s, fauna, and vulnerabil ity discussed in this 1990 Chapter. Localized information on endangered or threatened species is available through 1991 the state natural heritage programs (see Box 5.2). 1992 Box 5.2 Identifying Local Ecological Communities and Species at Risk 1993 1994 Every state and Washington, D.C. has Natural Heritage Programs (NHPs) that inventory and track the 1995 natural diversity of the state, including rare or e ndangered species. These programs provide an excellent 1996 resource for identifying local ecological communities a nd species at risk. Contact information for NHPs 1997 throughout the mid-Atlantic region is provided in Box Table 5.1. 1998 1999 Box Table 5.1 State Natural Heritage Program Contact Information Office Website Phone New York State Department of Environmental Conservation, Division of

Fish, Wildlife and Marine Resources <http://www.nynhp.org/> (518) 402- 8935 New Jersey Department of Environmental Protection, Division of Parks and Forestry, Office of Natural Lands Management <http://www.state.nj.us/dep/parksandfore sts/natural/heritage/index.html> (609) 984- 1339 Pennsylvania Department of Conservation and Natural Resources, Office of Conservation Science <http://www.naturalheritage.state.pa.us/> (717) 783- 1639 Delaware Department of Natural Resources and Environmental Control, Division of Fish <http://www.dnrec.state.de.us/nhp/> (302) 653- 2880CCSP 4.1 January 15, 2009

244 of 784 Final Report and Wildlife Maryland Department of Natural Resources, Wildlife and Heritage Service <http://www.dnr.state.md.us/wildlife/> (410) 260- 8DNR The District of Columbia's Department of

Health, Fisheries and Wildlife Division <http://doh.dc.gov/doh/cwp/view,a,1374, Q,584468,dohNav_GID,1810,.asp> (202) 671- 5000 Virginia Department of Conservation and Recreation <http://www.dcr.virginia.gov/natural_her itage/index.shtml> (804) 786- 7951 North Carolina Department of Environment and Natural Resources, Office of Conservation and Community Affairs <http://www.ncnhp.org/index.html> (919) 715- 4195 2000 A useful resource for species data outside of each state’s own NHP is NatureServe Explorer . NatureServe 2001 (<http://www.natureserve.org/>) is a non-profit cons ervation organization which represents the state 2002 Natural Heritage Programs and other conservation data centers. NatureServe Explorer allows users to 2003 search for data on the geographic incidence of plan t and animal species in the United States and Canada. 2004 The program provides an ex tensive array of search criteria, incl uding species’ taxonomies, classification 2005 status, ecological communities, or their national and sub-national distribution. For example, one could 2006 search for all vertebrate species federally listed as threatened that live in Delaware’s section of the 2007 Chesapeake Bay. For identifying threatened and endange red species extant in vulnerable areas, the smallest 2008 geographic unit of analysis is county-level. 2009 2010 Table 5.1 Key Fauna/Habitat Associ ations and Degree of Dependence Habitat Type

FaunaTidal MarshForestedWetlandSea-Level FensSAVTidal FlatsEstuarineBeachesUnvegetatedCliffs

Fish (Juvenile)  - -    - Fish (Adult)  - -    - Crustaceans/ Mollusks  - -    - Other invertebrates        Turtles/ Terrapins     -  - Other reptiles/ amphibians     - - - Wading Birds  - - -   - Shorebirds  - - -   - Waterbirds  - -    - Songbirds   - - - -  Mammals   - - -   Notes: Symbols represent the degree of dependence that particular fauna have on habitat types, as described in the sections below.  indicates that multiple species, or certain rare or endangered species, depend heavily on that habitat.  indicates that the habitat provides substantial benefits to the fauna.  indicates that some species of that fauna type may re ly on the habitat, or that portions of their lifecycle may be carried out there. – indicates that negligible activity by a type of fauna occurs in the habitat. Further details on these interactions, including relevant references, are in the sections by habitat below. SAV is submerged aquatic vegetation, discussed later in this Chapter (Section 5.5). 2011CCSP 4.1 January 15, 2009

245 of 784 Final Report Salt marshes (back-barrier lagoon marsh or saline fr inge marsh, described in Table 4.1) 2012 are among the most productive systems in the world because of the extraordinarily high 2013 amount of above- and below-ground plant matter that many of them produce, up to 25 2014 metric tons per hectare (h a) aboveground alone (Mitsch a nd Gosselink, 1993). In turn, 2015 this large reservoir of primary production suppor ts a wide variety of invertebrates, fish, 2016 birds, and other animals that make up the estuarine food web (Teal , 1986). Insects and 2017 other small invertebrates feed on this organic material of the marsh as well as detritus and 2018 algae on the marsh surface. These in turn provide food for larger organisms, including 2019 crabs, shrimp, and small fishes, which then provide food for larger consumers such as 2020 birds and estuarine fishes that move into the marsh to forage (Mitsch and Gosselink, 2021 1993). 2022
2023 Although much of the primary production in a marsh is used within the marsh itself, 2024 some is exported to adjacent estuaries and marine waters. In addition, some of the 2025 secondary production of marsh resident fishes, particularly mummichog , and of juveniles, 2026 such as blue crab, is exported out of th e marsh to support both n earshore estuarine food 2027 webs as well as fisheries in coastal ar eas (Boesch and Turner, 1984; Kneib, 1997, 2000; 2028 Deegan et al. , 2000; Beck et al. , 2003; Dittel et al. , 2006; Stevens et al. , 2006) 2 . As 2029 studies of flood pulses have shown, the extent of the benefits provided by wetlands may 2030 be greater in regularly floode d tidal wetlands than in irre gularly flooded areas (Bayley, 2031 1991; Zedler and Calloway, 1999). 2032
2033

2 See Glossary for a list of corresponden ce between common and scientific names.CCSP 4.1 January 15, 2009

246 of 784 Final Report 2034 Figure 5.1 Marsh and tidal creek, Bethels Beach (Mat hews County) Virginia. June 2002. 2035 2036 Tidal creeks and channels (Figure 5.1) freque ntly cut through low marsh areas, draining 2037 the marsh surface and serving as routes for nutrient-rich plant detritus (dead, decaying 2038 organic material) to be flushed out into deep er water as tides recede and for small fish, 2039 shrimp, and crabs to move into the marsh during high tides (Mitsc h and Gosselink, 1993; 2040 Lippson and Lippson, 2006). In addition to mu mmichog, fish species found in tidal 2041 creeks at low tide include Atlantic silversi de, striped killifish, and sheepshead minnow 2042 (Rountree and Able, 1992). Waterbirds such as gr eat blue herons and egrets are attracted 2043 to marshes to feed on the abundant small fish, snails, shrimp, clams, and crabs found in 2044 tidal creeks and marsh ponds. 2045
2046 Brackish marshes support many of the same wildlife species as salt marshes, with some 2047 notable exceptions. Bald eagles forage in brackish marshes and nest in nearby wooded 2048 areas. Because there are few resident mammalian predators (such as red fox and 2049 raccoons), small herbivores such as meadow vol es thrive in these marshes. Fish species 2050 common in the brackish waters of the Mid-Atlantic include striped bass and white perch, 2051 which move in and out of brackish waters year-round. Anadromous fish found in the 2052CCSP 4.1 January 15, 2009

247 of 784 Final Report Mid-Atlantic (those that live primarily in salt water but return to freshwater to spawn) 2053 include herring and shad, while marine transi ents such as Atlantic menhaden and drum 2054 species are present in summer and fall (White, 1989). 2055 2056 Tidal fresh marshes are characteristic of the upper reach es of estuarine tributaries. In 2057 general, the plant species composition of fr eshwater marshes depends on the degree of 2058 flooding, with some species germinating well when completely submerged, while others 2059 are relatively intolerant of flooding (Mits ch and Gosselink, 2000). Some tidal fresh 2060 marshes possess higher plant diversity than ot her tidal marsh types (Perry and Atkinson, 2061 1997). 2062 2063 Tidal fresh marshes provide shelter, fora ge, and spawning habitat for numerous fish 2064 species, primarily cyprinids (minnows, shin ers, carp), centrarchids (sunfish, crappie, 2065 bass), and ictalurids (catfish ). In addition, some estuarine fish and shellfish species 2066 complete their life cycles in freshwater mars hes. Tidal fresh marshes are also important 2067 for a wide range of bird species. Some ecolo gists suggest that fres hwater tidal marshes 2068 support the greatest diversity of bird species of any mars h type (Mitsch and Gosselink, 2069 2000). The avifauna of these marshes incl udes waterfowl; wading birds; rails and 2070 shorebirds; birds of prey; gulls , terns, kingfishers, and crow s; arboreal birds; and ground 2071 and shrub species. Perching birds such as red- winged blackbirds are common in stands of 2072 cattail. Tidal freshwater marshes support add itional species that are rare in saline and 2073 brackish environments, such as frogs , turtles, and snakes (White, 1989). 2074 2075CCSP 4.1 January 15, 2009

248 of 784 Final Report Marsh islands are a critical subdivis ion of the tidal marshes. These islands are found 2076 throughout the mid-Atlantic study region, and are particularly vulnerable to sea-level rise 2077 (Kearney and Stevenson, 1991). Islands are co mmon features of salt marshes, and some 2078 estuaries and back-barrier bays have islands formed by deposits of dredge spoil. Many 2079 islands are a mixture of hab itat types, with vegetated and unvegetated wetlands in 2080 combination with upland areas 3 . These isolated areas provide nesting sites for various 2081 bird species, particularly co lonial nesting waterbirds, wh ere they are protected from 2082 terrestrial predators such as red fox. Gull-billed terns, common terns, black skimmers, 2083 and American oystercatchers all nest on marsh islands (Rounds et al. , 2004; Eyler et al. , 2084 1999; McGowan et al ., 2005). 2085
2086 As discussed in Chapter 4, tidal marshes can keep pace with sea-level rise through 2087 vertical accretion ( i.e. , soil build up through sediment deposition and organic matter 2088 accumulation) as long as a sufficient sediment supply exists. Where inland movement is 2089 not impeded by artificial shore stru ctures (Figure 5.2) or by geology ( e.g. , steeply sloping 2090 areas between geologic terraces, as found around Chesapeake Bay) (Ward et al. , 1998; 2091 Phillips, 1986), tidal marshes can expand in land, which would increase wetland area if 2092 the rate of migration exceeds that of eros ion of the marsh’s seaward boundary. However, 2093 wetland area would decrease even when a marsh migrates inland if the rate of erosion of 2094 the seaward boundary exceeds the rate of migration. Further, in areas where sufficient 2095 accretion does not occur, increased tidal flooding will stress marsh plants through 2096

3 Thompson’s Island in Rehoboth Bay, Delaware, is a good example of a mature forested upland with substantial marsh and beach area. The island ho sts a large population of migratory birds. See Maryland and Delaware Coastal Bays in Strange et al. (2008).CCSP 4.1 January 15, 2009

249 of 784 Final Report waterlogging and changes in soil chemistry, leading to a change in plant species 2097 composition and vegetation zones. If marsh plants become too stressed and die, the marsh 2098 will eventually convert to open water or tidal flat (Callaway et al. , 1996; Morris et al ., 2099 2002) 4

. 2100
2101

2102 Figure 5.2 Fringing marsh and bulkhead, Monmouth County, New Jersey. 2103 2104 Sea-level rise is also increasing salinity upstream in some rivers, leading to shifts in 2105 vegetation composition and the conversion of some tidal fresh ma rshes into brackish 2106 marshes (MD DNR, 2005). At the same time, brackish marshes can deteriorate as a result 2107 of ponding and smothering of marsh plants by beach wrack (seaweed and other marine 2108 detritus left on the shore by th e tide) as salinity increases and storms accentuate marsh 2109 fragmentation 5 (Strange et al. , 2008). While this process may allow colonization by 2110 lower-elevation marsh species, that outcom e is not certain (Stevenson and Kearney, 2111

4 The Plum Tree Island National Wildlife Refuge is an example of a marsh deteriorating through lack of sediment input. Extensive mudflats front the ma rsh (see Appendix 1.F for additional details). 5 Along the Patuxent River, Maryland, refuge manage rs have noted marsh deterioration and ponding with sea-level rise. See Appendix 1.F for additional details.CCSP 4.1 January 15, 2009

250 of 784 Final Report 1996). Low brackish marshes can change dynami cally in area and composition as sea 2112 level rises. If they are lost, forage fish and i nvertebrates of the low marsh, such as fiddler 2113 crabs, grass shrimp, and ribbed mussels, may also be lost, which would affect fauna 2114 further up the food chain (Strange et al. , 2008). Though more ponding may provide some 2115 additional foraging areas as mars hes deteriorate, the associated increase in salinity due to 2116 evaporative loss can also inhibit the grow th of marsh plants (MD DNR, 2005). Many 2117 current marsh islands will be inundated; howev er, in areas with sufficient sediment, new 2118 islands may form, although research on this possibility is limited (Cleary and Hosler, 2119 1979). New or expanded marsh is lands are also formed through dredge spoil projects 6

. 2120
2121 Effects of marsh inundation on fish and shellfish species are li kely to be complex. In the 2122 short term, inundation may make the marsh surface more accessible, increasing 2123 production. However, benefits will decrease as submergence decreases total marsh 2124 habitat (Rozas and Reed, 1993). For example, increased deteriorati on and mobilization of 2125 marsh peat sediments incr eases the immediate biologi cal oxygen demand and may 2126 deplete oxygen in marsh creeks and channels below levels needed to sustain fish. In these 2127 oxygen-deficient conditions, mummichogs and other killifish may be among the few 2128 species able to persist (Stevenson et al. , 2002). 2129
2130 In areas where marshes are reduced, remnant marshes may provide lower quality habitat, 2131 fewer nesting sites, and greater predation risk for a number of bird species that are marsh 2132 specialists and are also impor tant components of marsh food webs, including the clapper 2133

6 For example, see discussions of Hart-Miller and Poplar Islands in Chesapeake Bay in Appendix 1.F.CCSP 4.1 January 15, 2009

251 of 784 Final Report rail, black rail, least bittern, Forster’s tern, willet, and la ughing gull (Figure 5.3) (Erwin et 2134 al. , 2006). The majority of the Atlantic Coast breeding populations of Forster’s tern and 2135 laughing gull are considered to be at risk b ecause of loss of lagoonal marsh habitat due to 2136 sea-level rise (Erwin et al. , 2006). In a Virginia study, scie ntists found that the minimum 2137 marsh size to support significant marsh bird communities was 4.1 to 6.7 hectares (ha) 2138 (10.1 to 16.6 acres [ac]) (Watts, 1993). Some species may require even larger marsh 2139 sizes; minimum marsh size for successful comm unities of the saltmarsh sharp-tailed 2140 sparrow and the seaside sparrow, both on the Pa rtners in Flight Watch List, are estimated 2141 at 10 and 67 ha (25 and 166 ac), resp ectively (Benoit and Askins, 2002). 2142
2143

2144 Figure 5.3 Marsh drowning and hummock in Blackwater Wildlife Refuge, Maryland. November, 2002. 2145 2146CCSP 4.1 January 15, 2009

252 of 784 Final Report 2147 Figure 5.4 Pocosin in Green Swamp, North Carolina 2148 2149 5.3 FRESHWATER FORESTED WETLANDS 2150 Forested wetlands influenced by sea level line the mid-Atlantic coast. Limited primarily 2151 by their requirements for low-salinity water in a tidal regime, tidal fresh forests occur 2152 primarily in upper regions of tidal tribut aries in Virginia, Maryland, Delaware, New 2153 Jersey, and New York (NatureServe, 2006). Th e low-lying shorelines of North Carolina 2154 also contain large stands of forested we tlands, including cypress swamps and pocosins 2155 (Figure 5.4). Also in the mi d-Atlantic coastal plains ( e.g. , around Barnegat Bay, New 2156 Jersey) are Atlantic white ced ar swamps, found in areas where a saturated layer of peat 2157 overlays a sandy substrate (NatureServe, 2006). Forested wetlands support a variety of 2158 wildlife, including the prothonot ary warbler, the two-toed amphiuma salamander, and the 2159 bald eagle. Forested wetlands with thick unde rstories provide shelter and food for an 2160 abundance of breeding songbirds (Lippson and Lippson, 2006). Various rare and greatest 2161 conservation need (GCN) species reside in mid-Atlantic tidal swamps, including the 2162 Delmarva fox squirrel (federally listed as endangered), the eastern red bat, bobcats, bog 2163 turtles, and the redbellied watersnake (MD DNR, 2005). 2164CCSP 4.1 January 15, 2009

253 of 784 Final Report 2165 Tidal fresh forests, such as those found in the Mid-Atlantic, face a variety of threats, 2166 including sea-level rise, and are currently considered globally imperiled 7 . The responses 2167 of these forests to sea-leve l rise may include retreat at the open-water boundary, 2168 drowning in place, or expansion inland. Fleming et al. (2006) noted that, “Crown dieback 2169 and tree mortality are visible and nearly ubiquitous phenomena in these communities and 2170 are generally attributed to sea- level rise and an upstream shift in the salinity gradient in 2171 estuarine rivers”. Figure 5.5 presents an example of inundation and tree mortality. In 2172 Virginia, tidal forest research has indicat ed that where tree death is present, the 2173 topography is limiting inland migration of the hardwood swamp and the understory is 2174 converting to tidal marsh (Rheinhardt, 2007). 2175
2176

2177 Figure 5.5 Inundation and tree mortality in forested wetlands at Swan’s Point, Lower Potomac River. 2178 These wetlands are irregularly flooded by wind-generat ed tides, unaffected by astronomic tides; their 2179 frequency of inundation is controlled directly by sea level. 2180 2181

7 As presented in NatureServe (<http://www.natureserve.o rg/>), the prevalent tidal forest associations such as freshwater tidal woodlands and tidal freshwater cypress swamps ar e considered globally imperiled.CCSP 4.1 January 15, 2009

254 of 784 Final Report 5.4 SEA-LEVEL FENS 2182 Sea-level fens are a rare type of coastal wetland with a mix of freshwater tidal and 2183 northern bog vegetation, resu lting in a unique assemblage that includes carnivorous 2184 plants such as sundew and bladderworts (Fleming et al. , 2006; VNHP, 2006). Their 2185 geographic distribution includes isolated locations on Long Is land's South Shore; coastal 2186 New Jersey; Sussex County, Delaware; and Accomack County, Virginia. The eastern 2187 mud turtle and the rare elfin skimmer dra gonfly are among the animal species found in 2188 sea-level fens. Fens may occur in areas wher e soils are acidic and a natural seep from a 2189 nearby slope provides nutrient -poor groundwater (VNHP, 2006). Little research has been 2190 conducted on the effects of sea-level rise on groundwater fens; however, the Virginia 2191 Natural Heritage Program has conc luded that sea-level rise is a primary threat to the fens 2192 (VNHP, 2006). 2193 2194 5.5 SUBMERGED AQUATIC VEGETATION 2195 Submerged aquatic vegetation (SAV) is distri buted throughout the mi d-Atlantic region, 2196 dominated by eelgrass in the higher-salinity areas and a large number of brackish and 2197 freshwater species elsewhere ( e.g. , widgeon grass, wild celery) (Hurley, 1990). SAV 2198 plays a key role in estuarine ecology, helpi ng to regulate the oxygen content of nearshore 2199 waters, trapping sediments and nutrients, st abilizing bottom sediments, and reducing 2200 wave energy (Short and Neckles, 1999). SAV also provides food and shelter for a variety 2201 of fish and shellfish and the species that prey on them. Organisms that forage in SAV 2202 beds feed on the plants themselves, the detr itus and the epiphytes on plant leaves, and the 2203 small organisms found within the SAV bed ( e.g. , Stockhausen and Lipcius [2003] for 2204CCSP 4.1 January 15, 2009

255 of 784 Final Report blue crabs; Wyda et al. [2002] for fish). The commercially valuable blue crab hides in 2205 eelgrass during its molting periods, when it is otherwise vulnerable to predation. In 2206 Chesapeake Bay, summering sea tu rtles frequent eelgrass beds. The Kemp’s ridley sea 2207 turtle, federally listed as endangered, forages in eelgrass beds and flats, feeding on blue 2208 crabs in particular (Chesapeake Bay Program , 2007). Various waterbirds feed on SAV, 2209 including brant, canvasbac k, and American black duck (Perry and Deller, 1996). 2210
2211 Forage for piscivorous birds and fish is also provided by residents of nearby marshes that 2212 move in and out of SAV beds with the tid es, including mummichog, Atlantic silverside, 2213 naked goby, northern pipefish, fourspine stickleb ack, and threespine stickleback (Strange 2214 et al. , 2008). Juveniles of many commercially an d recreationally impor tant estuarine and 2215 marine fishes (such as menhaden, herring, shad, spot, croaker, weakfish, red drum, 2216 striped bass, and white perch) and smaller a dult fish (such as bay and striped anchovies) 2217 use SAV beds as nurseries (NOAA Chesapeake Bay Office, 2007; Wyda et al. , 2002). 2218 Adults of estuarine and marine species such as sea trout, bluefish, perch, and drum search 2219 for prey in SAV beds (Strange et al. , 2008). 2220
2221 Effects of sea-level rise on SAV beds are unc ertain because fluctuations in SAV occur on 2222 a year-to-year basis, a signifi cantly shorter timescale than can be attributed to sea-level 2223 rise 8 . However, Short and Neckles (1999) estimate that a 50 centimeter (cm) increase in 2224 water depth as a result of sea-level rise coul d reduce light penetrati on to current seagrass 2225 beds in coastal areas by 50 percent. This w ould result in a 30 to 40 percent reduction in 2226

8 For example, nutrient enrichment and resultant eutrophication are a common problem for SAV beds (USFWS, undated)CCSP 4.1 January 15, 2009

256 of 784 Final Report seagrass growth in those areas due to d ecreased photosynthesis (Short and Neckles, 2227 1999). Increased erosion, with concomitant in creased transport and delivery of sediment, 2228 would also reduce availabl e light (MD DNR, 2000). 2229
2230 Although plants in some portion of an SAV bed may decline as a result of such factors, 2231 landward edges may migrate inland depending on shore slope and s ubstrate suitability. 2232 SAV growth is significantly be tter in areas where erosion prov ides sandy substrate, rather 2233 than fine-grained or high orga nic matter substrates (Stevenson et al. , 2002). 2234 2235 Sea-level rise effects on the tidal range could also impact SAV, and the effect could be 2236 either detrimental or benefici al. In areas where the tidal ra nge increases, plants at the 2237 lower edge of the bed will receive less light at high tide, increasing plant stress (Koch and 2238 Beer, 1996). In areas where the tid al range decreases, the decr ease in intertidal exposure 2239 at low tide on the upper edge of the bed will reduce plant stress (Short and Neckles, 2240 1999). 2241
2242 Shore construction and armoring will impede shoreward movement of SAV beds (Short 2243 and Neckles, 1999) (see Chapter 6 for additiona l information on shore protections). First, 2244 hard structures tend to affect the imme diate geomorphology as well as any adjacent 2245 seagrass habitats (Strange et al. , 2008). Particularly during storm events, wave reflection 2246 off of bulkheads or seawalls can increase wa ter depth and magnify the inland reach of 2247 waves on downcoast beaches (Plant and Gr iggs, 1992; USGS, 2003; Small and Carman, 2248 2005). Second, as sea level rises in armored ar eas, the nearshore area deepens and light 2249CCSP 4.1 January 15, 2009

257 of 784 Final Report attenuation increases, restricting and fina lly eliminating seagrass growth (Strange et al. , 2250 2008). Finally, high nutrient levels in the water limit vegetation growth. Sediment 2251 trapping behind breakwaters, which increases the organic conten t, may limit eelgrass 2252 success (Strange et al. , 2008). Low-profile armoring, in cluding stone sills and other 2253 “living shorelines” projects, may be benefici al to SAV growth (NRC, 2007). Projects to 2254 protect wetlands and restore adjacent SAV be ds are taking place and represent a potential 2255 protection against SAV loss ( e.g. , U.S. Army Corps of Engineers restoration for Smith 2256 Island in Chesapeake Bay) (USACE, 2004). 2257 2258 Loss of SAV affects numerous animals that depend on the vegetation beds for protection 2259 and food. By one estimate, a 50-percent reduc tion in SAV results in a roughly 25-percent 2260 reduction in Maryland striped bass produc tion (Kahn and Kemp, 1985). For diving and 2261 dabbling ducks, a decrease in SAV in their diets since the 1960s has been noted (Perry 2262 and Deller, 1996). The decreased SAV in Chesapeak e Bay is cited as a major factor in the 2263 substantial reduction in wintering waterfowl (Perry and Deller, 1996). 2264
2265 5.6 TIDAL FLATS 2266 Tidal flats are composed of mud or sand a nd provide habitat for a rich abundance of 2267 invertebrates. Tidal flats are critical fora ging areas for numerous birds, including wading 2268 birds, migrating shorebirds, and dabbling ducks (Strange et al. , 2008). 2269
2270 In marsh areas where accretion rates lag behind sea-level rise, marsh will eventually 2271 revert to unvegetated flats and eventu ally open water as seas rise (Brinson et al. , 1995). 2272CCSP 4.1 January 15, 2009

258 of 784 Final Report For example, in New York’s Jamaica Bay, several hundred acres of low salt marsh have 2273 converted to open shoals (see Appendix 1.B for additional details). In a modeling study, 2274 Galbraith et al. (2002) predicted that under a 2°C globa l warming scenario, sea-level rise 2275 could inundate significant areas of intertidal flats in some regions. In some cases where 2276 tidal range increases with increased rates of sea-level rise; however, there may be an 2277 overall increase in the acreage of tidal flats (Field et al. , 1991). 2278 2279 In low energy shores with high sediment supplies, where sediments accumulate in 2280 shallow waters, flats may become vegetated as low marsh encroaches waterward, which 2281 will increase low marsh at th e expense of tidal flats (Red field, 1972). If sediment inputs 2282 are not sufficient, tidal flats will convert to subtidal habi tats, which may or may not be 2283 vegetated depending on substr ate composition and water transparency (Strange et al. , 2284 2008). 2285
2286 Loss of tidal flats would eliminate a rich i nvertebrate food source for migrating birds, 2287 including insects, small crabs, and other shellfish (Strange et al. , 2008). As tidal flat area 2288 declines, increased crowding in remaining areas could lead to exclus ion and reductions in 2289 local shorebird populations (Galbraith et al. , 2002). At the same time, ponds within 2290 marshes may become more important foraging sites for the birds if flats are inundated by 2291 sea-level rise (Erwin et al. , 2004). 2292 2293CCSP 4.1 January 15, 2009

259 of 784 Final Report 2294 Figure 5.6 Estuarine beach and bulkhead along Arthur K ills, Woodbridge Township, New Jersey (August 2295 2003). 2296 2297 5.7 ESTUARINE BEACHES 2298 Throughout most of the mid-Atlantic region and its tributaries, estuarine beaches front 2299 the base of low bluffs and high cliffs as we ll as bulkheads and revetments (see Figure 2300 5.6) (Jackson et al. , 2002). Estuarine beaches can also occur in front of marshes and on 2301 the mainland side of barrier islands (Jackson et al ., 2002). 2302

2303 Figure 5.7 Peconic Estuary Beach, Riverhead, New York (September 2006). 2304CCSP 4.1 January 15, 2009

260 of 784 Final Report The most abundant beach organisms are micros copic invertebrates that live between sand 2305 grains, feeding on bacteria and single-celled pr otozoa. It is estimated that there are over 2306 two billion of these organisms in a singl e square meter of sand (Bertness, 1999). They 2307 play a critical role in beach food webs as a link between bacteria and larger consumers 2308 such as sand diggers, fleas, crabs, and othe r macroinvertebrates that burrow in sediments 2309 or hide under rocks (Strange et al. , 2008). Various rare and en dangered beetles also live 2310 on sandy shores. Diamondback terrapin and hor seshoe crabs bury their eggs in beach 2311 sands. In turn, shorebirds such as the piping plover, American oystercatcher, and 2312 sandpipers feed on these resources (USFWS, 1988). The insects and crustaceans found in 2313 deposits of wrack on estuarine beaches are also an important source of forage for birds 2314 (Figure 5.7) (Dugan et al. , 2003). 2315
2316 As sea level rises, the fate of estuarine beaches depends on their ability to migrate and the 2317 availability of sediment to replen ish eroded sands (F igure 5.8) (Jackson et al. , 2002). 2318 Estuarine beaches continually erode, but under natural c onditions the landward and 2319 waterward boundaries usually retreat by about the same di stance. Shoreline protection 2320 structures may prevent migration, effectiv ely squeezing beaches between development 2321 and the water. Armoring that traps sand in one area can limit or eliminate longshore 2322 transport, and, as a result, diminish the c onstant replenishment of sand necessary for 2323 beach retention in nearby locations (Jackson et al. , 2002). Waterward of bulkheads, the 2324 foreshore habitat will likely be lost through erosion, frequently even without sea-level 2325 rise. Only in areas with sufficient sedi ment input relative to sea-level rise ( e.g. , upper 2326CCSP 4.1 January 15, 2009

261 of 784 Final Report tributaries and upper Chesapeake Bay) are beaches likely to remain in place in front of 2327 bulkheads. 2328 2329

2330 Figure 5.8 Beach with beach wrack and marsh in Beth el Beach (Mathews County), Virginia. 2331 2332 In many developed areas, estuarine beaches may be maintained with beach nourishment 2333 if there are sufficient sources and the public pressure and economic ability to do so. 2334 However, the ecological effects of b each nourishment remain uncertain. Beach 2335 nourishment will allow retention in areas with a sediment deficit, but may reduce habitat 2336 value through effects on sediment characteri stics and beach slope (Peterson and Bishop, 2337 2005). 2338 2339 Beach loss will cause declines in local popul ations of rare beetles found in Calvert 2340 County, Maryland. While the Northeastern beach tiger beetle is able to migrate in 2341 response to changing conditions, suitable beach habitat must be available nearby 2342 (USFWS, 1994). 2343
2344CCSP 4.1 January 15, 2009

262 of 784 Final Report At present, the degree to which horseshoe cr ab populations will decline as beaches are 2345 lost remains unclear. Early research results i ndicate that horseshoe crabs may lay eggs in 2346 intertidal habitats other than estuarine b eaches, such as sandbars and the sandy banks of 2347 tidal creeks (Loveland and Botton, 2007). Noneth eless, these habitats may only provide a 2348 temporary refuge for horseshoe crabs if they are inundated as well (Strange et al. , 2008). 2349 2350 Where horseshoe crabs decline because of loss of suitable habitat for egg deposition, 2351 there can be significant implications for migra ting shorebirds, particul arly the red knot, a 2352 candidate for protection under the federal Enda ngered Species Act, which feeds almost 2353 exclusively on horseshoe crab eggs during stopovers in the Delaware Estuary (Karpanty 2354 et al. , 2006). 2355 2356 In addition, using high-precision elevation data from nest sites, researchers are beginning 2357 to examine the effects that sea-level rise wi ll have on oystercatchers and other shore birds 2358 (Rounds and Erwin, 2002). To the extent that es tuarine and riverine beaches, particularly 2359 on islands, survive better than barrier islands, sh orebirds like oystercat chers might be able 2360 to migrate to these shores (McGowan et al ., 2005). 2361
2362 5.8 CLIFFS 2363 Unvegetated cliffs and the sandy beaches sometimes present at their bases are constantly 2364 reworked by wave action, providing a dynamic ha bitat for cliff beetles and birds. Little 2365 vegetation exists on the cliff face due to c onstant erosion, and the eroding sediment 2366 augments nearby beaches. Cliffs are present on Chesapeake Bay’s western shore and 2367CCSP 4.1 January 15, 2009

263 of 784 Final Report tributaries and its northern tributaries (see Figu re 5.9), as well as in Hempstead Harbor on 2368 Long Island’s North Shore and other areas wh ere high energy shorelin es intersect steep 2369 slopes (Strange et al ., 2008). 2370
2371

2372 Figure 5.9 Crystal Beach, along the Elk River, Maryland (May 2005). 2373 2374 If the cliff base is armored to protect agai nst rising seas, erosion rates may decrease, 2375 eliminating the unvegetated cliff faces that are sustained by continuous erosion and 2376 provide habitat for species such as the Pu ritan tiger beetle and bank swallow. Cliff 2377 erosion also provides a sediment source to su stain the adjacent b each and littoral zone 2378 (the shore zone between high and low water marks) (Strange et al ., 2008). Naturally 2379 eroding cliffs are “severely threatened by s horeline erosion contro l practices” according 2380 to the Maryland Department of Natural Res ource’s Wildlife Diversity Conservation Plan 2381 (MD DNR, 2005). Shoreline protections may also subject adjacent cliff areas to wave 2382 undercutting and higher recession rates as well as reduction in beach sediment (Wilcock 2383CCSP 4.1 January 15, 2009

264 of 784 Final Report et al. , 1998). Development and shoreline stabili zation structures that interfere with 2384 natural erosional processes are cited as th reats to bank-nesting birds as well as two 2385 species of tiger beetles (federally listed as threatened) at Maryland’s Calvert Cliffs 2386 (USFWS, 1993, 1994; CCB, 1996). 2387
2388 5.9 SUMMARY OF IMPACTS TO WETLAND-DEPENDENT SPECIES 2389 Based on currently available information, it is possible to identify particular taxa and 2390 even some individual species that appear to be at greatest risk if coastal habitats are 2391 degraded or diminished in response to se a-level rise and shor eline hardening: 2392

 Degradation and loss of tidal marshes will a ffect fish and shellfish production in both 2393 the marshes themselves and adjacent estuaries. 2394

 Bird species that are marsh specialists, in cluding the clapper rail, black rail, least 2395 bittern, Forster’s tern, willet, and laughing gull, are particular ly at risk. At present, the 2396 majority of the Atlantic Coast breeding populations of Forster’s tern and laughing 2397 gull are considered to be at risk from loss of lagoonal marshes. 2398

 Increased turbidity and eutrophication in n earshore areas and increased water depths 2399 may reduce light penetration to SAV beds, reducing photosynthesis , and therefore the 2400 growth and survival of the vegetation. Degr adation and loss of SAV beds will affect 2401 the numerous organisms that feed, carry on re productive activities, and seek shelter in 2402 seagrass beds. 2403

 Diamondback terrapin are at risk of losi ng both marsh habitat that supports growth 2404 and adjoining beaches where eggs are buried. 2405CCSP 4.1 January 15, 2009

265 of 784 Final Report  Many marsh islands along the Mid-Atlantic , and particularly in Chesapeake Bay, 2406 have already been lost or severely reduced as a result of lateral erosion and flooding 2407 related to sea-level rise. Loss of such is lands poses a serious, near-term threat for 2408 island-nesting bird species su ch as gull-billed terns, co mmon terns, black skimmers, 2409 and American oystercatchers. 2410

 Many mid-Atlantic tidal forest associations may be at ri sk from sea-level rise and a 2411 variety of other threats, and are now considered globally imperiled. 2412

 Shoreline stabilization structures interfer e with natural erosional processes that 2413 maintain unvegetated cliff faces that provide habitat for bank-nesting birds and tiger 2414 beetles. 2415

 Loss of tidal flats could lead to increase d crowding of foraging birds in remaining 2416 areas, resulting in exclusion of many individuals; if a lternate foraging areas are 2417 unavailable, starvation of excluded individua ls may result, ultimately leading to 2418 reductions in local bird populations. 2419

 Where horseshoe crabs decline because of loss of suitable beach substrate for egg 2420 deposition, there could be significant im plications for migrating shorebirds, 2421 particularly the red knot, a candidate for protection under the federal Endangered 2422 Species Act. Red knot feed almost excl usively on horseshoe crab eggs during 2423 stopovers in the Delaware Estuary. 2424 2425CCSP 4.1 January 15, 2009

266 of 784 Final Report CHAPTER 5 REFERENCES 2426 * Indicates non-peer reviewed literature; available upon request 2427
2428 Bayley , P.B., 1991: The flood pulse advantage and the restor ation of river-floodplain 2429 systems. Regulated Rivers: Research and Management, 6(2) , 75-86. 2430

Beck , M.W., K.L. Heck Jr., K.W. Able, D.L. Ch ilders, D.B. Eggleston, B.M. Gillanders, 2431 B.S. Halpern, C.G. Hays, K. Hoshino, T.J. Minello, R.J. Orth, P.F. Sheridan, and 2432 M.P. Weinstein, 2003: The role of nears hore ecosystems as fish and shellfish 2433 nurseries. Issues in Ecology, 11 , 1-12. 2434
Benoit , L.K. and R.A. Askins, 2002: Relatio nship between habitat area and the 2435 distribution of tidal marsh birds. The Wilson Bulletin , 114(3) , 314-323. 2436

Bertness , M.B., 1999: The Ecology of A tlantic Shorelines . Sinauer Associates, 2437 Sunderland, MA, 417 pp. 2438

Boesch , D.F. and R.E. Turner, 1984: Dependence of fishery species on salt marshes: the 2439 role of food and refuge. Estuaries, 7(4A) , 460-468. 2440
Brinson , M.M., R.R. Christian, and L.K. Blum, 1995: Multiple states in the sea level 2441 induced transition from terre strial forest to estuary. Estuaries, 18(4) , 648-659. 2442 Callaway , J.C., J.A. Nyman, and R.D. DeLaune , 1996: Sediment accretion in coastal 2443 wetlands: A review and a simulation model of processes. Current Topics in 2444 Wetland Biogeochemistry, 2 , 2-23. 2445
CCB (The Center for Conservation Biol ogy), 1996: Fieldwork concluded on bank2446 nesting bird study. Cornerstone Magazine , 2 , 1. 2447 <https://www.denix.osd.mil/denix/Public/ESPrograms/Conservation/Legacy/Corn 2448 er-stone/corner.html> 2449

* Chesapeake Bay Program [sea turtles] , 2007: Sea turtles guide . [web si te] 2450 <http://www.chesapeakebay.net/seaturtle.htm> 2451CCSP 4.1 January 15, 2009

267 of 784 Final Report Childers , D.L., J.W. Day Jr., and H.N. Kellar Jr., 2000: Twenty more years of marsh and 2452 estuarine flux studies: revisiting Nixon (1980). In: Concepts and Controversies in 2453 Tidal Marsh Ecology . [Weinstein, M.P. and D.A. Kreeger (eds.)]. Kluwer 2454 Academic, Dordrecht, the Netherlands, pp. 391-424. 2455 Cleary , W.J. and P.E. Hosler, 1979: Genesis a nd significance of marsh islands within 2456 southeastern North Carolina lagoons. Journal of Sedimentary Research , 49(3) , 2457 703-709. 2458 Deegan , L.A., J.E. Hughes, and R.A. Rountree, 2000: Salt marsh ecosystem support of 2459 marine transient species. In: Concepts and Controversies in Tidal Marsh Ecology

. 2460 [Weinstein, M.P. and D.A. Kreeger (eds .)]. Kluwer Academic, Dordrecht, the 2461 Netherlands, pp. 333-368. 2462
Dittel , A.I., C.E. Epifanio, and M.L. Fogel, 2006: Trophic relationships of juvenile blue 2463 crabs ( Callinectes sapidus ) in estuarine habitats. Hydrobiologia, 568(1) , 379-390. 2464 Dugan , J.E., D.M. Hubbard, M.D. McCrary, a nd M.O. Pierson, 2003: The response of 2465 macrofauna communities and shorebir d communities to macrophyte wrack 2466 subsidies on exposed sandy beach es of southern California. Estuarine, Coastal, 2467 and Shelf Science, 58S , 25-40. 2468
Erwin , R.W., G.M. Sanders, and D.J. Pro sser, 2004: Changes in lagoonal marsh 2469 morphology at selected north eastern Atlantic coast si tes of significance to 2470 migratory waterbirds. Wetlands, 24(4) , 891-903. 2471
Erwin , R.M., G.M. Sanders, D.J. Prosser, and D.R. Cahoon, 2006: High tides and rising 2472 seas: potential effects on estuarine waterbirds. In: Terrestrial Vertebrates in Tidal 2473 Marshes: Evolution, Ecology, and Conservation . [Greenberg, R. (ed.)]. Studies in 2474 avian biology no. 32. Cooper Ornithological Society, Camarillo, CA, pp. 214-228. 2475 Eyler , T.B., R.M. Erwin, D.B. Stotts, and J. S. Hatfield, 1999: Aspects of hatching 2476 success and chick survival in gull-billed terns in coastal Virginia. Waterbirds, 2477 22(1) , 54-59. 2478CCSP 4.1 January 15, 2009

268 of 784 Final Report Field , D.W., A.J. Reyer, P.V. Genovese, and B.D. Shearer, 1991: Coastal Wetlands of 2479 the United States . National Oceanic and Atmospheric Administration and U.S. 2480 Fish and Wildlife Service, [Washington, DC], 58 pp. 2481 Fleming , G.P., P.P. Coulling, K.D. Patterson, and K. Taverna, 2006: The Natural 2482 Communities of Virginia: Classification of Ecological Community Groups

. 2483 Second approximation, version 2.2. Virginia Department of Conservation and 2484 Recreation, Division of Natu ral Heritage, Richmond, VA. 2485 <http://www.dcr.virginia.gov/natural_heritage/ncintro.shtml> 2486
Galbraith , H., R. Jones, P. Park, J. Clough, S. Herrod-Julius, B. Harrington, and G. 2487 Page, 2002: Global climate change and sea leve l rise: potential loss es of intertidal 2488 habitat for shorebirds. Waterbirds, 25(2) , 173-183. 2489 Hurley , L.M., 1990: Field Guide to the Submerged A quatic Vegetation of Chesapeake 2490 Bay. U.S. Fish and Wildlife Service, Chesapeake Bay Estuary Program, 2491 Annapolis, MD, 48 pp. 2492

Jackson , N.L., K.F. Nordstrom, and D.R. Smit h, 2002: Geomorphic-biotic interactions 2493 on beach foreshores in estuaries. Journal of Coastal Research , Special issue 36 , 2494 414-424. 2495

Kahn , J.R. and W.M. Kemp, 1985: Economic losse s associated with the degradation of 2496 an ecosystem: the case of submerged a quatic vegetation in Chesapeake Bay. 2497 Journal of Environmental Economics and Management , 12(3) , 246-263. 2498 Karpanty , S.M., J.D. Fraser, J.M. Berkson, L. Niles, A. Dey, and E.P. Smith, 2006: 2499 Horseshoe crab eggs determine red knot distribution in Delaware Bay habitats. 2500 Journal of Wildlife Management, 70(6) , 1704-1710. 2501 Kearney , M.S. and J.C. Stevenson, 1991: Island land loss and marsh vertical accretion 2502 rate evidence for historical se a-level changes in Chesapeake Bay. Journal of 2503 Coastal Research , 7(2) , 403-416. 2504CCSP 4.1 January 15, 2009

269 of 784 Final Report Kneib , R.T., 1997: The role of tidal marshe s in the ecology of estuarine nekton. 2505 Oceanography and Marine Biology, 35 , 163-220. 2506
Kneib , R.T., 2000: Salt marsh ecoscapes and pro duction transfers by es tuarine nekton in 2507 the southeastern U.S. In: Concepts and Controversies in Tidal Marsh Ecology

. 2508 [Weinstein, M.P. and D.A. Kreeger (eds .)]. Kluwer Academic, Dordrecht, the 2509 Netherlands, pp. 267-291. 2510

Koch , E.W. and S. Beer, 1996: Tides, light and the distribution of zostera marina in 2511 Long Island Sound, USA. Aquatic Botany , 53(1-2) , 97-107. Referenced in: Short, 2512 F.A. and H.A. Neckles, 1999: The effects of global climate change on seagrasses. 2513 Aquatic Botany, 63(3-4) , 169-196. 2514 Lippson , A.J. and R.L. Lippson, 2006: Life in the Chesapeake Bay . Johns Hopkins 2515 University Press, Baltimore, MD, 3 rd ed., 324 pp. 2516
Litvin , S.Y. and M.P. Weinstein, 2009: Energy density and the biochemical condition of 2517 juvenile weakfish ( Cynoscion regalis ) in the Delaware Bay estuary, USA. 2518 Canadian Journal of Fisheries and Aquatic Sciences (in press). 2519

* Loveland , R.E. and M.L. Botton, 2007: The impor tance of alternative habitats to 2520 spawning horseshoe crabs ( Limulus polyphemus ) in lower Delaware Bay, New 2521 Jersey. Presentation at: Delaware Estuary Science Conference , Cape May, NJ. 2522 Program available online at 2523 <http://www.delawareestuary.org/pdf /ScienceConferenceProgram2007.pdf> 2524
McGowan , C.P., T.R. Simons, W. Golder, a nd J. Cordes, 2005: A comparison of 2525 American oystercatcher reproductive su ccess on barrier beach and river island 2526 habitats in coastal North Carolina. Waterbirds , 28(2) , 150-155. 2527

MD DNR (Maryland Department of Natural Resources), 2000: State of Maryland Shore 2528 Erosion Task Force . Maryland Department of Na tural Resources, Annapolis, 65 2529 pp. <http://www.dnr.state.md.us/ccws/sec/sccreport.html> 2530CCSP 4.1 January 15, 2009

270 of 784 Final Report MD DNR (Maryland Department of Natural Resources), 2005: Maryland DNR Wildlife 2531 Conservation Diversity Plan — Final Draft. 2532 <http://www.dnr.state.md.us/wildlife/divplan_wdcp.asp> 2533

MEA (Millennium Ecosystem Assessment), 2005: Climate change. In: Ecosystems and 2534 Human Well-Being: Policy Responses . Findings of the Responses Working 2535 Group. Millennium Ecosystem Assessment series volume 3. Island Press, 2536 Washington, DC, chapter 13. 2537
Mitsch , W.J. and J.G. Gosselink, 1993: Wetlands . Van Nostrand Reinhold, New York, 2538 2 nd ed., 722 pp. 2539
Mitsch , W.J. and J.G. Gosselink, 2000: Wetlands . Van Nostrand Reinhold, New York, 2540 3 rd ed., 920 pp. 2541
Morris , J.T., P.V. Sundareshwar, C.T. Niet ch, B. Kjerfve, and D.R. Cahoon, 2002: 2542 Responses of coastal wetla nds to rising sea level. Ecology , 83(10) , 2869-2877. 2543
NatureServe , 2006: NatureServe Explorer: An Online Encyclopedia of Life [web 2544 application]. Version 5.0. Na tureServe, Arlington, VA. 2545 <http://www.natureserve.org/explorer>. “N orthern Atlantic Coastal Plain Tidal 2546 Swamp” CES203.282 2547 <http://www.natureserve.org/explorer/ser vlet/NatureServe?searchSystemUid = 2548 ELEMENT_GLOBAL.2.723205> 2549 NOAA Chesapeake Bay Office, 2007: SAV overview. [web site] 2550 <http://noaa.chesapeakebay.net/HabitatSav.aspx> 2551
NRC (National Research Council), 2005: Valuing Ecosystem Services: Toward Better 2552 Environmental Decision-Making . National Academies Press, Washington, DC, 2553 277 pp. 2554
NRC (National Research Council), 2007: Mitigating Shore Eros ion Along Sheltered 2555 Coasts . National Academies Press, Washington, DC, 174 pp. 2556CCSP 4.1 January 15, 2009

271 of 784 Final Report Perry , J.E. and R.B. Atkinson, 1997: Plant dive rsity along a salinity gradient of four 2557 marshes on the York and Pamunkey Rivers in Virginia. Castanea, 62(2), 112-118. 2558 Perry , M.C. and A.S. Deller, 1996: Review of factors affecting the distribution and 2559 abundance of waterfowl in shallow- water habitats of Chesapeake Bay. Estuaries, 2560 19(2A) , 272-278. 2561

Peterson , C.H. and M.J. Bishop, 2005: Assessing the environmental impacts of beach 2562 nourishment. BioScience, 55(10) , 887-896. 2563 Phillips , J.D., 1986: Coastal submergence and marsh fringe erosion. Journal of Coastal 2564 Research , 2(4) , 427-436. 2565

Plant , N.G. and G.B. Griggs, 1992: Interactions between nearshore processes and beach 2566 morphology near a seawall. Journal of Coastal Research , 8(1) , 183-200. 2567
Redfield , A.C., 1972: Development of a New England salt marsh. Ecological 2568 Monographs, 42 , 201-237. 2569
Rheinhardt , R., 2007: Tidal freshwater swamps of a lower Chesapeake Bay subestuary. 2570 In: Ecology of Tidal Freshwat er Forested Wetlands of the Southeastern United 2571 States. [Conner, W.H., T.W. Doyle, and K.W. Krauss (eds.)]. Springer, 2572 Dordrecht, the Netherlands, 505 pp. 2573

* Rounds , R. and R.M. Erwin, 2002: Flooding and sea level rise at waterbird colonies in 2574 Virginia. Presentation at: 26th Annual Waterbird Society Meeting , November, La 2575 Crosse, WI. 2576 <http://www.vcrlter.virginia.edu /presentations/rounds0211/rounds0211.pdf> 2577

Rounds , R.A., R.M. Erwin, and J.H. Porter, 2004: Nest-site sele ction and hatching 2578 success of waterbirds in co astal Virginia: some results of habitat manipulation. 2579 Journal of Field Ornithology, 75(4) , 317-329. 2580CCSP 4.1 January 15, 2009

272 of 784 Final Report Rountree , R.A. and K.W. Able, 1992: Fauna of polyhaline subtidal marsh creeks in 2581 southern New Jersey: compos ition, abundance and biomass. Estuaries, 15(2) , 2582 171-185. 2583

Rozas , L.P. and D.J. Reed, 1993: Nekton use of marsh-surface habitats in Louisiana 2584 (USA) deltaic salt marshes undergoing submergence. Marine Ecology Progress 2585 Series , 96 , 147-157. 2586 Seitz, R.D., R.N. Lipcius, N.H. Olmstead, M.S. Seebo, and D.M. Lambert, 2006: 2587 Influence of shallow-water habitats and shoreline development on abundance, 2588 biomass, and diversity of benthic prey and predators in Chesapeake Bay. Marine 2589 Ecology Progress Series, 326 , 11-27. 2590
Short , F.T. and H.A. Neckles, 1999: The effect s of global climate change on seagrasses. 2591 Aquatic Botany, 63(3-4) , 169-196. 2592

* Small , D. and R. Carman, 2005: A history of th e Washington State Hydraulic Code and 2593 marine shoreline armoring in Puget Sound. Presented at: 2005 Puget Sound 2594 Georgia Basin Research Conference , March 29-31, Seat tle, WA, [14 pp.] 2595 <http://www.engr.washington.edu/epp/psgb/2005psgb/2005proceedings/papers/P 2596 5_SMALL.pdf> 2597
Stevens , P.W., C.L. Montague, and K.J. Sula k, 2006: Fate of fish production in a 2598 seasonally flooded saltmarsh. Marine Ecology Progress Series, 327 , 267-277. 2599
Stevenson , J.C. and M.S. Kearney, 1996: Shoreline dynamics on the windward and 2600 leeward shores of a larg e temperate estuary. In: Estuarine Shores: Evolution, 2601 Environments, and Human Alterations . [Nordstrom, K.F. and C.T. Roman (eds.)]. 2602 Wiley, New York, pp. 233-259. 2603
Stevenson , J.C., M.S. Kearney, and E.W. Koch, 2002: Impacts of sea level rise on tidal 2604 wetlands and shallow water habitats: a case study from Chesapeake Bay. 2605 American Fisheries Society Symposium , 32 , 23-36. 2606CCSP 4.1 January 15, 2009

273 of 784 Final Report Stockhausen , W.T. and R.N. Lipcius, 2003: Simu lated effects of seagrass loss and 2607 restoration on settlement and recruitment of blue crab postlarvae and juveniles in 2608 the York River, Chesapeake Bay. Bulletin of Marine Science, 72(2) , 409-422. 2609 Strange , E.M., A. Shellenbarger Jones, C. Bosch, R. Jones, D. Kreeger, and J.G. Titus, 2610 2008: Mid-Atlantic coastal habitats and e nvironmental implications of sea level 2611 rise. Section 3 in: Background Documents Supporting Climate Change Science 2612 Program Synthesis and Assessment Pr oduct 4.1: Coastal Elevations and 2613 Sensitivity to Sea Level Rise [Titus, J.G. and E.M. Strange (eds.)]. EPA 2614 430R07004. U.S. Environmental Protection Agency, Washington, DC, pp. 188- 2615 342. <http://epa.gov/climatechange/e ffects/coastal/background.html> 2616

Teal , J.M., 1986: The Ecology of Regularly Floode d Salt Marshes of New England: A 2617 Community Profile. Biological report 85(7.4). U.S. Fish and Wildlife Service, 2618 Washington, DC, 69 pp. 2619
USACE (U.S. Army Corps of Engineers), 2004: Smith Island, Maryland Environmental 2620 Restoration and Protection Project . [web site] U.S. Army Corps of Engineers, 2621 Baltimore Division. 2622 <http://www.nab.usace.army.mil/projects/Maryland/smithisland.htm> 2623
USFWS (U.S. Fish and Wildlife Service), Undated: Nutrient Pollution . [web site] 2624 USFWS Chesapeake Bay Field Office. 2625 <http://www.fws.gov/chesapeakebay/nutrient.htm> 2626
USFWS (U.S. Fish and Wildlife Service), 1988: Endangered Species Information 2627 Booklet: Piping Plover . U.S. Fish and Wildlife Service, Arlington, VA. 2628
USFWS (U.S. Fish and Wildlife Service), 1993: Puritan Tiger Beetle ( Cicindela puritana 2629 G. Horn) Recovery Plan . Hadley, MA, 45 pp. 2630
USFWS (U.S. Fish and Wildlife Service), 1994: Recovery Plan for the Northeastern 2631 Beach Tiger Beetle ( Cicindela dorsalis dorsalis ). Hadley, MA. 2632CCSP 4.1 January 15, 2009

274 of 784 Final Report USGS (U.S. Geological Survey), 2003: A Summary Report of Sediment Processes in 2633 Chesapeake Bay and Watershed . [Langland, M. and T. Cronin (eds.)]. Water 2634 resources investigations report 03 -4123. U.S. Geological Survey, New 2635 Cumberland, PA, 109 pp. 2636

VNHP (Virginia Natural Heritage Program), 200 6: Natural Heritage Resources Fact 2637 Sheet: Virginia’s Rare Natural Environments: Sea-level Fens. Virginia 2638 Department of Conservation a nd Recreation, [Richmond, VA,] 2 pp. 2639 <http://www.dcr.virginia.gov/natural _heritage/documents/fsslfen.pdf> 2640

Ward , L.G., M.S. Kearney, and J.C. Stevenson, 1998: Variations in sedimentary 2641 environments and accretionary patterns in estuarine marshes undergoing rapid 2642 submergence, Chesapeake Bay. Marine Geology, 151(1-4) , 111-134. 2643

Watts , B.D., 1993: Effects of Marsh Size on Inci dence Rates and Avian Community 2644 Organization Within the Lower Chesapeake Bay . Center for Conservation 2645 Biology technical repor t CCBTR-93-03. College of William and Mary, 2646 Williamsburg, VA, 53 pp. 2647
Weinstein , M.P., 1979: Shallow marsh habitats as primary nurseries for fishes and 2648 shellfish, Cape Fear River, North Carolina. Fishery Bulletin, 77(2) , 339-357. 2649
Weinstein , M.P., 1983: Population dynamics of an estuarine-dependent fish, the spot 2650 ( Leisotomus xanthurus ) along a tidal creek-seagrass meadow coenocline. 2651 Canadian Journal of Fisheries and Aquatic Sciences , 40(10) , 1633-1638. 2652
Weinstein , M.P., S.Y. Litvin, and V.G. Guida, 2005: Considerations of habitat linkages, 2653 estuarine landscapes, and the trophic spectrum in wetland restoration design. 2654 Journal of Coastal Research , Special issue 40 , 51-63. 2655
White , C.P., 1989: Chesapeake Bay: Nature of the Estuary: A Field Guide . Tidewater 2656 Publishers, Centreville, MD, 212 pp. 2657CCSP 4.1 January 15, 2009

275 of 784 Final Report Wilcock , P.R., D.S. Miller, R.H. Shea, and R.T. Kerhin, 1998: Frequency of effective 2658 wave activity and the recession of coas tal bluffs: Calvert Cliffs, Maryland. 2659 Journal of Coastal Research, 14(1) , 256-268. 2660 Wyda , J.C., L.A. Deegan, J.E. Hughes, and M.J. Weaver, 2002: The response of fishes to 2661 submerged aquatic vegetation complexity in two ecoregions of the mid-Atlantic 2662 bight: Buzzards Bay and Chesapeake Bay. Estuaries, 25(1) , 86-100. 2663

Zedler , J.B. and J.C. Callaway, 1999: Tracking wetland restoration: do mitigation sites 2664 follow desired trajectories? Restoration Ecology, 7(1) , 69-73. 2665
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## Part II Overview. Societal Impacts and Implications 2667

2668 Authors: James G. Titus, U.S. EPA; Stephen K. Gill, NOAA 2669
2670 The previous chapters in Part I examined so me of the impacts of sea-level rise on the 2671 Mid-Atlantic, with a focus on the natural environment. Part II examines the implications 2672 of sea-level rise for develope d lands. Although the direct eff ects of sea-level rise would 2673 be similar to those on the natural envir onment, people are part of this “built 2674 environment”; and people will generally respond to changes as they emerge, especially if 2675 important assets are threatened. The choices that people make could be influenced by the 2676 physical setting, the properties of the built environment, human aspirations, and the 2677 constraints of laws and economics. 2678 2679 The chapters in Part II examine the impacts on four human activities: shore 2680 protection/retreat, human ha bitation, public access, and flood hazard mitigation. This 2681 assessment does not predict the choices that people will make; instead it examines some 2682 of the available options and assesses actions that federal and state governments and 2683 coastal communities can take in response to sea-level rise. 2684
2685 As rising sea level threatens coastal lands, the most fundame ntal choice that people face 2686 is whether to attempt to hold back the sea or allow nature to takes its course. Both choices 2687 have important costs and uncertainties. “Shore protection” allows homes and businesses 2688 to remain in their current locations, but often damages coastal habitat and requires 2689CCSP 4.1 January 15, 2009

277 of 784 Final Report substantial expenditure. “Retreat” can avoid the costs and environmental impacts of shore 2690 protection, but often at the expense of lost land and—in the case of developed areas—the 2691 loss of homes and possibly entire communities. In nature reserves and major cities, the 2692 preferred option may be obvious. Yet becau se each choice has some unwelcome 2693 consequences, the decision may be more diffi cult in areas that ar e developing or only 2694 lightly developed. Until this choice is made, however, preparing for long-term sea-level 2695 rise in a particular lo cation may be impossible. 2696 2697 Chapter 6 outlines some of the key factors likely to be a part of any dialogue on whether 2698 to protect or retreat in a given area: 2699

 What are the technologies available fo r shore protection a nd the institutional 2700 measures that might help foster a retreat? 2701

 What is the relationship between land use and shore protection? 2702

 What are the environmental and social consequences of s hore protection and 2703
retreat? 2704

 Is shore protection sustainable? 2705 Most areas lack a plan that specifically addresses whether the shore will retreat or be 2706 protected. Even in those areas where a state plan s to hold the line or a park plans to allow 2707 the shore to retreat, the plan is based on existing conditions. Current plans do not 2708 consider the costs or environmental conseque nces of sustaining shore protection for the 2709 next century and beyond. 2710
2711CCSP 4.1 January 15, 2009

278 of 784 Final Report One of the most important decisions that pe ople make related to sea-level rise is the 2712 decision to live or build in a low-lying area. Chapter 7 provides an uncertainty range of 2713 the population and number of households with a direct stake in possible inundation as sea 2714 level rises. The results are based on censu s data for the year 2000, and thus are not 2715 estimates the number of people or value of structures that will be affected, but rather 2716 estimate the number of people who have a stake today in the possible future 2717 consequences of rising sea level. Because cen sus data estimates the total population of a 2718 given census block, but does not indicate wher e in that block the people live or the 2719 elevation of their homes, the estimates in Ch apter 7 should not be viewed as the number 2720 of people whose homes would be lost. Rath er, it estimates the number of people who 2721 inhabit a parcel of land with at least some land within a gi ven elevation above the sea. 2722 The calculations in this Chapter build quant itatively on some of the elevation studies 2723 discussed in Chapter 2, and consider uncerta inties in both the el evation data and the 2724 location of homes within a given census block. Chapte r 7 also summarizes a study 2725 sponsored by the U.S Department of Trans portation on the potential impacts of global 2726 sea-level rise on the tran sportation infrastructure. 2727
2728 Chapter 8 looks at the implicati ons of sea-level rise for publ ic access to the shore. The 2729 published literature suggests that the direct impact of sea level rise on public access 2730 would be minor because the boundary between public and private lands moves inland as 2731 the shore retreats. But responses to sea-level rise could ha ve a substantial impact. One 2732 common response (publicly funded beach nourishment) sometimes increases public 2733

access to the shore; but another class of respons es (privately funded shoreline armoring) 2734CCSP 4.1 January 15, 2009

279 of 784 Final Report can eliminate public access along the shore if the land seaw ard of the shore protection 2735 structure erodes. In parts of New Jersey, regulations governing permits for shoreline 2736 armoring avoid this impact by requiring pr operty owners to provide access along the 2737 shore inland of the new shore protection structures. 2738 2739 Finally, Chapter 9 examines the implicat ions of rising sea level for flood hazard 2740 mitigation, with a particular focus on th e implications for the Federal Emergency 2741 Management Agency (FEMA) and other coastal floodplain managers

. Rising sea level 2742 increases the vulnerability of coastal areas to flooding because higher sea level increases 2743 the frequency of floods by providing a higher base for flooding to build upon. Erosion of 2744 the shoreline could also make flooding more likely because erosion removes dunes and 2745 other natural protections agai nst storm waves. Higher sea le vel also raises groundwater 2746 levels, which can increase basement floodi ng and increase standing water. Both the 2747 higher groundwater tables and higher surface wa ter levels can slow the rate at which 2748 areas drain, and thereby increase the flooding from rainstorms. 2749 2750 Chapter 9 opens with results of studies on the relationship of coastal storm tide elevations 2751 and sea-level rise in the Mid-Atlantic. It then provides background on government 2752 agency floodplain management and on state ac tivities related to flooding and sea-level 2753 rise under the Coastal Zone Management Ac t. Federal agencies, such as FEMA, are 2754 beginning to specifically plan fo r future climate change in their strategic planning. Some 2755 coastal states, such as Maryland, have conduc ted state-wide assessments and studies of 2756CCSP 4.1 January 15, 2009

280 of 784 Final Report the impacts of sea-level rise and have taken steps to integrate this knowledge with local 2757 policy decisions. 2758 2759 The chapters in Part II incorporate the underlyi ng sea-level rise scen arios of this Product 2760 differently, because of the differences in th e underlying analytical approaches. Chapter 6 2761 evaluates the population and property vulnerable to a 100-centimeter rise in sea level, and 2762 summarizes a study by the U.S. Department of Tr ansportation concerning the impact of a 2763 59-centimeter rise. Chapters 6, 8 and 9 provide qualitative analyses that are generally 2764 valid for the entire uncertainty ra nge of future sea level rise. 2765
2766 2767CCSP 4.1 January 15, 2009

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## Chapter 6. Shore Protection and Retreat 2768 2769 Lead Authors: James G. Titus, U.S. EPA; Michael Craghan, Middle Atlantic Center for 2770 Geography and Environmental Studies 2771 2772 Contributing Authors: Stephen K. Gill, NOAA; S. Jeffress Williams, USGS 2773 2774 2775 KEY FINDINGS 2776

 Many options are available for protecti ng land from inundation, er osion, and flooding 2777 (“shore protection”), or for minimizi ng hazards and environmental impacts by 2778 removing development from the most vulnerable areas (“retreat”). 2779

 Coastal development and shore protection can be mutually reinforcing. Coastal 2780 development often encourages shore protection because shore protection costs more 2781 than the market value of undeveloped la nd, but less than the value of land and 2782 structures. Shore protection sometimes en courages coastal development by making a 2783 previously unsafe area safe for developmen t. Under current polic ies, shore protection 2784 is common along developed shores and rare along shores managed for conservation, 2785 agriculture, and forestry. Policymakers ha ve not decided whether the practice of 2786 protecting development should continue as s ea level rises, or be modified to avoid 2787 adverse environmental consequences and increased costs of shore protection. 2788

 Most shore protection structur es are designed for the current sea level, and retreat 2789 policies that rely on setting development back from the coast are designed for the 2790 current rate of sea-level ri se. Those structures and po licies would not necessarily 2791 accommodate a significant acceleration in the rate of sea-level rise. 2792CCSP 4.1 January 15, 2009

282 of 784 Final Report  Although shore protection and re treat both have environmental impacts, the long-term 2793 impacts of shore protection are likely to be greater. 2794

 In the short-term, retreat is more socially disruptive than shore protection. In the long2795 term, however, shore protection may be more disruptive—especially if it fails or 2796 proves to be unsustainable. 2797

 We do not know whether “business as us ual” shore protection is sustainable. 2798

 A failure to plan now could limit the flexib ility of future generations to implement 2799 preferred adaptation strategi es. Short-term shore protec tion projects can impair the 2800 flexibility to later adopt a retreat strategy. By contrast, short-term retreat does not 2801 significantly impair the ability to later erect shore protection structures inland from 2802 the present shore. 2803
2804 6.1 TECHNIQUES FOR SHORE PROTECTION AND RETREAT 2805 Most of the chapters in this Product discuss some aspect of shore protection and retreat. 2806 This Section provides an overview of th e key concepts and common measures for 2807 holding back the sea or facilitating a landwar d migration of people, property, wetlands, 2808 and beaches. Chapter 9 discusses floodproofi ng and other measures that accommodate 2809 rising sea level without nece ssarily involving choosing between shore protection and 2810

retreat. 2811
2812 6.1.1 Shore Protection 2813 The term “shore protection” generally refers to a class of coastal engineering activities 2814 that reduce the risk of floodi ng, erosion, or inundation of la nd and structures (USACE, 2815CCSP 4.1 January 15, 2009

283 of 784 Final Report 2002). The term is somewhat of a misnomer because shore-protection measures protect 2816 land and structures immediat ely inland of the shore rath er than the shore itself 9 . Shore2817 protection structures sometimes eliminate th e existing shore, and shore protection does 2818 not necessarily mean environmental preservation. This Product focuses on shore2819 protection measures that prev ent dry land from being flooded, or converted to wetlands or 2820 open water. 2821
2822 Shore-protection measures can be divided in to two categories: shoreline armoring and 2823 elevating land surfaces. Shore line armoring replaces the natural shoreline with an 2824 artificial surface, but areas inland of the s hore are generally untouched. Elevating land 2825 surfaces, by contrast, can maintain the natu ral character of the shore, but requires 2826 rebuilding all vulnerable land. Some met hods are hybrids of both approaches. For 2827 centuries, people have used both shore line armoring (Box 6.1) and elevating land 2828 surfaces (Box 6.2) to reclaim dry land from the sea. This Section discusses how those 2829 approaches might be used to prevent a risi ng sea level from converting dry land to open 2830 water. For a comprehensive discussion, see the Coastal Engineering Manual (USACE, 2831 2002). 2832
2833

9 The shore is the land immediately in contact with the water.CCSP 4.1 January 15, 2009

284 of 784 Final Report Strat box*** 2834 BOX 6.1 Historic use of Dikes to Reclaim Land in the Delaware Estuary 2835 Until the twentieth century, tidal wetlands were often converted to dry land through the use of dikes and 2836 drainage systems very similar to the systems that might be used to prevent land from being inundated as sea 2837 level rises. Nowhere in the United States was more ma rsh converted to dry land than along the Delaware 2838 River and Delaware Bay. A Dutch governor of New Jersey diked the marsh on Burlington Island, New 2839 Jersey. In 1680, after the English governor took po ssession of the island, observers commented that the 2840 marsh farm had achieved greater yields of grai n than nearby farms created by clearing woodland 2841 (Danckaerts, 1913). In 1675, an English governor ordered the construction of dikes to facilitate 2842 construction of a highway through the marsh in New Castle County, Delaware (Sebold, 1992). 2843 2844 Colonial (and later state) governments in New Jers ey chartered and authorized “meadow companies” to 2845 build dikes and take ownership of the reclaimed lands. During the middle of the nineteenth century, the 2846 state agriculture department extolled the virtues of reclaimed land for growing salt hay. By 1866, 20,000 2847 acres of New Jersey’s marshes had been reclaimed fr om Delaware Bay, mostly in Salem and Cumberland 2848 counties (Sebold, 1992). In 1885, the U.S. Department of Agriculture cited land reclamation in Cumberland 2849 County, New Jersey, as among the most impressive in the nation (Nesbit, 1885, as quoted in Sebold, 1992). 2850 By 1885, land reclamation had converted 10,000 out of 15,000 acres of the marsh in New Castle County to 2851 agricultural lands, as well as 8,000 acres in Delaware ’s other two counties (Nesbit, 1885). In Pennsylvania, 2852 most of the reclaimed land was just south of the mouth of the Schuylkill along the Delaware River, near the 2853 present location of Philadelphia International Airport. 2854 2855 During the twentieth century, these land reclamation efforts were revers ed. In many cases, lower prices for 2856 salt hay led farmers to abandon the dikes (DDFW, 2007). In some cases, where dikes remain, rising sea 2857 level has limited the ability of dikes to drain the land, and the land behind the dike has converted to marsh, 2858 such as the land along the Gibbstown Levee (See Box A1.4 in Appendix 1and Figure 11.4 c and d). Efforts 2859 are under way to restore the hydrology of many lands that were formerly diked (DDFW, 2007). In areas 2860 where dikes protect communities from flooding, howev er, public officials area also considering the 2861 possibility of upgrading the dikes and drainage systems. 2862 2863 End box*** 2864 Start box*** 2865
Box 6.2 Creation of the National Monument Area in Washington D.C. through Nineteenth Century 2866 Dredge and Fill 2867 Like many coastal cities, important parts of Washington , D.C. are on land that was previously created by 2868 filling wetlands and navigable waterways. When the city of Washington was originally planned, the 2869 Potomac River was several times as wide immediately south of Georgetown as above Georgetown (see Box 2870 Figure 6.2). L’Enfant’s plan put the President’s residence just northeast of the mouth of Tiber Creek. Thus, 2871 the White House grounds originally had a tidal shoreline. To improve navigation, canals connected Tiber 2872 Creek to the Anacostia River (Bryan, 1914). The White House and especially the Capitol were built on high 2873 ground immune from flooding, but much of the land between the two was quite low. 2874 2875 During the nineteenth century, soil eroded from upstream farming was deposited in the wide part of the 2876 river where the current slowed, which created wide mudflats below Georgetown. The success of railroads 2877 made canals less important, while the increasing population converted the canals into open sewers. During 2878 the early 1870s, Governor Boss Sh ephard had the canals filled and re placed with drain pipes. A large 2879 dredge-and-fill operation excavated Washington Channel from the mudflats, and used the material to create 2880 the shores of the Tidal Basin and the dry land on which the Lincoln Memorial, Jefferson Memorial, 2881 Reflecting Pool, East Potomac Park, and Hains Point s it today (Bryan, 1914). Similarly, about half of the 2882CCSP 4.1 January 15, 2009

285 of 784 Final Report width of the Anacostia River was filled downstream from Poplar Point, creating wh at later became the U.S. 2883 Naval Air Station (now part of Bolling Air Force Base). 2884 2885

2886 2887 Figure Box 6.2 L’Enfant’s Plan for the City of Washington 2888 Source: Library of Congress (Labels for White House, Georgetown, and Tiber Creek added). 2889 End box*** 2890 6.1.1.1 Shoreline Armoring 2891 Shoreline armoring involves the use of structures to keep th e shoreline in a fixed position 2892 or to prevent flooding when water levels ar e higher than the land. Although the term is 2893 often synonymous with “shoreline hardenin g”, some structures are comprised of 2894 relatively soft material, such as earth and sand. 2895 2896 Keeping the shoreline in a fixed position 2897 Seawalls are impermeable barriers designed to withstand the stronge st storm waves and 2898 to prevent overtopping during a storm. Du ring calm periods, their seaward side may 2899 either be landward of a beach or in the wa ter. Seawalls are often used along important 2900 transportation routes such as highw ays or railroads (Figure 6.1a). 2901CCSP 4.1 January 15, 2009

286 of 784 Final Report 2902 Figure 6.1 Seawalls and Bulkheads (a) Galveston Seawall in Texas (May 2003) and (b) Bulkheads with 2903 intervening beach along Magothy River in Anne Arundel County, Maryland (August 2005). 2904 2905 Bulkheads are vertical walls designed to prevent the land from slumping toward the water 2906 (Figure 6.1b). They must resist waves and currents to accomplish their design intent, but 2907 unlike seawalls, they are not designed to w ithstand severe storms. They are usually found 2908 along estuarine shores where waves have less energy, particularly in marinas and other 2909 places where boats are docked, and residential areas where homeowners prefer a tidy 2910 shoreline. Bulkheads hold soils in place, but they do not normally extend high enough to 2911 keep out foreseeable floods. Like seawalls, their seaward sides may be inland of a beach 2912 (or marsh) or in the water. 2913 2914 Retaining structures include several types of structur es that serve as a compromise 2915 between a seawall and a bulkhead. They are of ten placed at the rear of beaches and are 2916 unseen. Sometimes they are sheet piles driven downward into the sand; sometimes they 2917 are long, cylindrical, sand-filled “geo-tubes” (F igure 6.2). Retaining structures are often 2918 concealed as the buried core of an artificial sand dune. Like seawalls, they are intended to 2919 be a final line of defense against waves afte r a beach erodes during a storm; but they can 2920 not survive wave attack for long. 2921CCSP 4.1 January 15, 2009

287 of 784 Final Report 2922 Figure 6.2 Geotube (a) before and (b) af ter being buried by beach sand at Bolivar Peninsula, Texas (May 2923 2003). 2924 2925
Revetments are walls whose sea side follows a slop e. Like the beach they replace, their 2926 slope makes them more effective at dissipati ng the energy of storm waves than bulkheads 2927 and seawalls. As a result, revetments are less likely than bulkheads and seawalls to cause 2928 the beach immediately seaward to erode (USACE, 1995), which makes them less likely 2929 to fail during a storm (Basco, 2003; USACE, 1995). Some revetments are smooth walls, 2930 while others have a very rough appearance (Figure 6.3). 2931

2932 Figure 6.3 Two types of stone revetments (a) near Surfside, Texas and (b) at Jamestown, Virginia. 2933 2934Protecting Against Flooding or Permanent Inundation 2935CCSP 4.1 January 15, 2009

288 of 784 Final Report Dikes are high, impermeable earthen walls desi gned to keep the area behind them dry. 2936 They can be set back from the shoreline if th e area to be protected is a distance inland and 2937 usually require an interior drainage system. Land belo w mean low water requires a 2938 pumping system to remove rainwater and any water that seeps through the ground below 2939 the dike. Land whose elevation is between low and high tide can be drained at low tide, 2940 except during storms (Figure 6.4a). 2941 2942
Dunes are accumulations of windblown sand and other materials which function as a 2943 temporary barrier against wave runup a nd overwash (Figure 6.4b, see also Section 2944 6.1.1.2). 2945

2946 Figure 6.4 (a) A dike in Miami-Dade County, Florida, and (b) a newly-created dune in Surf City, New 2947 Jersey. 2948 2949 Tide gates are barriers across small creeks or dr ainage ditches. By opening during low 2950 tides and closing during high tides, they enable a low-lying area above mean low water to 2951 drain without the use of pumps (Figure 6.5). 2952CCSP 4.1 January 15, 2009

289 of 784 Final Report 2953 Figure 6.5: The tide gate at the mouth of Army Creek on the Delaware side of the Delaware River. The 2954 tide gate drains flood and rain water out of the creek to prevent flooding. The five circular mechanisms on 2955 the gate open and close to control water flow (courtesy NOAA Photo Library). 2956 2957 2958 Storm surge barriers are similar to tide gates, except that they close only during storms 2959 rather than during high tides, and they are usua lly much larger, closing off an entire river 2960 or inlet. The barrier in Providence, Rhode Island (Figure 6.6) has gates that are lowered 2961 during a storm; the Thames River Barrie r in London, by contrast, has a submerged 2962 barrier, which allows tall ships to pass. As sea level rises and storm surges become higher 2963 (see Chapter 9), these barriers must be closed more frequently. The gates in Providence, 2964 Rhode Island (Figure 6.6), for example, are currently closed an average of 19 days per 2965 year (NOAA Coastal Services Center, 2008). 2966

2967 Figure 6.6 Storm surge barriers. (a) Fox Point Hurricane Barrier, Providence, Rh ode Island (March 1966) 2968 and (b) Moses Lake Floodgate, Texas City, Texas (March 2006). 2969 2970 6.1.1.2 Elevating Land Surfaces 2971CCSP 4.1 January 15, 2009

290 of 784 Final Report A second general approach to shore protecti on is to elevate land and structures. Tidal 2972 marshes have long adapted to sea-level rise by elevating their land surfaces to keep pace 2973 with the rising sea (Chapter 4). Elevating land and structur es by the amount of sea-level 2974 rise can keep a community’s assets at the sa me elevation relative to the sea and thereby 2975 prevent them from becoming more vulnerable as sea level rises. These measures are 2976 sometimes collectively known as “soft” shore protection. 2977 2978 Beachfill, also known as beach nourishment or s and replenishment, involves the 2979 purposeful addition of the nativ e beach material (usually sand but possibly gravel) to a 2980 beach to make it higher and wider. Sand from an offshore or inland source is added to a 2981 beach to provide a buffer against wave action and flooding (USACE, 2002; Dean and 2982 Dalrymple, 2002). Placing sand onto an eroding beach can offset the erosion that would 2983 otherwise occur over a limited time; but erosion processes co ntinue, necessitating 2984 periodic re-nourishment. 2985 2986
Dunes are often part of a beach nourishm ent program. Although they also occur 2987 naturally, engineered dunes are designed to intercept wind- transported sand and keep it 2988 from being blown inland and off the beach. Planting dune grass and installing sand 2989 fencing increases the effectiv eness and stability of dunes. 2990 2991Elevating land and structures is the equivalent of a b eachfill operation in the area 2992 landward of the beach. In most cases, existing structures are temporarily elevated with 2993 hydraulic jacks and a new masonry wall is buil t up to the desired el evation, after which 2994CCSP 4.1 January 15, 2009

291 of 784 Final Report the house is lowered onto the wall (See Figure 12 .5). In some cases the house is moved to 2995 the side, pilings are drilled, and the house is moved onto the pilings. Finally, sand, soil, or 2996 gravel are brought to the prope rty to elevate the land surface . After a severe hurricane in 2997 1900, most of Galveston, Texas was elevated by more than one meter (NRC, 1987). This 2998 form of shore protection can be implemented by individual property ow ners as needed, or 2999 as part of a comprehensive program. Seve ral federal and state programs exist for 3000 elevating homes, which has become commonplace in some coastal areas, especially after 3001 a major flood (see also Chapters 9 and 10). 3002
3003 Dredge and fill was a very common approach until th e 1970s, but it is rarely used today 3004 because of the resulting loss of tidal wetla nds. Channels were dredged through the marsh, 3005 and the dredge material was used to elevat e the remaining marsh to create dry land ( e.g. , 3006 Nordstrom, 1994). The overall effect was th at tidal wetlands were converted to a 3007 combination of dry land suitable for home construction and navigable waterways to 3008 provide boat access to the new homes. The lega cy of previous dredge-and-fill projects 3009 includes a large number of very low-lying co mmunities along estuaries, including the bay 3010 sides of many developed barrier islands. Recently, some wetland restoration projects 3011 have used a similar approach to create wetlands, by using material from dredged 3012 navigation channels to elevate shallow water up to an elevation that sustains wetlands. 3013 (USFWS, 2008; see Section 11.2.2 in Chapter 11). 3014 3015 6.1.1.3 Hybrid Approaches to Shore Protection 3016CCSP 4.1 January 15, 2009

292 of 784 Final Report Several techniques are hybrids of shoreline armoring and the softer approaches to shore 3017 protection. Often, the goal of these approaches is to retain some of the storm-resistance of 3018 a hard structure, while also maintaining so me of the features of natural shorelines. Groins 3019 are hard structures perpendicu lar to the shore extending from the beach into the water, 3020 usually made of large rocks, wood, or concre te (see Figure 6.7b.). Their primary effect is 3021 to diminish forces that transport sand along th e shore. Their protectiv e effect is often at 3022 the expense of increased erosion farther down along the shore; so they are most useful 3023 where an area requiring protec tion is updrift from an area wh ere shore erosion is more 3024 acceptable. Jetties are similar structures intended to guard a harbor entrance, but they 3025 often act as a groin, causing large erosion on one side of the inlet and accretion on the 3026 other side. 3027
3028 Breakwaters are hard structures placed offshore, generally parallel to the shore (see 3029 Figure 6.7a). They can mitigate shore erosion by preventing large waves from striking the 3030 shore. Like groins, breakwat ers often slow the transport of sand along the shore, and 3031 thereby increase erosion of shores adjacent to the area protected by the breakwaters. 3032
3033 Dynamic revetments (also known as cobble beaches ) are a hybrid of beach nourishment 3034 and hard structures, in which an eroding mud or sand beach in an area with a light wave 3035 climate is converted to a cobble or pebble beach (see Figure 6.7d). The cobbles are heavy 3036 enough to resist erosion, yet small enough to create a type of beach environment 3037 (USACE, 1998; Komar, 2007; Allan et al ., 2005). 3038 3039CCSP 4.1 January 15, 2009

293 of 784 Final Report Recently, several state agencies, scientists , environmental organizations, and property 3040 owners have become interested in measures designed to reduce er osion along estuarine 3041 shores, while preserving more habitat than bulkheads and revetments (see Box 6.3). 3042

“ Living Shorelines ” are shoreline management options that allow for natural coastal 3043 processes to remain through the strategic placem ent of plants, stone, sand fill, and other 3044 structural and organic materials. They often rely on native plants, sometimes 3045 supplemented with groins, breakwa ters, stone sills, or biologs 10 to reduce wave energy, 3046 trap sediment, and filter runoff, while ma intaining (or increasing) beach or wetland 3047 habitat (NRC, 2007). 3048 Start box******** 3049
Box 6.3 Shore Protection Alternatives in Maryland: Living Shorelines 3050 3051 Shore erosion and methods for its control are a major concern in estuarine and marine ecosystems

. 3052 However, awareness of the negative impacts that many traditional shoreline protection methods have, 3053 including loss of wetlands and their buffering cap acities, impacts on nearshore biota, and ability to 3054 withstand storm events, ha s grown in recent years

. Non-structural approaches, or hybrid-type projects that 3055 combine a marsh fringe with groins or breakwaters, ar e being considered along all shorelines except for 3056 those with large waves (from eith er boat traffic or a long fetch)

. The initial cost for these projects is often 3057 significantly less than for bulkheads or revetments; the long-run cost can be greater or less depending on 3058 how frequently the living shoreline must be rebuilt

. 3059 3060 These projects typically combin e marsh replanting (generally Spartina patens and Spartina alterniflora ) 3061 and stabilization through sills, groins, or breakwaters

. A survey of projects on th e eastern and western sides 3062 of Chesapeake Bay (including Wye Island, Epping Forest near Annapolis, and the Jefferson Patterson Park 3063 and Museum on the Patuxent) found that the sill stru ctures or breakwaters we re most successful in 3064 attenuating wave energy and allowing the development of a stable marsh environment. 3065

10 Biologs are assemblages of woody, organic, and biodegradable material in a log-shaped form.CCSP 4.1 January 15, 2009

294 of 784 Final Report 3066 Box Figure 6.1 Depiction of Living Shoreline Treatments from the Jefferson Patterson Park and Museum, 3067 Patuxent River. 3068 3069 Sources: Content developed by David G. Burke for Je fferson Patterson Park and Museum, <www.jefpat.org>. 3070 End box*************** 3071 3072 In addition to the hybrid techniques, commun ities often use a combination of shoreline 3073 armoring and elevation. Many barrier isla nd communities apply beach nourishment on 3074 the ocean side, while armoring the bay side. Ocean shore protection projects in urban 3075 areas sometimes include both beach nourishment and a seawall to provide a final line of 3076 defense if the beach erodes during a stor m. Beach nourishment pr ojects along estuaries 3077 often include breakwaters to reduce wave eros ion (Figure 6.7a), or a terminal groin to 3078 keep the sand within the area meant to be nourished (see Figure 6.7 c). 3079
3080CCSP 4.1 January 15, 2009

295 of 784 Final Report 3081 3082

3083 3084 Figure 6.7 Hybrid approaches to shore protection. (a) Breakwaters and groins along Chesapeake Bay in 3085 Bay Ridge (near Annapolis) Maryland (July 2008). The rock structures parallel to the shore in the bay are 3086 breakwaters; the structures perpendi cular to the shore are groins; (b) wooden groins and bulkhead along the 3087 Peconic Estuary on Long Island, New York (September 2006). The beach is wider near the groin and 3088 narrower between groins; (c) a nourished beach w ith a terminal groin at North Beach (Maryland) 3089 (September 2008); (d) a dynamic revetment placed ov er the mud shore across Sw an Creek from the Fort 3090 Washington (Maryland) unit of National Capital Parks East. Logs have washed onto the shore since the 3091 project was completed (July 2008). 3092 3093 6.1.2 Retreat 3094 The primary alternative to “shore protection” is co mmonly known as retreat (or 3095 relocation )

. Shore protection generally involves coastal engineering to manage the forces 3096 of nature and environmental engineering to manage environmental consequences. By 3097 contrast, retreat often emphasizes the manageme nt of human expectations, so that people 3098 do not make investments inconsiste nt with the eventual retreat. 3099CCSP 4.1 January 15, 2009

296 of 784 Final Report 3100 A retreat can either occur as an unplanned resp onse in the aftermath of a severe storm or 3101 as a planned response to avoid the costs or other adverse e ffects of shore protection. In 3102 Great Britain, an ongoing planned retreat is known as “managed realignment” (Rupp3103 Armstrong and Nicholls, 2007; Shih and Ni cholls, 2007; UK Environment Agency, 2007; 3104 Midgley and McGlashan, 2004). An optimal retr eat generally requires a longer lead time 3105 than shore protection ( e.g. , Yohe and Neumann, 1997; Titus, 1998; IPCC CZMS, 1992) 3106 because the economic investments in buildings and infrastructure, and human investment 3107 in businesses and communities, can have usef ul lifetimes of many decades or longer. 3108 Therefore, planning, regulatory, and legal mech anisms usually play a more important role 3109 in facilitating a planne d retreat than for shore protection, which for most projects can be 3110 undertaken in a matter of months or years. So me retreat measures are designed to ensure 3111 that a retreat occurs in areas where shores would otherwise be prot ected; other measures 3112 are designed to decrease the costs of a retreat but not necessarily change the likelihood of 3113 a retreat occurring. For a comprehensive review, see Shoreline Management Technical 3114 Assistance Toolbox (NOAA, 2006). The most widely assessed and implemented 3115 measures are discussed below. 3116

3117 Relocating structures is possibly the most engineering-related activity involved in a 3118 retreat. The most ambitious relocation in the Mi d-Atlantic during the last decade has been 3119 the landward relocation of the Cape Hattera s Lighthouse (Figure 6.8a; see also Section 3120 A1.G.4.2 in Appendix 1). More commonplace are the routine “structural moving” 3121CCSP 4.1 January 15, 2009

297 of 784 Final Report activities involved in relocati ng a house back several tens of meters within a given 3122 shorefront lot, and the removal of structur es threatened by shor e erosion (Figure 6.8b). 3123

3124
Figure 6.8 Relocating structures along the Outer Banks (a) Cape Hatteras Li ghthouse after relocation at 3125 the Cape Hatteras National Seashore, Buxton, North Ca rolina (June 2002); the original location is outlined 3126 in the foreground, and.(b) a home threatened by sh ore erosion in Kitty Hawk, North Carolina (June 2002). 3127 The geotextile sand bags are used to protect the septic system. 3128 3129 Buyout programs provide funding to compensate landowners for losses from coastal 3130 hazards by purchasing vulnerable property. In e ffect, these programs transfer some of the 3131 risk of sea-level rise from the property ow ner to the public, which pays the cost (see 3132 Chapter 12). 3133

3134

Conservation easements are an interest in land that al lows the owner of the easement to 3135 prevent the owner of the land from developi ng it. Land conservation organizations have 3136 purchased non-development easements along coastal bays and Chesapeake Bay in 3137 Maryland (MALPF, 2003). In most cases, the or iginal motivation for these purchases has 3138 been the creation of a buffer zone to pr otect the intertidal ecology (MDCPB, 1999; 3139 MALPF, 2003). These vacant lands also leav e room for landward migration of wetlands 3140 and beaches (a concept also recognized in New Jersey Coastal Management Program 3141CCSP 4.1 January 15, 2009

298 of 784 Final Report 2006). Organizations can also create bu ffers specifically for the purpose of 3142 accommodating rising sea level. Blackwater Wildlife Refuge in Maryland and Gateway 3143 National Recreation Area in New York both own considerable amounts of land along the 3144 water onto which wetlands and beaches, respectively, could migrate inland. 3145

3146 Acquisition programs involve efforts by government or a conservation entity to obtain 3147 title to the land closest to the sea. Titles may be obtained by voluntary transactions, 3148 eminent domain, or dedication of flood-prone la nds as part of a permitting process. In 3149 Barnegat Light, New Jersey and Virginia B each, Virginia, for example, governments own 3150 substantial land along the shore between the Atlantic Ocean and the oceanside 3151 development. 3152

3153

Setbacks are the regulatory equivalent to conservation easements and purchase programs. 3154 The most common type of setback used to prepare for sea-level rise is the erosion-based 3155 setback , which prohibits development on land that is expected to erode within a given 3156 period of time. North Carolina requires new st ructures to be set back from the primary 3157 dune based on the current erosion rate time s 30 years for easily moveable homes, or 60 3158 years for large immoveable structures (s ee Section A1.G.4.1 in Appendix 1). Maine’s 3159 setback rule assumes a 60 centimeter (cm) ri se in sea level during the next 100 years 11,12

. 3160

3161

11 06-096 Code of Maine Rules §355.5(C), (2007). 12 06-096 Code of Maine Rules §355.5(C), (2007).CCSP 4.1 January 15, 2009

299 of 784 Final Report Flood hazard regulations sometimes prohibit development based on elevation, rather 3162 than proximity to the shore. Asid e from preventing flood damages, these elevation-based 3163 setbacks can ensure that there is room for wetlands or other intertidal habitat to migrate 3164 inland as sea level rises in areas that are vulnerable to inundation rather than wave3165 generated erosion. Two counties in Delawa re prohibit development in the 100-year 3166 floodplain along the Delaware River and Delaware Bay (Section A1.D.2.2 in Appendix 3167 1). 3168

3169 Rolling easements are regulatory mechanisms (Burka, 1974) or interests in land (Titus, 3170 1998) that prohibit shore protection and inst ead allow wetlands or beaches to migrate 3171 inland as sea level rises. Rolling easements transf er some of the risk of sea-level rise from 3172 the environment or the public to the property owner (Titus, 1998). When implemented as 3173 a regulation, they are an alte rnative to prohibiting all development in the area at risk, 3174 which may be politically infeasible, inequitable, or a violation of th e “takings clause” of 3175 the U.S. Constitution (Titus, 1998; Caldwell and Segall, 2007). When implemented as an 3176 interest in land, they are an alternative to outright purchases or conservation easements 3177 (Titus, 1998). 3178

3179 The purpose of a rolling easement is to align the property owner’s expectations with the 3180 dynamic nature of the shore (Titus, 1998). If retreat is the eventual objective, property 3181 owners can more efficiently prepare for that ev entuality if they expect it than if it takes 3182 them by surprise (Yohe et al ., 1996; Yohe and Neumann, 19 97). Preventing development 3183 in the area at risk through setbacks, conser vations easements, and land purchases can also 3184CCSP 4.1 January 15, 2009

300 of 784 Final Report be effective—but such restrictions could be costly if applied to thousands of square 3185 kilometers of valuable coastal lands (T itus, 1991). Because rolling easements allow 3186 development but preclude shore protection, th ey are most appropriate for areas where 3187 preventing development is not feasible and shore protection is uns ustainable. Conversely, 3188 rolling easements are not useful in ar eas where shore prot ection or preventing 3189 development are preferred outcomes. 3190

3191 Rolling easements were recognized by the co mmon law along portions of the Texas Gulf 3192 Coast ( Feinman v. State; Matcha v. Mattox ) and reaffirmed by the Texas Open Beaches 3193
Act 13 , with the key purpose being to preserve th e public right to tr averse the shore. 3194 Massachusetts and Rhode Island prohibit shor eline armoring along some estuarine shores 3195 so that ecosystems can migrate inland, and several states limit armoring along ocean 3196 shores (see Chapter 11). Rolling easements can also be implemented as a type of 3197 conservation easement, purchased by government agencies or conservancies from willing 3198 sellers, or dedicated as part of a planning review process (Titus, 1998); but to date, rolling 3199 easements have only been implemented by regulation. 3200

3201 Density restrictions allow some development but limit dens ities near the shore. In most 3202 cases, the primary motivation has been to reduce pollution runo ff into estuaries; but they 3203 also can facilitate a retreat by decreasing the number of structures potentially lost if 3204 shores retreat. Maryland limits developmen t to one home per 8.1 hectares (20 acres) 3205

13 TEX. NAT. RES. CODE ANN. §§ 61.001-.178 (West 1978 & Supp. 1998).CCSP 4.1 January 15, 2009

301 of 784 Final Report within 305 meters (m) (1000 feet [ft]) of th e shore in most coastal areas (see Section 3206 A1.F.2.1 in Appendix 1). In areas without public sewer systems, zoning regulations often 3207 restrict densities ( e.g ., Accomack County, 2008; U.S. EPA, 1989). 3208

3209
Size limitations also allow development but limit the intensity of the development placed 3210 at risk. Moreover, small struct ures are relocated more easily than a large structure. North 3211 Carolina limits the size of new commercial or multi-family residential buildings to 464 3212 square meters (sq m) (5000 square feet [sq ft]) in the area that woul d be subject to shore 3213 erosion during the next 60 years given the curre nt rate of shore eros ion, or within 36 m 3214 (120 ft) of the shore, wh ichever is farther inland 14

. Maine’s Sand Dune Rules prohibit 3215 structures taller than 10.7 m ( 35 ft) or with a “footprint” greater than 232 sq m (2500 sq 3216 ft) in all areas that are potentially vulnerable to a 60 cm rise in sea level 15

. 3217

3218

6.1.3 Combinations of Shore Protection and Retreat 3219 Although shore protection and retreat are fundamentally differe nt responses to sea-level 3220 rise, strategies with elements of both appr oaches are possible. In most cases, a given 3221 parcel of land at a particular time is either being protected or not —but a strategy can vary 3222 with both time and place, or hedge against un certainty about the eventual course of 3223 action. 3224

3225

14 15A NCAC 07H. 0305-0306. The required setback for single-family homes and smaller commercial structures is half as great (see Section A1.G.4 in Appendix 1 for details). 15 06-096 Code of Maine Rules §355 (5) (D). (2007).CCSP 4.1 January 15, 2009

302 of 784 Final Report Time. Sometimes a community switches from retr eat to protection. It is common to allow 3226 shores to retreat as long as onl y vacant land is lost, but to er ect shore protection structures 3227 once homes or other buildings are threaten ed. Setbacks make it more likely that an 3228 eroding shore will be allowed to retreat (Beatley et al ., 2002; NRC, 1987; NOAA, 2007); 3229 once the erosion reaches the setback line, th e economics of shore protection are similar 3230 to what they would have been without th e setback. Conversely, protection can switch to 3231 retreat. Property owners sometimes erect low-cost s hore protection ( e.g. , geotextile 3232 sandbags, shown in Figure 6.7b) that extends the lifetimes of their property, but 3233 ultimately fails in a storm. Increasing environmental implications or costs of shore 3234 protection may also motivate a switch from protection to retreat (see Section 6.5). To 3235 minimize economic and human impacts, retreat policies based on rolling easements can 3236 be designed to take effect 50 to 100 years hence, until which time protection might be 3237 allowed (Titus, 1998). 3238

3239

Place. Different responses operate on different scales. In genera l, a project to retreat or 3240 protect a given parcel will usually have e ffects on other parcels. For example, sand 3241 provided to an open stretch of ocean beach will be transported along the shore a 3242 significant distance by waves and currents; hence, beach nourishment along the ocean 3243 coast generally involves at le ast a few kilometers of shore line or an entire island. Along 3244 estuaries, however, sands are not transported as far—especial ly when the shoreline has an 3245 indentation—so estuarine shore protection can operate on a smaller scale. Shoreline 3246 armoring that protects one parcel may cause adjacent shores to erode or accrete. 3247 Nevertheless, along tidal creeks and other areas with small wave s, it is often feasible to 3248CCSP 4.1 January 15, 2009

303 of 784 Final Report protect one home with a hard structure, while allowing an adjacent vacant lot to erode. In 3249 areas with low density zoning, it may be possible to protect the land immediately 3250 surrounding a home while the rest of the lot conv erts to marsh, mudflat, or shallow water 3251 habitat. 3252

3253 Uncertainty. Some responses to sea-level rise ma y be appropriate in communities whose 3254 eventual status is unknown. Floodproofing ho mes (see Chapter 9), elevating evacuation 3255 routes, and improving drainage systems can provide cost -effective protection from 3256 flooding in the short term, whether or not a given neighborhood will eventually be 3257 protected or become subjected to tidal i nundation. A setback can reduce hazards whether 3258 or not a shore protection project wi ll eventually be implemented. 3259

3260 6.2 WHAT FACTORS INFLUENCE THE DECISION WHETHER TO PROTECT 3261 OR RETEAT? 3262 6.2.1 Site-Specific Factors 3263 Private landowners and government agencies who contemplate possible shore protection 3264 are usually motivated by either storm da mages or the loss of land (NRC, 2007). They 3265 inquire about possible shore pr otection measures, investigate the costs and consequences 3266 of one or more measures, and consider whet her undertaking the cost s of shore protection 3267 is preferable to the consequences of not doing so. For most homeowners, the costs of 3268 shore protection include the costs of bot h construction and necessary government 3269 permits; the benefits include the avoided damages or loss of land and structures. 3270 Businesses might also consider avoided di sruptions in business operations. Regulatory 3271CCSP 4.1 January 15, 2009

304 of 784 Final Report authorities that issue or deny permits for private shore protection consider possible 3272 impacts of shore protection on the environm ent, public access along ocean shores, and 3273 whether the design minimizes those impacts (NRC, 2007). Government agencies consider 3274 the same factors as private owners as well as public benefits of s hore protection, such as 3275 greater recreational opportunitie s from wider beaches, increased development made 3276 possible by the shore protection (where applicable), and public safety. 3277
3278 Accelerated sea-level rise does not change th e character of those considerations, but it 3279 would increase the magnitude of both the be nefits and the consequences (monetary and 3280 otherwise) of shore protection. In some ar eas, accelerated sea-level rise would lead 3281 communities that are unprotected today to a dopt shore protection; in other areas, the 3282 increased costs of shore protection may begin to outweigh the benefits. No published 3283 study provides a comprehensive assessment of how sea-level rise changes the costs and 3284 benefits of shore protection. However, th e available evidence suggests that the 3285 environmental and social impacts could increas e more than proportiona tely with the rate 3286 of sea-level rise (see S ection 6.3 and 6.4). A case study of Long Beach Island, New 3287 Jersey (a densely developed barrier island with no high-ri se buildings) concluded that 3288 shore protection is more cost-effective than re treat for the first 50 to 100 cm of sea-level 3289 rise (Titus, 1990). If the rise continues to accelerate, however, then eventually the costs of 3290 protection would rise more rapidly than the benefits, and a strategi c retreat would then 3291 become the more cost-effective response, a ssuming that the island could be sustained by 3292 a landward migration. An economic analysis by Yohe et al. (1996) found that higher rates 3293 of sea-level rise make s hore protection less cost-effective in marginal cases. 3294CCSP 4.1 January 15, 2009

305 of 784 Final Report 3295 6.2.2 Regional Scale Factors 3296 Potential benefits and consequences are us ually the key to unde rstanding whether a 3297 particular project will be adopted. At a br oader scale, however, land use and shoreline 3298 environment are often indicators of the like lihood of shore protect ion. Land use provides 3299 an indicator of the resources being protecte d, and the shoreline environment provides an 3300 indicator of the type of shore pr otection that would be needed. 3301
3302 Most land along the mid-Atlantic ocean coast is either developed or part of a park or 3303 conservation area. This region has approxima tely 1,100 kilometers (almost 700 miles) of 3304 shoreline along the Atlantic Ocea n. Almost half of this coastl ine consists of ocean beach 3305 resorts with dense development and high pr operty values. Federal shore protection has 3306 been authorized along most of these devel oped shores. These lands are fairly evenly 3307 spread throughout the mid-A tlantic states, except Virgin ia (see Section A1.E.2.1 in 3308 Appendix 1). However, a large part of the coast is owned by landowners who are 3309 committed to allowing natural shoreline processes to operate, such as The Nature 3310 Conservancy, National Park Service (see Se ction 11.2.1), and U.S. Fish and Wildlife 3311 Service. These shores include most of Nort h Carolina’s Outer Banks, all of Virginia’s 3312 Atlantic coast except for part of Virginia Beach and a NASA insta llation, more than two3313 thirds of the Maryland coast and New York’s Fire Island. The rest of the ocean coast in 3314 this region is lightly developed, yet shore prot ection is possible for these coasts as well 3315 due to the presence of important coastal highways. 3316
3317CCSP 4.1 January 15, 2009

306 of 784 Final Report Development is less extensive along many estu aries than along the ocean coast. The 3318 greatest concentrations of low-lying undeve loped lands along estuaries are in North 3319 Carolina, the Eastern Shore of Chesap eake Bay, and portions of Delaware Bay. 3320 Development has come more slowly to the lands along the Albemarle and Pamlico 3321 Sounds in North Carolina than to other part s of the mid-Atlantic coast (Hartgen, 2003.) 3322 Maryland law prevents development along mu ch of the Chesapeak e Bay shore (Section 3323 A1.F.2.1 in Appendix 1), and a combination of floodplain regulati ons and aggressive 3324 agricultural preservation pr ograms limit development along the Delaware Bay shore in 3325 Delaware (Section A1.D.2.2 in Appendix 1). Yet there is increasing pressure to develop 3326 land along tidal creeks, rivers, and bays (USCOP, 2004; DNREC, 2000; Titus, 1998), and 3327 barrier islands are in a continual state of re development in which seasonal cottages are 3328 replaced with larger homes and high-rises ( e.g. , Randall, 2003). 3329
3330 If threatened by rising sea le vel, these developed lands ( e.g. , urban, residential, 3331 commercial, industrial, transportation) woul d require shore protection for current land 3332 uses to continue. Along estuaries, the co sts of armoring, elevating, or nourishing 3333 shorelines are generally less than the value of the land to the landow ner, suggesting that 3334 under existing trends shore prot ection would continue in most of these areas. But there 3335 are also some land uses for which the cost and effort of shore protection may be less 3336 attractive than allowing the la nd to convert to wetland, beach , or shallow water. Those 3337 land uses might include marginal farmla nd, conservations lands, portions of some 3338 recreational parks, and even portions of back yards where lot sizes are large. Along the 3339 ocean, shore protection costs are greater—but so are land values. 3340CCSP 4.1 January 15, 2009

307 of 784 Final Report 3341 Shore protection is likely al ong much of the coastal zone , but substantial areas of 3342 undeveloped (but developable) lands remain along the mid- Atlantic estuaries, where 3343 either shore protection or wetland migrati on could reasonably be expected to occur 3344 (NRC, 2007; Yohe et al ., 1996; Titus et al ., 1991). Plans and designs for the development 3345 of those lands generally do not consider impli cations of future sea-level rise (see Chapter 3346 11). A series of studies have been undertaken that map the likelihood of shore protection 3347 along the entirety of the U.S. Atlantic Coast as a func tion of land use (Nicholls et al. , 3348 2007; Titus, 2004, 2005; Clark, 2001; Nuckols, 2001). 3349 3350 6.2.3 Mutual Reinforcement Between Coastal Development and Shore Protection 3351 Lands with substantial shore protection are more extensiv ely developed than similar 3352 lands without shore protection, both because shore protection encourages development 3353 and development encourages shore protecti on. People develop floodplains, which leads to 3354 public funding for flood control structures, whic h in turn leads to additional development 3355 in the area protected ( e.g. , Burby, 2006). Few studies have measured this effect, but 3356 possible mechanisms include: 3357

 Flood insurance rates that are lower in protected areas (see Chapter 10); 3358

 Development that may be allowed in locat ions that might otherwise be off limits; 3359

 Erosion-based setbacks that require less of a setback if shore protection slows or 3360 halts erosion (see Section 6.1); and 3361

 Fewer buildings that are destroyed by stor ms, so fewer post-disaster decisions to 3362 abandon previously developed land ( e.g. , Weiss, 2006) would be expected. 3363CCSP 4.1 January 15, 2009

308 of 784 Final Report 3364 The impact of coastal development on shore protection is more firmly established. 3365 Governments and private landowners generally implement a shore pr otection project only 3366 when the value of land and structures protected is greater than the cost of the project (see 3367 Sections 6.1 and 12.2.3). 3368 3369 6.3 WHAT ARE THE ENVIRONMENTA L CONSEQUENCES OF RETREAT 3370 AND SHORE PROTECTION? 3371 In the natural setting, sea-level rise can si gnificantly alter barrier islands and estuarine 3372 environments (Chapters 3, 4, and 5). Because a policy of retreat allo ws natural processes 3373 to work, the environmental impacts of retrea t in a developed area can be similar to the 3374 impacts of sea-level rise in the natural setting, provided th at management practices are 3375 adopted to restore lands to approximatel y their natural condition before they are 3376 inundated, eroded, or flooded. In the abse nce of management practices, possible 3377 environmental implications of retreat include: 3378

 Contamination of estuarine waters fro m flooding of hazardous waste sites (Flynn et 3379 al. , 1984) or areas where homes and bus inesses store toxic chemicals; 3380

 Increased flooding (Wilcoxen, 1986; Titus et al., 1987) or infiltration into public 3381 sewer systems (Zimmerman and Cusker, 2001); 3382

 Groundwater contamination as septic tanks a nd their drain fields become submerged; 3383

 Debris from abandoned structures; and 3384CCSP 4.1 January 15, 2009

309 of 784 Final Report  Interference with the ability of wetlands to keep pace or migrate inland due to 3385 features of the built landscape ( e.g. , elevated roadbeds, dr ainage ditches, and 3386 impermeable surfaces). 3387
3388 Shore protection generally has a greater envi ronmental impact than retreat (see Table 3389 6.1). The impacts of beach nourishment and othe r soft approaches are different than the 3390 impacts of shoreline armoring. 3391 3392 Beach nourishment affects the environment of both the beach being filled and the nearby 3393 seafloor “borrow areas” that are dredged to provide the sand. Adding large quantities of 3394 sand to a beach is potentially disruptive to tu rtles and birds that ne st on dunes and to the 3395 burrowing species that inhabit the beach (N RC, 1995), though less disruptive in the long 3396 term than replacing the beach and dunes with a hard structure. The impact on the borrow 3397 areas is a greater concern: Th e highest quality sand for nourishment is often contained in 3398 a variety of shoals which are essential ha bitat for shellfish and related organisms 3399 (USACE, 2002). For this reason, the U.S. Army Corps of Engineers has denied permits to 3400 dredge sand for beach nourishment in New England ( e.g. , NOAA Fisheries Service, 3401 2008; USACE, 2008a). As technology improves to recover smaller, thinner deposits of 3402 sand offshore, a greater area of ocean floor mu st be disrupted to provide a given volume 3403 of sand. Moreover, as sea level rises, the required volume is likely to increase, further 3404 expanding the disruption to the ocean floor. 3405
3406CCSP 4.1 January 15, 2009

310 of 784 Final Report As sea level rises, shoreline armoring even tually eliminates oc ean beaches (IPCC, 1990); 3407 estuarine beaches (Titus, 1998), wetlands (IPCC, 1990), mudflats (Galbraith et al ., 2002), 3408 and very shallow open water areas by blocki ng their landward migration. By redirecting 3409 wave energy, these structures can increase estuarine water depths and turbidity nearby, 3410 and thereby decrease intertidal habitat a nd submerged aquatic vegetation. The more 3411 environmentally sensitive “living shoreline” approaches to shore protection preserve a 3412 narrow strip of habitat along the shore (NRC, 2007); however, they do not allow large3413 scale wetland migration. To the extent that th ese approaches create or preserve beach and 3414 marsh habitat, it is at the expense of th e shallow water habitat that would otherwise 3415 develop at the same location. 3416
3417 The issue of wetland and beach migration has received considerable attention in the 3418 scientific, planning, and legal literature for the last few decades (NRC, 1987; Barth and 3419 Titus, 1984; IPCC, 1990). Wetlands and beaches provide important natural resources, 3420 wildlife habitat, and storm protection (see Ch apter 5). As sea level rises, wetlands and 3421 beaches can potentially migrate inland as new areas become subjected to waves and tidal 3422 inundation—but not if human ac tivities prevent such a migr ation. For example, early 3423 estimates ( e.g. , U.S. EPA, 1989) suggested that a 70 cm rise in sea level over the course 3424 of a century would convert 65 percent of th e existing mid-Atlantic wetlands to open 3425 water, and that this region w ould experience a 65 percent overall loss if all shores were 3426 protected so that no new wetlands could form inland. The results in Chapter 4 are broadly 3427 consistent with the 1989 study. That loss w ould only be 27 percent, however, if new 3428CCSP 4.1 January 15, 2009

311 of 784 Final Report wetlands were able to form on undeveloped lands, and 16 percent if existing developed 3429 areas converted to marsh as well. 3430
3431 Very little land has been set aside for the express purpose of ensu ring that wetlands and 3432 other tidal habitat can migrate inland as sea level rises (s ee Chapter 11 of this Product; 3433 Titus, 2000), but those who own and manage estuarine conservation lands do allow 3434 wetlands to migrate onto adjacent dry land. With a few notable exceptions 16 , the 3435 managers of most conservation lands along th e ocean and large bays allow beaches to 3436 erode as well (see Chapter 11) The potentia l for landward migration of coastal wetlands 3437 is limited by the likelihood that many shorelines will be preserved for existing land uses 3438 ( e.g. , U.S. EPA, 1989; IPCC, 1990; Nicholls et al ., 1999). Some preliminary studies ( e.g. , 3439 Titus, 2004) indicate that in the mid-Atlantic region, the land potentially available for 3440 new wetland formation would be almost twi ce as great if future shore protection is 3441 limited to lands that are al ready developed, than if both developed and legally 3442 developable lands are protected. 3443 3444

16 Exceptions include Cape May Meadows in New Jersey (protecting freshwater wetlands near the ocean), beaches along both sides of Delaware Bay (horseshoe crab habitat) and Assateague Island, Maryland (to prevent the northern part of the island from disintegrating).CCSP 4.1 January 15, 2009

312 of 784 Final Report Table 6.1 Selected Measures for Responding to Sea-Level Rise: Objective and Environmental Effects 3445 3446 Response Measure Method for Protection or Retreat Key Environmental effects Shoreline armoring that interferes with waves and currents Breakwater Reduce erosion May attract marine life; downdrift erosion Groin Reduce erosion May attract marine life; downdrift erosion Shoreline armoring used s to define a shoreline Seawall Reduce erosion, protect against flood and wave overtopping Elimination of beach; scour and deepening in front of wall; erosion exacerbated at terminus Bulkhead Reduce erosion, protect new land fill Prevents inland migration of wetlands and beaches. Wave reflection erodes bay bottom, preventing SAV. Prevents amphibious movement from water to land. Revetment Reduce erosion, protect land from storm waves, protect new land fill Prevents inland migration of wetlands and beaches. Traps horseshoe crabs and prevents amphibious movement. May create habitat for oysters and refuge for some species. Shoreline armoring used protect against floods and/ or permanent inundation Dike Prevents flooding and permanent inundation (when combined with a drainage system). Prevents wetlands from migrating inland. Thwarts ecological benefits of floods ( e.g ., annual sedimentation, higher water tables, habitat during migrations, productivity transfers) Tide gate Reduces tidal range by draining water at low tide and closing at high tide. Restricts fish movement. Reduced tidal range reduces intertidal habitat. May convert saline habitat to freshwater habitat. Storm surge barrier Eliminates storm surge flooding; could protect against all floods if operated on a tidal schedule Necessary storm surge flooding in salt marshes is eliminated. Elevating land Dune Protect inland areas from storm waves, provide a source of sand during storms to offset erosion. Can provide habitat; can set up habitat for secondary dune colonization behind it Beachfill Reverses shore er osion, and provide some protection from storm waves. Short-term loss of shallow marine habitat; could provide beach and dune habitat Elevate land and structures Avoid flooding and inundation from sea-level rise by elevating everything as much as sea rises. Deepening of estuary unless bay bottoms are elevated as well.
Retreat Setback Delay the need for shore protection by keeping development out of the most vulnerable lands. Impacts of shore protection delayed until shore erodes up to the setback line. Impacts of development also reduced. Rolling easement Prohibit shore protection structures. Impacts of shore protection structures avoided. Density or size restriction Reduce the benefits of shore protection and thereby make it less likely. Depends on whether owners of large lots decide to protect shore. Impacts of intense development reduced. 3447
3448CCSP 4.1 January 15, 2009

313 of 784 Final Report 6.4 WHAT ARE THE SOCI ETAL CONSEQUENCES OF SHORE PROTECTION 3449 AND RETREAT AS SEA LEVEL RISES? 3450 3451 6.4.1 Short-Term Consequences 3452 Shore protection generally is designed to enable existing land uses to continue. By 3453 insulating a community from erosion, storms, a nd other hazards, the social consequences 3454 of sea-level rise can be minimal, at least for the short term. In the Netherlands, shore 3455 protection helped to foster a sense of co mmunity as residents battled a common enemy 3456 (Disco, 2006). In other cases, the interests of some shor efront property owners may 3457 diverge from the interests of other resi dents (NRC, 2007). For example, many property 3458 owners in parts of Long Beach Islan d, New Jersey strongly supported beach 3459 nourishment—but some shorefront owners in areas with wide beaches and dunes have 3460 been reluctant to provide the state with the necessary easements (NJDEP, 2006; see 3461 Section A1.C.2 in Appendix 1). 3462
3463 Allowing shores to retreat can be disruptive. If coastal erosion is gra dual, one often sees a 3464 type of coastal blight in what would othe rwise be a desirable community, with exposed 3465 septic tanks and abandoned homes standing on the beach, and piles of rocks or geotextile 3466 sand bags in front of homes that remain o ccupied (Figures 6.8b and 6.9). If the loss of 3467 homes is episodic, communities can be se verely disrupted by the sudden absence of 3468 neighbors who previously contributed to the local economy and sense of community 3469 (IPCC, 1990; Perrin et al. , 2008; Birsch and Wachter, 2006). People forced to relocate 3470 after disasters are often at increased ri sk to both health problems (Yzermans et al ., 2005) 3471 and depression (Najarian et al ., 2001). 3472 3473CCSP 4.1 January 15, 2009

314 of 784 Final Report 3474 Figure 6.9 The adverse impacts of retreat on safety and aesthetic appeal of recreational beaches (a) 3475 Exposed septic tank and condemned houses at Kitty Hawk, North Carolina (June 2002); (b) Beach 3476 unavailable for recreation where homes were built to withstand shore erosion and storms, at Nags Head, 3477 North Carolina (June 2007). 3478 3479 6.4.2 Long-Term Consequences 3480 The long-term consequences of a retreat can be similar to the short-term consequences. In 3481 some areas, however, the consequences ma y become more severe over time. For 3482 example, a key roadway originally set far back from the shore may become threatened 3483 and have to be relocated. In the case of ba rrier islands, the long-term implications of 3484 retreat depend greatly on whether new land is created on the bay side to offset oceanfront 3485 erosion. If so, communities can be sustained as lost oceanfront homes are rebuilt on the 3486 bay side; if not, the entire commun ity could be eventually lost. 3487
3488 The long-term consequences of shore protecti on could be very different from the short3489 term consequences. As discussed below, shore protection costs could escalate. The 3490 history of shore protection in the United St ates suggests that so me communities would 3491 respond to the increased costs by tolerating a lower level of shore protection, which could 3492 lead eventually to dike failures (Seed et al. , 2005; Collins, 2006) and resulting unplanned 3493 retreat. In other cases, communities would not voluntarily accept a lower level of 3494CCSP 4.1 January 15, 2009

315 of 784 Final Report protection, but the reliance on state or federa l funding can lead to a lower level while 3495 awaiting funds (a common situation for comm unities awaiting beach nourishment). For 3496 communities that are able to keep up with the escalated costs, tax burdens would 3497 increase, possibly leading to divisive debates over a re consideration of the shore 3498 protection strategy. 3499
3500 6.5 HOW SUSTAINABLE ARE SHORE PROTECTION AND RETREAT? 3501 Coastal communities were designed and built without recognition of rising sea level. 3502 Thus, people in areas without shore protection will have to flood-proof structures (see 3503 Chapter 9), implement shore protection, (Sect ion 6.1.1) or plan a retreat (Section 6.1.2). 3504 Those who inhabit areas with shore protection are potentially vulnera ble as well. Are the 3505 known approaches to shore protection and retr eat sustainable, that is, can they be 3506 maintained for the foreseeable future? 3507 3508 Most shore protection structures are de signed for current sea level and may not 3509 accommodate a significant rise

. Seawalls (Kyper and Sorenson, 1985; NRC, 1987), 3510 bulkheads (Sorenson et al ., 1984

. ), dikes, (NRC, 1987), sewers (Wilcoxen, 1986) and 3511 drainage systems (Titus et al. , 1987) are designed based on the waves, water levels, and 3512 rainfall experienced in the past. If conditions exceed what the designers expect, disaster 3513 can result—especially when sea level rises above the level of the la nd surface. The failure 3514 of dikes protecting land below sea level resu lted in the deaths of approximately 1800 3515 people in the Netherlands in a 1953 storm ( Roos and Jonkman, 2006) , and more than 3516 1000 people in the New Orleans area from Hurricane Katrina in 2005 (Knabb et al. , 3517CCSP 4.1 January 15, 2009

316 of 784 Final Report 2005). A dike along the Industrial Canal in Ne w Orleans which failed during Katrina had 3518 been designed for sea level approximately 60 cm lower than today, because designers did 3519 not account for the land subsidence during the previous 50 years (Interagency 3520 Performance Evaluation Taskforce, 2006). 3521 3522 One option is to design structures for futu re conditions. Depending on the incremental 3523 cost of designing for higher sea level compared with the cost of rebuilding later, it may 3524 be economically rational to build in a safety factor today to account for future conditions, 3525 such as higher and wider shor e protection structures (see Ch apter 10). But doing so is not 3526 always practical. Costs genera lly rise more than proporti onately with higher water 3527 levels 17 . Project managers would generally be reluctant to overdesign a structure for 3528 today’s conditions (Schmeltz, 1984). Moreover, aesthetic factors such as loss of 3529 waterfront views or preservati on of historic structures ( e.g ., Charleston Battery in South 3530 Carolina; see Figure 6.10) can also make pe ople reluctant to build a dike or seawall 3531 higher than what is needed today. 3532

3533

17 Weggel et al ., (1989) estimate that costs are proportional to the height of the design water level raised to the 1.5 power.CCSP 4.1 January 15, 2009

317 of 784 Final Report Figure 6.10. Historic homes along the Charleston Batte ry. Charleston, South Carolina. (April 2004). 3534 3535

6.5.1 Is “Business as Usual” Sho re Protection Sustainable? 3536 Public officials and property owners in densely developed recreational communities 3537 along the mid-Atlantic coast generally expect governmental actions to stabilize shores. 3538 But no one has assessed the cost and availabil ity of sand required to keep the shorelines 3539 in their current locations through beach nouris hment even if require d sand is proportional 3540 to sea-level rise, which previous assessments of the cost of sea level rise have assumed 3541 ( e.g ., U.S. EPA, 1989; Leatherman, 1989; Titus et al. , 1991). The prospects of barrier 3542 island disintegration and segmentation examined in Chapter 3 would require much more 3543 sand to stabilize the shore. Maintaining the s hore may at first seem to require only the 3544 simple augmentation of sand along a visible beac h, but over a century or so other parts of 3545 the coastal environment would capture increasing amounts of sand to maintain elevation 3546 relative to the sea. In effect, beach nourishm ent would indirectly elevate those areas as 3547 well (by replacing sand from the beach that is transported to raise those areas), including 3548 the ocean floor immediately offshore, tidal deltas, and eventually back-barrier bay 3549 bottoms and the bay sides of barrier islands . Similarly, along armored shores in urban 3550 areas, land that is above sea level today would become farther and farther below sea 3551 level, increasing the costs of shore protection and setting up gr eater potential disasters in 3552 the event of a dike failure. It is not possible to forecast whether these costs will be greater 3553 than what future generations will choose to bear. But in those few cases where previous 3554 generations have bequeathed this generation with substantial communities below sea 3555 level, a painful involuntary relocation sometimes occurs after severe storms ( e.g. , New 3556 Orleans after Katrina). 3557CCSP 4.1 January 15, 2009

318 of 784 Final Report 3558 Most retreat policies are designed for current rates of sea-level rise and would not 3559 necessarily accommodate a significant accelerati on in the rate of sea-level rise. Erosion3560 based setbacks along ocean shores generally require homes to be set back from the 3561 primary dune by a distance equal to the a nnual erosion rate times a number years 3562 intended to represent the economic lifetime of the structure ( e.g. , in North Carolina, 60 3563 years times the erosion rate for large build ings [see Section A1.G.1 in Appendix 1). If 3564 sea-level rise accelerates and increases the er osion rate, then the buildings will not have 3565 been protected for the presumed economic lifet imes. Yet larger setback distances may not 3566 be practicable if they exceed the depth of bu ildable lots. Moreover, erosion-based setback 3567 policies generally do not articulate what wi ll happen once shore erosion consumes the 3568 setback. The retreat policies followed by orga nizations that manage undeveloped land for 3569 conservation purposes may account for foreseeable erosion, but not for the consequences 3570 of an accelerated erosion that cons umes the entire coastal unit. 3571 3572 6.5.2 Sustainable Shore Protection May Require Regional Coordination 3573 Regional Sediment Management is a rela tively new strategy or planning tool for 3574 managing sand as a resource (NRC, 2007). The strategy recogni zes that coastal 3575 engineering projects have regional impacts on sediment transport processes and 3576 availability. This approach includes: 3577 • Conservation and management of sediments in along the shore and immediate 3578 offshore areas, viewing sand as a resource; 3579CCSP 4.1 January 15, 2009

319 of 784 Final Report • Attempt to design with nature, understan ding sediment movement in a region and 3580 the interrelationships of projects and management actions; 3581 • Conceptual and programmatic connectio ns among all activities that involve 3582 sediment in a region ( e.g ., navigation channel maintenance, flood and storm damage 3583 reduction, ecosystem restoration and prot ection, beneficial uses of dredged 3584 material); 3585 • Connections between existing and new proj ects to use sediment more efficiently; 3586 • Improved program effectiveness through collaborative partnerships between 3587 agencies; and 3588 • Overcoming institutional barriers to efficient management (Martin, 2002). 3589 3590 The Philadelphia and New York Districts of the U.S. Army Corps of Engineers have a 3591 joint effort at regional sediment management for the Atlantic coast of New Jersey 3592 (USACE, 2008b). By understanding sediment s ources, losses, and transport; how people 3593 have altered the natural flow; and ways to work with natural dyna mics, more effective 3594 responses to rising sea level are possible. 3595 3596 One possible way to promote better regiona l sediment management would be the 3597 development of a set of “best sediment ma nagement practices”. Previously, standard 3598 practices have been identified to minimize th e runoff of harmful sediment into estuaries 3599 (NJDEP, 2004; City of Santa Cruz, 2007). A similar set of practices for managing 3600 sediments along shores could help reduce the environmental and economic costs of shore 3601 protection, without requiring each project to conduct a regional sediment management 3602 study. 3603CCSP 4.1 January 15, 2009

320 of 784 Final Report 3604 6.5.3 Either Shore Protection or a Failure to Pl an can Limit the Flexibility of Future 3605 Generations 3606 The economic feasibility of sustained shore protection as sea level rises is unknown, as is 3607 the political and social feasibility of a planne d retreat away from the shore. The absence 3608 of a comprehensive long-term shoreline plan often leaves property owners with the 3609 assumption that the existing development can and should be maintained. Property3610 specific shoreline armoring and small beach nourishment projects further reinforce the 3611 expectation that the existing shoreline will be maintained indefinitely, often seeming to 3612 justify additional investme nts by property owners in more expensive dwellings 3613 (especially if there is a through -road parallel to the shore). 3614 3615 Shore protection generally limits flexibility more than retreat. Once shore protection 3616 starts, retreat can be very difficult to enact because inve stments and expectations are 3617 based on the protection, which in turn increa ses the economic justification for continued 3618 shore protection. A policy of retreat can be mo re easily replaced with a policy of shore 3619 protection, because people do not make subs tantial investments on the assumption that 3620 the shore will retreat. This is not to say that all dikes and seawalls would be maintained 3621 and enlarged indefinitely if sea level continues to rise. Neverthele ss, the abandonment of 3622 floodprone communities rarely (if ever) occurs because of the potential vulnerability or 3623 cost of flood protection, but rather in the aftermath of a flood disaster ( e.g ., Missouri 3624 State Emergency Mana gement Agency, 1995). 3625
3626CCSP 4.1 January 15, 2009

321 of 784 Final Report CHAPTER 6 REFERENCES 3627 * Indicates non-peer reviewed literature; available upon request 3628 3629 Accomack County, 2008: Respecting the Past, Creating the Future: The Accomack 3630 County Comprehensive Plan: Revised Draft. Accomac, Virginia: Planning 3631 Department, Accomack County. [Note: The town and county are spelled 3632 differently.] 3633 Allan, J.C., R. Geitgey, and R. Hart, 2005: Dynamic Revetments for Coastal Erosion in 3634 Oregon: Final Report

. Oregon Department of Transportation, Salem. 3635 <http://www.oregon.gov/ODOT/TD/TP_RES/ docs/Reports/DynamicRevetments. 3636 pdf> 3637

Basco , D.R., 2003: Shore protection projects. In: Coastal Engineering Manual

. 3638 Engineer manual 1110-2-1100. U.S. Army Corps of Engineers, Washington, DC, 3639 Part V, chapter 3. 3640

Barth , M.C. and J.G. Titus (eds.), 1984: Greenhouse Effect and Sea Level Rise: A 3641 Challenge for this Generation . Van Nostrand Reinhold, New York, 325 pp. 3642 Beatley , T., D.J Brower, and A.K. Schwab, 2002: An Introduction to Coastal Zone 3643 Management . Island Press, Washington DC, 285 pp. 3644
Birch , E.L. and S.M. Wachter (eds.), 2006: Rebuilding Urban Places after Disaster: 3645 Lessons from Katrina . University of Pennsylvania Press, Philadephia, 375 pp. 3646 Bryan , W.B, 1914: A Hisory of the National Capita l from its Foundation Through the 3647 Period of Adoption of the Organic Act. The Macmillan Company, New York, 2 3648 volumes. 3649

Burka , P., 1974: Shoreline erosion: implications for public rights and private ownership. 3650 Coastal Zone Management Journal, 1(2) , 175-195. 3651CCSP 4.1 January 15, 2009

322 of 784 Final Report Burby , R.J., 2006: Hurricane Katrina and the paradoxes of government disaster policy: 3652 bringing about wise governmental decisions for hazardous areas . The Annals of 3653 the American Academy of Political and Social Science , 604(1) , 171-191. 3654
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* DDFW (Delaware Division of Fi sh and Wildlife), 2007: Northern Delaware Wetlands 3676 Rehabilitation Program . [website] 3677 <http://www.dnrec.state.de.us/fw/intmrmt.htm> 3678CCSP 4.1 January 15, 2009

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* DNREC (Department of Natural Resource and Environmental Control), 2000: Land 3682 Use and Population . [Delaware Department of Natural Resource and 3683 Environmental Control, Dover], 1 p. 3684 <http://www.dnrec.state.de.us/dnrec2000/Ad min/WholeBasin/InlandBays/land.pd 3685 f> 3686
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Komar , P.D., 2007: The design of stable and aest hetic beach fills: learning from nature 3711 In: Coastal Sediments '07 . Proceedings of the Sixth International Symposium on 3712 Coastal Engineering and Science of Co astal Sediment Processes, May 13–17, 3713 2007, New Orleans, LA. [Kraus, N.C. and J. D. Rosati (eds.]. American Society of 3714 Civil Engineers, Reston, VA, pp. 420-433. 3715 Kyper , T.N. and R.M. Sorensen, 1985: The impact of selected sea level rise scenarios on 3716 the beach and coastal structur es at Sea Bright, N.J. In: Coastal Zone ’85

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328 of 784 Final Report Seed, R.B., P.G. Nicholson, R.A. Dalrymple, J. Battjes, R.G. Bea, G. Boutwell, J.D. 3812 Bray, B.D. Collins, L.F. Harder, J.R. Headland, M. Inamine, R.E. Kayen, R. 3813 Kuhr, J.M. Pestana, R. Sanders, F. S ilva-Tulla, R. Storesund, S. Tanaka, J. 3814 Wartman, T.F. Wolff, L. W ooten, and T. Zimmie, 2005: Preliminary Report on 3815 the Performance of the New Orleans Levee Systems in Hurricane Katrina on 3816 August 29, 2005 . Report no. UCB/CITRIS – 05/01. Un iversity of California at 3817 Berkeley and American Society of Civil Engineers, Berkeley. 3818
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Titus , J.G., 1991: Greenhouse effect and coasta l wetland policy: how Americans could 3827 abandon an area the size of Ma ssachusetts at minimum cost. Environmental 3828 Management , 15(1) , 39-58. 3829
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Titus , J.G., 2000: Does the US government real ize that the sea is rising? How to 3833 restructure federal programs so that wetlands and beaches survive. Golden Gate 3834 University Law Review, 30(4) , 717-778. 3835

* Titus , J.G., 2004: Maps that depict the business-as-usual res ponse to sea level rise in 3836 the decentralized United States of America. Presented at: Global Forum on 3837CCSP 4.1 January 15, 2009

329 of 784 Final Report Sustainable Development , Paris, 11-12 November 2004. Organization of 3838 Economic Cooperation and Development, Paris. 3839
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Titus , J.G., R.A. Park, S.P. Leatherman, J.R. Weggel, M.S. Greene, P.W. Mansel, S. 3848 Brown, G. Gaunt, M. Treehan, and G. Y ohe. 1991: Greenhouse effect and sea 3849 level rise: the cost of holding back the sea. Coastal Management , 19(2) , 171-204. 3850 UK Environment Agency , 2007: Managed Realignment Electronic Platform. Version 3851 1.0. <http://www.intertidalmanagement.co.uk/> 3852
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USACE (U.S. Army Corps of Engineers), 2002: Coastal Engineering Manual . Engineer 3860 manual 1110-2-1100. U.S. Army Corps of Engineers, Washington, DC, (in 3861 6volumes issued between 2002 and 2006). 3862

* USACE (U.S. Army Corps of Engineers), 2008a: Corps of Engineers Public Interest 3863 Review Results in Permit Denial for Winthrop Beach . News Release April 23, 3864CCSP 4.1 January 15, 2009

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* USFWS (United States Fish and Wildlife Service), 2008: Blackwater National Wildlife 3878 Refuge: Wetland Restoration . [web site] 3879 <http://www.fws.gov/blackwa ter/restore.html> 3880 Weggel , J.R., S. Brown, J.C. Escajadillo, P. Br een, and E.L. Doheny, 1989: The cost of 3881 defending developed shorelines along shelte red waters of the United States from a 3882 two meter rise in mean sea level. In: The Potential Effects of Global Climate 3883 Change on the United States. Appendix: B, Sea Level Rise . EPA 230-05-89-052. 3884 U.S. Environmental Protection Agen cy, Washington, DC, pp. 3-1 to 3-90. 3885 <http://epa.gov/climatechange/effects/coastal/appB.html> 3886
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331 of 784 Final Report Journal , 14(3) , 173-192. 3892 Yohe, G. and J.E. Neumann, 1997: Planning for sea level rise and shore protection under 3893 climate uncertainty. Climatic Change , 37(1) , 243-270. 3894 Yohe, G., J.E. Neumann, P. Marshall, and H. Ameden, 1996: The economic cost of 3895 greenhouse induced sea level ri se in the United States. Climatic Change , 32(4) , 3896 387-410. 3897

Yzermans , C.J., G.A. Donker, J.J. Kerssens, A.J.E Dirkzwager, R.J.H. Soeteman, and 3898 P.M.H. ten Veen, 2005: Health problems of victims before and after disaster: a 3899 longitudinal study in general practice. International Journal of Epidemiology , 3900 34(4) , 820-826. 3901
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332 of 784 Final Report 

## Chapter 7. Population, Land Use, and Infrastructure 3908

3909 Lead Authors: Stephen K. Gill, NOAA; Robb Wright , NOAA; James G. Titus, U.S. 3910
EPA 3911 Contributing Authors : Robert Kafalenos, DOT; Kevin Wright, ICFI, Inc. 3912 3913 3914 KEY FINDINGS 3915

 The comprehensive high-resolution and precise analyses of the spatial 3916 distributions of population and infrastructu re vulnerable to sea-level rise in the 3917 Mid-Atlantic required for planning and re sponse do not exist at the present time. 3918 Existing studies do not have the required underlying land elevation data with the 3919 degree of confidence necessary for lo cal and regional decision-making (see 3920 Chapter 2 of this Product). 3921

 Existing generalized data can only support a range of estimates. For instance, in 3922 the Mid-Atlantic, between approximately 900,000 and 3,400,000 people (between 3923 3 and 10 percent of the total population in the mid-Atlantic coastal region) live on 3924 parcels of land or city blocks with at least some land less than 1 meter above 3925 monthly highest tides. Approximately 40 percent of this population is located 3926 along the Atlantic Ocean shoreline or sma ll adjacent inlets and coastal bays (as 3927 opposed to along the interior shorelines of the large estuaries, such as Delaware 3928 Bay and Chesapeake Bay). 3929CCSP 4.1 January 15, 2009

333 of 784 Final Report  Agriculture lands, forests, wetlands, and de veloped lands in lower elevation areas 3930 are likely to be most impacted by a 1-me ter sea-level rise for the Mid-Atlantic. 3931

 The coupling of sea-level rise with stor m surge is one of the most important 3932 considerations for assessing impacts of sea-level rise on infrastructure. Sea-level 3933 rise poses a risk to trans portation in ensuring reliable and sustained transportation 3934 services. 3935 3936 7.1 INTRODUCTION 3937 Coastal areas in the United States have competing interests of population growth 3938 (accompanied by building of the necessary supp orting infrastructure), the preservation of 3939 natural coastal wetlands and creation of buffer zones. Increasing sea level will put 3940 increasing stress on the ability to manage thes e competing interests effectively and in a 3941 sustained manner. This Chapter examines the current population, infrastructure, and 3942 socioeconomic activity that may potentia lly be affected by sea-level rise. 3943 3944 7.2 POPULATION STUDY ASSESSMENT 3945 The population assessment for the Mid-Atlantic can be put into a re gional perspective by 3946 first examining some recent national statisti cs and trends that illustrate the relative 3947 socioeconomic stress on our coasts: 3948 3949

 Using an analysis of coastal counties de fined to have a coastline bordering the 3950 ocean or associated water bodies, or thos e containing special velocity zones (V 3951 Zones) defined by the Federal Emergency Management Administration (FEMA), 3952CCSP 4.1 January 15, 2009

334 of 784 Final Report Crowell et al. (2007) estimate that 37 percent of the total U.S. population is found 3953 in 364 coastal counties, including the Gr eat Lakes. Excluding the Great Lakes 3954 counties, 30 percent of th e total U.S. population is found in 281 coastal counties. 3955

 Using an analysis with a broader defin ition of a coastal county to include those 3956 found in coastal watersheds in add ition to those bordering the ocean and 3957 associated water bodies, the National Oceanic and Atmospheric Administration 3958 (NOAA) estimates that U.S. coastal c ounties, including the Great Lakes and 3959 excluding Alaska, contain 53 percent of the nation’s population, yet account for 3960 only 17 percent of the tota l U.S. land area (Crossett et al., 2004) 3961

 Twenty-three of the 25 most densely populat ed U.S. counties ar e coastal counties. 3962 From 1980 to 2003, population density (def ined as persons per unit area) 3963 increased in coastal counties by 28 percent and was expected to increase another 4 3964 percent by 2008 (Crossett et al ., 2004). 3965

 Construction permits can be used to i ndicate economic growth and urban sprawl. 3966 More than 1,540 single family housing units are permitted for construction every 3967 day in coastal counties across the United States. From 1999 to 2003, 2.8 million 3968 building permits were issued for single family housing units (43 percent of U.S. 3969 total) and 1.0 million building permits we re issued for multi-family housing units 3970 (51 percent of the U.S. total) (Crossett et al ., 2004). 3971

 In 2000, there were approximately 2.1 million seasonal or vacation homes in 3972 coastal counties (54 percent of the U.S. total) (Crossett et al ., 2004). 3973 3974CCSP 4.1 January 15, 2009

335 of 784 Final Report Regional trends for the Mid-Atlantic can also be summarized, based on Crossett et al. 3975 (2004). This Product includes the mid-Atlantic states, defined in the Product to include 3976 the area from New York to Virginia, as part of their defined Northeast region, with North 3977 Carolina included in the Southeast region. The statistics serve to illustrate the relative 3978 vulnerability of the coastal socioeconomic infras tructure, either direct ly or indirectly, to 3979 sea-level rise. 3980

 Of the 10 largest metropolitan areas in the United States, three (New York, 3981 Washington, D.C., and Philadelphia) are lo cated in the coastal zone of the mid3982 Atlantic region. 3983

 The coastal population in the Northeast (M aine to Virginia) is expected to 3984 increase by 1.7 million people from 2003 to 2008, and this increase will occur 3985 mostly in counties near or in major metropolitan centers. Six of the counties near 3986 metropolitan areas with the largest expected population increases are in the New 3987 York City area and four are in the Washington, D.C. area. 3988

 The greatest percent population changes from 2003 to 2008 in the U.S. Northeast 3989 are expected to occur in Maryland and Virginia. Eight of the 10 coastal counties 3990 with the greatest expected percent populat ion increases are locat ed in Virginia and 3991 two are located in Maryland. 3992

 North Carolina coastal counties rank among the highest in the U.S. Southeast for 3993 expected percent population change from 2003 to 2008. For instance, Brunswick 3994 County is expected to have the greates t percent increase, at 17 percent. 3995 3996CCSP 4.1 January 15, 2009

336 of 784 Final Report Crossett et al . (2004), show the mid-Atlantic states in context with the larger Atlantic 3997 Coast region. By presenting total land area a nd coastal land area, as well as total and 3998 coastal county populatio n statistics, both in absolute num bers and in population density, 3999 the NOAA report quantifies the socioeconomic stressor of population change on the 4000 coastal region. As pointed out by Crowell et al . (2007), the coastal c ounties used in the 4001 NOAA study represent counties in a broader watershed area that include more than those 4002 counties that border the land-water interface and that detailed analyses and summary 4003 statistics for populations at di rect risk for inundation due to sea-level rise must use only 4004 that subset of coastal counties subject to potential inundation. The anal yses and statistics 4005 discussed in subsequent sections of th is Product use those subsets. Crossett et al . (2004) 4006 is used simply to illustrate the increasing stress on coastal areas in general. The mid4007 Atlantic coastal counties are among the most developed and densely populated coastal 4008 areas in the nation. It is this environment that coastal managers must plan strategies for 4009 addressing impacts of climate change , including global sea-level rise. 4010 4011 Several regionally focused reports on examini ng populations at risk to sea-level rise in 4012 the Mid-Atlantic are found in the literature. For example Gornitz et al . (2001) includes a 4013 general discussion of population densities and flood risk zones in the New York 4014 metropolitan region and examines impacts of sea-le vel rise on this area. In this report, the 4015 authors also consider that low- lying areas will be more at risk to episodic flooding from 4016 storm events because storm tide elevations for a given storm will be higher with sea-level 4017 rise than without. They suggest that the ove rall effect for any given location will be a 4018 reduction in the return period of the 100-year storm flooding event. A similar analysis 4019CCSP 4.1 January 15, 2009

337 of 784 Final Report was performed for the Hampton Ro ads, Virginia area by Kleinosky et al. (2006) that 4020 attempts to take into account in creased population scenarios by 2100. 4021
4022
Bin et al. (2007) studied the socioeconomic impacts of sea-level rise in coastal North 4023 Carolina, focusing on four repr esentative coastal counties (New Hanover, Dare, Carteret, 4024 and Bertie) that range from high-development to rural, and from marine to estuarine 4025 shoreline. Their socioeconomic analyses stud ied impacts of sea-level rise on the coastal 4026 real estate market, on coastal recreation and tourism, and th e impacts of tropical storms 4027 and hurricanes on business activity us ing a baseline year of 2004. 4028 4029 Comprehensive assessments of impacts of sea-level rise on transportation and 4030 infrastructure are found in the CCSP S ynthesis and Assessment Product (SAP) 4.7 4031 (CCSP, 2008), which focuses on the Gulf of Mexico, but provides a general overview of 4032 the scope of the impacts on transportation and infrastructure. In the Mid-Atlantic, focused 4033 assessments on the effects of sea-level rise to infrastructure in the New York City area 4034 are available in Jacob et al

. (2007). 4035
4036 Some of the recent regional population and in frastructure assessments typically use the 4037 best available information layers (described in the following section), gridded elevation 4038 data, gridded or mapped population distributi ons, and transportation infrastructure maps 4039 to qualitatively depict areas at risk and vulnerability (Gornitz et al ., 2001). The 4040 interpretation of the results from these assessments is limited by the vertical and 4041 horizontal resolution of the various data laye rs, the difference in re solution and matching 4042CCSP 4.1 January 15, 2009

338 of 784 Final Report of the fundamental digital-layer data cells, and the lack of spatia l resolution of the 4043 population density and other data layers with in the fundamental area blocks used (see 4044 Chapter 2 for further discussion). As discusse d in Chapter 2, the avai lable elevation data 4045 for the entire mid-Atlantic region do not support inundation modeling for sea-level rise 4046 scenarios of 1 meter or less. Therefore, the results reported in this Chapter should not be 4047 considered as reliable quantitative findings, and they serve only as demonstrations of the 4048 types of analyses that should be done wh en high-accuracy elev ation data become 4049 available. 4050 4051 7.3 MID-ATLANTIC POPULATION ANALYSIS 4052 In this Chapter, the methodology for addr essing population and land use utilizes a 4053 Geographic Information Systems (GIS) analys is approach, creating data layer overlays 4054 and joining of data tables to provide useful summary inform ation. GIS data are typically 4055 organized in themes as data layers. Data can then be input as separate themes and 4056 overlaid based on user requirements. Essentially, the GIS analysis is a vertical layering of 4057 the characteristics of the Earth's surface and is used to logically order and analyze data in 4058 most GIS software. Data layers can be expr essed visually as map layers with underlying 4059 tabular information of the da ta being depicted. The analys is uses data layers of 4060 information and integrates them to obtain th e desired output and estimated uncertainties 4061 in the results. The GIS layers used here are population statistics, land use information, 4062 and land elevation data. 4063
4064CCSP 4.1 January 15, 2009

339 of 784 Final Report The population and land use statistics tabulated in the regional summary tables (Tables 4065 7.1 through 7.6) use an area-adjusted system that defines regions and subregions for 4066 analysis such that they are (1) higher than the zero reference contour (Spring High Water) 4067 used in a vertical datum-adjusted elevati on model, and (2) not considered a wetland or 4068 open water, according to the state and Na tional Wetlands Inventory wetlands data 4069 compiled by the U.S. Fish and Wildlife Service (USFWS, 2007). Uncertainties are 4070 expressed in the tables in term s of low and high statistical estimates (a range of values) in 4071 each case to account for the varying quality of topographic information and the varying 4072 spatial resolution of the other data layers. Th e estimated elevation of spring high water is 4073 used as a boundary that dis tinguishes between normal inunda tion that would occur due to 4074 the normal monthly highest tides and the adde d inundation due to a 1-meter (m) rise in 4075 sea level (Titus and Cacela, 2008) . 4076
4077 Census block statistics determined for the estimated area and the percent of a block 4078 affected by sea-level rise and the estimated number of people and households affected by 4079 sea-level rise are based on two methods: (1) a uniform distribution throughout the block 4080 and (2) a best estimate based on assump tions concerning elev ation and population 4081 density. For instance, there is an uncertainty regardi ng where the population resides 4082 within the census block, and the relationship between the portion of a block’s area that is 4083 lost to sea-level rise and the portion of th e population residing in the vulnerable area is 4084 also uncertain. Analysis estimates of vulne rable population are based on the percentage 4085 of a census block that is inundated. Homes are not necessarily distributed uniformly 4086 throughout a census block. In addition, the differe nces in grid sizes between the census 4087CCSP 4.1 January 15, 2009

340 of 784 Final Report blocks and the elevation laye rs results in various blocks straddling differing elevation 4088 grids and adds to the uncertainty of the process. 4089 4090 Discussion on coastal elevations and mapping li mitations and uncertainties as applied for 4091 inundation purposes is provided in Chapter 2. Given these limitations and uncertainties, 4092 the population and land use analyses presen ted here are only demonstrations of 4093 techniques using a 1-meter (m) sea-level rise scenario. More precise quantitative 4094 estimates require high-resolution elevation da ta and population data with better horizontal 4095 resolution. 4096 4097 Figure 7.1 illustrates the three GIS data la yers used in the population and land use 4098 analysis: the elevation laye r (Titus and Wang, 2008), a cen sus layer (Geo Lytics, 2001), 4099 and a land-use layer (USGS, 2001). 4100
4101 Figures 7.2, 7.3, and 7.4 show the fundamental unde rlying layers used in this study, using 4102 Delaware Bay as an example. The GIS layers used here are: 4103

 Elevation data : The elevation data is the dr iving parameter in the population 4104 analysis. The elevation data is gridded into 30-m pixels thro ughout the region. All 4105 other input datasets are gri dded to this system from their source format (Titus and 4106 Wang, 2008). The elevations are adjusted su ch that the zero-c ontour line is set 4107 relative to the Spring High Water vertical datum, which is interpolated from point 4108 sources derived from NOAA tide sta tion data (Titus and Cacela, 2008). 4109CCSP 4.1 January 15, 2009

341 of 784 Final Report  Census data : Census 2000 dataset (GeoLytics, 2001) is used in the analysis. Block 4110 boundaries are the finest-scale data available, and are th e fundamental units of area 4111 of the census analysis. Tract, county, and state bo undaries are derived from 4112 appropriate aggregations from their defi ning blocks. The census tract boundaries are 4113 the smallest census unit that contains property and tax valu es. Tract and county 4114 boundaries also extend fully into water bodi es. For this analysis, these boundaries 4115 are cropped back to the sea- level boundary, but source census data remain intact. 4116

 Land use data : The National Land Cover Data (N LCD) (USGS, 2001) dataset is 4117 used in this analysis. It consists of a 30-m pixel cl assification from circa 2001 4118 satellite imagery and is consistently deri ved across the region. The caveat with the 4119 product is that pixels are clas sified as “wetland” and “open water” in places that are 4120 not classified as such by the wetland laye r. Wetland layers are derived from state 4121 wetlands data (Titus and Wang, 2008). Usua lly, the NLCD Wetland class turns out 4122 to be forested land and the water tends to be edge effects (or uncertainty due to lack 4123 of resolution) along the shor e or near farm ponds. This analysis folds the NLCD 4124 wetland pixels into forested land. 4125
4126 Figure 7.2 is an example of the county overl ay, and Figure 7.3 is an example of the 4127 census tract overlay. A census tract is a small, relatively permanent statistical subdivision 4128 of a county used for presenting census data . Census tract boundaries normally follow 4129 visible features such as roads and rive rs, but may follow governmental unit boundaries 4130 and other non-visible features in some instances; they ar e always contained within 4131 counties. Census tracts are designed to be relatively homogeneous units with respect to 4132CCSP 4.1 January 15, 2009

342 of 784 Final Report population characteristics, economic status , and living conditions at the time of 4133 establishment, and they average about 4,000 in habitants. The tracts may be split by any 4134 sub-county geographic entity. 4135
4136 Figure 7.4 provides an example of the cen sus block overlay. A census block is a 4137 subdivision of a census tract (or, prior to 2000, a block numbering area). A block is the 4138 smallest geographic unit for which the Cens us Bureau tabulates data. Many blocks 4139 correspond to individual city blocks bounded by streets; how ever, blocks–especially in 4140 rural areas—may include many square kilometers and due to lack of roads, may have 4141 some boundaries that are other features such as rivers and streams. The Census Bureau 4142 established blocks covering th e entire nation for the first time in 1990. Previous censuses 4143 back to 1940 had blocks established only fo r part of the United States. More than 8 4144 million blocks were identified for Census 2000 (U.S. Census Bureau, 2007). 4145
4146 The Digital Elevation Mode l (DEM) (Titus and Wang, 2008) was the base for this 4147 analysis. The areas of various land use, counties, tracts, and blocks are rasterized 4148

( converted in a vector graphics format [shapes]) into a gri dded raster image (pixels or 4149 dots) to the DEM base. This ensures a sta ndard projection (an e qual-area projection), 4150 pixel size (30 m), grid system (so pixels ove rlay exactly), and geographic extent. A GIS 4151 data layer intersection was completed for each of the geographic reporting units (land 4152 use, county, tract, and block) with elev ation ranges to produce a table of unique 4153 combinations. 4154 4155CCSP 4.1 January 15, 2009

343 of 784 Final Report 4156 Figure 7.1 The three input data layers to the GIS analysis. 4157

4158 Figure 7.2 The county overlay example for Delaware Bay with each colored area depicting a county. 4159 4160CCSP 4.1 January 15, 2009

344 of 784 Final Report 4161

4162 Figure 7.3 The census tract overlay example for Delaware Ba y with each colored area depicting a census 4163 tract. 4164 4165

4166

4167 Figure 7.4 The census block overlay example for Delaware Bay with gray lines outlining individual areas 4168 of a census block. 4169 4170CCSP 4.1 January 15, 2009

345 of 784 Final Report This Chapter examines the mid-Atlantic region and makes some inferences on the 4171 populations that may be affected by sea-le vel rise. This assessment divides the mid4172 Atlantic region into sub-regions defined by watersheds (Crossett et al ., 2004), as shown 4173 in Figure 7.5. The general populations within the various watersheds, although sometimes 4174 in more than one state, have to address common problems driven by common 4175 topographies, and natural hydrological regime s. Most of the watershed boundaries are 4176 clear, for instance the Potomac River a nd Chesapeake Bay. The watershed boundaries 4177 used do not include the upland portions of th e watershed located in upland mountains and 4178 hills; those portions are not required for the analyses of the low-lying areas. The Atlantic 4179 Ocean watershed is the most complex because it is not defined by a discrete estuarine 4180 river watershed boundary, but by exposure to the outer coast line, and it has components 4181 in several states. 4182CCSP 4.1 January 15, 2009

346 of 784 Final Report 4183 4184 Figure 7.5 The mid-Atlantic region generalized watersheds. 4185 4186 7.3.1 Example Population Analysis Results 4187 Not everyone who resides in a wa tershed lives in a low-lying ar ea that may be at risk to 4188 the effects of sea-level rise. Table 7.1 provi des a summary analysis of those populations 4189 in each watershed at potential risk for a 1-m sea-level rise. The low and high estimates in 4190 Table 7.1 provide the range of uncertainty by using the low and high DEMs (Titus and 4191 Wang, 2008; Titus and Cacela, 2008). The high elevation is equal to the best estimate 4192 plus the vertical error of the elevation data; the low elevation estimate is equal to the best 4193 estimate minus the vertical error. The high vulnerability estimate uses the low elevation 4194 estimate because if elevations are lower than expected a greater population is vulnerable. 4195 Similarly, the low vulnerability estimate uses the high end of the uncertainty range of 4196CCSP 4.1 January 15, 2009

347 of 784 Final Report elevation estimates. These DEMs are required to express the uncertainty in the numerical 4197 results because of the varying scales and reso lutions of the data in the various overlays 4198 (for instance, the census block boundaries may not line up with specific elevation 4199 contours being used and inter polation algorithms must be used to derive population 4200 statistics within certain contour intervals. As previously mentioned, this analysis is also 4201 limited by the assumption that population has uniform density within the inhabited 4202 portion of particular census block. The census data provide no information where the 4203 population resides within a particular block. 4204 4205 The uncertainty in how much of a particular census tract or block may be inundated must 4206 also be addressed by listing high and low es timates. Table 7.1 is a maximum estimate of 4207 the potential populations because it is for census blocks that could have any inundation at 4208 all and thus includes a maximum count. Simila rly, it should be noted that Table 7.3 also 4209 provides maximum estimates for the Chesapeake Bay and the Atlantic Ocean. 4210
4211 Table 7.1 Estimated mid-Atlantic low and high po pulation estimates by watershed for a 1-meter sea4212 level rise (population is based on Census [2000 ] data). The reported numb ers are subject to the 4213 caveat given at the end of Section 7.2. 4214 4215 Population count 1m Sea level Rise
Watershed Low Estimate High Estimate Long Island Sound 1,640 191,210 Peconic Bay 7,870 29,140 NHY-Raritan Bay 35,960 678,670 Delaware Bay 22,660 62,770 Delaware River 19,380 239,480 Chesapeake Bay 326,830 807,720 Potomac River 0 124,510CCSP 4.1 January 15, 2009

348 of 784 Final Report Albemarle Sound 61,140 75,830 Pamlico Sound 69,720 147,290 Atlantic Ocean 362,800 1,109,280

All Watersheds 908,020 3,465,940 4216
4217 To illustrate the nature of using the various sets of data and layers for analyses, and the 4218 uncertainty in the population distributions within a census block, a second type of 4219 analysis is useful. Because there is an uncer tainty regarding where the population resides 4220 within the census block, the re lationship between the portion of a block’s area that is lost 4221 to sea-level rise and the porti on of the population residing in the vulnerable area is also 4222 uncertain. Analysis estimates of vulnerable population are based on the percentage of a 4223 census block that is inundated. For inst ance, the total 2000 p opulation low and high 4224 estimated counts for a 1-m sea-level rise for all watersheds are 908,020 and 3,465,940 for 4225 “any inundation” of census block (see Table 7.1). However, homes are not necessarily 4226 distributed uniformly throughout a census block. If 10 percent of a block is very low, for 4227 example, that land may be part of a ravine, or below a bluff, or simply the low part of a 4228 large parcel of land. Therefore, the assumpti on of uniform density would often overstate 4229 the vulnerable population. Table 7.2 provides estimates that a ssume distributions other 4230 than uniform density regarding the percentage of a block that must be vulnerable before 4231 one assumes that homes are at risk. (This tabl e presents the results by state rather than by 4232 subregion.) If it is assumed that 90 percent of a block must be lost before homes are at 4233 risk, and that the population is uniformly dist ributed across the highe st 10 percent of the 4234 block, then between 26,000 and 959,000 people live less than one meter above the 4235 elevation spring high water (see NOAA, 2000 and Titus and Wang, 2008), allowing for 4236CCSP 4.1 January 15, 2009

349 of 784 Final Report low and high elevation estimates. The estimate d elevation of spring high water is used as 4237 a boundary that distinguishes between norma l inundation that would occur due to the 4238 normal monthly highest tides and the added inun dation due to a 1-m rise in sea level. The 4239 spread of these estimated numbers dependi ng upon the underlying assumptions listed at 4240 the end of Table 7.2 underscore the uncer tainty inherent in making population 4241 assessments based in limited elevation data. As reported in Chapte r 2, the disaggregation 4242 of population density data into a more realis tic spatial distribution would be to use a 4243 Dasymetric mapping technique (M ennis, 2003) which holds prom ise for better analysis of 4244 population, or other socioeconomic data, and to report statistical su mmaries of sea-level 4245 rise impacts within vulnerable zones. 4246
4247 The census information also allows further analysis of the population, broken down by 4248 owner and renter-occupied residences. Th is information gives a sense of the 4249 characterization of permanent home owners versus the more transient rental properties 4250 that could translate to infrastructure and lo cal economy at risk as well. The estimated 4251 number of owner- and renter-occupied housi ng units in each watershed are shown in 4252 Tables 7.3 and 7.4. Similar to the estimates in Table 7.1, these are high estimates for 4253 which any portion of a particul ar census block is inundated. 4254 Table 7.2 Low and High estimates of population liv ing on land within one meter above spring high 4255 water ( Using assumptions other than uniform population density about how much of the land must 4256 be lost before homes are lost). The reported numbers are subject to the caveat given at the end of 4257 Section 7.2. 4258 4259 Percentage of census block within 1 m above spring high water
99 1 90 2 50 3 0 4 State Low High Low High Low High Low HighCCSP 4.1 January 15, 2009

350 of 784 Final Report NY 780 421,900 780 470,900 2,610 685,500 42,320 1,126,290 NJ 12,540 302,800 15,770 352,510 41,260 498,650 177,500 834,440 DE 480 7,200 810 9,230 2,040 16,650 44,290 85,480 PA 640 7,830 640 8,940 1,530 15,090 10,360 43,450 VA 950 59,310 1,020 84,360 5,190 173,950 232,120 662,400 MD 610 4,840 1,890 8,040 4,380 17,710 46,890 137,490 DC 0 0 0 0 0 40 0 9,590 NC 1,920 14,140 5,320 25,090 17,450 60,090 283,590 345,530 Total 17,920 818,020 26,230 959,070 74,460 1,467,680 837,070 3,244,670

1 Population estimates in this column assume that no homes are vulnerable unless 99 percent of the dry land in census block is within 1 m above spring high water. 2 Population estimates in this column assume that no homes are vulnerable unless 90 percent of the dry land in census block is within 1 m above spring high water. 3 Population estimates in this column assume that no homes are vulnerable unless 50 percent of the dry land in census block is within 1 m above spring high water. 4 Assumes uniform population distribution. 4260
4261 The actual coastal population pote ntially affected by sea-leve l rise also includes hotel 4262 guests and those temporarily staying at vaca tion properties. Population census data on 4263 coastal areas are rarely able to fully re flect the population and resultant economic 4264 activity. The analysis presented in this Product does not include vacant properties used 4265 for seasonal, recreational, or occasional us e nor does it characterize the “transient” 4266 population, who make up a large portion of the people found in ar eas close to sea level in 4267 the Mid-Atlantic during at leas t part of the year. These te mporary residents include the 4268 owners of second homes. A significant portion of coastal homes are likely to be second 4269 homes occupied for part of the year by owne rs or renters who list an inland location as 4270 their permanent residence for purposes of census data. In many areas, permanent 4271CCSP 4.1 January 15, 2009

351 of 784 Final Report populations are expected to increase as reti rees occupy their seasonal homes for longer 4272 portions of the year. 4273
Table 7.3 Low and high estimates of number of owner o ccupied residences in each watershed region 4274 for a 1- meter sea-level rise scenario. The reported numbers are subject to the caveat given at the end 4275 of Section 7.2. 4276 4277 4278 Number of owner occupied residences 1- meter rise in sea level
Watershed Low Estimate High Estimate Long Island Sound 0 0 Peconic Bay 3,400 11,650 NYH-Raritan Bay 13,440 269,420 Delaware Bay 8,720 23,610 Delaware River 6,010 89,710 Chesapeake Bay 120,790 299,550 Potomac River 0 46,070 Albemarle Sound 22,760 28,720 Pamlico Sound 26,730 52,450 Atlantic Ocean 140,670 423,540 All Watersheds 342,520 1,244,720 4279 4280 Table 7.4 Low and high estimates of the number of rent er occupied housing units by watershed for a 4281 1-meter sea-level rise scenario. The reported numbers are subject to the caveat given at the end of 4282 Section 7.2. 4283 4284 4285 Number of renter occupied residences 1- meter rise in sea level Watershed Low Estimate High Estimate Long Island Sound 70 31,010 Peconic Bay 520 2,460 NYH-Raritan Bay 4,270 178,790 Delaware Bay 2,630 5,880 Delaware River 2,110 32,760 Chesapeake Bay 35,880 84,630 Potomac River 0 17,470 Albemarle Sound 5,260 6,830 Pamlico Sound 6,000 10,660 Atlantic Ocean 40,220 154,500CCSP 4.1 January 15, 2009

352 of 784 Final Report All Watersheds 96,960 524,990 4286 7.4 LAND USE 4287 The National Land Cover Database (USGS, 2001 ) is used to overlay land use onto the 4288 DEMs for a 1-m scenario of sea-level rise . Major land-use categories used for this 4289 analysis include: agriculture, barren land, de veloped land, forest, grassland, shrub-scrub, 4290 water, and wetland. An estimate of the ar ea of land categorized by land use for all 4291 watersheds for the Mid-Atlantic is listed in Table 7.5. In the land-use tables, ranges of 4292 uncertainty are provided by showing the low and high estimated size of the areas for the 4293 1-m sea-level rise scenario. The high and lo w estimates show significant differences in 4294 area and express the uncertainty in using this type of data layer integration. 4295 Table 7.5 Mid-Atlantic All Watersheds Summary by Land Use category, depicting low and high 4296 estimates of areas affected by a 1- meter sea-level rise (in hectares; 1 hectare is equal to 2.47 acres). 4297 The reported numbers are subject to the caveat given at the end of Section 7.2. 4298 4299 Area (in hectares) 1-meter rise in sea level Land Use Category Low Estimate High estimate Agriculture 43,180 141,800 Barren Land 5,040 14,750 Developed 11,970 92,950 Forest 27,050 94,280 Grassland 7,640 14,200 Shrub-scrub 3,790 7,720 Water 1,960 4,110 Wetland 34,720 66,590 4300 The developed land-use acreage dominates northeast watersheds such as Long Island 4301 Sound and New York Harbor, as we ll as the Atlantic Coast waters hed. This is in contrast 4302 to the Chesapeake Bay watershed that is dominated by agriculture and forest. 4303

4304CCSP 4.1 January 15, 2009

353 of 784 Final Report Table 7.6 Low and high area estimates by land us e category for the mid-Atlantic for a 1-meter sea4305 level rise scenario (in hectares). The reported numbers are subject to the caveat given at the end of 4306 Section 7.2. 4307 4308 Area (in hectares) For a 1-meter rise in sea level Watershed Land Use Category Low Estimate High Estimate Long Island Sound Agriculture 0 20 Barren Land 0 180 Developed 90 3,280 Forest 0 210 Grassland 0 100 Shrub-scrub 0 60 Water 0 90 Wetland 0 530 Peconic Bay Agriculture 20 360 Barren Land 20 340 Developed 100 1,580 Forest 50 760 Grassland 0 170 Shrub-scrub 0 70 Water 10 150 Wetland 70 770 NYH-Raritan Bay Agriculture 30 870 Barren Land 40 340 Developed 330 21,090 Forest 40 720 Grassland 0 10 Shrub-scrub 0 10 Water 9 230 Wetland 140 2,600 Delaware Bay Agriculture 950 9,590 Barren Land 280 1,040 Developed 210 1,760 Forest 590 4,280 Water 80 130 Wetland 900 2,420 Delaware River Agriculture 310 8,190 Barren Land 20 560 Developed 430 10,960 Forest 90 2,130 Water 20 200 Wetland 330 3,010 4309 4310CCSP 4.1 January 15, 2009

354 of 784 Final Report Table 7.6 (continued) Low and high area estimates by land use category for the mid-Atlantic for a 1- 4311 meter sea-level rise scenario (in hectares). The rep orted numbers are subject to the caveat given at 4312 the end of Section 7.2. 4313 4314 Area (in hectares) For a 1- meter rise in sea level Watershed Land Use Category Low Estimate High Estimate Chesapeake Bay Agriculture 11,180 40,460 Barren Land 2,070 4,650 Developed 2,220 13,180 Forest 9,100 38,370 Water 160 660 Wetland 5,010 14,280 Potomac River Agriculture 0 490 Barren Land 0 460 Developed 0 1,830 Forest 0 4,630 Water 0 130 Wetland 0 1,120 Albemarle Sound Agriculture 16,440 12,810 Barren Land 320 5,900 Developed 2,460 8,270 Forest 8,680 4,950 Grassland 4,790 44,720 Shrub-scrub 2,720 10 Water 750 8,440 Wetland 14,480 920 Pamlico Sound Agriculture 1,3130 3,9670 Barren Land 470 1,327 Developed 1,620 4,583 Forest 5,490 1,380 Grassland 2,010 3,570 Shrub-scrub 670 1,430 Water 210 290 Wetland 8,500 12,070 Atlantic Ocean Agriculture 1,090 8,220 Barren Land 1,800 5,410 Developed 4,470 29,210 Forest 2,980 11,540 Grassland 820 2,010 Shrub-scrub 380 1,360 Water 690 1,210 Wetland 5,260 10,870 4315 4316CCSP 4.1 January 15, 2009

355 of 784 Final Report 7.5 TRANSPORTATION INFRASTRUCTURE 4317 7.5.1 General Considerations 4318 The coupling of sea-level rise with stor m surge is one of the most important 4319 considerations for assessing im pacts of sea-level rise on in frastructure. Sea-level rise 4320 poses a risk to transportation in ensuring re liable and sustained tr ansportation services. 4321 Transportation facilities serve as the life-line to communitie s, and inundation of even the 4322 smallest component of an inte rmodal system can result in a much larger system shut4323 down. For instance, even though a port facility or a railway terminal may not be affected, 4324 the access roads to the port and railways coul d be, thus forcing the terminal to cease or 4325 curtail operation. 4326
4327 Sea-level rise will reduce the 100-year flood return periods and will lower the current 4328 minimum critical elevations of infrastructure such as airports, tunne ls, and ship terminals 4329 (Jacob et al ., 2007). Some low-lying railroads, tu nnels, ports, runways, and roads are 4330 already vulnerable to flooding and a rising s ea level will only exacerbate the situation by 4331 causing more frequent and more serious disrupti on of transportation serv ices. It will also 4332 introduce problems to infrastructure not pr eviously affected by these factors. 4333
4334 The CCSP SAP 4.7 (Kafalenos et al., 2008) discusses impacts of sea-level rise on 4335 transportation infrastructure by addressing the impacts generally on highways, transit 4336 systems, freight and passenger rail, marine fa cilities and waterways, aviation, pipelines, 4337 and implications for transportation emergency management and also specifically for the 4338CCSP 4.1 January 15, 2009

356 of 784 Final Report U.S. Gulf Coast region. Each of these transpor tation modes also apply to the mid-Atlantic 4339 region. 4340
4341 One impact of sea-level rise not generally mentioned is the decreased clearance under 4342 bridges. Even with precise timing of the st age of tide and passage under fixed bridges, 4343 sea-level rise will affect the number of low water windows available for the large vessels 4344 now being built. Bridge clearance has alre ady become an operational issue for major 4345 ports, as evidenced by the inst allation of real-time reporting air gap/bridge clearance 4346 sensors in the NOAA Physical Oceanogra phic Real-Time System (PORTS) (NOAA, 4347 2005). Clearance under bridges has become import ant because the largest vessels need to 4348 synchronize passage with the stage of tide and with high waters due to weather effects 4349 and high river flows. To provide pilots with this critical information, air gap sensors in 4350 the Mid-Atlantic have been deployed at the Verrazano Narrows Bridge at the entrance to 4351 New York Harbor, the Chesapeake Bay Bridge located in mid-Chesapeake Bay, and on 4352 bridges at both ends of the Chesapeake and Delaware Canal connecting the upper 4353 Chesapeake Bay with mid-De laware Bay (NOAA, 2008). 4354 4355 There are other potential navigation system effects as well because of sea-level rise. 4356 Estuarine navigation channels may need to be extended landward from where they 4357 terminate now to provide access to a retreating sh oreline. The corollary benefit is that less 4358 dredging will be required in deeper water because a rising water elevation will provide 4359 extra clearance. 4360
4361CCSP 4.1 January 15, 2009

357 of 784 Final Report This discussion is limited in scope to transportation infrastructure. Complete 4362 infrastructure assessments need to include other at-risk engineer ing and water control 4363 structures such as spillways, dams, levees a nd locks, with assessments of their locations 4364 and design capacities. 4365
4366 7.5.2 Recent U.S. Department of Transportation Studies 4367 The U.S. Department of Transportation (US DO T) studied the impacts of sea-level rise 4368 on transportation, as discussed in US DOT ( 2002). The study addresses the impacts of 4369 sea-level rise on navigation, av iation, railways and tunnels , and roads, and describes 4370 various options to address those impacts, such as elevating land and structures, protecting 4371 low-lying infrastructure with dikes, and applying retreat and ac commodation strategies. 4372
4373 The US DOT has recently completed an update of the first phase of a study, “The 4374 Potential Impacts of Global Sea Level Rise on Transportation Infrastructure” (US DOT, 4375 2008). The study covers the mid-Atlantic region and is being implemented in two phases: 4376 Phase 1 focuses on North Carolina, Virginia, Washington, D.C., and Maryland. Phase 2 4377 focuses on New York, New Jers ey, Pennsylvania, Delaware, South Carolina, Georgia, 4378 and the Atlantic Coast of Florida. This sec ond phase is expected to be completed by the 4379 end of 2008. This study was designed to pr oduce rough quantitative estimates of how 4380 future climate change, specifically sea-le vel rise and storm surge, might affect 4381 transportation infrastructure on a portion of the East Coast of the United States. The 4382 major purpose of the study is to aid polic y makers responsible for transportation 4383 infrastructure including roads, rails, airports , and ports in incorpor ating potential impacts 4384CCSP 4.1 January 15, 2009

358 of 784 Final Report of sea-level rise in planni ng and design of new infrastructure and in maintenance and 4385 upgrade of existing infrastructure. 4386
4387 The report considers that the risi ng sea level, combined with the possibility of an increase 4388 in the number of hurricanes and other severe weather related incidents, could cause 4389 increased inundation and more fr equent flooding of roads, railroads, and airports, and 4390 could have major consequences for port facilities and coastal shipping. 4391 4392 The GIS approach (US DOT, 2008) produces maps and statistics that demonstrate the 4393 location and quantity of transportation infrastr ucture that could be regularly inundated by 4394 sea-level rise and at risk to storm surge under a range of potential sea-level rise scenarios. 4395 The elevation data for the transportation facil ities is the estimated elevation of the land 4396 upon which the highway or rail line is built.) 4397 4398 The three basic steps involved in the US DOT analysis help identify areas expected to be 4399 regularly inundated or that are at-risk of periodic flooding due to storm surge: 4400

 Digital Elevation Models were used to ev aluate the elevation in the coastal areas 4401 and to create tidal surfaces in order to describe the current and future predicted 4402 sea water levels. 4403

 Land was identified that, without protecti on, will regularly be inundated by the 4404 ocean or is at risk of inundation due to storm surge under each sea-level rise 4405 scenario. 4406CCSP 4.1 January 15, 2009

359 of 784 Final Report  Transportation infrastructure was identifie d that, without prot ection, will regularly 4407 be inundated by the ocean or be at risk of inundation due to storm surge under the 4408 given sea-level rise scenario. 4409

4410 The US DOT study compares current conditi ons (for 2000) to estimates of future 4411 conditions resulting from increas es in sea level. The study exam ines the effects of a range 4412 of potential increases in sea le vel up to 59 centimeters (cm). The estimates of increases in 4413 sea level are based upon two sources: (1) the ra nge of averages of the Atmosphere-Ocean 4414 General Circulation Models for all 35 SRES (Special Report on Emi ssion Scenarios), as 4415 reported in Figure 11.12 18 from the IPCC Third Assessment Report and (2) the highest 4416 scenario (59 cm) that corresponds with the highest emission scenario modeled by the 4417 IPCC Fourth Assessment Report (Meehl et al. , 2007). 4418 4419 As noted above, the US DOT study was not inte nded to create a new estimate of future 4420 sea levels or to provide a detailed view of a particular area un der a given scenario; 4421 similarly, the results should not be viewed as predicting the specific timing of any 4422 changes in sea levels. The inherent value of th is study is the broad vi ew of the subject and 4423 the overall estimates identified. Due to the overview aspect of the US DOT study, and 4424 systematic and value uncertainties in the involved models, this US DOT analysis 4425 appropriately considered sea- level rise estimates from the IPCC reports as uniform sea4426 level rise estimates, rather than estimat es for a particular geographic location. The 4427 confidence stated by IPCC in the regional distribution of sea-level change is low , due to 4428

18 IPCC3, WG1, c.11, page 671. <http://www.grid a.no/climate/ipcc_tar/ wg1/pdf/TAR-11.PDF>CCSP 4.1 January 15, 2009

360 of 784 Final Report significant variations in the in cluded models; thus, it would be inappropriate to use the 4429 IPCC model series to estimate local cha nges. Local variations, whether caused by 4430 erosion, subsidence (sinking of la nd) or uplift, local steric (volumetric incr ease in water 4431 due to thermal expansion) factors or even coas tline protection, were not considered in this 4432 study 19 . Given the analysis and cautionary statem ents presented in Chapter 2 regarding 4433 using the USGS National Elevation Data (NED) with small increments of sea-level rise 4434 as used in this US DOT study, only representa tive statistical estim ations are presented 4435 here for just the largest 59-cm scenario. B ecause the 59-cm sea-level rise scenario is 4436 within the statistical uncertainty of the eleva tion data, the statistics are representative of 4437 the types of analyses that could be done if accurate elevation data were available. 4438 4439 The study first estimates the ar eas that would be regularly inundated or at risk during 4440 storm conditions, given nine pot ential scenario s of sea-level rise. It defines regularly 4441 inundated areas or base sea level as NOA A’s mean higher high water (MHHW) for 2000. 4442 The regularly inundated areas examined are th e regions of the coas t that fall between 4443 MHHW in 2000 and the adjusted MHHW levels (MHHW in 2000 plus for several 4444 scenarios up to 59 cm). For at-risk areas or areas that could be affected by storm 4445 conditions, the study uses a base level of NOAA’s highest observed water levels 4446 (HOWL) for 2000, and adjusts this upwards base d on the nine sea-level rise scenarios. 4447 The at-risk areas examined are those areas falling between the adjusted MHHW levels 4448 and the adjusted HOWL levels. 4449

19 It is recognized that protection su ch as bulkheads, seawalls or other protective measures may exist or be built that could protect specific land areas but, due to the overview nature of this study, they were not included in the analysis.CCSP 4.1 January 15, 2009

361 of 784 Final Report 4450 A sample of output tables from the US DOT study are shown in Table 7.7, which covers 4451 the state of Virginia. The numerical values for length and area in Tables 7.7 and 7.8 have 4452 been rounded down to the nearest whole number to be conservative in the estimates for 4453 lengths and areas at risk. This was done to avoid overstating the estimates as there are no 4454 estimates of uncertainty or e rror in the numbers presented. 4455 4456

Table 7.7 A representative output table for Virginia showing estimates of regularly inundated and 4457 at-risk areas and lengths under the 59 centimeter (cm) scenario, the highest level examined in the 4458 U.S. Department of Transportati on (US DOT) study. The percent a ffected represent the proportion 4459 for the entire state, not only co astal areas (From US DOT, 2008). The reported numbers are subject 4460 to the caveat given at the end of Section 7.2. 4461 4462

4463 Table 7.7 indicates there is some transportati on infrastructure at risk under the 59-cm sea 4464 level rise scenario. Less than 1 percent (7 kilometers [km] ofinterstates, 12 km of non4465 interstate principal arterials) of the Virgin ia highways examined in the US DOT study 4466 would be regularly inundated, while an addition al 1 percent (16 km of interstates, 62 km 4467 State of Virginia Statistics For a 59-cm rise in sea level Regularly Inundated At-Risk to Storm Surge Total By Length in Kilometers (km) Length (km) Percent Affected Length (km) Percent Affected Length (km) Percent Affected Interstates 7 0% 16 1% 23 1% Non-Interstate Principal Arterials 12 0% 62 1% 74 2% NHS Minor Arterials 2 0% 9 0% 11 0% National Highway System (NHS) 22 0% 64 1% 86 2% Rails 19 0% 64 1% 83 1% By Area in Hectares Area (Hectares) Percent Affected Area (Hectares) Percent Affected Area (Hectares) Percent Affected Ports 60 11% 132 24% 192 35% Airport Property 277 2% 365 3% 642 4% Airport Runways 29 2% 37 3% 66 5% Total Land Area Affected 68,632 1% 120,996 1% 189,628 2%CCSP 4.1 January 15, 2009

362 of 784 Final Report of non-interstate principal arterials) could be affected by storm conditions. It should be 4468 noted that these percentages are given as a perc entage of the total for each state, not only 4469 for coastal counties. 4470
4471 Table 7.8 provides the areas and percent of total areas affect ed of the various regularly 4472 inundated and at-risk transportation categorie s for the US DOT (2008) 59-cm sea-level 4473 rise scenario for Washington, D.C., Vi rginia, Maryland, and North Carolina. 4474 4475
Table 7.8 Summary of estimated areas and lengths for the total of regularly inundated and at risk 4476 infrastructure combined for a 59 centimeters (cm) increase in sea-level rise (based on US DOT, 4477 2008). The reported numbers ar e subject to the caveat given at the end of Section 7.2. 4478 4479 Total, Regularly Inundated and At Risk For a 59-cm increase in sea level Washington, D.C. Virginia Maryland North Carolina By Length in Kilometers(km) Length (km) % Affected Length (km) % Affected Length (km) % Affected Length (km) % Affected Interstates 1 5% 25 1% 2 0% 1 0% Non-Interstate Principal Arterials 7 4% 75 2% 21 1% 130 2% Minor Arterials 0 0% 11 0% 66 4% 209 4% National Highway System (NHS) 7 5% 87 2% 19 1% 305 4% Rails 3 5% 84 1% 44 2% 105 1% By Area in hectares Hectares % Affected Hectares % Affected Hectares % Affected Hectares % Affected Ports n/a n/a 192 35% 120 32% 88 47% Airport Property n/a n/a 642 4% 59 1% 434 3% Airport Runways n/a n/a 66 5% 1 0% 27 2% Total Land Area Affected 968 6% 189,628 2% 192,044 8% 743,029 6% 4480
4481 Based on the small percentage (1 to 5 percen t) statistics in Table 6.8, the combination of 4482 rising sea level and storm surge appears to have the potential to affect only a small 4483CCSP 4.1 January 15, 2009

363 of 784 Final Report portion of highways and roads across the regi on. However, because these transportation 4484 systems are basically networks, just a sma ll disruption in one portion could often be 4485 sufficient to have far-reaching effects, anal ogous to when a storm causes local closure of 4486 a major airport, producing ripple effects na tion-wide due to scheduling and flight 4487 connections and delays. Local flooding could have similar ri pple effects in a specific 4488 transportation sector. 4489 4490 North Carolina appears slightly more vulnera ble to regular inundation due to sea-level 4491 rise, both in absolute terms a nd as a percentage of the state highways: less than 1 percent 4492 of interstates (0.3 km), 1 pe rcent of non-interstate principal arterials (59 km) and 2 4493 percent of National Highway Sy stem (NHS) minor arterials (9 3 km) in the state would be 4494 regularly inundated given a sea- level rise of 59 cm. This US DOT study focuses on larger 4495 roads but there are many miles of local roads an d collectors that could also be affected. In 4496 general, areas at risk to storm surge ar e limited. Washington, D.C. shows the greatest 4497 vulnerability on a percentage basis for both interstates and NHS roads for all sea-level 4498 rise scenarios examined. 4499 4500 Please refer to the US DOT study for complete results, at: 4501 <http://climate.dot.gov/ publications/potential_impacts_of _global_sea_level_rise/index.ht 4502 ml> 4503
4504 4505CCSP 4.1 January 15, 2009

364 of 784 Final Report CHAPTER 7 REFERENCES 4506 Bin , P., C. Dumas, B. Poulter, and J. Whitehead, 2007: Measuring the Impacts of Climate 4507 Change on North Carolina Coastal Resources. Department of Economics, 4508 Appalachian State University, Boone, NC, 91 pp. 4509 <http://econ.appstate.edu/climate/ > 4510
CCSP (Climate Change Science Program), 2008: Impacts of Climate Change and 4511 Variability on Transportation Systems and Infrastructure: Gulf Coast Study, 4512 Phase I. [Savonis, M.J., V.R. Burkett and J.R. Potter (eds.)]. Climate Change 4513 Science Program Synthesis and Assessment Product 4.7. U.S. Department of 4514 Transportation, Washington DC, 445 pp. 4515
Crossett , K.M., T.J. Culliton, P.C. Wiley, and T.R. Goodspeed, 2004: Population Trends 4516 along the Coastal United States 1980-2008 . NOAA National Ocean Service, 4517 Special Projects Office, [Silver Spring, MD], 47 pp. 4518 Crowell, M., S. Edelman, K. Coulton, and S. McAfee, 2007: How many people live in 4519 coastal areas? Journal of Coastal Research , 23(5) , iii-vi. 4520 GeoLytics , 2001: CensusCD 2000. Version 1.1. GeoLytics, Inc., East Brunswick, NJ. 4521
Gornitz , V., S. Couch, and E.K. Hartig, 2001: Imp acts of sea level rise in the New York 4522 City metropolitan area. Global and Planetary Change , 32(1) , 61-88. 4523

Jacob , K., V. Gornitz, and C. Rosenzweig, 2007: Vulnerability of the New York City 4524 metropolitan area to coastal hazards, including sea-level rise: Inferences for urban 4525 coastal risk management a nd adaptation policies. In: Managing Coastal 4526 Vulnerability . [McFadden, L., R.J. Nicholls, a nd E.C. Penning-Rowsell (eds.)]. 4527 Elsevier, Amsterdam and Oxford, pp. 139-156. 4528
Kafalenos , R.S., K.J. Leonard, D.M. Beagan, V.R. Burkett, B.D. Keim, A. Meyers, D.T. 4529 Hunt, R.C. Hyman, M.K. Maynard, B. Frits che, R.H. Henk, E.J. Seymour, L.E. 4530 Olson, J.R. Potter, and M.J. Savonis, 2008: What are the implications of climate 4531 change and variability for Gulf Coast transportation? In: Impacts of Climate 4532CCSP 4.1 January 15, 2009

365 of 784 Final Report Change and Variability on Transportation Systems and Infrastructure: Gulf Coast 4533 Study, Phase I. [Savonis, M.J., V.R. Burkett, and J.R. Potter (eds.)]. Climate 4534 Change Science Program Synthesis and Assessment Product 4.7. U.S. Department 4535 of Transportation, Washington DC, [104 pp.] 4536 Kleinosky , L.R., B. Yarnal, and A. Fisher, 2006 : Vulnerability of Hampton Roads, 4537 Virginia to storm-surge flooding and sea level rise. Natural Hazards, 40(1) , 43-70. 4538

Meehl , G.A., T.F. Stocker, W.D. Collins, P. Frie dlingstein, A.T. Gaye, J.M. Gregory, A. 4539 Kitoh, R. Knutti, J.M. Murphy, A. Noda , S.C.B. Raper, I.G. Watterson, A.J. 4540 Weaver, and Z.-C. Zhao, 2007: Global climate projections. In: Climate Change 4541 2007: The Physical Science Basis. Contribution of Worki ng Group I to the Fourth 4542 Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, 4543 S., D. Qin, M. Manning, Z. Chen, M. Mar quis, K.B. Averyt, M. Tignor, and H.L. 4544 Miller (eds.)]. Cambridge University Press, Cambridge, UK, and New York, pp. 4545 747-845. 4546
Mennis , J., 2003: Generating surface models of population using dasymetric mapping. 4547 Professional Geographer , 55(1) , 31-42. 4548
NOAA (National Oceanic and Atmospheric Administration), 2000: Tide and Current 4549 Glossary . NOAA National Ocean Service, Silver Spring, MD, 29 pp. 4550 <http://tidesandcurre nts.noaa.gov/publica tions/glossary2.pdf> 4551
NOAA (National Oceanic and Atmospheric Administration), 2005: Microwave Air Gap4552 Bridge Clearance Sensor Test, Evaluation, and Implementation Report . NOAA 4553 technical report NOS CO-OPS 042. NOA A National Ocean Service Ocean 4554 Systems Test and Evaluation Pr ogram, Silver Spring, MD, 111 pp. 4555
NOAA (National Oceanic and Atmospheric Administration), 2008: The Physical 4556 Oceanographic Real-Time System (PORTS). [Website] 4557 <http://tidesandcurrent s.noaa.gov/ports.html> 4558CCSP 4.1 January 15, 2009

366 of 784 Final Report Titus , J.G. and P. Cacela, 2008: Uncertainty rang es associated with EPA’s estimates of 4559 the area of land close to sea level. Section 1.3b in: Background Documents 4560 Supporting Climate Change Science Progr am Synthesis and Assessment Product 4561 4.1: Coastal Elevations and Sens itivity to Sea Level Rise [Titus, J.G. and E.M. 4562 Strange (eds.)]. EPA 430R07004. U.S. Environmental Protection Agency, 4563 Washington, DC, pp. 69-133. 4564 <http://epa.gov/climatechange/e ffects/coastal/background.html> 4565
Titus , J.G. and J. Wang, 2008: Maps of lands cl ose to sea level along the middle Atlantic 4566 coast of the United States: an elevation data set to use while waiting for LIDAR. 4567 Section 1.1 in: Background Documents Supporting Climate Change Science 4568 Program Synthesis and Assessment Pr oduct 4.1: Coastal Elevations and 4569 Sensitivity to Sea Level Rise [Titus, J.G. and E.M. Strange (eds.)]. EPA 4570 430R07004. U.S. Environmental Protection Agency, Washington, DC, pp. 2-44. 4571 U.S. Census Bureau, 2000: United States Census 2000 . [Website] U.S. Census Bureau, 4572 Washington, DC. <http://www.census.gov/main/www/cen2000.html> 4573
U.S. Census Bureau , 2007: American FactFinder Glossary . [U.S. Census Bureau, 4574 Washington, DC.] <http://factfinder.cen sus.gov/home/en/epss/glossary_a.html> 4575
US DOT (Department of Transportation), 2002 : The Potential Impacts of Climate 4576 Change on Transportation , Workshop Proceedings; J. Titus: Does Sea Level Rise 4577 matter to Transportation along the Atlantic Coast? October 1-2, 2002, Summary 4578 and Discussion Papers. 4579 <http://www.epa.gov/climatechange/effects/downloads/Transportation_Paper.pdf 4580
> 4581
US DOT , 2008: The Potential Impacts of Global Sea Level Rise on Transportation 4582 Infrastructure, Phase 1 - Final Report: th e District of Columbia, Maryland, North 4583 Carolina and Virginia . Center for Climate Change and Environmental 4584 Forecasting, U.S. Department of Transportation, Washington DC. 4585CCSP 4.1 January 15, 2009

367 of 784 Final Report USGS (U.S. Geological Survey), 2001: National Land Cover Database 2001 . U.S. 4586 Geological Survey, Sioux Falls, SD. <http://www.mrlc.gov/mrlc2k_nlcd.asp> 4587

4588CCSP 4.1 January 15, 2009

368 of 784 Final Report 

## Chapter 8. Public Access 4589

4590 Author: James G. Titus, U.S. EPA 4591 4592 4593
KEY FINDINGS 4594

 The Public Trust Doctrine provides access along the shore below mean high 4595 water, but it does not include the right to cross private property to reach the shore. 4596 Therefore, access to the shore varies greatly, de pending on the availability of 4597 roads and public paths to the shore. 4598

 Rising sea level alone does not have a si gnificant impact on either access to the 4599 shore or access along the shore; however, re sponses to sea-level rise can decrease 4600 or increase access. 4601

 Shoreline armoring generally eliminat es access along estuarine shores, by 4602 eliminating the intertidal zone along whic h the public has access. New Jersey has 4603 regulatory provisions requiring shorefront property owners in some urban areas to 4604 provide alternative access inland of new shore protection structures. Other mid4605 Atlantic states lack similar provi sions to preserve public access. 4606

 Beach nourishment has minimal impact in areas with ample access; however, it 4607 can increase access in areas where public access is restricted. Federal and state 4608 policies generally require public access to and along a shore before providing 4609 subsidized beach nourishment. In seve ral communities, property owners have 4610 assigned public access easements in return for beach nourishment. 4611CCSP 4.1 January 15, 2009

369 of 784 Final Report Responses based on allowing shores to retrea t generally have minimal impact on public 4612 access to and along the shore. 4613
4614 8.1 INTRODUCTION 4615 Rising sea level does not inherently increase or decrease public access to the shore, but 4616 the response to sea-level ri se can. Beach nourishment tends to increase public access 4617 along the shore because federal (and some state) laws preclude beach nourishment 4618 funding unless the public has access to the b each that is being restored. Shoreline 4619 armoring, by contrast, can decrease public acces s along the shore, because the intertidal 4620 zone along which the public has access is eliminated. 4621
4622 This Chapter examines the impacts of sea- level rise on public access to the shore and 4623 describes existing public access to the shore (S ection 8.2), the likely impacts of shoreline 4624 changes (Section 8.3), and how responses to sea-level rise might change public access 4625 (Section 8.4) The focus of this Chapter is on the public’s legal right to access the shore, 4626 not on the transportation and other infras tructure that faci litates such access 20

. 4627
4628 8.2 EXISTING PUBLIC ACCESS AND THE PUBLIC TRUST DOCTRINE 4629 The right to access tidal waters and shores is well established. Both access to and 4630 ownership of tidal wetlands and beaches is defined by the “Public Trust Doctrine”, which 4631 is part of the common law of all the mid-Atla ntic states. According to the Public Trust 4632

20 Chapter 7 discusses impacts on transportation infrastructure.CCSP 4.1 January 15, 2009

370 of 784 Final Report Doctrine, navigable waters and the underlying lands were publicly owned at the time of 4633 statehood and remain so today. 4634 4635 The Public Trust Doctrine is so well es tablished that it often overrides specific 4636 governmental actions that seem to transfer ownership to private parties (Lazarus, 1986; 4637 Rose, 1986). Many courts have invalidated state actions that extinguished public 4638 ownership or access to the shore ( Illinois Central R.R. v. Illinois; Arnold v. Mundy ; see 4639 also Slade, 1990 ) . Even if a land deed states that someone’s property extends into the 4640 water, the Public Trust Doctri ne usually overrides that lang uage and the public still owns 4641 the shore 21 . In those cases when government agenci es do transfer ownership of coastal 4642 land to private owners, the public still has th e right to access along the shore for fishing, 4643 hunting, and navigation, unless the state explicitly indicates an intent to extinguish the 4644 public trust (Lazarus, 1986; Slade, 1990). 4645
4646 Figure 8.1 illustrates some key terminology us ed in this Chapter. Along sandy shores 4647 with few waves, the wet beach lies between mean high water and mean low water

. 4648 (Along shores with substantial waves, the be ach at high tide is wet inland from the mean 4649 high water mark, as waves run up the beach.) The dry beach extends from approximately 4650 mean high water inland to the seaward edge of the dune gras s or other terrestrial plant 4651 life, sometimes called the vegetation line (Slade, 1990). The dune gr ass generally extends 4652 inland from the point where a storm in the prev ious year struck with sufficient force to 4653 erode the vegetation (Pilkey, 1984), whic h is well above mean high water. Along marshy 4654

21 The “mean low water states” (i.e., Virginia, Delawa re, and Pennsylvania), are an exception. See Figure 8.2.CCSP 4.1 January 15, 2009

371 of 784 Final Report shores, mudflats are found between m ean low water and mean sea level, low marsh is 4655 found between mean sea level and mean high water, and high marsh extends from mean 4656 high water to spring high water . Collectively, the lands between mean high water and 4657 mean low water (mudflats, low marsh, and wet beaches) are commonly known as 4658 tidelands

. 4659

4660 MSL = Mean Sea level 4661 MLW = Mean Low Level 4662 MHW = Mean High Water 4663 SHW = Spring High Water 4664 Storm = Average Annual Storm Tide 4665 4666 Figure 8.1 Legal and geological tideland zonation. The area below mean high water is usually publicly 4667 owned, and in all cases is subject to public acce ss for fishing and navigation. Along the ocean, the dry 4668 beach above mean high water may be privately owned; however, in several states the public has an 4669 easement. Along the bay, the high marsh above mean high water is also privately owned, but wetland 4670 protection laws generally prohibit or discourage development. 4671 4672 The Public Trust Doctrine includes these wetlands and beaches because of the needs 4673 associated with hunting, fishi ng, transportation along the shore, and landing boats for rest 4674 or repairs (Figure 8.2). In most states, the public owns all la nd below the high water mark 4675 (Slade, 1990) which is generally construed as mean high water. The precise boundary 4676CCSP 4.1 January 15, 2009

372 of 784 Final Report varies in subtle ways from state to state. The portion of the wet beach inland of mean 4677 high water resulting from wave runup has also been part of th e public trust lands in some 4678 cases (see e.g. , State v. Ibbison and Freedman and Higgins [undated]). Thus, in general, 4679 the public trust includes mudflats, low marsh, and wet beach, while private parties own 4680 the high marsh and dry beach (Figure 8.3). Ne vertheless, Figure 8.4.shows that there are 4681 some exceptions. In Pennsylvania, Delaware, and Virginia, the publicly owned land 4682 extends only up to the low water mark (S lade, 1990). In New York, by contrast, the 4683 inland extent of the public trust varies; in some areas the public owns the dry beach as 4684 well 22 . The public has also obtained ownership to some beaches through government 4685 purchase, land dedication by a developer, or other means (see Slade 1990; Figure 8.5). 4686

4687 Figure 8.2 . Traditional purposes of the Public Trust Doct rine include fishing and transportation along the 4688 shore. (a) New Jersey side of Delaware River, belo w Delaware Memorial Bridge (March 2003). (b) Beach 4689 provided primary access to homes along the beach at Surfside, Texas (May 2003). 4690 4691

22 e.g. Dolphin Lane Assocs. v. Town of Southampton, 333 N.E.2d 358, 360 (N.Y. 1975)CCSP 4.1 January 15, 2009

373 of 784 Final Report 4692 Figure 8.3 . Privately owned dunes adjacent to publicly owned intertidal beach . Southold, New York. 4693 (September 2006). 4694 4695 4696

Below mean low water; access to wet beach for hunting, fishing, navigation Wet beach below high water Wet and dry beach Wet beach; access along dry The Public Owns:

4697 Figure 8.4 The public’s common law interest in the shores of various coastal states. Source: Titus (1998) 4698 4699
4700CCSP 4.1 January 15, 2009

374 of 784 Final Report 4701 Figure 8.5 Public beach owned by local government. Beaches that are owned by local governments 4702 sometimes have access restrictions for nonresidents . Atlantic Beach, New York (September, 2006). 4703 4704 Ownership, however, is only part of the pictur e. In Pennsylvania, Delaware, and Virginia, 4705 the Public Trust Doctrine provides an easem ent along the tidelands for hunting, fishing, 4706 and navigation. In New Jersey, the Public Trust Doctrine includes access along the dry 4707 part of the beach for recreation, as well as the traditional public trust purposes ( Matthews 4708 v. Bay Head ). Other states have gradually obtained easements for access along some dry 4709 beaches either through purchases or volunt ary assignment by the property owners in 4710 return for proposed beach nourishment. The federal policy precludes funding for beach 4711 nourishment unless the public has access (USACE, 1996). Some state laws specify that 4712 any land created with beach nourishment belong to the state ( e.g. , M D
. C ODE A NN ., N AT

. 4713
R ES . II 8-1103 [1990]). 4714 4715 The right to access along the shore does not mean that the public has a right to cross 4716 private land to get to the shore. Unless there is a public road or path to the shore, access 4717 along the shore is thus only us eful to those who either reac h the shore from the water or 4718 have permission to cross private land. Alt hough the public has easy access to most ocean 4719 beaches and large embayments like Long Island Sound and Delaware Bay, the access 4720CCSP 4.1 January 15, 2009

375 of 784 Final Report points to the shores along most sma ll estuaries are widely dispersed ( e.g. , Titus, 1998). 4721 However, New Jersey is an exception: its Public Trust Doctrine recognizes access to the 4722 shore in some cases ( Matthews v. Bay Head ); and state regulations require new 4723 developments with more than three units along all tidal waters to in clude public access to 4724 the shore (NJAC 7:7E-8.11 [d-f]). Given the fe deral policy promoting access, the lack of 4725 access to the shore has delayed several beach nourishment projects. To secure the 4726 funding, many communities have improved public access to the shore, not only with 4727 more access ways to the beach, but also by upgr ading availability of parking, restrooms, 4728 and other amenities ( e.g. , New Jersey, 2006). 4729
4730 8.3 IMPACT OF SHORE EROSION ON PUBLIC ACCESS 4731 The rule that property lines retreat whenever shores erode gradually has been part of the 4732 common law for over one thousand years ( County of St. Clair v. Lovingston ; DNR v. 4733 Ocean City ), assuming that the shoreline change is natural. Therefore, as beaches migrate 4734 landward, the public’s access ri ghts to tidal wetlands and be aches do not change, they 4735 simply migrate landward along with the wetlan ds and beaches. Nevertheless, the area to 4736 which the public has access may increase or decr ease, if sea-level rise changes the area of 4737 wetlands or beaches. 4738 4739 When riparian landowners cau sed the shorelines to adva nce seaward, the common law 4740 did not vest owners with tit le to land reclaimed from th e sea, although legislatures 4741 sometimes have (ALR, 1941). If beach nourishment or a federal navigation jetty 4742 artificially creates new la nd, a majority of states ( e.g. , M D
. C ODE A NN ., E NVIR
. 16-201) 4743CCSP 4.1 January 15, 2009

376 of 784 Final Report award the new land to the ripari an owner if he or she is not responsible for creating the 4744 land (Slade, 1990); a minority of states ( e.g. , Garrett v. State of New Jersey; N.C. Gen 4745 Stat §146-6[f]) vest the state public tr ust with the new la nd. Although these two 4746 approaches were established be fore sea-level rise was wide ly recognized, legal scholars 4747 have evaluated the existing rules in th e analogous context of shore erosion ( e.g. , Slade, 4748 1990). Awarding artificially created land to the riparian owner has two practical 4749 advantages over awarding it to the state. Firs t, determining what portion of a shoreline 4750 change resulted from some artificial causes, ( e.g. , sedimentation from a jetty or a river 4751 diversion) is much more difficult than determining how much the shoreline changed 4752 when the owner filled some wetlands. Second, this approach prevents the state from 4753 depriving shorefront owners of their ripa rian access by pumping sand onto the beach and 4754 creating new land ( e.g ., Board of Public Works v. Larmar Corp ). A key disadvantage is 4755 that federal and state laws ge nerally prevent the use of publ ic funds to create land that 4756 accrues to private parties. Therefore, part of the administrative requirements of a beach 4757 nourishment project is to obtain easements or title to the newly created land. Obtaining 4758 those rights can take time, and significan tly delayed a beach nourishment project at 4759 Ocean City, Maryland (Titus, 1998). 4760
4761 Sea-level rise causes shores to retreat bot h through inundation and erosion. Although the 4762 case law generally assumes that the shore is moving as a result of sediment being 4763 transported, inundation and shore erosion are legally indistin guishable. Among the causes 4764 of natural shoreline change, the major legal distinction ha s been between gradual and 4765 imperceptible shifts, and sudden shifts that leave land intact but on the other side of a 4766CCSP 4.1 January 15, 2009

377 of 784 Final Report body of water, often known as “avulsion”. Shor eline erosion changes ownership; avulsion 4767 does not. If an inlet formed 200 meters (m) west of one’s home during a storm after 4768 which an existing inlet 200 m east of the home closed, an owner would still own her 4769 home because this shoreline change is c onsidered to be avulsion. But if the inlet 4770 gradually migrated 400 m west, entirely erodi ng the property but late r creating land in the 4771 same location, all of the newl y created land will belong to the owner to the east (see 4772 Figure 8.6). The public trust has the same rights of access to beaches created through 4773 avulsion as to beaches migrating by gradual erosion in New York ( People v. Steeplechase 4774 Park Co. ) and North Carolina (Kalo, 2005). In othe r states, the law is less clear (Slade, 4775 1990). 4776
4777CCSP 4.1 January 15, 2009

378 of 784 Final Report 4778 Figure 8.6 Impact of inlet migration and inlet breech on land ownership. In this example, the island to the 4779 west is privately owned while the island to the east is a county park. 4780 4781 Because the public has acce ss to the intertidal zone as long as it exists, the direct effect of 4782 sea-level rise on public access depends on how the intertidal zone changes. Along an 4783 undeveloped or lightly developed ocean beach, public access is essentially unchanged as 4784 the beach migrates inland (except perhaps wh ere a beach is in front of a rocky cliff, 4785 which is rare in the Mid-Atlantic). If privately owned high marsh becomes low marsh, 4786 then the public will have additional lands on which they may be allowed to walk 4787 private

p rivate

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p rivatel y p rivate

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count y count y

count y count y count y Initial Condition

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20 years later

30 years later

After storm creates new inlet Initial Condition Gradual inlet migration

p rivatel p rivatel count y

count y p rivate p rivatel After old inlet closes Inlet breech followed by inlet closingCCSP 4.1 January 15, 2009

379 of 784 Final Report (provided that environmenta l regulations to protect th e marsh do not prohibit it). 4788 Conversely, if sea-level rise reduces the area of low marsh, then pedestrian access may be 4789 less, although areas that convert to open water rema in in the public trust. 4790 4791 8.4 IMPACT OF RESPONSES TO SEA- LEVEL RISE ON PUBLIC ACCESS 4792 Although sea-level rise appears to have a small direct effect on public access to the shore, 4793 responses to sea-level rise can have a significant impact, es pecially in developed areas. 4794 Along developed bay beaches, by contrast, public access along the shore can be 4795 eliminated if the shorefront property owne r erects a bulkhead, because the beach is 4796 eventually eliminated. A number of options are available fo r state governments that wish 4797 to preserve public access along armored s hores, such as public purchases of the 4798 shorefront (Figure 8.7) and protecting public access in pe rmits for shore protection 4799 structures. New Jersey requires pathways to be at least 5 m (16 feet [ft]) wide between 4800 the shore and new developments with more than three units along urban tidal rivers 4801 (NJAC 7.7E-8.11[e]; see also Section A1.D.2 in Appendix 1) and some other areas, and 4802 has a more general requirement to preserve public access elsewhere. (NJAC 7.7E-8.11 [d] 4803 [1]). However, single-family homes are ge nerally exempt (NJAC 7.7E-8.11[f] [7])—and 4804 other mid-Atlantic states have no such require ments. Therefore, sea-level rise has reduced 4805 public access along many estuarine shores and is likely to do so in the future as well. 4806
4807CCSP 4.1 January 15, 2009

380 of 784 Final Report 4808 Figure 8.7 Public access along a bulkheaded shore. In North Beach, Maryland, one block of Atlantic 4809 Avenue is a walkway along Chesapeake Bay (May,2006). 4810 4811 Government policies related to beach nourishm ent, by contrast, set a minimum standard 4812 for public access (USACE, 1996), which often increases public access along the shore. 4813 Along the ocean shore from New York to North Carolina, the public does not have access 4814 along the dry beach under the Public Trust Doctrine (except in New Jersey) 23 . However, 4815 once a federal beach nourishment project takes place, the public gains access. Beach 4816 nourishment projects have increased public access along the shore in Ocean City, 4817 Maryland and Sandbridge (Virginia Beach), Virginia, where property owners had to 4818 provide easements to the newly created beach before the projects began (Titus, 1998; 4819 Virginia Marine Res ources Commission, 1988). 4820
4821 Areas where public access to the beach is currently limited by a small number of access 4822 points include the area along the Outer Banks from Southern Shores to Corolla, North 4823 Carolina (NC DENR, 2008); northern Long Beach Township, New Jersey (USACE, 4824

23 In some places, the public has obtained access through government purchase , land dedication by a developer, or other means. See Slade (1990).CCSP 4.1 January 15, 2009

381 of 784 Final Report 1999); and portions of East Hampton, S outh Hampton, Brookhaven, and Islip along the 4825 South Shore of Long Island, New York (Section A1.A.2 in Appendix 1). In West 4826 Hampton, landowners had to provide six easem ents for perpendicular access from the 4827 street to the beach in order to meet the New York state requirement of public access 4828 every one-half mile (see Section A1.A.2 in Appendix 1). A planned $71 million beach 4829 restoration project for Long Beach Isla nd has been stalled (Urgo, 2006), pending 4830 compliance with the New Jersey state requirement of perpendicular access every one4831 quarter mile (USACE, 1999). An additional 200 parking spaces for beachgoers must also 4832 be created in Northern Long Beach Township (USACE, 1999). Private communities 4833 along Delaware Bay have granted public access to the beaches in return for state 4834 assistance for beach protecti on (Beaches 2000 Planning Group, 1988). 4835
4836 If other communities with limited access seek federal beach nourishment in the future, 4837 public access would similarly increase. Improved access to the beach for the disabled 4838 may also become a requirement for future beach nourishment activities ( e.g. , Rhode 4839 Island CRMC, 2007). This is not to say that a ll coastal communities would provide public 4840 access in return for federal funds. But aside from the portion of North Carolina southwest 4841 of Cape Lookout, the Mid-Atlantic has no pr ivately owned gated barrier islands, unlike 4842 the Southeast, where several communities have chosen to expend their own funds on 4843 beach nourishment rather than give up their exclusivity. 4844 4845 Ultimately, the impact of sea-level rise on public access will depend on the policies and 4846 preferences that prevail ove r the coming decades. Sometimes the desire to protect 4847CCSP 4.1 January 15, 2009

382 of 784 Final Report property as shores erode will come at the expense of public access. Sometimes it will 4848 promote an entire re-engineer ing of the coast, which unde r today’s policies generally 4849 favors public access. It is possible that rising s ea level is already starting to cause people 4850 to rethink the best way to protect property along estuarine shores (NRC, 2007) to protect 4851 the environmental benefits of natural shor es. If access along estuarine shores becomes a 4852 policy goal, techniques are av ailable for preserving public access as sea level rises. 4853 4854
4855CCSP 4.1 January 15, 2009

383 of 784 Final Report CHAPTER 8 REFERENCES 4856 * Indicates non-peer reviewed literature; available upon request 4857

4858 ALR, 1941: Annotation: Waters: rights in respec t of changes by accretio n or reliction due 4859 to artificial conditions. American Law Review , 134 , 467-472. 4860 Arnold v. Mundy , 6 N.J.L. 1 (1821) 4861 Beaches 2000 Planning Group , 1988: Beaches 2000: Report to the Governor 4862 [Delaware], June 21, 1988. 4863 Board of Pub. Works v. Larmar Corp ., 277 A.2d 427, 436 (Md. 1971) 4864 County of St. Clair v. Lovingston , 90 U.S. (23 Wall.) 46, 66-69 (1874) (quoting the 4865 Institutes of Justinian, Code Napoleon, and Blackstone for the universal rule that a 4866 boundary shifts w ith the shore) 4867

DNR (Department of Natural Resources) v. Ocean City, 332 A.2d 630-638 (Md. 1975) 4868

Freedman , J. and M. Higgins, Undated: What Do You Mean by High Tide? The Public 4869 Trust Doctrine in Rhode Island. Rhode Island Coastal Resources Management 4870 Council, Wakefield, 5 pp. 4871 <http://www.crmc.state.ri.us/present ations/presentations/wdymbht.pdf > 4872
Garrett v. State [of New Jersey]. 118 N.J. Super. 594 (Ch. Div. 1972), 289 A.2d 542 4873 (N.J. Super 1972). 4874
Illinois Central R.R. v. Illinois , 146 U.S. 387 (1982) 4875

Kalo , J.J., 2005: North Carolina oceanfront property and public waters and beaches: the 4876 rights of littoral owners in the twenty-first century. North Carolina Law Review , 4877 83 , 1427-1506. 4878

Lazarus , R.J., 1986: Changing conceptions of property and sovereignty in natural 4879 resources: questioning the Public Trust Doctrine. Iowa Law Review , 71 , 631. 4880CCSP 4.1 January 15, 2009

384 of 784 Final Report Matthews v. Bay Head Improvement Association, 471 A.2d 355-358 (N.J. 1984) 4881 New Jersey , 2006: Highlights of the Public Access Proposal . New Jersey Department of 4882 Environmental Protection Coas tal Management Program, 4 pp. 4883 <http://www.nj.gov/dep/cmp/access/pa_rule_highlights.pdf> 4884 NC DENR ( North Carolina Department of Environment and Natural Resources), 2008: 4885 Public Beach & Waterfront Access Interactive Mapping. 4886
< http://dcm2.enr.state.nc.us/Access/sites.htm> 4887
NRC (National Research Council), 2007: Mitigating Shore Eros ion Along Sheltered 4888 Coasts . National Academies Press, Washington DC, 188 pp. 4889 People v. Steeplechase Park Co

. , 82 Misc 247, 255-256; 143, N.Y.S. 503, 509 4890 Pilkey , O.H., Jr. (ed.), 1984: Living with the East Florida Shore . Duke University Press, 4891 Durham, NC, 259 pp. 4892
Rhode Island CRMC (Coastal Resources Management Council), 2007: Coastal 4893 Resources Management Program, as Amended (a.k.a. the “Red Book”). State of 4894 Rhode Island Coastal Resources Ma nagement Council, Providence, RI. 4895 <http://www.crmc.state.ri.us/regulations/programs/redbook.html> 4896

Rose , C., 1986: The comedy of the commons: cu stom, commerce, and inherently public 4897 property. University of Chicago Law Review , 53 , 711, 715-723. 4898
Slade , D.C., 1990: Lands, waters and living re sources subject to the Public Trust 4899 Doctrine. In: Putting the Public Trust Doctrine to Work . Coastal States 4900 Organization, Washington, DC, pp. 13, 59. 4901
State v. Ibbison . 448 A.2d 728 (Rhode Island, 1982). Titus , J.G., 1998: Rising seas, 4902 coastal erosion, and the takings clause: how to save wetlands and beaches without 4903 hurting property owners. Maryland Law Review , 57(4) , 1277-1399. 4904CCSP 4.1 January 15, 2009

385 of 784 Final Report Titus , J.G., 1998: Rising seas, coastal erosi on and the taking clause: how to save 4905 wetlands and beaches without hurting property owners. Maryland Law Review , 4906 57(4) , 1277-1399. 4907

* Urgo , J.L., 2006: A standoff over sand: A stat e beach project requires more public 4908 access, but in Loveladies and North B each, it’s meeting some resistance. 4909 Philadelphia Inquirer , June 11, 2006. 4910
USACE (U.S. Army Corps of Engineers), 1996: Digest of Water Re sources Policies and 4911 Authorities 14-1: Shore Protection . EP 1165-2-1, U.S. Army Corps of Engineers, 4912 Washington, DC. 4913
USACE (U.S. Army Corps of Engineers), 1999: Barnegat Inlet to Little Egg Inlet . Final 4914 Feasibility Report and Integrated Fina l Environmental Impact Statement. 4915
USACE (U.S. Army Corps of Engineers), and Ne w Jersey Department of Environmental 4916 Protection, 1999: Barnegat Inlet to Little Egg Inlet, Final Feasibility and 4917 Integrated Final Environmental Impact Statement

. 4918 Virginia Marine Resources Commission , 1988: Criteria for the Placement of Sandy 4919 Dredged Material along Beaches in the Commonwealth . Regulation VAC 20- 4920 400-10 et seq. <http://www.mrc.virginia.gov/regulations/fr400.shtm> 4921

4922 4923CCSP 4.1 January 15, 2009

386 of 784 Final Report 

## Chapter 9. Coastal Flooding, Floodplains and Coastal 4924 

## Zone Management Issues 4925

4926 Lead Authors: Stephen K. Gill, NOAA; Doug Marcy, NOAA 4927 4928 Contributing Author: Zoe Johnson, Maryland Department of Natural Resources 4929 4930 KEY FINDINGS 4931

 Rising sea level increases the vulnerab ility of coastal areas to flooding. The 4932 higher sea level provides a higher base for storm surges to build upon. It also 4933 diminishes the rate at which low-lying ar eas drain, thereby increasing the risk of 4934 flooding from rainstorms. Increased shor e erosion can further increase flood 4935 damages by removing protective dunes, beaches, and wetlands, thus leaving 4936 previously protected properties closer to the water' s edge. In addition to flood 4937 damages, many other effects, responses, and decisions are likely to occur during 4938 or in the immediate aftermath of severe storms. Beach erosion and wetlands loss 4939 often occur during storms, and the rebuild ing phase after a severe storm often 4940 presents the best opportunity for developed areas to adapt to future sea-level rise. 4941

 Coastal storms could have higher flooding pot ential in the future due to higher sea 4942 levels relative to the land. 4943

 The most recent Federal Emergency Management Agency (FEMA) study on the 4944 potential effects of sea-level rise on the Nation’s flood insurance program was 4945CCSP 4.1 January 15, 2009

387 of 784 Final Report published in 1991. Because of the uncertain ties in the projections of potential 4946 changes in sea level at th e time and the ability of th e rating system to respond 4947 easily to a 0.3 meter rise in sea le vel, the 1991 FEMA study (FEMA, 1991) 4948 concluded that no immediate pr ogram changes were needed. 4949

 The mid-Atlantic coastal zone mana gement community is increasingly 4950 recognizing that sea-level ri se is a high-risk coastal hazard as evidenced by the 4951 recent comprehensive analyses and studies needed to make recommendations for 4952 state policy formulation performed by Maryland. 4953

4954

9.1 INTRODUCTION 4955 This Chapter examines the effects of sea-le vel rise on coastal fl oodplains and on coastal 4956 flooding management issues confronting the U.S. Federal Emergency Management 4957 Agency (FEMA), the floodplain management community, the coastal zone management 4958 community, coastal resource managers, and th e public, including private industry. Sea4959 level rise is just one of nume rous complex scientific and soci etal issues these groups face. 4960 There is also uncertainty in the local rate of sea-level change, which needs to be taken 4961 into account along with the in terplay with extreme storm ev ents (see Chapter 1). In 4962 addition, impacts of increased flooding frequency and extent on coastal areas can be 4963 significant for marine ecosystem health a nd human health in those areas (Boesch et al. , 4964 2000). This Chapter provides a discussion of the current state of knowledge and provides 4965 assessments for a range of actions being ta ken by many state and federal agencies and 4966 other groups related to coastal flooding. 4967 4968CCSP 4.1 January 15, 2009

388 of 784 Final Report 9.2 PHYSICAL CHARACTERISTICS 4969 9.2.1 Floodplain 4970 In general, a floodplain is any normally dry land surrounding a natural water body that 4971 holds the overflow of water during a flood. B ecause they border water bodies, floodplains 4972 have been popular sites to es tablish settlements, which subsequently become susceptible 4973 to flood-related disasters. Most management and regulatory definitions of floodplains 4974 apply to rivers; however, open-coast floodpl ains characterized by beach, dunes, and 4975 shrub-forest are also impor tant since much of the pr oblematic development and 4976 infrastructure is concentrated in these areas (see Chapter 3 for a de tailed description of 4977 this environment). 4978 4979 The federal regulations governing FEMA (2008) via Title 44 of the Code of Federal 4980 Regulations defines floodplains as “any land area susceptibl e to being inundated by flood 4981 waters from any sour ce”. The FEMA (2002) Guidelines and Specifications for Flood 4982 Hazard Mapping Partners Glossary of Terms defines floodplains as: 4983
1. A flat tract of land bordering a river, main ly in its lower reach es, and consisting of 4984 alluvium deposited by the river. It is fo rmed by the sweeping of the meander belts 4985 downstream, thus widening the valley, th e sides of which may become some 4986 kilometers apart. In time of flood, when th e river overflows its banks, sediment is 4987 deposited along the valley banks and plains. 4988 2. Synonymous with the 100-year floodpl ain, which is defined as the land area 4989 susceptible to being inundated by stream derived waters with a 1-percent-annual4990 chance of being equaled or exceeded in a given year. 4991CCSP 4.1 January 15, 2009

389 of 784 Final Report The National Oceanic and Atmospheric Administration (NOAA) National Weather 4992 Service (NWS) defines a floodplain as the portion of a river valley that has been 4993 inundated by the river during historic floods. None of these formal definitions of 4994 floodplains include the word “coastal”. Howe ver, as river systems approach coastal 4995 regions, river base levels appr oach sea level, and the rivers become influenced not only 4996 by stream flow, but also by coastal processes such as tides, waves, and storm surges. In 4997 the United States, this complex interac tion takes place near the governing water body, 4998 either open ocean, estuarie s, or the Great Lakes. 4999 5000 The slope and width of the coastal plain dete rmines the size and inland extent of coastal 5001 influences on river systems. Coastal regi ons are periodically inundated by tides, and 5002 frequently inundated by high waves and storm surges. Therefore, a good working 5003 definition of a coastal floodplain, borrowing from the general rive r floodplain definition, 5004 is any normally dry land area in coastal regi ons that is susceptible to being inundated by 5005 water from any natural source, including oceans ( e.g. , tsunami runup, coastal storm surge, 5006 relative sea-level rise), rive rs, streams, and lakes. 5007 5008 Floodplains generally contain unconsolidated sediments, often extending below the bed 5009 of the stream or river. These accumulations of sand, gravel, loam, silt, or clay are often 5010 important aquifers; the water drawn from them is prefiltered compared to the water in the 5011 river or stream. Geologically ancient floodplains are often re vealed in the landscape by 5012 terrace deposits, which are old floodplain depo sits that remain relatively high above the 5013 current floodplain and often indicate fo rmer courses of rivers and streams. 5014CCSP 4.1 January 15, 2009

390 of 784 Final Report 5015 Floodplains can support particul arly rich ecosystems, both in quantity and diversity. 5016 These regions are called riparian zones or sy stems. Wetting of the floodplain soil releases 5017 an immediate surge of nutrients, both those left over from the la st flood and those from 5018 the rapid decomposition of organic matter that accumulated since the last flood. 5019 Microscopic organisms thrive and larger species enter a rapid breeding cycle. 5020 Opportunistic feeders (particularly birds) m ove in to take advantage of these abundant 5021 populations. The production of nutrients peaks and then declines quickly; however, the 5022 surge of new growth endures for some ti me, thus making floodplains particularly 5023 valuable for agriculture. Markedly different species grow within floodplains compared to 5024 surrounding regions. For instance, certain riparian trees specie s (that grow in floodplains 5025 near river banks) tend to be very tolerant of root disturbance and thus tend to grow 5026 quickly, compared to different tree species gr owing in a floodplain some distance from a 5027 river. 5028 5029 9.3 POTENTIAL IMPACTS OF SE A-LEVEL RISE ON COASTAL 5030 FLOODPLAINS 5031 Assessing the impacts of sea-level rise on coastal floodplains is a complicated task, 5032 because those impacts are coupled with imp acts of climate change on other coastal and 5033 riverine processes and can be offset by human actions to protect life and property. 5034 Impacts may range from extended periods of drought and lack of se diments to extended 5035 periods of above-normal freshwater runoff and associated sediment loading. Some 5036 seasons may have higher than normal freque ncy and intensity of coastal storms and 5037CCSP 4.1 January 15, 2009

391 of 784 Final Report flooding events. Impacts will also depend on construction and maintenance of dikes, 5038 levees, waterways, and divers ions for flood management. 5039 5040 With no human intervention, the hydrologic an d hydraulic characteristics of coastal and 5041 river floodplain interactions will change with sea-level rise. Fundamentally, the 5042 floodplains will become increasingly vulnera ble to inundation. In tidal areas, the tidal 5043 inundation characteristics of the floodplain may change with the range of tide and 5044 associated tidal currents increasing with se a-level rise. With this inundation, floodplains 5045 will be vulnerable to increased coastal erosion from waves, river and tidal currents, 5046 storm-induced flooding, and tidal flo oding. Upland floodplain boundaries will be 5047 vulnerable to horizontal movement. Coastal marshes could be vulnerable to vertical 5048 buildup or inundation (see Chapte r 4 for further discussion). 5049 5050 In a study for the state of Maine (Slovinsky and Dickson, 2006), the impacts of sea-level 5051 rise on coastal floodplains were characte rized by marsh habitat changes and flooding 5052 implications. The coast of Maine has a signifi cant spring tidal range of 2.6 to 6.7 meters 5053 (m) (8.6 to 22.0 feet [ft]), such that impacts of flooding are coupled with the timing of 5054 storms and the highest astronomical tides on top of sea-level rise . The study found that 5055 there was increasing susceptibility to inle t and barrier island breaches where existing 5056 breach areas were historically found, in creased stress on existing flood-prevention 5057 infrastructure (levees, dikes, roads), and a gr adual incursion of low marsh into high marsh 5058 with development of a steeper bank topogra phy. On the outer coast, impacts included 5059 increased overwash and erosion. 5060CCSP 4.1 January 15, 2009

392 of 784 Final Report 5061 In addition, the effects of significant local or regional subsidence of the land will add to 5062 the effects of sea-level rise on coastal floodplains. Regional areas with significant 5063 subsidence include the Mississi ppi River Delta region (AGU , 2006), the area around the 5064 entrance to the Chesapeake Bay (Poag, 1997), and local areas such as the Blackwater 5065 National Wildlife Refuge on the Eastern Shore of Maryland (Larsen et al. , 2004). 5066 5067 9.4 POTENTIAL EFFECTS OF SEA-LE VEL RISE ON THE IMPACTS OF 5068 COASTAL STORMS 5069 The potential interaction among increased sea le vels, storm surges, and upstream rivers is 5070 complex. The storm surge of any individual stor m is a function of storm intensity defined 5071 by storm strength and structure, forward spee d, landfall location, angle of approach, and 5072 local bathymetry and topography. However, the absolute elevation of the maximum water 5073 levels observed relative to the land during a st orm (operationally defined as storm tides) 5074 are a combination of the storm surge de fined above, plus the non-storm-related 5075 background water level elevations due to the stage of tide, the time of year (sea level 5076 varies seasonally), river fl ow, local shelf circulation patterns (such as the Gulf Loop 5077 Current/eddies and the El Niño-Southern Osci llation [especially on the west coast]). 5078 Storm surge "rides” on top of these other va riations, including s ea level rise (NOAA, 5079 2008). Storm surge can travel several hundred kilometers up rivers at more than 40 5080 kilometers (km) (25 miles [mi]) per hour, as on the Mississippi River, where storm surge 5081 generated by land-falling hurricanes in the Gu lf of Mexico can be detected on stream 5082CCSP 4.1 January 15, 2009

393 of 784 Final Report gauges upstream of Baton Rouge, Louisiana, more than 480 km (300 mi) from the mouth 5083 of the river (Reed and Stucky, 2005). 5084 5085 Both NWS (for flood forecasting) and FEMA (for insurance purposes and land use 5086 planning) recognize the complexity of the interactions among sea-level rise, storm surge, 5087 and river flooding. For instance, NWS uses bot h a hurricane storm surge model (the Sea, 5088 Lakes, and Overland Surge from Hurri canes [SLOSH] model, Jelesnianski et al. , 1992) 5089 and a riverine hydraulic mode l (the Operational Dynamic Wave Model) to forecast 5090 effects of storm surge on river stages on th e Mississippi River. The two models are 5091 coupled such that the output of the stor m surge model is used as the downstream 5092 boundary of the river model. This type of model coupling is needed to determine the 5093 effects of sea-level rise and storm surge on riverine systems. Other modeling efforts are 5094 starting to take into account river and coastal physical process interact ions, such as use of 5095 the two-dimensional hydrodynamic model (t he Advanced Circulation Model or 5096 ADCIRC; Luettich et al. , 1992) on the Wacammaw River in South Carolina to predict 5097 effects of storm surge on river stages as fa r inland as Conway, 80 km (50 mi) from the 5098 Atlantic Ocean (Hagen et al. , 2004). These model coupli ng routines are becoming 5099 increasingly more common and have been id entified as future research needs by such 5100 agencies as NOAA and the U.S. Geological Survey (USGS), as scientists strive to model 5101 the complex interactions between coastal and ri verine processes. As sea level rises, these 5102 interactions will become ever more importa nt to the way the coastal and riverine 5103 floodplains respond (Pietrafesa et al. , 2006). 5104 5105 9.4.1 Historical Comparison at Tide Stations 5106CCSP 4.1 January 15, 2009

394 of 784 Final Report There is the potential for higher elevations of coastal flooding from coastal storms over 5107 time as sea level rises relative to the land. L ooking at storms in hi storical context and 5108 accounting for sea level change is one way to estimate maximum potential storm water 5109 levels. For example, this assessment can be made by analyzing the historical record of 5110 flooding elevations observed at NOAA tide stations in the Chesapeake Bay. The 5111 following analysis compares the elevation of the storm tides for a particular storm at a 5112 particular tide station; that is from when it occurred historica lly to as if the same exact 5113 storm occurred today under the exact same c onditions, but adjusted for relative sea level 5114 rise at that station. These comparisons are enabled because NOAA carefully tabulates 5115 water level elevations over time relative to a common reference datum that is connected 5116 to the local land elevations at each tide station. From this, re lative sea level trends can be 5117 determined and maximum water level elevati ons recorded during co astal storms can be 5118 directly compared over the time period of r ecord (Zervas, 2001). The relative sea level 5119 trend provides the numerical adjustment need ed depending on the date of each storm. 5120 5121 The NOAA post-hurricane report (Hovis, 2004) on the observed storm tides of Hurricane 5122 Isabel assessed the potential effects of sea- level rise on maximum observed storm tides 5123 for four long-term tide stations in the Ch esapeake Bay. Prior to Hurricane Isabel, the 5124 highest water levels reache d at the NOAA tide stations at Baltimore, Maryland; 5125 Annapolis, Maryland; Washington, D.C.; and Se wells Point, Virginia occurred during the 5126 passage of an unnamed hurricane in August, 1933. At the Washington, D.C. station, the 5127 1933 hurricane caused the third highest recorded water level, surpassed only by river 5128 floods in October 1942 and March 1936. Hurrican e Isabel caused water levels to exceed 5129CCSP 4.1 January 15, 2009

395 of 784 Final Report the August 1933 levels at Baltimore, A nnapolis and Washington, D.C. by 0.14, 0.31, and 5130 0.06 meters (m), respectively. At Sewells Poin t, the highest water level from Hurricane 5131 Isabel was only 0.04 m below the level reached in August 1933. Zerv as (2001) calculated 5132 sea-level rise trends for Baltimore, Anna polis, Washington, and Sewells Point of 3.12, 5133 3.53, 3.13, and 4.42 millimeters (mm) per year, re spectively. Using these rates, the time 5134 series of monthly highest water level were adjusted for the subsequent sea-level rise up to 5135 the year 2003. The resulting time series, summarized in Tables 9.1, 9.2, 9.3, and 9.4, 5136 indicate the highest level reached by each st orm as if it had taken place in 2003 under the 5137 same conditions, thus allowing an unbiased comparison of storms. The purpose of Tables 5138 9.1 through 9.4 is to show that the relative ranking of the floodi ng elevations from 5139 particular storm events changes at any give n station once the adjustment for sea level 5140 trend is taken into account. The 1933 hu rricane, especially, moves up in ranking at 5141 Baltimore and Washington, DC once adjusted for the local sea level trend. Hurricane 5142 Hazel moved up in ranking at Annapolis. If the 1933 hurricane occurred today under the 5143 same conditions, it would have had the highest water level of record at Baltimore, not 5144 Hurricane Isabel. Elevations are relative to the tidal datum of mean higher high water 5145 (MHHW). Noting the earlier discussion in this section on the operational difference 5146 between storm surge and the actual observed storm tide elevation, the tables suggest that, 5147 while not affecting intensity of storms and the resulting amplitude of storm surges, sea5148 level rise could increasingly add to the potential maximum water level elevations 5149 observed relative to the la nd during coastal storms. 5150 5151
Table 9.1 Five highest water levels for Baltimore, Maryland in meters above mean higher high 5152 water. Ranked first by absolute elevation and then ranked again after adjustment for sea level rise. 5153 5154CCSP 4.1 January 15, 2009

396 of 784 Final Report Absolute water level Corrected for sea-level rise to 2003 5155 Event Date Elevation (m) Event Date Elevation (m) 5156 Hurricane Isabel Sep 2003 1.98 Hurricane Aug 1933 2.06 Hurricane Aug 1933 1.84 Hurricane Isabel Sep 2003 1.98

Hurricane Connie Aug 1955 1.44 Hurricane Connie Aug 1955 1.59

Hurricane Hazel Oct 1954 1.17 Hurricane Aug 1915 1.38 Hurricane Aug 1915 1.11 Hu r. Hazel Oct 1954 1.32 5157 5158 Table 9.2 Five highest water levels for Anna polis, Maryland in meters above mean higher high 5159 water. Ranked first by absolute elevation and then ranked again after adjustment for sea level rise. 5160 5161 Absolute water level. Corrected for sea-level rise to 2003 5162 Event Date Elevation (m) Event Date Elevation (m) 5163 Hurricane Isabel Sep 2003 1.76 Hurricane Isabel Sep 2003 1.76 Hurricane Aug 1933 1.45 Hurricane Aug 1933 1.69 Hurricane Connie Aug 1955 1.08 Hurricane Connie Aug 1955 1.25 Hurricane Fran Sep 1996 1.04 Hurricane Hazel Oct 1954 1.19

Hurricane Hazel Oct 1954 1.02 Hurricane Fran Sep 1996 1.06 5164 5165 Table 9.3 Five highest water levels for Washington, D. C. in meters above me an higher high water. 5166 Ranked first by absolute elevation and then ranked again after adjustment for sea level rise. 5167 5168 Absolute water level Corrected for sea-level rise to 2003 5169 Event Date Elevation (m) Event Date Elevation (m) 5170 Flood Oct 1942 2.40 Flood Oct 1942 2.59 Flood Mar 1936 2.25 Flood Mar 1936 2.46 Hurricane Isabel Sep 2003 2.19 Hurricane Aug 1933 2.35 Hurricane Aug 1933 2.13 Hurricane Isabel Sep 2003 2.19 Flood Apr 1937 1.70 Flood Apr 1937 1.91 5171 5172 Table 9.4 Five highest water levels for Sewells Point, Virginia in meters above mean higher high 5173 water. Ranked first by absolute elevation and then ranked again after adjustment for sea level rise. 5174 5175 Absolute water level Corrected for sea-level rise to 2003 5176 Event Date Elevation (m) Event Date Elevation (m) 5177 Hurricane Aug 1933 1.60 Hurricane Aug 1933 1.91CCSP 4.1 January 15, 2009

397 of 784 Final Report Hurricane Isabel Sep 2003 1.56 Hurricane Isabel Sep 2003 1.56

Winter Storm Mar 1962 1.36 Winter Storm Mar 1962 1.54 Hurricane Sep 1936 1.21 Hurricane Sep 1936 1.50 Winter Storm Feb 1998 1.16 Hurricane Sep 1933 1.33 5178 5179 9.4.2 Typical 100-Year Storm Surge Elevat ions Relative to Mean Higher High 5180 Water within the Mid-Atlantic Region 5181 A useful application of long-term tide gauge da ta is a return frequency analysis of the 5182 monthly and annual highest and lowest observed water levels . This type of analysis 5183 provides information on how often extreme wa ter levels can be expected to occur ( e.g. , 5184 once every 100 years, once every 50 years, onc e every 10 years?) On the East Coast and 5185 in the Gulf of Mexico, hurricanes and winter storms interact with the wide, shallow, 5186 continental shelf to produce large extreme storm tides. A generalized extreme value 5187 distribution can be derived for each station af ter correcting the values for the long-term 5188 sea-level trend (Zervas, 2005). Theoretical ex ceedance probability statistics give the 99- 5189 percent, 50-percent, 10-percent, and 1-percent annual ex ceedance probability levels. 5190 These levels correspond to av erage storm tide return peri ods of 1, 2, 10, and 100 years. 5191 The generalized extreme value analyses are run on the historical data from each tide 5192 station. Interpolating exceedance probability results away from the tide station location is 5193 not recommended as elevations of tidal datu ms and the extremes are highly localized. 5194 Figures 9.1 and 9.2 show the variations in thes e statistics along the mid-Atlantic coast. 5195 Figure 9.1 shows exceedance elevations above local mean sea level (LMSL) at mid5196 Atlantic stations relative to the 1983 to 2001 National Tidal Datum Epoch (NTDE). 5197CCSP 4.1 January 15, 2009

398 of 784 Final Report Figure 9.2 shows the same exceedance elevations , except the elevations are relative to 5198 mean higher high water (MHHW) comput ed for the same 1983 to 2001 NTDE. 5199 5200 In Figure 9.1, the elevations relative to LMSL are highly correlated with the range of tide 5201 at each station (Willets Point, New York has a very high range of tide, 2.2 m), except for 5202 the 1-percent level at Wash ington D.C., which is susceptible to high flows of the 5203 Potomac River. Due to their varying locations , the 1-percent eleva tion level varies the 5204 most among the stations. Figure 9.2 shows a s lightly geographically decreasing trend in 5205 the elevations from north to south. 5206 5207 Exceedance Probability Elevations: Mid-Atlantic Tide Stations - Relative to Local Mean Sea Level

-0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

N ew Lon d on,CT Bridgeport, CT

N ew R och elle, N Y

Po

r t Jeff e rson, NY

W

illets Point, NY

Sa

n dy H o ok, N J The Batter y, N Y C

A

t lant

ic C it y, N J

C

ape May, NJ Le

w

es

, D

E
Ph

il

a d elphia , PA CB

B T , V

A Sewells P oi

nt,V A Portsmouth, VA Gloucester Point, VA

K ip

to

peake, V A

C

amb r idge, M D

S

o lomon s Islan d, MD Annapolis, MD Baltimore, MD

L

e wisett a, V A

C

o lon

ial Be ach, V A Washin g ton, D

C

B

e aufort, N C Wilmington, NCElevation Relative to Local MSL (meters)

1% 10% 50% 99% MHHW NAVD88

5208 Figure 9.1 Exceedance probabilities for mid-A tlantic tide stations relative to local mean sea level. 5209CCSP 4.1 January 15, 2009

399 of 784 Final Report 5210 Exceedance Probability Elevations: Mid-Atlantic Tide Stations Relative to MHHW

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

N

ew

L ondon ,CT

B

r idgeport , C T

N

ew

R

ochelle, N Y

P

ort

J effer s on,

N

Y

W

i l le

ts

Poi

n t,

N

Y

S

a n dy Hook, NJ

T he Battery, N YC

A tlant ic Cit y , N

J

C

a pe May , N J
L

ew

es

, D

E Phil a delphia,PA CBBT , VA

S

e w el

l s P

o i nt

, VA

P

or

t s m

out

h,

V

A

G

l ouc e s te

r Poi

nt

, VA

K iptopeake, VA Ca

m b

r idge, MD Solomo ns

I sla

n d, MD

A

nnap o lis,

MD

B altim o re, M D Lewisetta, VA Colonial Beach, VA

W

as

hingt on, DC

B eaufor t

, NC

W

i l mi

ngton, NCElevation Above MHHW (meters)

1% 10% 50% 99%

5211 Figure 9.2 Exceedance probabilities at mid- Atlantic tide stations relative to mean higher high water. 5212 5213 Examining the effects of sea-level rise on the highest water level during a hurricane or 5214 coastal storm does not provide a complete pict ure because the impacts of sea-level rise on 5215 the duration of the inundation ca n be as important as the ma ximum height. Sea-level rise, 5216 coupled with any increased frequency of extr a-tropical storms (nor’easters), may also 5217 increase the durations of inundation from extra-tropical storms (NOAA, 1992). For 5218 instance, some of the most severe impacts of nor’easters are generally felt in bays where 5219 water can get in but not out for several days as the storms slowly transit parallel to the 5220

coast. 5221 5222CCSP 4.1 January 15, 2009

400 of 784 Final Report Other federal agencies, such as NOAA, have been sponsoring applied research programs 5223 to bring an integrated approach to unders tanding the effects of sea-level rise into 5224 operations. One such study on the ecological effect s of sea-level rise is discussed in Box 5225 9.1 (NOAA, 2007), which is due to come out with a final report in 2009. 5226
5227 9.5 FLOODPLAIN MAPPING AND SEA-LEVEL RISE 5228 A nationwide study was performed by FEMA (1991) (see Box 9.2) in which costs for 5229 remapping floodplains were estimated at $150,000 per county (in 1991 dollars) or $1,500 5230 per map panel (the standard map presentati on used by FEMA). With an estimated 283 5231 counties (5,050 map panels) pote ntially in need of remapping, the total cost of restudies 5232 and remapping was estimated at $30 million (in 1991). Based on this study and assuming 5233 that the maps are revised on a regular basis, such an undertaking today would cost about 5234 $46.5 million. The 1991 study concluded that “there are no immediate program changes 5235 needed” (FEMA, 1991). 5236 5237 At present, FEMA periodically revises Flood Insurance Rate Maps (FIRMs) to reflect 5238 new engineering, scientific, and imager y data. In addition, under their Map 5239 Modernization and post-Map Modernization Programs, FEMA intends to assess the 5240 integrity of the flood hazard data by reviewi ng the flood map inventor y every five years. 5241 Where the review indicates th e flood data integrity has degr aded the flood maps (due to 5242 outdated data and known changes in hydrology and floodplain elevation since the last 5243 maps were issued), updates will be provided or new studies will be performed. Whenever 5244 an update or remap of coastal areas is made, changes that ha d occurred in the interim due 5245CCSP 4.1 January 15, 2009

401 of 784 Final Report to sea-level rise will be accounted for. An upcoming Impact of Climate Change on the 5246 National Flood Insurance Program study (schedul ed to begin at the end of fiscal year 5247 2008 and last 1.5 years) may come up with different conclusions than the 1991 study and 5248 cause FEMA to rethink the issue. 5249 5250 The primary floodplain management adjustment fo r sea-level rise is th e local increase in 5251 required base flood elevation (BFE) for new construction. Elevating a building’s lowest 5252 floor above predicted flood elevations by a small additional height, generally 0.3 to 0.9 5253 meters above National Flood Insurance Program (NFIP) minimum height requirements, 5254 is termed a freeboard addition. Freeboard additions are genera lly justified for other more 5255 immediate purposes including th e lack of safety factor in the 1-percent flood and 5256 uncertainties in prediction and modeling. FE MA encourages freeboa rd adoptions through 5257 the Community Rating System, which offers community-wide flood insurance premium 5258 discounts for higher local standards and for individuals through premium discounts for 5259 higher than minimum elevation on higher risk buildings. Velocity flood zones, known as 5260 V Zones or coastal high hazard areas, have been identified by FEMA as areas "where 5261 wave action and/or high velocity water can cause structural damage in the 100-year 5262 flood", a flood with a 1 percent chance of occu rring or being exceeded in a given year. 5263 FEMA also defines A Zones as areas inundate d in a 100-year storm event that experience 5264 conditions of less severity, for example, wave heights less than 1 m, than conditions 5265 experienced in V Zones. Accurate determinati on of the spatial extent of these zones is 5266 vital to understanding the le vel of risk for a partic ular property or activity. 5267 5268CCSP 4.1 January 15, 2009

402 of 784 Final Report A recent historical overview of FEMA’s Coas tal Risk Assessment process is found in 5269 Crowell et al. (2007), and includes overviews of the FEMA Map Modernization 5270 Program, revised coastal guidelines, and FE MA’s response to recommendations of a 5271 Heinz Center report, Evaluation of Erosion Hazards (Heinz Center, 2000). 5272 5273 9.6 STUDIES OF FUTURE COASTA L CONDITIONS AND FLOODPLAIN 5274 MAPPING 5275 9.6.1 FEMA Coastal Studies 5276 Currently, communities can opt to use fu ture conditions (projected) hydrology for 5277 mapping according to FEMA rules established in December 2001 24 . Showing future 5278 conditions flood boundaries has be en provided at the request of some communities in 5279 Flood Map Modernization, but it is not a rou tine product. As outlined in those rules, 5280 showing a future condition boundary in additi on to the other boundaries normally shown 5281 on a FIRM is acceptable. FEMA shows future condition boundaries for informational 5282 purposes only and carries with it no additiona l requirements for floodplain management. 5283 Insurance would not be rated using a futu re condition boundary. The benefits showing 5284 future condition flood boundaries relate to the fa ct that future increases in flood risk can 5285 lead to significant increases in both calculated and experienced flood he ights, resulting in 5286 serious flood losses (structural damage and economic) as well as loss of levee 5287 certification and loss of flood protection for compliant post-FIRM st ructures. Providing 5288 this information to communities may lead to coordinated watershed-wide actions to 5289 manage for, or otherwise mitig ate, these future risks. 5290

24 Input to author team during CCSP SAP 4.1 Federa l Advisory Committee review , Mark Crowell, FEMA.CCSP 4.1 January 15, 2009

403 of 784 Final Report 5291 A recent increase in losses from coastal stor ms has been recognized by FEMA (Crowell, 5292 2008). In 2005, Hurricane Katrina clearly illustrate d this, reporting the most losses of any 5293 U.S. natural disaster to date. This fact, coupled with the facts that new developments in 5294 modeling and mapping technology have allo wed for more accurate flood hazard 5295 assessment over the past few years and that populations at risk ar e growing in coastal 5296 areas, has caused FEMA to develop a new nati onal coastal strategy. This strategy consists 5297 of assessing coastal Flood Insurance Studies on a national scale and developing a 5298 nationwide plan for improved coastal flood hazard identification. The assessment will 5299 prioritize regional studies, look at funding allo cations, and develop timelines for coastal 5300 study updates. 5301 5302 River models that are affected by tides a nd storm surge require the downstream boundary 5303 starting water surface elevation to be the “1-percent-annual-chance” base flood elevation 5304 (BFE) from an adjacent coasta l study. If the coastal study BFE is raised by 0.3 m or even 5305 0.9 m because of sea-level rise, the river st udy flood profile will be changed as well and 5306 this will ultimately affect the resulting FI RMs that are published. This is a complicated 5307 issue and points out the fact that simply raising the coastal BFEs to estimate a new 1- 5308 percent-annual-chance floodplain is not taking into account the more complex hydraulics 5309 that will have undetermined effects on the upstream 1-percent-a nnual-chance floodplains 5310 as well. The 1991 study does not f actor in the complexity of different tidal regimes that 5311 would be occurring because of an increased s ea level and how those regimes would affect 5312CCSP 4.1 January 15, 2009

404 of 784 Final Report the geomorphology of the floodplains

. This is because FEMA is restricted in what it can 5313 and cannot do in the regulated NFIP process (Crowell, 2008). 5314 5315 Maryland has completed a comprehensive stat e strategy document in response to sea5316 level rise (MD DNR, 2000). The Maryland Department of Natural Resources (MD DNR, 5317 2000) requires all communities to adopt standard s that call for all structures in the non5318 tidal floodplain to be elevated 0.3 m (1 ft ) above the 100-year floodplain elevation, and 5319 all coastal counties except Worcester, So merset, and Dorchester (the three most 5320 vulnerable to exacerbated flooding due to sea-le vel rise) have adopted the 1-ft freeboard 5321 standard. Although 1 foot of freeboard provide s an added cushion of protection to guard 5322 against uncertainty in floodplain projections , it may not be enough in the event of 0.6 to 5323 0.9 m (2 to 3 ft) of sea-level ri se, as MD DNR ( 2000) points out. 5324 5325 Crowell et al . (2007) identified a need for a tide-gauge analysis for FEMA Region III, 5326 which encompasses the mid-Atla ntic states, similar to new studies being done currently 5327 on Chesapeake Bay by the state of Maryla nd. Each coastal FEMA region has been 5328 evaluated and new guidelines and specifica tions have been developed by FEMA for 5329 future coastal restudies, the first of wh ich was for the Pacific Coast region. These 5330 guidelines outline new coastal storm surge modeling and mapping procedures and allow 5331 for new flooding and wave models to be used for generating coastal BFEs. 5332 5333 To aid in ongoing recovery and rebuilding efforts, FEMA initiated short-term projects in 5334 2004 and 2005 to produce coastal flood recovery ma ps for areas that were most severely 5335CCSP 4.1 January 15, 2009

405 of 784 Final Report affected by Hurricanes Ivan, Katrina, and R ita. The Katrina maps, for example, show 5336 high water marks surveyed after the storm, an inundation limit developed from these 5337 surveyed points, and FEMA’s Advisory Base Flood Elevations (ABFEs) and estimated 5338 zone of wave impacts. 5339 5340 These maps and associated ABFEs (generated for Katrina and Rita only) were based on 5341 new flood risk assessments that were done immediately following the storms to assist 5342 communities with rebuilding. The recovery maps provide a graphical depiction of ABFEs 5343 and coastal inundation associated with the obs erved storm surge high water mark values, 5344 in effect documenting the flood imprint of the event to be used in future studies and 5345 policy decisions. Adherence to the ABFEs fo llowing Katrina affected eligibility for 5346 certain FEMA-funded mitigation and recovery projects. They were used until the Flood 5347 Insurance Studies (FIS) were updated for the Gulf region and are available as advisory 5348 information to assist communities in rebuilding efforts. 5349 5350 FEMA cannot require the use of future conditions data based on planned land-use 5351 changes or proposed development for fl oodplain management or insurance rating 5352 purposes unless statutory and regulatory change s to the NFIP are made. In addition, using 5353 projected coastal erosion information for land-use management and insurance rating 5354 purposes through the NFIP would require a legislative mandate and regulatory changes. 5355 5356 9.6.2 Mapping Potential Impacts of Sea- Level Rise on Coastal Floodplains 5357CCSP 4.1 January 15, 2009

406 of 784 Final Report Floodplain management regulations are intende d to minimize damage as a result of 5358 flooding disasters, in conjunction with other local land-use requirements and building 5359 codes. Meeting only these minimum require ments will not guarantee protection from 5360 storm damages. Management activities that focus on mitigating a single, short-term 5361 hazard can result in structures that are built only to withstand the hazards as they are 5362 identified today, with no easy way to accommodate an increased risk of damage in the 5363 coming decades (Honeycutt and Mauriell o, 2005). The concept of going above and 5364 beyond current regulations to provide additi onal hazards information other than BFEs 5365 and the 1-percent-annual-chance flood (coa stal erosion and storm surge inundation 5366 potential) has been advocated in some quarter s with a No Adverse Impact (NAI) program 5367 (Larson and Plasencia, 2002). A NAI toolkit was developed that outlines a strategy for 5368 communities to implement a NAI approach to floodplain management (ASFPM, 2003, 5369 2008). 5370 5371 The International Codes (FEMA, 2005) include freeboard (elevations above the BFE) and 5372 standards for coastal A Zones that are more stringent than the NFIP criteria. The 5373 International Codes also incorporate criter ia from the national consensus document 5374 ASCE 24-05 Flood Resistant Design and Construction Standard (ASCE, 2006). 5375 5376 9.7 HOW COASTAL RESOURCE MANAGERS COPE WITH SEA-LEVEL RISE 5377 AND ISSUES THEY FACE 5378 9.7.1 Studies by the Association of State Floodplain Managers 5379 The Association of State Floodplain Mange rs (ASFPM) recently completed a study that 5380 contains a broad spectrum of recommendati ons for improving the management of U.S. 5381CCSP 4.1 January 15, 2009

407 of 784 Final Report floodplains (ASFPM, 2007). In their study, ASFPM not ed that changing climate was one 5382 of the major challenges for the significant chan ges in social, environmental, and political 5383 realities and their impact on floodplain mana gement, and highlights the wide spread 5384 implications for flood protection. 5385 5386 9.7.2 The Response through Floodproofing 5387 The U.S. Army Corps of Engineers heads the national floodproofing committee, 5388 established through the USACE’s floodplain ma nagement services program, to promote 5389 the development and use of proper floodproofin g techniques throughout the United States 5390 (USACE, 1996). The USACE publication on fl oodproofing techniques, programs, and 5391 references gives an excellent overview of currently accepted flood mitigation practices 5392 from an individual structure perspective. 5393 5394 Mitigating flooding or “floodproofing” is a process for preventing or reducing flood 5395 damages to structures and/or to the contents of buildings loca ted in flood hazard areas. It 5396 mainly involves altering or changing existi ng properties; however, it can also be 5397 incorporated into the design and construction of new buildin gs. There are three general 5398 approaches to floodproofing: 5399
1. Raising or moving the structure. Raising or moving the structure such that 5400 floodwaters cannot reach damageable porti ons of it is an effective floodproofing 5401 approach. 5402

2. Constructing barriers to stop flood water from entering the building . Constructing 5403 barriers can be an effective approach us ed to stop floodwaters from reaching the 5404CCSP 4.1 January 15, 2009

408 of 784 Final Report damageable portions of structures. There are two techniques employed in 5405 constructing barriers. The first techni que involves constructing free-standing 5406 barriers that are not attached to the stru cture. The three primary types of free5407 standing barriers used to reduce flood da mages are berms, levees, or floodwalls. 5408 The second technique that can be used to construct a barrier against floodwaters is 5409 known as “dry floodproofing”. With this tec hnique, a building is sealed such that 5410 floodwaters cannot get inside. 5411

3. Wet Floodproofing . This approach to floodpr oofing involves modifying a 5412 structure to allow floodwaters inside, but ensuring that there is minimal damage to 5413 the building's structure and to its conten ts. Wet floodproofing is often used when 5414 dry floodproofing is not possi ble or is too costly. We t floodproofing is generally 5415 appropriate in cases where an area is available above flood levels to which 5416 damageable items can be relocated or temporarily stored. 5417 The recommended techniques of levees, berm s, floodwalls and wet floodproofing are not 5418 allowed under the NFIP to protect new indi vidual structures. These techniques may also 5419 have limited use in protecting older existi ng structures in coastal areas. Although dry 5420 floodproofing is allowed in A Zones (not V Zones), FEMA does not generally 5421 recommend its use for new non-residential stru ctures in the coastal A Zones due to the 5422 potential flood forces. Under the NFIP , all new construction and substantial 5423 improvements of residential buildings in A Zone s must have the lowest floor elevated to 5424 or above the BFE. All new construction and substantial improvement of non-residential 5425 buildings in A Zones must have either the lowest floor elev ated to or above the BFE or 5426 the building must be dry floodproofed to the BFE. In V Zones, all new construction and 5427CCSP 4.1 January 15, 2009

409 of 784 Final Report substantial improvements must have the bot tom of the lowest horizontal structural 5428 member of the lowest floor elevated to or above the BFE on a pile or column foundation. 5429 Although the NFIP allows dry floodproofing in coastal A Zone areas, FEMA does not 5430 recommend its use in the coastal A Zone because of the potential for severe flood 5431 hazards. While Base Flood Elevations in coas tal A Zones contain a wave height of less 5432 than 3 feet, the severity of the hazard in co astal A Zones is often much greater than in 5433 non-coastal A Zones due to the combination of water velocity, wave action, and debris 5434 impacts that can occur in these areas. For exis ting, older structures in the coastal area, the 5435 best way to protect the structure is el evating or relocating the structure. 5436

5437 9.7.3 Coastal Zone Management Act 5438 Dramatic population growth along the coast br ings new challenges to managing national 5439 coastal resources. Coastal and floodplain mana gers are challenged to strike the right 5440 balance between a naturally changing shorel ine and the growing popul ation’s desire to 5441 use and develop coastal areas. Challenges in clude protecting life and property from 5442 coastal hazards; protecting coastal wetlands and habitats while accommodating needed 5443 economic growth; and settling conflicts be tween competing needs such as dredged 5444 material disposal, commercial development, r ecreational use, national defense, and port 5445 development. Coastal land loss caused by chronic erosion has been an ongoing 5446 management issue in many coastal states th at have Coastal Zone Management (CZM) 5447 programs and legislation to mitigate erosi on using a basic retreat policy. With the 5448 potential impacts of sea-leve l rise, managers and lawmaker s must now decide how or 5449CCSP 4.1 January 15, 2009

410 of 784 Final Report whether to adapt their current suite of tools and regulations to face the prospect of an 5450 even greater amount of land loss in the decades to come. 5451 5452 The U.S. Congress recognized the importanc e of meeting the challenge of continued 5453 growth in the coastal zone and responded by passing the Coastal Zone Management Act 5454 in 1972. The amended act (CZMA, 1996), administered by NOAA, provides for 5455 management of U.S. coastal resources, incl uding the Great Lakes, and balances economic 5456 development with environmental conservation. 5457 5458 As a voluntary federal–state partnership, the CZMA is designed to encourage state5459 tailored coastal management programs. It outlines two national programs, the National 5460 Coastal Zone Management Program and th e National Estuarine Research Reserve 5461 System, and aims to balance competing land a nd water issues in the coastal zone, while 5462 estuarine reserves serve as field laboratories to provi de a greater understanding of 5463 estuaries and how humans impact them. The overall program objectives of CZMA 5464 remain balanced to “preserve, protect, deve lop, and where possible, to restore or enhance 5465 the resources of the nation’ s coastal zone” (CZMA, 1996). 5466 5467 9.7.4 The Coastal Zone Management Act and Sea-Level Rise Issues 5468 The CZMA language (CZMA, 1996) refers specifi cally to sea-level rise issues (16 U.S.C. 5469 § 1451). Congressional findings (§ 302) calls for coastal states to anticipate and plan for 5470 sea-level rise and climate change impacts. 5471 5472CCSP 4.1 January 15, 2009

411 of 784 Final Report In 16 U.S.C. § 1452, Congression al declaration of policy (§ 303), the Congress finds and 5473 declares that it is the national policy to mana ge coastal development to minimize the loss 5474 of life and property caused by improper deve lopment in flood-prone, storm surge, 5475 geological hazard, and erosion-prone areas, a nd in areas likely to be affected by or 5476 vulnerable to sea-level rise, land subsid ence, and saltwater intrusion, and by the 5477 destruction of natural protectiv e features such as beaches, dunes, wetlands, and barrier 5478 islands; to study and develop plans for addr essing the adverse effects upon the coastal 5479 zone of land subsidence and of sea-level rise; and to encour age the preparation of special 5480 area management plans which provide increas ed specificity in protecting significant 5481 natural resources, reasonable coastal-dependent economic growth, improved protection 5482 of life and property in hazardous areas, including those areas li kely to be affected by land 5483 subsidence, sea-level rise, or fluctuating water levels of the Great Lakes, and improved 5484 predictability in governmental decision-making. 5485
5486 9.7.5 The Coastal Zone Enhancement Program 5487 The reauthorization of CZMA in 1996 by the U. S. Congress led to the establishment of 5488 the Coastal Zone Enhancement Program (CZM A §309), which allows states to request 5489 additional funding to amend their coastal programs in order to support attainment of one 5490 or more coastal zone enhancement objectiv es. The program is designed to encourage 5491 states and territories to develop program cha nges in one or more of the following nine 5492 coastal zone enhancement areas of national significance: wetlands, coastal hazards, 5493 public access, marine debris, cumulative and secondary impacts, special area 5494 management plans, ocean/Great Lakes reso urces, energy and government facility citing, 5495CCSP 4.1 January 15, 2009

412 of 784 Final Report and aquaculture. The Coastal Zone Enhancement Grants (§ 309) defi nes a “Coastal zone 5496 enhancement objective” as “preventing or significantly reducing threats to life and 5497 destruction of property by eliminating deve lopment and redevelopment in high-hazard 5498 areas, managing development in other hazard areas, and anticipating and managing the 5499 effects of potential sea-level ri se and Great Lakes level rise”. 5500 5501 Through a self-assessment process, state coastal programs identify high-priority 5502 enhancement areas. In consultation with NOAA, state coastal programs then develop 5503 five-year strategies to achieve changes (e nhancements) to their coastal management 5504 programs within these high-prio rity areas. Program changes often include developing or 5505 revising a law, regulation or administrative guideline, developing or revising a special 5506 area management plan, or crea ting a new program such as a coastal land acquisition or 5507 restoration program. 5508 5509 For coastal hazards, states base thei r evaluation on the following criteria: 5510
1. What is the general level or risk from specific coastal hazards ( i.e. , hurricanes, 5511 storm surge, flooding, shoreline erosi on, sea-level rise, Great Lakes level 5512 fluctuations, subsidence, and geological ha zards) and risk to life and property due 5513 to inappropriate development in the state? 5514
2. Have there been significant changes to the state’s hazards protection programs 5515 ( e.g. , changes to building setbacks/restri ctions, methodologies for determining 5516 building setbacks, restriction of hard s horeline protection st ructures, beach/dune 5517CCSP 4.1 January 15, 2009

413 of 784 Final Report protection, inlet management plans, lo cal hazard mitigation planning, or local 5518 post-disaster redevelopment plans, ma pping/GIS/tracking of hazard areas)? 5519
3. Does the state need to direct future public and private development and 5520 redevelopment away from hazardous areas , including the high hazard areas 5521 delineated as FEMA V Zones and areas vul nerable to inundation from sea- and 5522 Great Lakes level rise? 5523
4. Does the state need to preserve and re store the protective functions of natural 5524 shoreline features such as beaches, dunes, and wetlands? 5525 5. Does the state need to prevent or mi nimize threats to existing populations and 5526 property from both episodic and chronic coastal hazards? 5527 Section 309 grants have bene fited states such as Virg inia in developing local 5528 conservation corridors that id entify and prioritize habita t areas for conservation and 5529 restoration; and New Jersey for supporting new requirements for permittees to submit 5530 easements for land dedicated to public acce ss, when such access is required as a 5531 development permit condition and is supporting a series of workshops on the Public Trust 5532 Doctrine and ways to enhance public access (see 5533 <http://coastalmanagement.no aa.gov/nationalsummary.html>). 5534 5535 9.7.6 Coastal States Strategies 5536 Organizations such as the Coastal States Organization have recently become more 5537 proactive in how coastal zone management programs consider adaptation to climate 5538 change, including sea-level rise (Coastal States Organization, 2007) and are actively 5539 leveraging each other’s experi ences and approaches as to how best obtain baseline 5540CCSP 4.1 January 15, 2009

414 of 784 Final Report elevation information and inundation maps, how to assess impacts of sea-level rise on 5541 social and economic resources and coastal ha bitats, and how to de velop public policy. 5542 There have also been several i ndividual state-wide studies on the impact of sea-level rise 5543 on local state coastal zones ( e.g. , Johnson [2000] for Maryland; Cooper et al . [2005] for 5544 New Jersey). Many state coastal management websites show an activ e public education 5545 program with regards to providing info rmation on impacts of sea-level rise: 5546 New Jersey: <http://www.nj.gov/dep/njgs/enviroed/infocirc/sealevel.pdf> 5547 Delaware: 5548 <http://www.dnrec.delaware.gov/Climate+change+shoreline+erosion.htm> 5549 Maryland: <http://www.dnr.state.md .us/Bay/czm/sea_level_rise.html> 5550 5551 9.7.6.1 Maryland’s Strategy 5552 The evaluation of sea-level rise response plan ning in Maryland and the resulting strategy 5553 document constituted the bulk of the state’s CZMA §309 Coastal Hazard Assessment and 5554 Strategy for 2000–2005 and in the 2006-2010 Assessment and Strategy (MD DNR, 5555 2006). Other mid-Atlantic states mention sea-level rise as a co ncern in their assessments, 5556 but have not yet developed a comprehensive strategy. 5557 5558 The sea-level rise strategy is designed to achieve the desired outcome within a five-year 5559 time horizon. Implementation of the strategy is evolving over time and is crucial to 5560 Maryland’s ability to achieve sustainable management of its coastal zone. The strategy 5561 states that planners and legi slators should realize that the implementation of measures to 5562 mitigate impacts associated with erosion, flooding, and wetland inundation will also 5563CCSP 4.1 January 15, 2009

415 of 784 Final Report enhance Maryland’s ability to protect coas tal resources and communities whether sea 5564 level rises significantly or not. 5565 5566 Maryland has taken a proactive step to wards addressing a growing problem by 5567 committing to implementation of this strategy and increasing awareness and 5568 consideration of sea-level rise issues in both public and governmental arenas. The 5569 strategy suggests that Maryland will achieve success in planning for sea-level rise by 5570 establishing effective response mechanisms at both the state and lo cal levels. Sea-level 5571 rise response planning is crucia l in order to ensure future survival of Maryland’s diverse 5572 and invaluable coastal resources. 5573 5574 Since the release of Maryland’s sea-level ri se response strategy (Johnson, 2000), the state 5575 has continued to progressively plan for sea-le vel rise. The strategy is being used to guide 5576 Maryland’s current sea-level rise resear ch, data acquisition, and planning and policy 5577 development efforts at both the state and lo cal level. Maryland set forth a design vision 5578 for “resilient coastal communities” in its CZMA §309 Coastal Haza rd Strategy for 2006– 5579
2010 (MD DNR, 2006). The focus of the approach is to integrate the use of recently 5580 acquired sea-level rise data - and technology-based products into both state and local 5581 decision-making and planning processes. Ma ryland’s coastal program is currently 5582 working with local governments and other st ate agencies to: (1) build the capacity to 5583 integrate data and mapping efforts into land-use and comprehensive planning efforts; (2) 5584 identify specific opportunities ( i.e. , statutory changes, code ch anges, comprehensive plan 5585 amendments) for advancing sea-level rise at the local level; and (3) improve state and 5586CCSP 4.1 January 15, 2009

416 of 784 Final Report local agency coordination of sea-level rise planning and response activities (MD DNR, 5587 2006). 5588 5589 In April 2007, Maryland’s Governor, Mart in O’Malley, signed an Executive Order 5590 establishing a Commission on Climate Change (Maryland, 2007) that is charged with 5591 advising both the Governor and Maryland’s General Assembly on matters related to 5592 climate change and is charged with developi ng a Plan of Action that will address climate 5593 change on all fronts, including both the dr ivers and the consequences. The Maryland 5594 Commission on Climate Change released its Climate Action Plan in August 2008 5595 (Maryland, 2008). A key component of the Ac tion Plan is The Comprehensive Strategy 5596 to Reduce Maryland’s Vulnerability to C limate Change. The Strategy, which builds upon 5597 Maryland’s sea-level rise response strategy (Johnson, 2000), sets forth specific actions 5598 necessary to protect Maryland’s people, property, natural re sources, and public 5599 investments from the impacts of climate ch ange, sea-level rise, and coastal storms. A 5600 comprehensive strategy and plan of action we re presented to the Maryland’s Governor 5601 and General Assembly in April 2008. 5602 5603 The Maryland Department of Natural Resource s has been active in developing an online 5604 mapping tool for general information and edu cational purposes that provides user-driven 5605 maps for shoreline erosion and for va rious sea-level rise scenarios (see 5606 <http://shorelines.dnr.state.md.us/coastal_h azards.asp#slr>) and has completed case 5607 studies with other agencies (see Box 9.3) for studying implic ation of sea-level rise for 5608 county level planning. Although this particul ar case study did not base results on a 5609CCSP 4.1 January 15, 2009

417 of 784 Final Report numerical storm surge model, it represents the type of initial analyses that local planners 5610 need to undertake. 5611
5612CCSP 4.1 January 15, 2009

418 of 784 Final Report CHAPTER 9 REFERENCES 5613 AGU (American Geophysical Union), 2006: Hurricanes and the U.S. Gulf Coast: 5614 Science and Sustainable Rebuilding . American Geophysical Union, [Washington, 5615 DC], 29 pp. <http://www.agu.org/report/hurricanes> 5616
ASCE (American Society of Civil Engineers), 2006: Flood Resistant Design and 5617 Construction. ASCE/SEI 24-05. American Society of Civil Engineers, Reston, 5618 VA, 61 pp. 5619
ASFPM (Association of State Floodplain Managers), 2003: No Adverse Impact. A 5620 Toolkit for Common Sense Floodplain Management. [Larson, L.A., M.J. Klitzke, 5621 and D.A Brown eds.]. Association of State Floodplain Mana gers, Madison, WI, 5622 108 pp. 5623
ASFPM (Association of State Floodplain Managers), 2007: National Flood Programs 5624 and Policies in Review – 2007 . Association of Stat e Floodplain Managers, 5625 Madison, WI, 92 pp. 5626
ASFPM (Association of State Floodplain Managers), 2008: Coastal No Adverse Impact 5627 Handbook . Association of State Floodpl ain Managers, Madison, WI, 165 pp. 5628 <http://www.floods.org/CNAI/CNAI_Handbook.asp> 5629 Boesch, D.F., J.C. Field, and D. Scavia, (eds.): 2000 . The Potential Consequences of 5630 Climate Variability and Change on Coasta l Areas and Marine Resources: Report 5631 of the Coastal Areas and Marine Re sources Sector Team, U.S. National 5632 Assessment of the Potential Consequen ces of Climate Variability and Change, 5633 U.S. Global Change Research Program . NOAA Coastal Ocean Program decision 5634 analysis series no. 21. NOAA Coastal Ocean Program, Silver Spring, MD, 163 5635 pp. 5636 Coastal States Organization, 2007: The Role of Coastal Zone Management Programs in 5637 Adaptation to Climate Change . CSO Climate Change Work Group, Washington, 5638 DC, 27 pp. 5639CCSP 4.1 January 15, 2009

419 of 784 Final Report <http://www.coastalstates.org/uploads/PDFs/CSO%20Climate%20Change%20Re 5640 port%20-%20Final%2010-1-07.pdf> 5641 Cooper , M.J.P., M.D. Beevers, and M. Oppenheimer, 2005: Future Sea Level Rise And 5642 The New Jersey Coast: Assessing Po tential Impacts and Opportunities. Science, 5643 Technology and Environmental Policy Pr ogram, Woodrow Wilson School of 5644 Public and International Affairs, Pr inceton University, Princeton, NJ, 36 pp. 5645 <http://www.princeton.edu/~cmi/news/ Future%20of%20Sea%20Level%20Rise% 5646 20and%20the%20New%20Jersey%20Coast.pdf> Crowell , M., E. Hirsch, and 5647 T.L. Hayes, 2007: Improving FEMA’s coastal risk assessment through the 5648 National Flood Insurance Program: an historical overview. Marine Technology 5649 Science , 41(1) , 18-27. 5650
CZMA (Coastal Zone Management Act) , 1996: The Coastal Zone Management Act of 5651 1972, as amended through P.L. 104-150, Th e Coastal Zone Protection Act of 5652 1996, 16 U.S.C. § 1451 through 16 U.S.C. § 1465. 5653

FEMA (Federal Emergency Management Agency), 1991: Projected Impact of Relative 5654 Sea-level Rise on the National Flood Insurance Program . Federal Emergency 5655 Management Agency, Washington, DC, 61 pp. 5656

FEMA (Federal Emergency Management Agency), 2002: Guidelines and Specifications 5657 for Flood Hazard Mapping Partners Archive . [web site] Federal Emergency 5658 Management Agency. <http://www.fema.gov/plan/prevent/fhm/gs_arch.shtm> 5659

FEMA (Federal Emergency Management Agency), 2005: Reducing Flood Losses 5660 Through the International Codes, Meeti ng the Requirements of the National 5661 Flood Insurance Program. Federal Emergency Management Agency and 5662 International Code Council, [Washington, DC], 2 nd edition, 156 pp. 5663

FEMA (Federal Emergency Management Agency), 2008: National Flood Insurance 5664 Program Definitions [web page] 5665 <http://www.fema.gov/business/nfip/19def2.shtm> 5666CCSP 4.1 January 15, 2009

420 of 784 Final Report Hagen , S.C., W. Quillian, and R. Garza, 2004: A Demonstration of Real-time Tide and 5667 Hurricane Storm Surge Predictions for the National Weather Service River 5668 Forecast System. Technical report, UCAR Contract No. S01-32794. CHAMPS 5669 Laboratory, University of Central Florida, Orlando. 5670
Heinz Center , 2000: Evaluation of Erosion Hazards. The H. John Heinz III Center for 5671 Science, Economics and the Environment, Washington, DC, 203 pp. 5672 Honeycutt , M.G. and M.N. Mauriello, 2005: Multi-h azard mitigation in the coastal zone: 5673 when meeting the minimum regulat ory requirements isn’t enough: In: Solutions to 5674 Coastal Disasters 2005 , Proceedings of the conference, May 8-11, Charleston, 5675 SC. American Society of Civil Engineers, Reston VA, pp. 713-722. 5676
Hovis , J., W. Popovich, C. Zervas, J. Hubbard, H.H. Shih, and P. Stone, 2004: Effect of 5677 Hurricane Isabel on Water Levels: Data Report . NOAA technical Report NOS 5678 CO-OPS 040. NOAA, Silver Spring, MD, 120 pp. 5679
Jelesnianski , C.P., J. Chen, and W.A. Shaffer, 1992: SLOSH: Sea, Lake, and Overland 5680 Surges from Hurricanes . NOAA technical report NWS 48. National Weather 5681 Service, Silver Spring, MD, 71 pp. 5682

Johnson , Z.P., 2000: A Sea Level Response Strategy for the State of Maryland . Maryland 5683 Department of Natural Resources, Co astal Zone Management Division, 5684 Annapolis, 49 pp. 5685

Larsen , C., I. Clark, G.R. Guntenspergen, D.R. Cahoon, V. Caruso, C. Hupp, and T. 5686 Yanosky, 2004: The Blackwater NWR Inundation M odel. Rising Sea Level on a 5687 Low-lying Coast: Land Use Planning for Wetlands. U.S. Geological Survey open 5688 file report 04-1302. U.S. Geological Survey, Reston, VA. 5689 <http://pubs.usgs.gov/of/2004/1302/> 5690
Luettich , R.A., Jr., J.J. Westeri nk, and N.W. Scheffner, 1992: ADCIRC: An Advanced 5691 Three-dimensional Circulati on Model of Shelves, Coasts and Estuaries, Report 1: 5692 Theory and Methodology of ADCIRC-2DD1 and ADCIRC-3DL . Technical report 5693CCSP 4.1 January 15, 2009

421 of 784 Final Report DRP-92-6. U.S. Army Engineer Waterway s Experiment Station, Vicksburg, MS, 5694 141 pp. 5695 Maryland , 2007: Maryland Executive Order 01.01.2007.07, Commission on Climate 5696 Change. State of Maryland, Executive Department, [Annapolis]. 5697 Maryland , 2008: Climate Action Plan . Maryland Commission on Climate Change and 5698 Maryland Department of Environment, Baltimore, 356 pp. 5699 <http://www.mdclimatechange.us/> 5700

MD DNR (Maryland Department of Natural Re sources), Coastal Zone Management 5701 Program, 2006: Coastal Zone Manageme nt Assessment, Section 309, Assessment 5702 and Strategy. 5703
NOAA (National Oceanic and Atmospheric Administration), 1992: Effects of the Late 5704 October 1991 North Atlantic Extra-Tropical Storm on Water Levels: Data 5705 Report . NOAA National Ocean Service, Rockville, MD, 46 pp. 5706
NOAA (National Oceanic and Atmospheric Administration), 2007: NOAA’s Sea level 5707 Rise Research Program: North Caro lina Managers Meetings Fact Sheet . NOAA 5708 National Centers for Coastal Ocean Science, Silver Spring, MD, 2 pp. 5709 http://www.cop.noaa.gov/stressors/climat echange/current/slr/SLR_manager_hand 5710 out.pdf 5711
NOAA (National Oceanic and Atmospheric Administration), 2008: Glossary of NHC 5712 Terms . NOAA National Weather Service, Nati onal Hurricane Center, Miami, FL. 5713 See defintions for Storm Surge and for Storm Tide. 5714 <http://www.nhc.noaa.gov/aboutgloss.shtml> 5715
Pietrafesa , L.J., E.B. Buckley, M. Peng, S. Bao, H. Liu, S. Peng, L. Xie, and D.A. 5716 Dickey, 2007: On coastal ocean systems, coupled model architectures, products 5717 and services: morphing from observations to operations and applications. Marine 5718 Technology Societyl , 41(1) , 44-52. 5719CCSP 4.1 January 15, 2009

422 of 784 Final Report Poag, C.W., 1997: Chesapeake Bay bolide impact: a convulsive event in Atlantic Coastal 5720 Plain evolution. Sedimentary Geology , 108(1-4) , 45-90. 5721

Reed , D.B. and B.E. Stucky, 2005: Forecasting st orm surge on the Mississippi River. In: 5722 Solutions to Coastal Disasters , Proceedings of the conference, May 8-11, 5723 Charleston, SC. American Society of Ci vil Engineers, Reston, VA, pp. 52-60. 5724 Slovinsky , P.A. and S.M. Dickson, 2006: Impacts of Future Sea Level Rise on the 5725 Coastal Floodplain. MGS open-file 06-14. Maine Geological Survey, Augusta, 5726 ME, [26 pp.] <http://www.maine.gov/doc/nrimc/mgs/explore/marine/sea5727 level/contents.htm> 5728
USACE (U.S. Army Corps of Engineers), 1996: Flood Proofing Techniques, Programs 5729 and References . U.S. Army Corps of Engin eers, Washington, DC, 25 pp. 5730 Worcester County Planning Commission , 2006: Comprehensive Plan, Worcester 5731 County Maryland . Worcester County Commissioners, Snow Hill, MD, 96 pp. 5732 <http://www.co.worcester.md.us/cp/finalcomp31406.pdf> 5733

Zervas , C.E., 2001: Sea Level Variations for the Unites States 1854-1999 . NOAA 5734 technical report NOS CO-OPS 36. NOAA Nati onal Ocean Service, Silver Spring, 5735 MD, 186 pp. <http://tidesandc urrents.noaa.gov/publica tions/techrpt36doc.pdf> 5736

Zervas , C.E., 2005: Extreme Storm Tide Levels of the United States 1897-2004 . Poster 5737 paper presented at NOAA Climate Pr ogram Office, Office of Climate 5738 Observations Annual Meeting, Silver Spring, MD. 5739

5740CCSP 4.1 January 15, 2009

423 of 784 Final Report 

## Part III Overview. Preparing for Sea-Level Rise 5741

5742 Author: James G. Titus, U.S. EPA 5743
5744 For at least the last four centuries, people ha ve been erecting perman ent settlements in the 5745 coastal zone of the Mid- Atlantic without regard to the f act that the sea is rising. Because 5746 the sea has been rising slowly and only a sm all part of the coast was developed, the 5747 consequences have been relatively isolated and manageable. Part I of this Product 5748 suggests, however, that a 2 millimeter pe r year acceleration of sea-level rise could 5749 transform the character of the mid-Atlantic co ast, with a large scale loss of tidal wetlands 5750 and possible disintegration of barrier islands . A 7 millimeter per year acceleration is 5751 likely to cause such a transformation, although shore protectio n may prevent some 5752 developed barrier islands from disintegra ting and low-lying communities from being 5753 taken over by wetlands. 5754 5755 For the last quarter century, scientific asse ssments have concluded that regardless of 5756 possible policies to reduce emi ssions of greenhouse gases, people will have to adapt to a 5757 changing climate and rising sea level. Adap tation assessments differentiate “reactive 5758 adaptation” from “anticipatory adaptation”. 5759 5760 Part III focuses on what might be done to pr epare for sea-level rise . Chapter 10 starts by 5761 asking whether preparing for sea-level rise is even necessary. In many cases, reacting 5762 later is more justifiable than preparing now , both because the rate and timing of future 5763CCSP 4.1 January 15, 2009

424 of 784 Final Report sea-level rise is uncertain and the additional cost of acting now can be high when the 5764 impacts are at least several decades in the future. Nevert heless, for several types of 5765 impacts, the cost of preparing now is very sm all compared to the cost of reacting later. 5766 Examples where preparing can be justified include: 5767

 Coastal wetland protection . It may be possible to re serve undeveloped lands for 5768 wetland migration, but once developed, it is ve ry difficult to make land available for 5769 wetland migration. Therefore, it is far mo re feasible to aid wetland migration by 5770 setting aside land before it is developed, th an to require development to be removed 5771 as sea level rises. 5772

 Some long-lived infrastructure . Whether it is benefici al to design coastal 5773 infrastructure to anticipate rising sea level depends on economic analysis of the 5774 incremental cost of designing for a highe r sea level now, and th e retrofit cost of 5775 modifying the structure at some point in the future. Most long-lived infrastructure in 5776 the threatened areas is sufficiently sensitive to rising sea level to warrant at least an 5777 assessment of the costs and benefits of preparing for rising sea level. 5778

 Floodplain management . Rising sea level increases th e potential disparity between 5779 rates and risk. Even without considering the possibility of accelerated sea-level rise, 5780 the National Academy of Sciences and a Federal Emergency Management Agency 5781 (FEMA)-supported study by the Heinz Ce nter recommended to Congress that 5782 insurance rates should reflect the changing risks resulti ng from coastal erosion. 5783 5784 Chapter 11 discusses organizati ons that are preparing for a possible acceleration of sea5785 level rise. Few organizations responsible for managing coas tal resources vulnerable to 5786CCSP 4.1 January 15, 2009

425 of 784 Final Report sea-level rise have modified their activities. Most of the best exam ples of preparing for 5787 the environmental impacts of sea-level rise are in New England, where several states 5788 have enacted policies to enable wetlands to migrate inland as sea-level rise. Ocean City, 5789 Maryland is an example of a town considering future sea-level rise in its infrastructure 5790 planning. 5791 5792 Chapter 12 examines the institutional barriers that make it difficult to take the potential 5793 impacts of future sea-level rise into account for coastal planning. Although few studies 5794 have discussed the challenge of institutiona l barriers and biases in coastal decision 5795 making, their implications for sea-level rise are relatively straightforward: 5796

 Inertia and short-term thinking . Most institutions ar e slow to take on new 5797 challenges, especially those that require pr eparing for the future rather than fixing a 5798 current problem. 5799

 The interdependence of decisions reinforces institutiona l inertia. In many cases, 5800 preparing for sea-level rise requires a decision as to whether a given area will 5801 ultimately be given up to the sea, protected with structures and drainage systems, or 5802 elevated as the sea rises. Until communities decide which of those three pathways 5803 they will follow in a given area, it is di fficult to determine which anticipatory or 5804 initial response measures should be taken. 5805

 Policies favoring protection of what is currently there . In some cases, longstanding 5806 preferences for shore protect ion (as discussed in Chap ter 6) discourage planning 5807 measures that foster retreat. Because retr eat may require a greater lead time than 5808 shore protection, the presumption that an area will be protected may imply that 5809CCSP 4.1 January 15, 2009

426 of 784 Final Report planning in unnecessary. On the other hand, these preferences may help accelerate 5810 the response to sea-level rise in ar eas where shore protection is needed. 5811

 Policies Favoring Coastal Development . One possible response to sea-level rise is to 5812 invest less in the lands likely to be thr eatened. However, longstanding policies that 5813 encourage coastal development can discour age such a response. On the other hand, 5814 increasingly dense coastal development improves the abili ty to raise funds required 5815 for shore protection. Therefore, policies th at encourage coastal development may be 5816 part of an institutional bias favoring shor e protection, but they are not necessarily a 5817 barrier to responding to sea-level rise. 5818 5819 Although most institutions have not been prep aring for a rising sea, (Chapter 11) , that 5820 may be changing. As these chapters were drafte d, several states have started to seriously 5821 examine possible responses. For example, Mary land enacted a statute to limit the adverse 5822 environmental impact of shore protection stru ctures as sea level rises; and FEMA is 5823 beginning to assess possible cha nges to the National Flood Insu rance Program. It is too 5824 soon to tell whether the increased interest in the consequences of climate change will 5825 overtake—or be thwarted by—the institutional barriers that have discouraged actionuntil 5826

now. 5827 5828 5829CCSP 4.1 January 15, 2009

427 of 784 Final Report 

## Chapter 10. Implications for Decisions 5830

5831 Lead Author : James G. Titus, U.S. EPA 5832 5833 Contributing Author : James E. Neumann, Industrial Economics, Inc. 5834 5835 KEY FINDINGS 5836

 In many cases, it is difficult to determine whether taking a specific action to 5837 prepare for sea-level rise is justified, due to uncertainty in the timing and 5838 magnitude of impacts, and difficulties in quantifying projected be nefits and costs. 5839 Nevertheless, published literature has iden tified some cases where acting now can 5840 be justified. 5841

 Key opportunities for preparing for sea-level rise concern coastal wetland 5842 protection, flood insurance rates, and the lo cation and elevation of coastal homes, 5843 buildings, and infrastructure. 5844

 Incorporating sea-level rise into coas tal wetlands programs can be justified 5845 because the Mid-Atlantic still has subs tantial vacant land onto which coastal 5846 wetlands could migrate as sea level rises. Po licies to ensure that wetlands are able 5847 to migrate inland are likely to be less expensive and more likely to succeed if the 5848 planning takes place before people devel op these dry lands th an after the land 5849 becomes developed. Possible tools include rolling easements, density restrictions, 5850 coastal setbacks, and vegetative buffers. 5851CCSP 4.1 January 15, 2009

428 of 784 Final Report  Sea-level rise does not threaten the fi nancial integrity of the National Flood 5852 Insurance Program. Incorporating sea-level rise into the program, however, could 5853 allow flood insurance rates to more clos ely reflect changing risk and enable 5854 participating local governments to more effectively manage coastal floodplains. 5855

 Long-term shoreline planning is likely to yi eld benefits greater than the costs; the 5856 more sea level rises, the greater the value of that planning. 5857 5858 10.1 INTRODUCTION 5859 Most decisions of everyday life in the coastal zone have little to do with the fact that the 5860 sea is rising. Some day-to-day decisions depend on today’s water levels. For example, 5861 sailors, surfers, and fishermen all consult ti de tables before deciding when to go out. 5862 People deciding whether to evacuate during a storm consider how high the water is 5863 expected to rise above the norma l level of the sea. Yet the fact that the normal sea level is 5864 rising about 0.01 millimeters (mm) per da y does not affect such decisions. 5865 5866 Sea-level rise can have greater impacts on the outcomes of decisions with long-term 5867 consequences. Those impacts do not all warran t doing things differently today. In some 5868 cases, the expected impacts ar e far enough in the future that people will have ample time 5869 to respond. For example, there is little need to anticipate sea-level ri se in the construction 5870 of docks, which are generally rebuilt ever y few decades, because the rise can be 5871 considered when they are rebuilt (NRC, 1987). In other cases, the adverse impacts of sea5872 level rise can be more effec tively addressed by preparing now than by reacting later. If a 5873 dike will eventually be required to protect a community, for example, it can be more cost- 5874CCSP 4.1 January 15, 2009

429 of 784 Final Report effective to leave a vacant right-of-way when an area is developed or redeveloped, rather 5875 than tear buildings down later. 5876 5877 People will have to adapt to a changi ng climate and rising sea level (NRC, 1983; 5878 Hoffman et al. , 1983; IPCC 1990, 1996, 2001, 2007). The previous chapters (as well as 5879 Appendix 1) discuss vulnerable private property and public resources, including 5880 ecosystems, real estate, infrastructure ( e.g. , roads, bridges, parks, playgrounds, 5881 government buildings), and commercial buildings ( e.g. , hotels, office buildings, industrial 5882 facilities). Those responsible for managing thos e assets will have to adapt to changing 5883 climate and rising sea level re gardless of possible efforts to reduce greenhouse gases, 5884 because society has already changed the atmos phere and will continue to do so for at 5885 least the next few decades (NRC, 1983; Hoffman et al. , 1983; IPCC 1990, 1996, 2001, 5886 2007). Some of these assets will be protecte d or preserved in th eir current locations, 5887 while others must be moved inland or be lost. Chapters 6, 8, and 9 examine government 5888 policies that are, in effect, the current response to sea-level rise. Previous assessments 5889 have emphasized the need to distinguish th e problems that can be solved by future 5890 generations reacting to changi ng climate from problems that could be more effectively 5891 solved by preparing today (Titus, 1990; Scheraga and Grambsch, 1998; Klein et al. , 5892 1999; Frankhauser et al ., 1999; OTA 1993). Part III ( i.e ., this Chapter and the next two 5893 chapters) makes that distinction. 5894 5895 This Chapter addresses the question: “Which decisions and activities (if any) have 5896 outcomes sufficiently sensitive to sea-level rise so as to justify doing things differently, 5897 depending on how much the sea is expect ed to rise?” (CCSP, 2006). Doing things 5898CCSP 4.1 January 15, 2009

430 of 784 Final Report differently does not always require novel technologies or land-use mechanisms; most 5899 measures for responding to erosion or floodi ng from sea-level rise have already been 5900 used to address erosion or flooding caused by other factors (see Section 6.1 in Chapter 6). 5901 Section 10.2 describes some categories of deci sions that may be sensitive to sea-level 5902 rise, focusing on the idea that preparing now is not worthwhile unless the expected 5903 present value of the benefits of preparing is greater than the cost. Sections 10.3 to 10.7 5904 examine five issues related to rising sea level: wetland protection, shore protection, long5905 lived structures, elevating home s, and floodplain management. 5906 5907 The examples discussed in this Chap ter focus on activities by governments and 5908 homeowners, not by corporations. Most publis hed studies about responses to sea-level 5909 rise have been funded by governments, with a goal to improve government programs, 5910 communicate risk, or provide technical suppor t to homeowners and small businesses. 5911 Corporations also engage in many of the activit ies discussed in this Chapter. It is possible 5912 that privately funded (and unpublished) strategi c assessments have identified other near5913 term decisions that are sensitive to sea-level rise. 5914 5915 A central premise of this Chapter is that the principles of economics and risk 5916 management provide a useful paradigm for th inking about the implications of sea-level 5917 rise for decision making. In this paradigm, d ecision makers have a well-defined objective 5918 concerning potentially vulnerable coastal re sources, such as maximizing return on an 5919 investment (for a homeowner or investor) or maximizing overall social welfare (for a 5920 government). Box 10.1 elaborates on this analytical framework. Although economic 5921CCSP 4.1 January 15, 2009

431 of 784 Final Report analysis is not the only method for ev aluating a decision, emotions, perceptions, 5922 ideology, cultural values, family ties, and other non-economic factors are beyond the 5923 scope of this Chapter. 5924 5925 This Chapter is not directly tied to specific sea-level rise scenarios. Instead, it considers a 5926 wide range of plausible sea- level rise over periods of time ranging from decades to 5927 centuries, depending on the decision being exam ined. The Chapter does not quantify the 5928 extent to which decisions might be affected by sea-level rise. All discussions of costs 5929 assume constant (infla tion-adjusted) dollars. 5930 5931 BOX 10.1: Conceptual Framework for Decision Making with Sea-Level Rise 5932 5933 This Chapter’s conceptual framew ork for decision making starts with the basic assumption that 5934 homeowners or governments with an interest in coas tal resources seek to ma ximize the value of those 5935 resources to themselves (homeowners) or to the pub lic as a whole (governments), over a period of time 5936 (planning horizon). Each year, coas tal resources provide some value to its owner. In the case of the 5937 homeowner, a coastal property might provide rental income, or it might provide "imputed rent" that the 5938 owner derives from owning the home rather than renting a similar home. The market value of a property 5939 reflects an expectation that property will generate similar income over many years. Because a dollar of 5940 income today is worth more than a dollar in the future , however, the timing of the income stream associated 5941 with a property also affects th e value (see explanation of "discounting" in Section 10.2). 5942 5943 Natural hazards and other risks can al so affect the income a property provides over time. Erosion, hurricane 5944 winds, episodic flooding, and other natural hazards can cause damages that reduce the income from the 5945 property or increase the costs of maintaining it, even without sea-level rise,. These risks are taken into 5946 account by owners, buyers, and sellers of property to the extent that they are known and understood. 5947 5948 Sea-level rise changes the risks to coastal resources, generally by increasing existing risks. This Chapter 5949 focuses on investments to mitigate those additional risks. 5950 5951 In an economic framework, investing to mitigate coastal hazards will only be worthw hile if the cost of the 5952 investment (incurred in the short term) is less than net expected returns (which accrue over the long-term). 5953 Therefore, these investments are more likely to be judged worthwhile when: (1) there is a large risk of near5954 term damage (and it can be effectively reduced); (2) th ere is a small cost to eff ectively reduce the risk; or 5955 (3) the investment shifts the risk to future years. 5956 5957 10.2 DECISIONS WHERE PREPARING FOR SEA-LEVEL RISE IS 5958 WORTHWHILE 5959CCSP 4.1 January 15, 2009

432 of 784 Final Report Sea-level rise justifies changing what peopl e do today if the outcome from considering 5960 sea-level rise has an expected ne t benefit, that is, the benefit is greater than the cost. Thus, 5961 when considering decisions where sea-level ri se justifies doing things differently, one can 5962 exclude from further consideration those d ecisions where either (1) the administrative 5963 costs of preparing are large compared to the im pacts, or (2) the net be nefits are likely to 5964 be small or negative. Few, if any, studies have analyzed the administrative costs of 5965 preparing for sea-level rise. Nevertheless, one can infer that administrative costs exceed 5966 any benefits from preparing for a very small rise in sea level. 25 Most published studies 5967 that investigate which decisi ons are sensitive to sea-le vel rise (IPCC, 1990; NRC 1987; 5968 Titus and Narayanan, 1996) concern decisions whose consequences last decades or 5969 longer, during which time a significant rise in sea level might occur. Those decisions 5970 mostly involve long-lived structures, land- use planning, or infrastructure, which can 5971 influence the location of development for centu ries, even if the structures themselves do 5972 not remain that long. 5973 5974 For what type of decision is a net benef it likely from considering sea-level rise? Most 5975 analyses of this question have focused on cas es where (1) the more sea level rises, the 5976 greater the impact; (2) the impacts will mostly occur in the future and are uncertain 5977 because the precise impact of sea-level ri se is uncertain; and (3) preparing now will 5978 reduce the eventual adverse consequences (see Figure 10.1). 5979 5980

25 Administrative costs ( e.g ., studies, regulations, compliance, trai ning) of addressing a new issue are roughly fixed regardless of how small the impact may be, while the benefits of addressing the issue depend on the magnitude of sea-level rise. Therefore, there would be a point below which the administrative costs would be greater than any benefits from addressing the issue.CCSP 4.1 January 15, 2009

433 of 784 Final Report In evaluating a specific activity, the first que stion is whether preparing now would be 5981 better than never preparing. If so, a second question is whether preparing now is also 5982 better than preparing during some future year. Preparing now to avoi d possible effects in 5983 the future involves two key economic pr inciples: uncertainty and discounting. 5984 5985 Uncertainty

. Because projections of sea-level rise and its precise effects are uncertain, 5986 preparing now involves spending today for the sake of uncertain benefits. If sea level 5987 rises less than expected, then preparing now may prove, in retrospect, to have been 5988 unnecessary. Yet if sea level rises more th an expected, whatever one does today may 5989 prove to be insufficient. That possibility tends to justify waiting to prepare later, if people 5990 expect that a few years later (1) they w ill know more about the threat and (2) the 5991 opportunity to prepare will still be available 26 . Given these reasons to delay, responding 5992 now may be difficult to justify, unless preparing now is either fairly inexpensive, or part 5993 of a “robust” strategy ( i.e. , it works for a wide range of possible outcomes). For example, 5994 if protecting existing development is important, beach nourishment is a robust way to 5995 prepare, because the sand will offset some shore erosion no matter how fast or slow the 5996 sea rises. 5997 5998

26 There is an extensive economic literature on decision-making and planning under uncertainty, particularly where some effects are irreversible. A revi ew of this literature on the topic of "quasi-option value" can be found in Freeman (2003),. Quasi-option va lue arises from the value of information gained by delaying an irreversible decision ( e.g. , to rebuild a structure to withstand higher water levels). In the sealevel rise context, it applies because the costs and bene fits of choosing to retreat or protect are uncertain, and it is reasonable to expect that uncertainty will na rrow over time concerning rates of sea level rise, the effects, how best to respond, and the costs of each response option. Two influential works in this area include Arrow and Fisher (1974) and Fisher and Hanemann (1987); an application to climate policy decisions can be found in Ha-Duong (1998).CCSP 4.1 January 15, 2009

434 of 784 Final Report Discounting

. Discounting is a procedure by which economists determine the “present 5999 value” of something given or received at a future date (U.S. EPA, 2000). A dollar today 6000 is preferred over a dollar in the future, even without inflation (Samuelson and Nordhaus, 6001 1989); therefore, a future dollar must be disc ounted to make costs and benefits received 6002 in different years comparable. Economists ge nerally agree that the appropriate way to 6003 discount is to choose an assumed annual inte rest rate and compound it year-by-year (just 6004 as interest compounds) and use the result to discount future dollars (U.S. EPA, 2000; 6005

C ongressional Research Serv ice, 2003; OMB, 1992; Nor dhaus, 2007a b; Dasgupta, 6006 2007). 6007
6008 Most of the decisions where preparing now has a positive net benefit fall into at least one 6009 of three categories: (1) the n ear-term impact may be large; (2) preparing now costs little 6010 compared to the cost of the possible impact; or (3) preparing now involves options that 6011 reallocate (or clarify) risk. 6012
6013 10.2.1 Decisions that Address Large Near-Term Impacts 6014 If the near-term impact of sea- level rise is large, prepari ng now may be worthwhile. Such 6015 decisions might include: 6016

 Beach nourishment to protect homes that are in imminent danger of being lost. 6017 The cost of beach nourishment is often less than the value of the threatened 6018 structures (USACE, 2000a). 6019CCSP 4.1 January 15, 2009

435 of 784 Final Report  Enhancing vertical accretion (build-up) of wetlands th at are otherwise in danger 6020 of being lost in the near term (Ken tula, 1999; Kussler, 2006). Once wetlands are 6021 lost, it can be costly (or in feasible) to br ing them back. 6022

 Elevating homes that are clearly below the exp ected flood level due to historic 6023 sea-level rise (see Sections 10.6 and 10.7). If elevating the home is infeasible 6024 ( e.g. , historic row houses), flood-proofing walls, doors, and windows may provide 6025 a temporary solution (see Chapter 9). 6026

 Fortifying dikes to the elevation necessary to pr otect from current floods. Because 6027 sea level is rising, dikes that once prot ected against a 100-year storm would be 6028 overtopped by a similar flood on top of today’s higher sea level (see e.g. , IPET, 6029 2006). 6030
6031 10.2.2 Decisions Where Prepar ing Now Costs Little 6032 These response options can be referred to as “low regrets” and “no regrets”, depending 6033 on whether the cost is little or nothing. Th e measures are justifiable, in spite of the 6034 uncertainty about future sea-level rise, becau se little or nothing is invested today, in 6035 return for possibly averting or delaying a serious impact. Examples include: 6036

 Setting a new home back from the sea within a given lot. Setting a home back 6037 from the water can push the eventual damage s from sea-level rise farther into the 6038 future, lowering their expected present value 27 . Unlike the option of not building, 6039 this approach retains almost the entire value of using the pr operty—especially if 6040 nearby homes are also set back so that al l properties retain the complete panorama 6041

27 The present value of a dollar T years in the future is 1/(1+i) T , where i is the interest rate (discount rate) used for the calculations (see Samuelson and Nordhaus, 1989).CCSP 4.1 January 15, 2009

436 of 784 Final Report view of the waterfront—provided that the lot is large enough to build the same 6042 house as would have been built without the setback requirement. 6043

 Building a new house with a higher floor elevation . While elevating an existing 6044 house can be costly, building a new house on pilings one meter (a few feet) higher 6045 only increases the construction co st by about 1 percent (Jones et al ., 2006). 6046

 Designing new coastal drainage systems with larger pipes to incorporate future 6047 sea-level rise . Retrofitting or rebuilding a drainage system can cost 10 to 20 times 6048 as much as including larger pipes in the initial construction (Titus et al. , 1987). 6049

 Rebuilding roads to a higher elevat ion during routine reconstruction. If a road 6050 will eventually be elevated, it is least e xpensive to do so when it is rebuilt for 6051 other purposes. 6052

 Designing bridges and other major facilities. As sea level rises, clearance under 6053 bridges declines, impairing navigation (T RB, 2008). Building the bridge higher in 6054 the first place can be less expe nsive than rebuilding it later. 6055 6056

6057 Figure 10.1 Homes set back from the shore. My rtle Beach, South Ca rolina. (April, 2004 ) 6058CCSP 4.1 January 15, 2009

437 of 784 Final Report 6059 10.2.3 Options That Reallocate or Clar ify Risks from Se a-Level Rise 6060 Instead of imposing an immediate cost to avoid problems that may or may not occur, 6061 these approaches impose a future cost, but only if and when the problem emerges. The 6062 premise for these measures is that current ru les or expectations can encourage people to 6063 behave in a fashion that increases costs more than necessary. People make better 6064 decisions when all of the costs of a decisi on are internalized (Samuelson and Nordhaus, 6065 1989). Changing rules and expectations can avoid some costs, for example, by 6066 establishing today that the eventual costs of sea-level rise will be borne by a property 6067 owner making a decision sensitive to sea-le vel rise, rather than by third parties ( e.g. , 6068 governments) not involved in the decision. Long-term shoreline planning and rolling 6069 easements are two example approaches. 6070
6071 Long-term shoreline planning can redu ce economic or environmental costs by 6072 concentrating development in ar eas that will not eventually have to be abandoned to the 6073 rising sea. People logically invest more al ong eroding shores if th ey assume that the 6074 government will provide subsidized shore pr otection (see Box 10.2) than in areas where 6075 owners must pay for the shore protection or where government rules require an eventual 6076 abandonment. The value to a buyer of that gove rnment subsidy is cap italized into higher 6077 land prices, which can further encourage in creased construction. Identifying areas that 6078 will not be protected can avoid misallocation of both financial and human resources. If 6079 residents wrongly assume that they can exp ect shore protection a nd the government does 6080 not provide it, then real estate prices can decline; in extreme cases, people can lose their 6081CCSP 4.1 January 15, 2009

438 of 784 Final Report homes unexpectedly. People’s liv es and economic investments can be disrupted if dunes 6082 or dikes fail and a community is destroyed. A policy that clearly warn s that such an area 6083 will not be protected (see Section 12.3 in Chapte r 12) could lead owne rs to strategically 6084 depreciate the physical property 28 and avoid some of the none conomic impacts that can 6085 occur after an unexpected relocation (see Section 6.4.1). (see Section 12.3 for further 6086 discussion). 6087
6088
START BOX HERE 6089 BOX 10.2: Erosion, Coastal Programs, and Property Values 6090 6091 Do government shore protection and flood insurance programs increas e property values and encourage 6092 coastal development? Economic theory would lead one to expect that in areas with high land values, the 6093 benefits of coastal development are already high compared to the cost of development, and thus most of 6094 these areas will become developed unless the land is acquired for other purposes. In these areas, 6095 government programs that reduce the cost of maintaining a home should generally be reflected in higher 6096 land values; yet they would not significantly increase development because development would occur 6097 without the programs. By contrast, in marginal areas with low land prices, coastal programs have the 6098 potential to reduce costs enough to make a marginal investment profitable. 6099 6100 Several studies have investigated the impact of flood insurance on development, with mixed results. 6101 Leatherman (1997) examined Nort h Bethany Beach, Delaware, a community with a checkerboard pattern 6102 of lands that were eligible and ineligible for federa l flood insurance due to the Coastal Barrier Resources 6103 Act. He found that ocean-front lots generally sold for $750,000, with homes worth about $250,000. 6104 Development was indistinguishable between areas eligible and ineligible for flood insurance. In the less 6105 affluent areas along the back bays, however, the absence of federal flood insurance was a deterrent to 6106 developing some of the lower priced lots. Most other studies have not explicitly attempted to distinguish 6107 the impact of flood insurance on low- and high-value lands. Some studies ( e.g. , Cordes and Yezer, 1998; 6108 Shilling et al. , 1989) have concluded that the highly subsidized flood insurance policies during the 1970s 6109 increased development, but the actuarial policies sin ce the early 1980s have had no detectable impact on 6110 development. Others have concluded that flood insurance has a minimal impact on development ( e.g. , 6111 GAO 1982; Miller, 1981). The Heinz Center (2000) examined the impacts of the National Flood Insurance 6112 Program (NFIP) and estimated that “the density of stru ctures built within the V Zone after 1981 may be 15 6113 percent higher than it would have been if the NFIP had not been adopted. Howe ver, the expected average 6114 annual flood and erosion damage to these structures dropped close to 35 percent. Thus, overall, the damage 6115 to V Zone structures built after 1981 is between 25 and 30 percent lower than it would have been if 6116 development had occurred at the lower densities, but higher expected damage that would have occurred 6117 absent the NFIP”. A report to the Federal Emergency Management Agency (FEMA) reviewed 36 published 6118 studies and commentaries concerning the impacts of flood insurance on development and concluded that 6119 none of the studies offer irrefutable evidence that the availability, or the lack of availability, of flood 6120 insurance is a primary factor in floodpla in development today (Evatt, 1999, 2000). 6121 6122 Considering shore protection and flood insurance togeth er, The Heinz Center (2000 ) estimated that “in the 6123 absence of insurance and other programs to reduce flood risk, development density would be about 25 6124

28 Yohe et al. (1996) estimated that the nationwide value of “foresight” regarding response to sea-level rise is $20 billion, based largely on the strategic depreciation that foresight makes possible.CCSP 4.1 January 15, 2009

439 of 784 Final Report percent lower in areas vulnerable to storm wavers ( i.e. , V Zones ) than in areas less susceptible to damage 6125 from coastal flooding”. Co rdes and Yezer (1998) modeled the impact on new building permit activity in 6126 coastal areas of shore protection activity in 42 coastal counties, including all of the counties with developed 6127 ocean coasts in New York, New Jersey , Maryland, and Virginia. They did not find a statistically significant 6128 relationship between shore protection and building permits. 6129 6130 The impact of federal programs on property values has not been assessed to the same extent. The Heinz 6131 Center (2000) reported that along th e Atlantic coast, a house with a remaining lifetime of 10 to 20 years 6132 before succumbing to erosion is worth 20 percent less than a home expected to survive 200 years. Landry et 6133 al. (2003) found that property values tend to be higher with wide beaches and low erosion risk. It would 6134 therefore follow that shore protection programs that widen beaches, d ecrease erosion risk, and lengthen a 6135 home’s expected lifetime would increase property values . Nevertheless, estimates of the impact on property 6136 values are complicated by the fact that proximity to the shore increas es the risk of erosion but also 6137 improves access to the beach and views of the water (Bin et al. , 2008). 6138 END BOX 6139 6140 Rolling easements can also reallocate or clar ify the risks of sea-le vel rise, depending on 6141 the pre-existing property rights of a given juri sdiction (Titus, 1998). A rolling easement is 6142 an arrangement under which property owners have no right or expectation of holding 6143 back the sea if their property is threatened. Rolling easements have been implemented by 6144 regulation along ocean and sheltered shores in three New England states (see Section 6145 11.2 in Chapter 11 and along ocean shores in Texas and South Carolina. Rolling 6146 easements can also be implemented as a type of conservation easement, with the 6147 easement donated, purchased at fair market value, or exacted as a permit condition for 6148 some type of coastal development (Titus, 1998). In either case, they prevent property 6149 owners from holding back the sea but otherwis e do not alter what an owner can do with 6150 the property. As the sea advances, the easem ent automatically moves or “rolls” landward. 6151 Without shoreline armoring, sediment tran sport remains undisturbed and wetlands and 6152 other tidal habitat can migrate naturally. Because the dry beach and intertidal land 6153CCSP 4.1 January 15, 2009

440 of 784 Final Report continues to exist, the rolli ng easement also preserves the public’s lateral access right to 6154 walk along the shore 29 ( Matcha versus Mattox , 1986). 6155 6156 Under a rolling easement, the property owner bears all of the risk of sea-level rise. 6157 Without a rolling easement, property owners alon g most shores invest as if their real 6158 estate is sustainable, and then expend re sources—or persuade governments to expend 6159 resources—to sustain the property. The overall effect of the rolling easement is that a 6160 community clearly decides to pur sue retreat instead of shore protection in the future. The 6161 same result could also be accomplished by purchasing (or prohibiting development on) 6162 the land that would potentially be eroded or su bmerged as sea level rises. That approach, 6163 however, would have a large near-term social co st because the coastal land would then be 6164 unavailable for valuable uses. By contrast, rolling easements do not prevent the property 6165 from being used for the next several decad es while the land remains dry. (Even if the 6166 government purchases the rolling easement, the purchase price is a tran sfer of wealth, not 6167 a cost to society 30 .) The landward migration from the rolling easement should also have 6168 lower eventual costs than having the governme nt purchase property at fair market value 6169 as it becomes threatened (Titus, 1991). Propert y owners can strategically depreciate their 6170 property and make other decisi ons that are consistent with the eventual abandonment of 6171 the property (Yohe et al. , 1996; Titus, 1998), efficiently responding to information on 6172

29 Another mechanism for allowing we tlands and beaches to migrate inla nd are setbacks, which prohibit development near the shore. Setbacks can often result in successful “takings” claims if a property is deemed undevelopable due to the se tback line. By contrast, rolling eas ements place no restrictions on development and hence are not constitutional takings (see, e.g. , Titus [1998]). 30 A social cost involves someone losing something of value ( e.g , . the right to develop coastal property) without a corresponding gain by someone else. A wealth transfer involves one party losing something of value with another party gaining something of equal value ( e.g ., the cost of a rolling easement being transferred from the government to a land owner). For additional details, see Samuelson and Nordhaus (1989).CCSP 4.1 January 15, 2009

441 of 784 Final Report sea-level rise as it becomes available. Fi gure 9.1 shows how a ro lling easement might 6173 work over time in an area already devel oped when rolling easements are obtained. 6174

6175 Figure 10.2 The landward migration of wetlands onto property subject to a rolling easement. A rolling 6176 easement allows construction near the shore, but requir es the property owner to recognize nature’s right-of6177 way to advance inland as sea level rises. In the case depicted, the high marsh reaches the footprint of the 6178 house 40 years later. Because the house is on pilings, it can still be occupied (assuming that it is hooked to 6179 a sewerage treatment plant. A flooded septic system would probably fail, because the drainfield must be a 6180 minimum distance above the water table). After 60 years, the marsh has advanced enough to require the 6181 owner to park their car along the street and construc t a catwalk across the front yard. After 80 years, the 6182 marsh has taken over the entire yard; moreover, the footprint of the house is now seaward of mean high 6183 water and hence, on public property. At this point, additional reinvestment in the property is unlikely. 6184 Twenty years later, the particular house has been removed, although other houses on the same street may 6185 still be occupied. Eventually, the entire area returns to nature. A home with a rolling easement would 6186 depreciate in value rather than appreciate like other coasta l real estate. But if the loss is expected to occur 6187 100 years from today, it would only offset the current property value by 1 to 5 percent, which could be 6188 compensated or offset by other permit considerations (Titus, 1998). 6189 6190 6191 10.3 PROTECTING CO ASTAL WETLANDS 6192 The nation’s wetland programs generally protec t wetlands in their current locations, but 6193 they do not explicitly consid er retreating shorelines. As sea level rises, wetlands can 6194CCSP 4.1 January 15, 2009

442 of 784 Final Report adapt by accreting vertically (Chapter 4) a nd migrating inland. Most tidal wetlands are 6195 likely to keep pace with the current rate of s ea-level rise but could become marginal with 6196 an acceleration of 2 millimeters (mm) per year, a nd are likely to be lost if sea-level rise 6197 accelerates by 7 mm per year (see Chapter 4). Although the dry land available for 6198 potential wetland migration or formation is es timated to be less than 20 percent of the 6199 current area of wetlands (see Titus and Wang 2008), these lands could potentially become 6200 important wetland areas in the future. Howe ver, given current policies and land-use 6201 trends, they may not be available for wetland migration and formation (Titus 1998, 6202 2001). Much of the coast is developed or being developed, and those who own developed 6203 dry land adjacent to the wetlands increasingly ta ke measures to prevent the wetlands from 6204 migrating onto their property (see Figure 10.4 and Chapter 6). 6205
6206

6207 Figure 10.3 Coastal Wetlands migrating onto previously dry lowland. Webbs Island, just east of 6208 Machipongo, in Northampton County, Virginia (June, 2007). 6209 6210 6211 6212CCSP 4.1 January 15, 2009

443 of 784 Final Report 6213 Figure 10.4 Wetland Migration thwarted by development an d shore protection. Elevating the land surface 6214 with fill prevents wetlands from migrating into the back yard with a small or modest rise in sea level. The 6215 bulkhead prevents waves from eroding the land, which would otherwise provide sand and other soil 6216 materials to help enable the wetlands to accrete with rising sea level (Monmouth New Jersey, August, 6217 2003). 6218 6219 Continuing the current practice of protecting al most all developed estuarine shores could 6220 reverse the accomplishments of important environmental programs ( e.g. , Titus 1991, 6221 2001, 2005). Until the mid-twentieth century, tid al wetlands were often converted to 6222 dredge-and-fill developments (see Section 6.1.1.2 in Chapter 6 for an explanation of 6223 these developments and their vulnerability to sea-level rise ). By the 1970s, the aggregate 6224 result of the combination of federal and st ate regulations had, for all practical purposes, 6225 halted that practice. Today, most tidal wetla nds in the Mid-Atlantic are off-limits to 6226 development. Coastal states generally prohibit the filling of low marsh, which is publicly 6227 owned in most states under the Publ ic Trust Doctrine (see Section 8.2). 6228 6229 A landowner who wants to fill tidal wetlands on private property must usually obtain a 6230 permit from the U.S. Army Corps of Engineers (USACE) 31 . These permits are generally 6231 not issued unless the facility is inherently water-related, such as a marina 32 . Even then, 6232

31 33 U.S.C. §§ 403, 409, 1344(a) 32 40 C.F.R. § 230.10(a)(3)CCSP 4.1 January 15, 2009

444 of 784 Final Report the owners usually must mitigate the loss of wetlands by creating or enhancing wetlands 6233 elsewhere (U.S. EPA and USACE, 1990). (A ctivities with small impacts on wetlands, 6234 however, are often covered by a nationwide permit, which exempts the owner from 6235 having to obtain a permit [see Section 12.2]). The overall effect of wetland programs has 6236 been to sharply reduce the rate of coastal wetland loss ( e.g. , Stockton and Richardson, 6237 1987; Hardisky and Klemas, 1983) and to pres erve an almost continuous strip of 6238 marshes, beaches, swamps, and mudflats al ong the U.S. coast. If sea-level rise 6239 accelerates, these coastal habitats could be lost by submergence and—in developed areas 6240 where shores are protected—by prevention of their natural inland migration (Reed et al. , 6241 2008), unless future generations use technology to ensure that wetland surfaces rise as 6242 rapidly as the sea (NRC, 2007). 6243
6244 Current approaches would not protect wetlands for future generations if sea level rises 6245 beyond the ability of wetlands to accrete, whic h is likely for most of Chesapeake Bay’s 6246 wetlands if sea level rises 50 centimeters (cm) in the next century, and for most of the 6247 Mid-Atlantic if sea level rises 100 cm (see Figure 4.4). 6248 6249 Current federal statutes are designed to prot ect existing wetlands, but the totality of the 6250 nation’s wetland protection program is the e nd result of decisions made by many actors. 6251 Federal programs discourage destruction of most existing coastal wetlands, but the 6252 federal government does little to allow tidal wetlands to migrate inland (Titus, 2000). 6253 North Carolina, Maryland, New Jersey, and New York own the tidal wetlands below 6254 Mean High Water; and Virginia, Delaware , and Pennsylvania have enough ownership 6255CCSP 4.1 January 15, 2009

445 of 784 Final Report interest under the Public Trus t Doctrine to preserve them (Titus, 1998). However, most 6256 states give property owners a near-universal permit to protect property by preventing 6257 wetlands from migrating onto dry land. Farmer s rarely erect shore protection structures, 6258 but homeowners usually do (Titus, 1998; NRC, 2006). Only a few coastal counties and 6259 states have decided to keep shorefront farms and forests undev eloped, (see Sections 6260 A1.D, A1.E, and A1.F in Appendix 1). G overnment agencies that hold land for 6261 conservation purposes are not purchasing the land or easements necessary to enable 6262 wetlands to migrate inland ( Section 11.2.1 discusses private c onservancies). In effect, the 6263 nation has decided to save its existing wetlands. Yet the overall impact of the decisions 6264 made by many different agenci es is very likely to eliminate wetlands by blocking their 6265 landward migration as a rising sea erodes their outer boundaries. 6266
6267 Not only is the long-term success of wetland prot ection sensitive to se a-level rise, it is 6268 also sensitive to when people decide to prep are. The political and economic feas ibility of 6269 allowing wetlands to take over a given parcel as sea level rises is much greater if 6270 appropriate policies are in place before that property is intensely developed. Many coastal 6271 lands are undeveloped today, but developmen t continues. Deciding now that wetlands 6272 will have land available to migrate inland c ould protect more wetlands at a lower cost 6273 than deciding later (Titus, 1991). In so me places, such policies might discourage 6274 development in areas onto which wetlands ma y be able to migrate. In other areas, 6275 development could occur with the understanding that eventually land will revert to nature 6276 if sea level rises enough to submerge it. As w ith beach nourishment, ar tificially elevating 6277 the surfaces of tidal wetlands would not always require a lead-time of several decades; 6278CCSP 4.1 January 15, 2009

446 of 784 Final Report but developing technologies to elevate the we tlands, and determining whether and where 6279 they are appropriate, could take decades. Fi nally, in some areas, the natural vertical 6280 accretion (build-up) of tidal we tlands is impaired by human activities, such as water flow 6281 management, development that alters draina ge patterns, and beach nourishment and inlet 6282 modification, which thwarts barrier island overwash. In those areas, restoring natural 6283 processes before the wetlands ar e lost is more effective than artificially re-creating them 6284 (U.S. EPA, 1995; U.S. EPA and USACE, 1990; Kruczynski, 1990). 6285
6286 Although the long-term success of the nation’s effo rts to protect wetlands is sensitive to 6287 sea-level rise, most of th e individual decisions that ultimately determine whether 6288 wetlands can migrate inland depend on factors th at are not sensitive to sea-level rise. The 6289 desire of bay-front homeowners to keep thei r homes is strong, and unlikely to diminish 6290 even with a significant accel eration of sea-level rise 33 . State governments must balance 6291 the public interest in tidal wetlands agains t the well-founded expect ations of coastal 6292 property owners that they will not have to yield their property. Only a few states (none in 6293 the Mid-Atlantic) have decided in favor of the wetlands (see Section 11.2.1). Local 6294 government decisions regarding land use reflec t many interests. Objec tives such as near6295 term tax revenues (often by seasonal reside nts who make relatively few demands for 6296 services) and a reluctance to undermine the economic interests of landowners and 6297 commercial establishments are not especially sensitive to rising sea level. 6298 6299

33 See Weggel et al. (1989), Titus et al. (1991), and NRC (2007) for an examination of costs and options for estuarine shore protection.CCSP 4.1 January 15, 2009

447 of 784 Final Report Today’s decentralized decision-making pro cess seems to protect existing coastal 6300 wetlands reasonably well at the current rate of sea-level rise; however, it will not enable 6301 wetlands to migrate inland as sea-level rise continues or accelerates. A large-scale 6302 landward migration of coastal wetlands is very unlikely to occur in most of the Mid6303 Atlantic unless a conscious decision is made for such a migration by a level of 6304 government with authority to do so. Tools fo r facilitating a landward migration include 6305 coastal setbacks, density rest rictions, rolling easements, ve getation buffers, and building 6306 design standards (see Sections 6.1.2 and A1.D , and A1.F in Appendix 1 for further 6307 details). 6308 6309 10.4 SHORE PROTECTION 6310 The case for anticipating sea-level rise as part of efforts to prevent erosion and flooding 6311 has not been as strong as th e case for wetland protection. Less lead time is required for 6312 shore protection than for a planned retrea t and wetland migration (NRC, 1987). Dikes, 6313 seawalls, bulkheads, and revetments can each be built within a few years. Beach 6314 nourishment is an incremental periodic activit y; if the sea rises more than expected, 6315 communities can add more sand. 6316
6317 The U.S. Army Corps of Engineers (USACE) has not evaluated whether sea-level rise 6318 will ultimately require fundamental changes in shore protection; such changes do not 6319 appear to be urgent. Since the early 1990s, USACE has recommended robust strategies: 6320 “Feasibility studies should c onsider which designs are most appropriate for a range of 6321 possible future rates of rise. Strategies that would be appropriate for the entire range of 6322CCSP 4.1 January 15, 2009

448 of 784 Final Report uncertainty should receive preference over thos e that would be optimal for a particular 6323 rate of rise but unsuccessful for other possi ble outcomes” (USACE, 2000a). To date, this 6324 guidance has not significan tly altered USACE’s appro ach to shore protection. 6325 Nevertheless, there is some question as to whether continued b each nourishment would 6326 be sustainable in the future if the rate of se a-level rise accelerates. It may be possible to 6327 double or triple the rate at which USACE nourishes beaches and to elevate the land 6328 surfaces of barrier islands 50 to 100 cm, and thereby enable land surfaces to keep pace 6329 with rising sea level in the next century. Yet continuing su ch a practice indefinitely 6330 would eventually leave back-barrier bays mu ch deeper than today (see Chapter 5), with 6331 unknown consequences for the environment and the barrier islands themselves. Similarly, 6332 it may be possible to build a low bulkhead along mainland shores as sea level rises 50 to 6333 100 cm; however, it could be more challenging to build a tall dike along the same shore 6334 because it would block waterfront views, require continual pumping, and expose people 6335 behind the dike to the risk of flooding should that dike fail (Titus, 1990). 6336
6337 10.5 LONG-LIVED STRUCTURES: SHOU LD WE PLAN NOW OR LATER? 6338 The fact that eventually a la ndowner will either hold back th e sea or allow it to inundate a 6339 particular parcel of land doe s not, by itself, imply that th e owner must respond today. A 6340 community that will not need a dike until th e sea rises 50 to 100 cm has little reason to 6341 build that dike today. Nevert heless, if the land where the dike would eventually be 6342 constructed is vacant now, the prospect of fu ture sea-level rise might be a good reason to 6343 leave that land vacant. A home owner whose house will be inu ndated (or eroded) in 30 to 6344 50 years has little reason to move the house b ack today, but if it is damaged by fire or 6345CCSP 4.1 January 15, 2009

449 of 784 Final Report storms, it might be advisable to rebuild the house on a higher (or more inland) part of the 6346 lot to provide the rebuilt structure a longer lifetime. 6347
6348 Whether one must be concerned about long-term sea-level rise ultimately depends on the 6349 lead time of the response options and on the costs and benefits of acting now versus 6350 acting later. A fundamental premise of cost-b enefit analysis is that resources not yet 6351 deployed can be invested prof itably in another activity and yield a return on investment. 6352 Delaying the response is economically efficien t if the most effective response can be 6353 delayed with little or no additional cost, which is the case with most engineering 6354 responses to sea-level rise. For a given le vel of protection, dikes, seawalls, beach 6355 nourishment, and elevating structures and ro adways are unlikely to cost more in the 6356 future than they cost today (USACE, 2000b, 2007). Moreover, these approaches can be 6357 implemented within the course of a few years. If shore protection is the primary approach 6358 to sea-level rise, respond ing now may not be necessary, with two exceptions. 6359
6360 The first exception could be called the “retrof it penalty” for failure to think long-term. It 6361 may be far cheaper to design for rising sea le vel in the initial desi gn of a new (or rebuilt) 6362 road or drainage system than to modify it later because modifying it later requires the 6363 facility, in effect, to be built twice. For example, in a particular watershed in Charleston, 6364 South Carolina, if sea level rises 30 cm (1 ft ), the planned drainage system would fail and 6365 need to be rebuilt, but it woul d only cost an extra 5 percent to initially design the system 6366 for a 30-cm rise (Titus et al. , 1987). Similarly, bridges are of ten designed to last for 100 6367 years, and although roads are paved every 10 to 20 years, the location of a road may stay 6368CCSP 4.1 January 15, 2009

450 of 784 Final Report the same for centuries. Thus, choices made today about the lo cation and design of 6369 transportation infrastructures can have a large impact on the feasibility and cost of 6370 accommodating rising sea level in the future (TRB, 2008). The design and location of a 6371 house is yet another example. If a house is desi gned to be movable, it can be relocated 6372 away from the shore; but non-moveable houses, such as a brick house on a slab 6373 foundation, could be more problematic. Similarl y, the cost of building a house 10 meters 6374 (m) farther from the shore may be minor if the lot is large enough, whereas the cost of 6375 moving it back 10 m could be s ubstantial (U.S. EPA, 1989). 6376
6377 The second exception concerns the incidental benefits of actin g sooner. If a dike is not 6378 needed until the sea rises 0.5 m, because at that point a 100-year storm would flood the 6379 streets with 1 m of water, the decision to not build the dike today implicitly accepts the 6380 0.5 m of water that such a stor m would provide today. If a dike is built now, it would stop 6381 this smaller flood as well as protect from the larger flood that will eventually occur. This 6382 reasoning was instrumental in leading the Br itish to build the Thames River Barrier, 6383 which protects London. Some peopl e argued that this expensiv e structure was too costly 6384 given the small risk of London flooding, but risi ng sea level implied that such a structure 6385 would eventually have to be built. Hence, the Greater London Council decided to build it 6386 during the 1970s (Gilbert and Horner, 1984). As expected, the barrier closed 88 times to 6387 prevent flooding between 1983 a nd 2005 (Lavery and Donovan 2005). 6388 6389 While most engineering responses can be delayed with little penalty, failure to consider 6390 sea-level rise when making land-use deci sions could be costly. Once an area is 6391CCSP 4.1 January 15, 2009

451 of 784 Final Report developed, the cost of vacating it as the sea ri ses is much greater than that cost would 6392 have been if the area was not developed. Th is does not mean that eventual inundation 6393 should automatically result in placing land off- limits to development. Even if a home has 6394 to be torn down 30 to 50 years hence, it might still be wo rth building. In some coastal 6395 areas where demand for beach access is great an d land values are higher than the value of 6396 the structures, rentals may recover the cost of home construction in less than a decade. 6397 However, once an area is developed, it is unlikely to be abandone d unless either the 6398 eventual abandonment was part of the origin al construction plan, or the owners can not 6399 afford to hold back the sea. Therefore, the mo st effective way to preserve natural shores 6400 is to make such a decision before an ar ea is developed. Because the coast is being 6401 developed today, a failure to deal with this issue now is, in effect, a decision to allow the 6402 loss of wetlands and bay beaches along most areas where development takes place. 6403
6404 Many options can be delayed, because the benef its of preparing for sea-level rise would 6405 still accrue later. Delaying action decreases the present value of the cost of acting and 6406 may make it easier to tailor the response to what is actually necessa ry. Yet delay can also 6407 increase the likelihood that people do not prep are until it is too late. One way to address 6408 this dilemma is to consider the lead times a ssociated with particular types of adaptation 6409 (IPCC CZMG, 1992; O’Callahan, 1994). Emergency beach nourishment and bulkheads 6410 along estuarine shores can be implemented in less than a year. Large-scale beach 6411 nourishment generally takes a few years. Majo r engineering projects to protect London 6412 and the Netherlands took a few decades to plan, gain consensus, and construct ( e.g. , 6413CCSP 4.1 January 15, 2009

452 of 784 Final Report Gilbert and Horner, 1984). To minimize th e cost of abandoning an area, land use 6414 planning requires a lead time of 50 to 100 years (Titus, 1991, 1998). 6415
6416 10.6 DECISIONS BY COASTAL PROP ERTY OWNERS ON ELEVATING 6417 HOMES 6418 People are increasingly eleva ting homes to reduce the risk of flooding during severe 6419 storms and, in very low-lying areas, people are also elevati ng their yards. The cost of 6420 elevating even a small wood-frame cottage on a block foundation is likely to be $15,000 6421 to $20,000; larger houses cost proportionately more (Jones et al ., 2006; FEMA, 1998). If 6422 it is necessary to drill pilings, the cost is higher because the house must be moved to the 6423 side and then moved back onto the pilings. If elevating the home prev ents its subsequent 6424 destruction within a few decades, it will have been worthwhile. At a 5 percent discount 6425 rate, for example, it is worth investing 25 per cent of the value of a structure to avoid a 6426 guaranteed loss 28 years later 34 . In areas where complete de struction is unlikely, people 6427 sometimes elevate homes to obtain lower insura nce rates and to avoi d the risk of water 6428 damages to walls and furniture. The decisi on to elevate involves other factors, both 6429 positive and negative, including better views of the water, increased storage and/or 6430 parking spaces, and greater difficulty for the elderly or disabled to enter their homes. 6431 Rising sea level can also be a motivating f actor when an owner is uncertain about 6432 whether the current risks justify elevating th e house, because rising water levels would 6433

34 i.e ., $25 invested today would be worth $25 x (1.05) 28 = $98 twenty eight years hence. Therefore, it is better to invest $25 today than to f ace a certain loss of $100 28 years hence (see glossary for definition of discount rate).CCSP 4.1 January 15, 2009

453 of 784 Final Report eventually make it necessary to elevate it (unless there is a good chance that the home 6434 will be rebuilt or replace d before it is flooded). 6435
6436 In cases where a new home is being construc ted, or an existing ho me is elevated for 6437 reasons unrelated to sea-level ri se (such as a realization of th e risk of flooding), rising sea 6438 level would justify a higher floor elevati on that would otherwise be the case. For 6439 example, elevating a $200,000 home on pilings to 30cm above the base flood elevation 6440 when the home is built would increase the construction cost by approximately $500-1000 6441 more than building the home at the base flood elevation (Jones et al ., 2006). Yet a 30 cm 6442 rise in sea level would incr ease the actuarial annual fl ood insurance premium by more 6443 than $2000 if the home was not elevat ed the extra 30 cm (NFIP, 2008). 6444 6445 10.7 FLOODPLAIN MANAGEMENT 6446 The Federal Emergency Management Agency (FEMA) works with state and local 6447 governments on a wide array of activities that are potentially sensitiv e to rising sea level, 6448 including floodplain mapping, fl oodplain regulations, flood insurance rates, and the 6449 various hazard mitigation activities that ofte n take place in the aftermath of a serious 6450 storm. Although the outcomes of these activitie s are clearly sensitive to sea-level rise, 6451 previous assessments have focused on coasta l erosion rather than on sea-level rise. 6452 Because implications of sea-level rise a nd long-term erosion overlap in many cases, 6453 previous efforts provide insights on cases wher e the risks of future sea-level rise may 6454 warrant changing the way th ings are done today. 6455 6456CCSP 4.1 January 15, 2009

454 of 784 Final Report 10.7.1 Floodplain Regulations 6457 The flood insurance program requires new or subs tantially rebuilt structures in the coastal 6458 floodplain to have the first floor above the base flood elevation, i.e ., 100-year flood level. 6459 (see Chapter 9). The program vests considerable discre tion in local officials to tailor 6460 specific requirements to local conditions, or to enact regulations that are more stringent 6461 than FEMA’s minimum requirements. Several communities have decided to require floor 6462 levels to be 30 cm (or more) a bove the base flood elevation ( e.g. , Township of Long 6463 Beach, 2008; Town of Ocean City, 1999; see also Box A1.5 in Appendix 1). In some 6464 cases, past or future sea-level rise has been cited as one of the justifications for doing so 6465 (Cape Cod Commission, 2002). There is considerable variation in both the costs and 6466 benefits of designing buildi ngs to accommodate future sea-level rise. If local 6467 governments believe that property owners n eed an incentive to op timally address sea6468 level rise, they can require more stringent ( i.e. , higher) floor elevati ons. A possible reason 6469 for requiring higher floor eleva tions in anticipation of sea-le vel rise (rather than allowing 6470 the owner to decide) is that, under the current structure of th e program, the increased risk 6471 from sea-level rise does not lead to proportionately higher insurance rates (see Section 6472 10.7.3.1) (although rates can rise for other reasons). 6473
6474 10.7.2 Floodplain Mapping 6475 Local jurisdictions have point ed out (see Box A1.6 in Appe ndix 1) that requiring floor 6476 elevations above the base flood elevation to prepare for sea level rise can create a 6477 disparity between property inside and out side the existing 100-year floodplain. 6478 6479CCSP 4.1 January 15, 2009

455 of 784 Final Report Unless floodplain mapping also takes sea-level ri se into account, a building in the current 6480 floodplain would have to be higher than adjace nt buildings on highe r ground just outside 6481 the floodplain (see Figure 10.5). T hus, the ability of local offi cials to voluntarily prepare 6482 for rising sea level is somewhat constraine d by the lack of floodplain mapping that takes 6483 sea-level rise into account. Incorporating s ea-level rise into floodplain maps would be a 6484 low-regrets activity, because it is relatively inexpensive and would enable local officials 6485 to modify requirements where appropriate. 6486
6487

6488 Figure 10.5 Rationale for incorporating sea-level rise into floodplain mapping . In this figure, the (left) 6489 three houses in the existing floodplain have first floor elevations about 80 centimeters (cm) above the level 6490 of the 100-year storm, to account for a projected 50-cm rise in sea le vel and the standard requirement for 6491 floors to be 30 cm above the base flood elevati on. The (right) three homes outside of the regulated 6492 floodplain are exempt from the requ irement. Actual floods, however, do not comply with floodplain 6493 regulations. A 100-year storm on top of the higher sea level would thus flood the buildings to the right 6494 which are outside of today’s floodplain, while the regulated buildings would escape the flooding. This 6495 potential disparity led the city of Baltimore to suggest that floodplain mapping should account for sea level 6496 rise as part of any process to increase the freeboard requirement (see Box A1.7, Section A1.F in Appendix 6497 1). 6498 6499 10.7.3 Federal Flood Insurance Rates 6500 The available reports on the im pacts of rising sea level or shoreline retreat on federal 6501 flood insurance have generally ex amined one of two questions: 6502

 What is the risk to the financial in tegrity of the flood insurance program? 6503

 Does the program discourage policyholders from preparing for sea-level rise by 6504 shielding them from the conse quences of increased risk? 6505CCSP 4.1 January 15, 2009

456 of 784 Final Report No assessment has found that sea-level rise threatens the federal program’s financial 6506 integrity. A 1991 report to Congress by FEMA, for example, concluded that there was 6507 little need to change the Flood Insurance Progr am because rates would be adjusted as sea 6508 level rises and flood maps are revised (FEM A, 1991). Nevertheless, the current rate 6509 structure can discourage some policyholders fr om preparing for increases in flood risks 6510 caused by sea-level rise, shore erosion, and other environmental changes. For new and 6511 rebuilt homes, the greater risks from sea-leve l rise cause a roughly proportionate increase 6512 in flood insurance premiums. For existing hom es, however, the greater risks from sea6513 level rise cause premiums to rise much le ss than proportionately, a nd measures taken to 6514 reduce vulnerability to sea-level rise do not necessarily cause rates to decline. 6515 6516 Flood insurance policies can be broadly divided into actuarial and s ubsidized. “Actuarial” 6517 means that the rates are designed to cover the expected costs; “subsidized” means that the 6518 rates are designed to be less than the cost, with the govern ment making up the difference. 6519 Most of the subsidized policies apply to “p re-FIRM” construction, that is, homes that 6520 were built before the Flood Insurance Ra te Map (FIRM) was adopted for a given 6521 locality 35 ; and most actuarial policies are for pos t-FIRM construction. Nevertheless, there 6522 are also a few small classes of subsidized policies for post-FIRM construction; and some 6523 owners of pre-FIRM homes pay actuarial ra tes. The following subs ections discuss these 6524 two broad categories in turn. 6525 6526 10.7.3.1 Actuarial (Post-FIRM) Policies 6527

35 Flood Insurance Rate Maps display the flood hazards of particular locations for purposes of setting flood insurance rates. The maps do not show flood insura nce rates (see Chapter 9 for additional details).CCSP 4.1 January 15, 2009

457 of 784 Final Report Flood Insurance Rate Maps show various hazar d zones, such as V (wave velocity) Zone, 6528 A (stillwater flooding during a 100-year st orm) Zone and the “shaded X Zone” 36 6529 (stillwater flooding during a 500-year storm) (see Chapter 9). These zones are used as 6530 classes for setting rates. The post-FIRM classe s pay actuarial rates. For example, the total 6531 premiums by all post-FIRM policyholders in the A Zone equals FEMA’s estimate of the 6532 claims and administrative costs for the A Zone 37 . Hypothetically, if sea-level rise were to 6533 double flood damage claims in the A Zone, then flood insurance premiums would double 6534 (ignoring administrative costs) 38 . Therefore, the impact of sea-level rise on post-FIRM 6535 policy holders would not threaten the program’s financial integrity under the current rate 6536

structure. 6537 6538 The rate structure can, however, insulate property owners from the effects of sea-level 6539 rise, removing the market signal 39 that might otherwise induce a homeowner to prepare or 6540 respond to sea-level rise. Although shoreline erosion and rising sea level increase the 6541 expected flood damages of a given home, the increased risk to a specific property does 6542 not cause the rate on that specific propert y to rise. Unless a home is substantially 6543

36 The shaded X Zone was formerly known as the B Zone. 37 Owners of pre-FIRM homes can also pay the actuari al rate, if it is less than the subsidized rate. 38 The National Flood Insurance Program (NFIP) modifies flood insurance rates every year based on the annual “Actuarial Rate Review”. Rates can either be increased, decreased, or stay the same, for any given flood insurance class. The rates for post-FIRM polic ies are adjusted based on the risk involved and accepted actuarial principals. As part of this rate ad justment, hydrologic models are used to estimate loss exposure in flood-prone areas. These models are rerun ev ery year using the latest hydrologic data available. As such, the models incorporate the retrospective effects of sea level rise. The rates for pre-FIRM (subsidized) structures are also modi fied every year based in part on a determination of what is known as the “Historical Average Loss Year”. The goal of the NF IP is for subsidized policyholders to pay premiums that are sufficient, when combined with the premium paid by actuarially priced (post-FIRM) policyholders, to provide the NFIP sufficient revenue to pay losses associated with the historical average loss year. 39 In economics, “market signal” refers to inform ation passes indirectly or unintentionally between participants in a market. For example, higher flood insurance rates convey the information that a property is viewed as being riskier than previously thought.CCSP 4.1 January 15, 2009

458 of 784 Final Report changed, its assumed risk is grandfathered 40 , that is, FEMA assumes that the risk has not 6544 increased when calculating the flood insurance rate ( e.g. , NFIP, 2007; Heinz Center, 6545 2000) 41 . Because the entire class pays an act uarial rate, the gr andfathering causes a 6546 “cross-subsidy” between new or rebuilt homes and the older grandfathered homes. 6547 6548 Grandfathering can discourage property owne rs from either anticip ating or responding to 6549 sea-level rise. If anticipated risk is likely to increase, for example, by about a factor of 10 6550 and a total loss would occur eventually ( e.g. , a home on an eroding shore), grandfathering 6551 the assumed risk may allow the policy holder to secure compensation for a total loss at a 6552 small fraction of the cost of that loss. For instance, a $250,000 home built to base flood 6553 elevation in the A Zone would typically pay about $900 per year (NFIP, 2008); but if 6554 shore erosion left the property in the V Zone , the annual rate would rise to more than 6555 $10,000 (NFIP, 2008) 42 , if the property was not grandfathered. Under such 6556 circumstances, the $9,000 difference in eventu al insurance premiums might be enough of 6557 a subsidy to encourage owners to build in locations more hazardous than where they 6558 might have otherwise built had they anticipated that they would bear the entire risk ( cf. 6559

40 Under the NFIP grandfathering policy, whenever FEMA revises the flood risk maps used to calculate the premium for specific homes, a policy holder can choose between the new map and the old map, whichever results in the lower rate (NFIP, 2007). 41 Although rates for individual policies may be grandfathered, rates for the entire A or V Zone (or any flood zone) can still increase each year up to a maxi mum of 10 percent; therefore a grandfathered policy may still see annual rate increases. For example, a pos t-FIRM structure might be originally constructed in an A Zone at 30 cm (1 ft) above base flood elevation. If shore erosion, sea-level rise, or a revised mapping procedure leads to a new map that shows the same property to be in the V Zone and 60 cm (2 ft) below base flood elevation, the policy holder can continue to pay as if the home was 30 cm above base flood elevation in the A Zone. However, the entire class of A Zone rates could still increase as a result of annual class-wide rate adjustments based on the annual “Act uarial Rate Review”. Those class-wide increases could be caused by long-term erosion, greater flooding from sea-level rise, increased storm severity, higher reconstruction or administrative costs, or any other factors that increase the cost of paying claims by policyholders. 42 This calculation assumes a storm-wave height adjustment of 90 cm and no sea-level rise (see NFIP, 2008).CCSP 4.1 January 15, 2009

459 of 784 Final Report Heinz Center, 2000). For homes built in the A Zo ne, the effect of gr andfathering is less, 6560 but still potentially si gnificant (see Figure 10.6). 6561 6562 Grandfathering can also remove the incentive to respond as sea level rises. Consider a 6563 home in the A Zone that is or iginally 30 cm (about 1 ft) above the base flood elevation. If 6564 sea level rises 30 to 90 cm (almost 1 to 3 ft), then the actuarial rates would typically rise 6565 by approximately two to ten times the orig inal amount (NFIP, 2008), but because of 6566 grandfathering, the owners would continue to pay the same premium. Therefore, if the 6567 owner were to elevate the home 30 to 90 cm, the insurance premium would not decline 6568 because the rate already assumes that the home is 30 cm above the flood level (see the 6569 bottom four panels of Figure 10.6). 6570 6571CCSP 4.1 January 15, 2009

460 of 784 Final Report 6572 6573 Figure 10.6 Impact of grandfathering and floor elevation on flood insurance rates in the A Zone as sea 6574 level rises. Without grandfathering, a 90-centimeter (cm) rise in sea level would increase the flood 6575 insurance rate from $355 to $4720, for a home built 60 cm above today’s 100-year flood elevation (left 6576 column); if the home is built 150 cm above the 100-year flood, sea level rise increases the rate from $280 to 6577 $355. Elevating the house 90 cm after sea level rise lowers the rate to what it had been originally, Thus, if 6578 the 90 cm rise is expected during the owner’s planning horizon, there would be a significant incentive to 6579 either build the house higher or el evate it later. With grandfathering , however, sea-level rise does not 6580 increase the rate and elevating the home later does no t reduce the rate. Thus, grandfathering reduces the 6581 incentive to anticipate sea level rise or react to it after the fact. 6582 Caveat : The numerical example is based on rates published in NFIP (2008), Table 3B, and does not include 6583 the impact of the annual changes in the rate struct ure. Such rate changes wo uld complicate the numerical 6584 illustration, but would not fundamentally alter the incentives illustrated, because the annual rate changes 6585 are across-the-board within a given class. For exampl e, if rates increased by 50 percent by the time sea 6586 level rises 90 cm, then all of the premiums shown in the bottom four boxes would rise 50 percent. 6587 6588CCSP 4.1 January 15, 2009

461 of 784 Final Report 6589 The importance of grandfathering is sensitive to the rate of sea-level rise. At the current 6590 rate of sea-level rise (3 mm per year), mo st homes would be rebui lt (and thus lose the 6591 grandfathering benefit) before the 100 to 300 ye ars it takes for the sea to rise 30 to 90 cm. 6592 By contrast, if sea level rises 1 cm per year , this effect would onl y take 30 to 90 years— 6593 and many coastal homes survive that long. 6594 6595 Previous assessments have examined this issue (although they were focused on shoreline 6596 erosion from all causes, rather than from sea-level rise). The National Academy of 6597 Sciences (NAS) has recommended that the Flood Insurance Program create mechanisms 6598 to ensure that insurance rates reflect the increased risks caused by long-term coastal 6599 erosion (NAS, 1990). NAS pointed out that Congress has explicitly included storm6600 related erosion as part of the damages covered by flood insurance (42 U.S.C. §4121), and 6601 that FEMA’s regulations (44 CFR Part 65.1) have already defined special “erosion 6602 zones”, which consider stor m-related erosion (NAS, 1990) 43 . A FEMA-supported report 6603 to Congress by The Heinz Center (2 000) and a theme issue in the Journal of Coastal 6604 Research (Crowell and Leatherman, 1999) also c oncluded that, because of existing long6605 term shore erosion, there can be a substantia l disparity between actual risk and insurance 6606

rates. 6607
6608

43 Note that: (1) the NFIP insures against damages caused by flood-related-erosion; (2) the probability of flood-related erosion is considered in defining the la ndward limit of V Zones; and (3) flood insurance rates in the V Zone are generally much higher than A Zone ra tes. Part of the reason fo r this is consideration of the potential for flood-related erosion.CCSP 4.1 January 15, 2009

462 of 784 Final Report Would sea-level rise justify changing the current approach? Two possible alternatives 6609 would be to (1) shorten the period during whic h the assumed risk is kept fixed so that 6610 rates can respond to risk and property owners can respond, or (2) lengthen the duration of 6611 the insurance policy to the peri od of time between risk calcul ations, that is, instead of 6612 basing rates on the risk when the house is built, which tends to increasingly 6613 underestimate the risk, base the rate on an estima te of the average risk over the lifetime of 6614 the structure, using “erosion-ha zard mapping” with assumed ra tes of sea-level rise, shore 6615 erosion, and structure lifetime. Both of th ese alternatives address changing risk by 6616 estimating risk over a time horizon equal to the period of time between risk recalculation. 6617 The erosion-hazard mapping approach has received considerable attention; the Heinz 6618 Center study also recommended that C ongress authorize erosion-hazard mapping. 6619 Although Congress has not provided FEMA with authority to base rates on erosion 6620 hazard mapping, FEMA has raised rates in the V Zone by 10 percent per year (during 6621 most years) as a way of an ticipating the increased flood da mages resulting from the long6622 term erosion that The Heinz Center evaluated (Crowell et al. , 2007). 6623
6624 The Heinz Center study and recent FEMA efforts have assumed current rates of sea-level 6625 rise. FEMA has not investigated whether a ccelerated sea-level rise would increase the 6626 disparity between risks and insurance rates enoug h to institute additional changes in rates; 6627 nor has it investigated the op tion of relaxing the grandfathe ring policy so that premiums 6628 on existing homes rise in propor tion to the increasing risk. Nevertheless, the Government 6629 Accountability Office (2007) recently reco mmended that FEMA analyze the potential 6630 long-term implications of climate change for the National Flood Insurance Program 6631CCSP 4.1 January 15, 2009

463 of 784 Final Report (NFIP). FEMA agreed to undertake such a study (Buckley, 2007) and initiated it in 6632 September 2008 (Department of Homeland Security, 2008). 6633
6634 10.7.3.2 Pre-FIRM and other Subsidized Policies 6635 Since the 1970s, the flood insu rance program has provided a subsidized rate for homes 6636 built before the program was implemented, that is, before the release of the first flood 6637 insurance rate map for a given location (Hayes et al. , 2006). The premium on a $100,000 6638 home, for example, is generally $650 and $1170 for the A and V Zones, respectively— 6639 regardless of how far above or below the base flood elev ation the structure may be 6640 (NFIP, 2008). Not all pre-FIRM homes obtain th e subsidized policy. The subsidized rate 6641 is currently greater than the ac tuarial rate in the A and V Zone s for homes that are at least 6642 30 cm and 60 cm, respectively, above the base flood elevation (NFIP, 2008). But the 6643 subsidy is substantial for homes that are below the base flood elevation. Homes built in 6644 the V Zone between 1975 and 1981 also receive a subsidized rate; which is about $1500 6645 for a $100,000 home built at the base flood elevation (NFIP, 2008). 6646
6647 Does sea-level rise justify changing the rate structure for subsidized policies? Economics 6648 alone can not answer that que stion because the subsidies ar e part of the program for 6649 reasons other than risk management and ec onomic efficiency, such as the original 6650 objective of providing communities with an in centive to join the NFIP and the policy 6651 goal of not pricing people out of their homes (Hayes et al. , 2006). Moreover, the 6652 implications depend in large measure on whether the NFIP responds to increased 6653 damages from sea-level rise by increasing prem iums or the subsidy, a question that rests 6654CCSP 4.1 January 15, 2009

464 of 784 Final Report on decisions that have not yet been made. Sea- level rise elevates th e base flood elevation; 6655 and the subsidized rate is the same regardle ss of how far below the base flood elevation a 6656 home is built. Considering those factors alone, sea-level rise increases expected damages, 6657 but not the subsidized rate. However, the NFIP sets the subsidized rates to ensure that the 6658 entire program covers its costs du ring the average non-catastrophic year 44 . Therefore, if 6659 total damages (which include inland flooding) rise by the same proportion as damages to 6660 subsidized policies, the subsidized portion would stay the same as sea level rises. 6661
6662 FEMA has not yet quantified whether climate ch ange is likely to increase total damages 6663 by a greater or smaller proportion than the in crease due to sea-leve l rise. Without an 6664 assessment of whether the subsidy would increa se or decrease, it would be premature to 6665 conclude that sea-level rise warrants a change in FEMA’s ra te structure. Nevertheless, 6666 sea-level rise is unlikely to threaten the financial integrity of the flood insurance program 6667 as long as subsidized rate s are set high enough to cover claims during all but the 6668 catastrophic loss years, and Congress con tinues to provide th e program with the 6669 necessary funds during the catastrophic year s. Because the pre-FIRM subsidies only 6670 apply to homes that are several decade s old, they do not encourage hazardous 6671 construction. As with grandfathering, the s ubsidized rate discourages owners of homes 6672 below the base flood elevation from elevati ng or otherwise reducing the risk to their 6673 homes as sea level rises, because the premiu m is already as low as it would be from 6674 elevating the home to th e base flood elevation 45

. 6675

44 The year 2005 (Hurricanes Katrina, Rita, and Wilma) is excluded from such calculations. 45 Pre-FIRM owners of homes a few feet below the base flood elevation could achieve modest saving by elevating homes a few feet above the base flood elevation; but those savings are small compared to the savings available to the owner of a post-FIRM home at the same elevation relative to base flood elevation.CCSP 4.1 January 15, 2009

465 of 784 Final Report 6676 The practical importance of the pre-FIRM subsid y is sensitive to the future rate of sea6677 level rise. Today, pre-FIRM policies account for 24 percent of all policies (Hayes et al. , 6678 2006). However, that fracti on is declining (Crowell et al. , 2007) because development 6679 continues in coastal floodplains, and because the total number of homes eligible for pre6680 FIRM rates is declining, as homes built befo re the 1970s are lost to fire and storms, 6681 enlarged, or replaced with larger homes. A subs tantial rise in sea level over the next few 6682 decades would affect a large class of subsidized policy holders by the year 2100. 6683 Nevertheless, the portion of pre-FIRM houses is likely to be very small, unless there is a 6684 shift in the factors that have caused people to replace small cottage s with larger houses 6685 and higher-density development (see Section 12.2.3). 6686
6687 Two other classes, which together account for 2 percent of policies, also provide 6688 subsidized rates. The A99 Zone consists of ar eas that are currently in the A Zone, but for 6689 which structural flood protection such as dikes are at least 50 percent complete. 6690 Policyholders in such areas pay a rate as if the structural protecti on was already complete 6691 (and successful). The AR Zone presents the opp osite situation: locations where structural 6692 protection has been decertified. Provided that the structures are on a schedule for being 6693 rebuilt, the rates are set to the rate that appl ies to the X Zone or the pre-FIRM subsidized 6694 rate, whichever is less. As sea level rises, the magnitude of these subsidies may increase, 6695 both because the base flood elevations (wit hout the protection) will be higher, and 6696 because more coastal lands may be protected with dikes and other structural measures. 6697 Unlike the pre-FIRM subsidies, the A99 and AR Zone subsidies may encourage 6698CCSP 4.1 January 15, 2009

466 of 784 Final Report construction in hazardous ar eas; but unlike other subsidie s, the A99 and AR Zone 6699 subsidies encourage protection measures that reduce hazards. 6700
6701 10.7.4 Post-Disaster Hazard Mitigation 6702 If a coastal community is ultimately going to be abandoned to the rising sea, a major 6703 rebuilding effort in the current location ma y be less useful than expending the same 6704 resources to rebuild the community on higher ground. On the other hand, if the 6705 community plans to remain in its current lo cation despite the increasing costs of shore 6706 protection, then it is important for peopl e to understand that commitment. Unless 6707 property owners know which path the commun ity is following, they do not know whether 6708 to reinvest. Moreover, if the community is go ing to stay in its current location, owners 6709 need to know whether their land will be prot ected with a dike or if land surfaces are 6710 likely to be elevated ove r time (see Section 12.3). 6711
6712 10.8 CONCLUSIONS 6713 The need to prepare for rising sea level de pends on the length of time over which the 6714 decision will continue to have consequences; how sensitive those consequences are to sea 6715 level; how rapidly the sea is expected to ri se and the magnitude of uncertainty over that 6716 expectation; the decision maker’s risk tole rance; and the implications of deferring a 6717 decision to prepare. Considering sea-level rise may be important if the decision has 6718 outcomes over a long period of time and concerns an activity that is sensitive to sea level, 6719 especially if what can be done to prepare today would not be feasible later. Those making 6720 decisions with outcomes over a short period of time concerning activities that are not 6721CCSP 4.1 January 15, 2009

467 of 784 Final Report sensitive to sea level probably need not cons ider sea-level rise, especially if preparing 6722 later is as effective as preparing today. 6723
6724 Instances where the existing l iterature provides an economic rationale for preparing for 6725 accelerated sea-level rise include: 6726

 Coastal wetland protection . Wetlands and the success of wetland-protection 6727 efforts are almost certainly sensitiv e enough to sea-level rise to warrant 6728 examination of some changes in coastal wetland protection efforts, assuming that 6729 the objective is to ensure that most estu aries that have extensive wetlands today 6730 will continue to have tidal wetlands in the future. Coastal wetlands are sensitive to 6731 rising sea level, and many of the possible m easures needed to ensure their survival 6732 as sea level rises are least disruptive with a lead time of several decades. Changes 6733 in management approaches would likely involve consideration of options at 6734 various levels of authority. 6735

 Coastal infrastructure . Whether it is beneficial to de sign coastal infrastructure to 6736 anticipate rising sea level depends on the ratio of the incremental cost of 6737 designing for a higher sea leve l now, compared with the re trofit cost of modifying 6738 the structure later. No general statement is possible because this ratio varies and 6739 relatively few engineering assessments of the question have been published. 6740 However, because the cost of analyzing th is question is very small compared with 6741 the retrofit cost, it is likely that most long- lived infrastructure in the coastal zone 6742 is sufficiently sensitive to rising sea level to warrant an analysis of the 6743 comparative cost of designing for higher water levels now and re trofitting later. 6744CCSP 4.1 January 15, 2009

468 of 784 Final Report  Building along the coast. In general, the economics of coastal development alone 6745 does not currently appear to be sufficientl y sensitive to sea-level rise to avoid 6746 construction in coastal areas. Land values are so high that development is often 6747 economic even if a home is certain to be lost within a few decades. The optimal 6748 location and elevation of new homes may be sensitive to how rapidly sea level is 6749 expected to rise. 6750

 Shoreline planning. A wide array of measures fo r adapting to rising sea level 6751 depend on whether a given area will be elev ated, protected with structures, or 6752 abandoned to the rising sea. Several studies have shown that in those cases where 6753 the shores will retreat and structures w ill be removed, the economic cost will be 6754 much less if people plan for that retr eat. The human toll of an unplanned 6755 abandonment may be much grea ter than if people graduall y relocate when it is 6756 convenient to do so. Conversely, people ma y be reluctant to invest in an area 6757 without some assurance that lands will not be lost to the sea. Therefore, long-term 6758 shoreline planning is generally justified and will save more than it costs; the more 6759 the sea ultimately rises, the grea ter the value of that planning. 6760

 Rolling easements, density rest rictions, and coastal setbacks. Several studies have 6761 shown that, in those cases where the shor es will retreat and structures will be 6762 removed, the economic cost will be much less if people plan for that retreat. 6763 Along estuaries, a retreat in developed area s rarely occurs and thus is likely to 6764 only occur if land remains lightly developed. It is very likely that options such as 6765 rolling easements, density restrictions, coastal setbacks, and vegetative buffers, 6766 would increase the ability of wetla nds and beaches to migrate inland. 6767CCSP 4.1 January 15, 2009

469 of 784 Final Report  Floodplain management: Consideration of reflecting actual risk in flood 6768
insurance rates. Economists and other commentators generally agree that 6769 insurance works best when the premiums reflect the actual risk. Even without 6770 considering the possibility of accelerated sea-level rise, the National Academy of 6771 Sciences (NAS, 1990) and a FEMA-suppor ted study by The Heinz Center (2000) 6772 concluded and recommended to Congress th at insurance rates should reflect the 6773 changing risks resulting from coastal erosion. Rising sea level increases the 6774 potential disparity between rates a nd risks of storm-related flooding. 6775
6776CCSP 4.1 January 15, 2009

470 of 784 Final Report CHAPTER 10 REFERENCES 6777 * Indicates non-peer reviewed literature; available upon request 6778 6779
Arrow , K.J. and A.C. Fisher, 1974: Envir onmental preservation, uncertainty, and 6780 irreversibility. Quarterly Journal of Economics, 88(1) , 312-319. 6781

Bin , O., T. Crawford, J.B. Kruse, and C.E. Landry, 2008: Viewscapes and flood hazard: 6782 coastal housing market response to amenities and risk. Land Economics, 84(3) , 6783 434-448. 6784 Buckley , M., 2007: Testimony of Michael Buckley, U.S. Senate Committee on 6785 Homeland Security and Government Affairs, April 19, 2007. 6786 Cape Cod Commission , 2002: Model Floodplain District Bylaw . Cape Cod 6787 Commission, Barnstable, MA, section 06.1. 6788 <http://www.capecodcommissi on.org/bylaws/floodplain.html> 6789
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. [Power, 6794 K. (analyst)]. RL31976. Congressional Research Service, Washington, DC, 26 pp. 6795
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Crowell , M. and S.P. Leatherman (eds.) , 1999: Coastal erosion mapping and 6799 management. Journal of Coastal Research , Special Issue 28 , 196 pp. 6800
Crowell , M., E. Hirsch, and T.L. Hayes, 2007: Improving FEMA’s coastal risk 6801 assessment through the National Flood Insurance Program: an historical 6802 overview. Marine Technology Society Journal , 41( 1) , 18-27. 6803CCSP 4.1 January 15, 2009

471 of 784 Final Report Dasgupta , P., 2007: Commentary: Th e Stern Review’s economics of climate change. 6804 National Institute Economic Review , 199 , 4-7. 6805 Department of Homeland Security , 2008: Impact of Climate Change on the National 6806 Flood Insurance Program . Solicitation number HSFEHQ-08-R-0082. 6807 <http://www.FedBizOpps.gov> 6808

Evatt , D.S., 1999: National Flood Insurance Program: Issues Assessment . Federal 6809 Emergency Management Agency, Washington, DC, 123 pp. 6810

Evatt , D.S., 2000: Does the national flood insura nce program drive floodplain 6811 development? Journal of Insurance Regulation , 18(4) , 497-523. 6812

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Gilbert , S. and R. Horner, 1984: The Thames Barrier . Thomas Telford, London, 182 pp. 6823 GAO ( General Accounting Office), 1982: National Flood Insurance: Marginal Impact 6824 on Floodplain Development, Administrative Improvements Needed . Report to the 6825 Subcommittee on Consumer Affairs, Committee on Banking, Housing, and Urban 6826 Affairs, U.S. Senate. General Acc ounting Office, Washington, DC, 59 pp. 6827CCSP 4.1 January 15, 2009

472 of 784 Final Report GAO (Government Accountability Office), 2007: Climate Change: Financial Risks to 6828 Federal and Private Insurers in Comi ng Decades are Potentially Significant

. 6829 GAO-07-285. Government Accountability Office, Washington DC, 68 pp. 6830 <http://www.gao.gov/new.items/d07285.pdf> 6831 Ha-Duong , M., 1998: Quasi-option value and climate policy choices. Energy Economics , 6832 20(5/6) , 599-620. 6833 Hardisky , M.A. and V. Klemas, 1983: Tidal we tlands natural and human-made change 6834 from 1973 to 1979 in Delaware: mapping techniques and results. Environmental 6835 Management , 7(4) , 339-344. 6836 Hayes , T.L., D.R. Spaffor d, and J.P. Boone, 2006: Actuarial Rate Review . National 6837 Flood Insurance Program, Washington DC, 34 pp. 6838 <http://www.fema.gov/library/viewRecord.do?id=2363> 6839
Heinz Center , 2000: Evaluation of Erosion Hazards. The H. John Heinz III Center for 6840 Science, Economics, and the E nvironment, Washington, DC, 252 pp. 6841 <http://www.heinzctr.org/publica tions.shtml#erosionhazards> 6842
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473 of 784 Final Report [Houghton, J.J., L.G. Meiro Filho, B.A. Ca llander, N. Harris, A. Kattenberg, and 6855 K. Maskell (eds.)]. Cambridge Universi ty Press, Cambridge, UK, and New York, 6856 572 pp. 6857
IPCC (Intergovernmental Panel on Climate Change), 2001: Climate Change 2001: The 6858 Scientific Basis. Contribution of Working Group I to the Third Assessment Report 6859 of the Intergovernmental Panel on Clim ate Change [Houghton, J.T., Y. Ding, D.J. 6860 Griggs, M. Noguer, P.J. van der Linden, X. Dai, K. Maskell, and C.A. Johnston 6861 (eds.)]. Cambridge University Pre ss, Cambridge, UK, and New York, 881 pp. 6862
IPCC (Intergovernmental Panel on Climate Change), 2007: Climate Change 2007: The 6863 Physical Science Basis. Contribution of Working Group I to the Fourth 6864 Assessment Report of the Intergovernment al Panel on Climate Change [Solomon, 6865 S., D. Qin, M. Manning, Z. Chen, M. Mar quis, K.B. Averyt, M. Tignor, and H.L. 6866 Miller (eds.)]. Cambridge University Press, Cambridge, UK, and New York, 996 6867 pp. 6868
IPCC CZMS (Intergovernmental Panel on Climate Change Coastal Zone Management 6869 Subgroup), 1992: Global Climate Change and the Rising Challenge of the Sea. 6870 IPCC Response Strategies Working Gr oup, Rijkswaterstaat, The Hague, the 6871 Netherlands. 6872

IPET (Interagency Performance Evaluation Task Force), 2006: Performance Evaluation 6873 of the New Orleans and Southeast L ouisiana Hurricane Protection System . U.S. 6874 Army Corps of Engineers, Washingt on, DC. <https://ipet.wes.army.mil/> 6875

Jones , C.P., W.L. Coulbourne, J. Marshall, and S.M. Roger Jr, 2006: Evaluation of the 6876 National Flood Insurance Program’s Building Standards. American Institutes for 6877 Research, Washington, DC. 6878

Kentula , M., 1999: Restoration, creation, and recovery of wetlands: wetland restoration 6879 and creation. In: National Water Summary on Wetland Resources. [Fretwell, 6880 J.D., R.J. Redman, and J.S. Williams (eds.)]. United States Geological Survey 6881CCSP 4.1 January 15, 2009

474 of 784 Final Report water supply paper 2425. U.S. Geological Survey, [Reston, VA]. 6882 <http://water.usgs.gov/nwsum/WSP2425/restoration.html> 6883
Klein , R.J.T., R.J. Nicholls, and N. Mimura, 1999: Coastal adaptation to climate change: 6884 Can the IPCC technical gui delines be applied? Mitigation and Adaptation 6885 Strategies for Global Change, 4(3-4) , 239-252. 6886 Kruczynski , W.L., 1990: Options to be considered in preparation and evaluation of 6887 mitigation plans. In: Wetland Creation and Restoration: The Status of the Science 6888 [Kusler, J.A. and M.E. Kentula (eds. )]. Island Press, Washington, DC, 594 pp. 6889

Kussler , J., 1999: Common Questions: Wetland Re storation, Creation, and 6890 Enhancement . Association of State Wetland Managerss, Berne, NY, 15 pp. 6891 <http://www.aswm.org/propub/20_restoration_6_26_06.pdf> 6892 Lavery , S. and B. Donovan, 2005: Flood risk management in the Thames Estuary 6893 looking ahead 100 years. Philosophical Transactions of the Royal Society A , 363 , 6894 1455-1474. 6895 Landry , C.E., A.G. Keeler, and W. Kriesel, 2003: An economic evaluation of beach 6896 erosion management alternatives. Marine Resource Economics , 18(2) , 105-127. 6897

Leatherman , S., 1997: Flood Insurance Availability in Coastal Areas: The Role It Plays in 6898 Encouraging Development Decisions . Federal Emergency Management Agency, 6899 Washington, DC. 6900
Matcha vs Maddox , 711 S.W.2d 95, 100 (Tex. App. 1986). 6901
Miller , H.C., 1981: Coastal Flood Hazards and the National Flood Insurance Program

. 6902 Federal Emergency Management Agency, Washington, DC, 50 pp. 6903
NAS (National Academy of Sciences), 1990: Managing Coastal Erosion . National 6904 Academy Press, Washington, DC, 182 pp. 6905CCSP 4.1 January 15, 2009

475 of 784 Final Report NFIP (National Flood Insurance Program), 2007: Fact Sheet: Saving on Flood Insurance 6906 Information about the NFIP’s Grandfathering Rule. FEMA, [Washington DC], 2 6907 pp. <http://www.fema.gov/library /viewRecord.do?id=2497> 6908

NFIP (National Flood Insurance Program) , 2008: Flood Insurance Manual . Federal 6909 Emergency Management Agency, Washington DC. 6910

Nordhaus , W.D., 2007a: Critical assumptions in the St ern Review on Climate Change. 6911 Science , 317(5835) , 201-202. 6912

Nordhaus , W.D., 2007b: A review of the Stern Review on The Economics of Climate 6913 Change

. Journal of Economic Literature , 45 , 686-702. 6914
NRC (National Research Council), 1983: Changing Climate . National Academy Press, 6915 Washington, DC, 496 pp. 6916
NRC (National Research Council), 1987: Responding to Changes in Sea Level: 6917 Engineering Implications . National Academy Press, Washington, DC, 148 pp. 6918
NRC (National Research Council), 2007: Mitigating Shore Eros ion Along Sheltered 6919 Coasts . National Academies Press, Washington, DC, 174 pp. 6920
O’Callahan , J. (ed.), 1994: Global Climate Change and the Ri sing Challenge of the Sea. 6921 Proceedings of the third IPCC CZMS work shop, Isla de Margarita, Venezuela, 9– 6922 13 March 1992. National Oceanic and Atmospheric Administration, Silver 6923 Spring, MD, 691 pp. 6924
OMB (Office of Management and Budget), 1992: Guidelines and Discount Rates for 6925 Benefit-Cost Analysis of Federal Programs. OMB Circular A-94, Office of 6926 Management and Budget, Washington, DC. 6927 <http://www.whitehouse.gov/omb/circulars/a094/a094.html> 6928
OTA (Office of Technology Assessment), 1993: Preparing for an Uncertain Climate – 6929 Volume I . OTA-O-567. U.S. Government Printing Office, Washington, DC, 359 6930 pp. 6931CCSP 4.1 January 15, 2009

476 of 784 Final Report Reed , D.J., D. Bishara, D. Cahoon, J. Donnell y, M. Kearney, A. Kolker, L. Leonard, 6932 R.A. Orson, and J.C. Stevenson, 2008: Site-specific scenarios for wetlands 6933 accretion as sea level rises in the mid-Atlantic region. Section 2.1 in: Background 6934 Documents Supporting Climate Change Science Program Synthesis and 6935 Assessment Product 4.1: Coastal Elevati ons and Sensitivity to Sea Level Rise 6936 [Titus, J.G. and E.M. Strange (eds .)]. EPA 430R07004. U.S. Environmental 6937 Protection Agency, Washington, DC, pp. 134-174. 6938 <http://epa.gov/climatechange/e ffects/coastal/background.html> 6939
Samuelson , P.A. and W.D. Nordhaus, 1989: Economics. McGraw-Hill, New York, 13th 6940 ed., 1013 pp. 6941 Scheraga , J.D. and A.E. Grambsch, 1998: Risks, opportunities, and adaptation to climate 6942 change. Climate Research, 11(1) , 85-95. 6943 Shilling , J.D., C.E. Sirmans, and J.D. Benjamin, 1989: Flood insurance, wealth 6944 redistribution, and urban property values. Journal of Urban Economics , 26(1) , 43- 6945 53. 6946
Stockton , M.B. and C.J. Richardson, 1987: Wetland development trends in coastal North 6947 Carolina, USA, from 1970 to 1984. Environmental Management, 11(5) , 649-657. 6948
Titus , J.G., 1990: Greenhouse effect, sea level ri se, and barrier islands: case study of 6949 Long Beach Island, New Jersey. Coastal Management, 18(1) , 65-90. 6950
Titus , J.G., 1991: Greenhouse effect and coasta l wetland policy: how Americans could 6951 abandon an area the size of Ma ssachusetts at minimum cost. Environmental 6952 Management , 15(1) , 39-58. 6953
Titus , J.G., 1998: Rising seas, coastal erosi on and the takings clause: how to save 6954 wetlands and beaches without hurting property owners. Maryland Law Review , 6955 57(4) , 1279-1299. 6956CCSP 4.1 January 15, 2009

477 of 784 Final Report Titus , J.G., 2000: Does the U.S. government r ealize that the sea is rising? How to 6957 restructure federal programs so that wetlands and beaches survive. Golden Gate 6958 Law Review, 30(4) , 717–786. 6959
Titus , J.G., 2005: Does shoreline armoring vi olate the Clean Water Act? Rolling 6960 easements, shoreline planning, and othe r responses to sea level rise. In: America’s 6961 Changing Coasts: Private Rights and Public Trust [Whitelaw, D.M. and G.R. 6962 Visgilio (eds.)]. Edward Elgar Publis hing, Cheltenham, UK, and Northampton, 6963 MA, 248 pp. 6964
Titus , J.G. and V. Narayanan, 1996: The risk of sea level rise. Climatic Change, 33(2), 6965 151-212. 6966
Titus , J.G. and J. Wang, 2008: Maps of lands cl ose to sea level along the middle Atlantic 6967 coast of the United States: an elevation data set to use while waiting for LIDAR. 6968 Section 1.1 in: Background Documents Supporting Climate Change Science 6969 Program Synthesis and Assessment Pr oduct 4.1: Coastal Elevations and 6970 Sensitivity to Sea Level Rise [Titus, J.G. and E.M. Strange (eds.)]. EPA 6971 430R07004. U.S. Environmental Protection Agency, Washington, DC, pp. 2-44. 6972
Titus , J.G., C.Y. Kuo, M.J. Gibbs, T.B. LaRo che, M.K. Webb, and J.O. Waddell, 1987: 6973 Greenhouse effect, sea level rise, and coastal drainage systems. Journal of Water 6974 Resources Planning and Management, 113(2) , 216-227. 6975
Titus , J.G., R.A. Park, S.P. Leatherman, J.R. Weggel, M.S. Greene, P.W. Mansel, S. 6976 Brown, G. Gaunt, M. Treehan, and G. Y ohe, 1991: Greenhouse effect and sea 6977 level rise: the cost of holding back the sea. Coastal Management , 19(2) , 171-204. 6978 Township of Long Beach (New Jersey) , 2008: Important Flood Information. 6979 <http://longbeachtownship.com/importantfloofing information.html> 6980 Town of Ocean City, Maryland , 1999: City Code § 38-71. 6981

TRB (Transportation Research Board), 2008: Potential Impacts of Climate Change on 6982 U.S. Transportation . National Academ ies Press, Washington, DC, 234 pp. 6983CCSP 4.1 January 15, 2009

478 of 784 Final Report USACE (U.S. Army Corps of Engineers), 2000a: Planning Guidance Notebook: 6984 Appendix E: Civil Works Missi ons and Evaluation Procedures . ER 1105-2-100. 6985 U. S. Army Corps of Engineers, Washington, DC, 310 pp. 6986 <http://www.usace.army.mil/publications/eng-regs/er1105-2-100/toc.htm> 6987
USACE (U.S. Army Corps of Engineers), 2000b: Civil Works Construction Cost Index 6988 System (CWCCIS) . EM 1110-2-1304. U.S. Army Corps of Engineers, 6989 Washington, DC. For updated CWCCIS data tables, see: 6990 <http://www.usace.army.mil/publications/e ng-manuals/em1110-2-1304/toc.htm> 6991
USACE (U.S. Army Corps of Engineers), 2007: Civil Works Construction Cost Index 6992 System (CWCCIS): Revised Tables . EM 1110-2-1304. U.S. Army Corps of 6993 Engineers, Washington, DC. Ta bles revised 30 September 2007. 6994 <http://www.usace.army.mil/publications/e ng-manuals/em1110-2-1304/toc.htm> 6995
U.S. EPA (Environmental Protection Agency), 1989: Potential Effects of Global Climate 6996 Change on the United States: Report to Congress . EPA 230-05-89-050. U.S. 6997 Environmental Protection Ag ency, Washington, DC. 6998
U.S. EPA (Environmental Protection Agency), 1995: Federal guidance for the 6999 establishment, use and operation of mitigation banks. Federal Register , 60(228) , 7000 58605-58614. 7001
U.S. EPA (Environmental Protection Agency), 2000: Guidelines for Preparing Economic 7002 Analyses . EPA 240-R-00-003. EPA Office of th e Administrator, [Washington 7003 DC]. <http://yosemite.epa.gov/ee/epa/ eed.nsf/webpages/Guidelines.html> 7004
U.S. EPA (Environmental Protection Agency) & USACE (U.S. Army Corps of 7005 Engineers), 1990: Mitigation Memora ndum of Agreement 4 (Feb. 6, 1990). 7006 Weggel , J.R., S. Brown, J.C. Escajadillo, P. Breen, and E. Doheyn, 1989: The cost of 7007 defending developed shorelines along shelte red waters of the United States from a 7008 two meter rise in mean sea level. In: Potential Effects of Global Climate Change 7009 on the United States. Appendix: B, Sea Level Rise . U.S. Environmental Protection 7010CCSP 4.1 January 15, 2009

479 of 784 Final Report Agency, Washington, DC, pp. 3-1 to 3-90. 7011 <http://epa.gov/climatechange/effects/coastal/appB.html> 7012

Yohe , G., J.E. Neumann, P. Marshall, and H. Ameden, 1996: The economic cost of 7013 greenhouse-induced sea-level rise for de veloped property in the United States. 7014 Climatic Change , 32(4) , 387-410. 7015

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## Chapter 11. Ongoing Adaptation 7017 7018 Author: James G. Titus, EPA 7019
7020 KEY FINDINGS 7021

 Most organizations are not yet taking sp ecific measures to prepare for rising sea 7022 level. Recently, however, many public a nd private organizations have begun to 7023 assess possible response options. 7024

 Most of the specific measures that have been taken to prepare for accelerated sea7025 level rise have had the purpose of reduc ing the long-term adverse environmental 7026 impacts. 7027
7028 11.1 INTRODUCTION 7029 Preparing for the consequences of rising sea level has been the exception rather than the 7030 rule in the Mid-Atlantic. Nevertheless, many coastal decision makers are now starting to 7031 consider how to prepare. 7032
7033 This Chapter examines those cases in which or ganizations are taking specific measures to 7034 consciously anticipate the eff ects of sea-level rise. It does not include most cases in 7035 which an organization has authorized a st udy but not yet acted upon the study. Nor does 7036 it catalogue the activities undertak en for other reasons that might also help to prepare for 7037 accelerated sea-level rise 46 , or cases where people responde d to sea level rise after the 7038 fact (see Box 11.1). Finally, it only consider s measures that had been taken by March 7039

46 Appendix 1, however, does examine such policies.CCSP 4.1 January 15, 2009

481 of 784 Final Report 2008. Important measures may have been adopted between the time this Product was 7040 drafted and its final publication. 7041
7042 11.2 ADAPTATION FOR ENVIRONMENTAL PURPOSES 7043 Many organizations that manage land for environmental purposes are starting to 7044 anticipate the effects of sea-level rise. Ou tside the Mid-Atlantic, some environmental 7045 regulators have also begun to address this issue. 7046
7047 11.2.1 Environmental Regulators 7048 Organizations that regulate land use for e nvironmental purposes generally have not 7049 implemented adaptation options to address th e prospects of accelerated sea-level rise. 7050 Congress has given neither the U.S. Army Corps of Engineers (USACE) nor the U.S. 7051 Environmental Protection Agency (EPA) a mandate to modify existing wetland 7052 regulations to address rising s ea level; nor have those agenci es developed approaches for 7053 moving ahead without such a mandate (see Chapter 12). For more than a decade, 7054 Maine 47 , Massachusetts 48 , and Rhode Island 49 have had statutes or re gulations that restrict 7055 shoreline armoring to enable dunes or wetla nds to migrate inland with an explicit 7056 recognition of rising se a level (Titus, 1998). 7057 7058 None of the eight mid-Atlantic states require landowners to allow wetlands to migrate 7059 inland as sea level rises ( NOAA, 2006). During 2008, however , the prospect of losing 7060 ecosystems to a rising sea prompted Maryland to enact the “Living Shoreline Protection 7061

47 06-096 Code of Maine Rules §355(3)(B)(1) (2007). 48 310 Code Mass Regulations §10.30 (2005). 49 Rhode Island Coastal Resource Management Program §210.3(B)(4) and §300.7(D) (2007).CCSP 4.1 January 15, 2009

482 of 784 Final Report Act” 50 . Under the Act, the Department of Environment will designate certain areas as 7062 appropriate for structural shoreline measures ( e.g. , bulkheads and revetm ents). Outside of 7063 those areas, only nonstructural measures ( e.g. , marsh creation, beach nourishment) will 7064 be allowed unless the property owner can de monstrate that nonstructural measures are 7065 infeasible 51 . The new statute does not ensure that we tlands are able to migrate inland; but 7066 Maryland’s coastal land use statute limits development to one home per 8.09 hectares 7067 (ha) (20 acres [ac]) in most rural areas within 305 meters (m ) (1000 feet [ft]) of the shore 7068 (see Section A1.F.2.1 in Appendix 1). Although th at statute was enacted in the 1980s to 7069 prevent deterioration of water quality, the state now considers it to be part of its sea-level 7070 rise adaptation strategy. 52 7071
7072 11.2.2 Environmental Land Managers 7073 Those who manage land for environmental purposes have taken some initial steps to 7074 address rising sea level. 7075 Federal Land Managers 7076 The Department of Interior (Secretaria l Order 3226, 2001) requires climate change 7077 impacts be taken into account in pla nning and decision making (Scarlett, 2007). The 7078 National Park Service has worked with the United States Geological Survey (USGS) to 7079 examine coastal vulnerability on 25 of its coastal parks (Pendleton et al ., 2004). The U.S. 7080 Fish and Wildlife Service is incorporating st udies of climate change impacts, including 7081 sea-level rise, in their Comprehensiv e Conservation Plans where relevant. 7082
7083

50 Maryland House Bill 273-2008. 51 MD Code Environment §16-201(c) 52 Maryland House Bill 273-2008.CCSP 4.1 January 15, 2009

483 of 784 Final Report The National Park Service and the U.S. Fish and Wildlife Service each have large coastal 7084 landholdings that could erode or become submerged as sea level rises (Thieler et al ., 7085 2002; Pendleton et al ., 2004). Neither organization has an explicit policy concerning sea7086 level rise, but both are starting to consider their options. The National Park Service 7087 generally favors allowing na tural shoreline processes to continue (NPS Management 7088 Policies §4.8.1), which allows ecosystems to mi grate inland as sea level rises (see Figure 7089 11.1). In 1999, this policy led the Park Serv ice to move the Cape Hatteras Lighthouse 7090 inland 900 m (2900 ft) at a cost of $12 million. The U.S. Fish and Wildlife Service 7091 generally allows dry land to convert to wetland s, but it is not necessa rily passive as rising 7092 sea level erodes the seaward boundary of tidal wetlands. Blackwater National Wildlife 7093 Refuge, for example, has used dredge material to rebuild wetlands on a pilot basis, and is 7094 exploring options to recreate about 3000 ha (7000 ac) of ma rsh (see Figure 11.2). Neither 7095 agency has made land purchases or easements to enable parks and refuges to migrate 7096 inland. 7097

7098 Figure 11.1 Allowing beaches and wetlands to migrate inland in the national parks (a) Cape Hatteras 7099 National Seashore. (June 2002) Until it was relocated inland in 1999, the lighthouse was just to the right of 7100 the stone groin in the foreground. (b) Jamestown Island ,Virginia (September 2004). As sea level rises, 7101 marshes have taken over land that was cultivated during colonial times. 7102 7103CCSP 4.1 January 15, 2009

484 of 784 Final Report 7104 7105 Figure 11.2 Responding to sea-level rise at Blackwate r National Wildlife Refuge, Maryland (October 7106 2002). (a) Marsh Deterioration. (b) Marsh Creation. The dredge fills the area between the stakes to create 7107 land at an elevation flooded by the tides, after which marsh grasses are planted 7108 7109 The Nature Conservancy 7110 The Nature Conservancy (TNC) is the largest private holder of cons ervation lands in the 7111 Mid-Atlantic. It has declared as a matter of policy that it is trying to anticipate rising sea 7112 level and climate change. Its initial focu s has been to preserve ecosystems on the 7113 Pamlico-Albemarle Peninsula, such as thos e shown in Figure 11.3 (Pearsall and Poulter, 7114 2005; TNC, 2007). Options under considerati on include: plugging canals to prevent 7115 subsidence-inducing saltwater in trusion, planting cypress trees where pocosins have been 7116 converted to dry land, and planting brackish ma rsh grasses in areas likely to be inundated. 7117 As part of that project, TNC undertook the first attempt by a private conservancy to 7118 purchase rolling easements (a lthough none were purchased). TNC owns the majority of 7119 barrier islands along the Delmarva Peninsula, but none of the mainland shore. TNC is 7120 starting to examine whether preserving the eco systems as sea level rises would be best 7121 facilitated by purchasing land on the mainland si de as well, to ensure sediment sources 7122 for the extensive mudflats so that they might keep pace with rising sea level. 7123CCSP 4.1 January 15, 2009

485 of 784 Final Report 7124 State conservation managers have not yet st arted to prepare for rising sea level (NOAA, 7125 2006). But at least one state (Maryland) is star ting to refine a plan for conservation that 7126 would consider the impact of rising sea level. 7127

7128

7129 Figure 11.3 The Albemarle Sound environment that the Nature Conservancy seeks to preserve as sea level 7130 rises (June 2002). (a) Nature Conservancy lands on Roan oke Island depict effects of rising sea level. Tidal 7131 wetlands (juncas and spartina patens) have taken over most of the area depicted as sea level rises, but a 7132 stand of trees remains in a small area of higher ground. (b) Mouth of the Roanoke River, North Carolina. 7133 Cypress trees germinate on dry land; but continue to grow in the water after the land is eroded or 7134 submerged by rising sea level. 7135 7136 7137 11.3 OTHER ADAPTATION OPTIONS BEI NG CONSIDERED BY FEDERAL, 7138 STATE, AND LOCAL GOVERNMENTS 7139 11.3.1 Federal Government 7140CCSP 4.1 January 15, 2009

486 of 784 Final Report Federal researchers have been examining how be st to adapt to sea-level rise for the last 7141 few decades, and those charged with implem enting programs are also now beginning to 7142 consider implications and options. The l ongstanding assessment programs will enable 7143 federal agencies to respond more rapidly a nd reasonably if and when policy decisions are 7144 made to begin preparing for the c onsequences of rising sea level. 7145
7146 The Coastal Zone Management Act is a typica l example. The Act encourages states to 7147 protect wetlands, minimize vulnerability to flood and erosion hazards, and improve 7148 public access to the coast. Since 1990, the Act has included sea-level rise in the list of 7149 hazards that states should address. This congressional mandate has induced NOAA to 7150 fund state-specific studies of the implications of sea-level rise, and encouraged states to 7151 periodically designate specific staff to keep track of the issue. But it has not yet altered 7152 what people actually do along the coast (New York, 2006; New Jersey, 2006; 7153 Pennsylvania, 2006; Delaware, 2005; Maryla nd, 2006; Virginia, 2006; North Carolina, 7154 2006). Titus (2000) and CSO (2007) have examin ed ways to facilita te implementation of 7155 this statutory provision, such as federal guidance and/or additional interagency 7156 coordination. Similarly, the U.S. Army Co rps of Engineers (USACE) has formally 7157 included the prospect of rising sea level for at least a decade in its planning guidance for 7158 the last decade (USACE, 2000), and staff have sometimes evaluated the implications for 7159 specific decisions ( e.g. , Knuuti, 2002). But the prospect of accelerated sea-level rise has 7160 not caused a major change in the agency’s ove rall approach to wetland permits and shore 7161 protection (see Chapter 12). 7162
7163CCSP 4.1 January 15, 2009

487 of 784 Final Report 11.3.2 State Government 7164 Maryland has considered the implications of s ea-level rise in some decisions over the last 7165 few decades. Rising sea level was one reason th at the state gave for changing its shore 7166 protection strategy at Ocean City from groins to beach nourishment (see Section A1.F in 7167 Appendix 1). Using NOAA funds, the state la ter developed a preliminary strategy for 7168 dealing with sea-level rise. As part of that strategy, the state al so recently obtained a 7169 complete lidar dataset of coastal elevations. 7170
7171 Delaware officials have long considered how be st to modify infrastructure as sea level 7172 rises along Delaware Bay, although they have not put together a comprehensive strategy 7173 (CCSP, 2007). 7174 7175 Because of the vulnerability of the New Jers ey coast to flooding, shoreline erosion, and 7176 wetland loss (see Figure 11.4) , the coastal management staff of the New Jersey 7177 Department of Environmental Protection have been guided by a long-term perspective on 7178 coastal processes, including th e impacts of sea-level rise. So far, neither Delaware nor 7179 New Jersey has specifically altered their activ ities because of projected sea-level rise. 7180 Nevertheless, New Jersey is currently undertak ing an assessment that may enable it to 7181 factor rising sea level into its strategy for preserving the Delaware Estuary (CCSP, 2007). 7182
7183 In the last two years, states have become increasingly interest ed in addressing the 7184 implications of rising sea level. A bill in th e New York General Assembly would create a 7185 sea-level rise task force (Bill AO9002 2007-2008 Regular Session). Maryland and 7186CCSP 4.1 January 15, 2009

488 of 784 Final Report Virginia have climate change task forces that have focused on adapting to rising sea 7187 level. (For a comprehensive survey of what state governments are doing in response to 7188 rising sea level, see Coasta l States Organization, 2007.) 7189 7190

7191

7192 Figure 11.4 Vulnerability of New Jersey’s coastal zone (a) Wetland fringe lacks room for wetland 7193 migration (Monmouth August 2003). (b) Low bay sides of barrier islands are vulnerable to even a modest 7194 storm surge. (Ship Bottom, September 2, 2006). (c) Gibbstown Levee and (d) associated tide gate protect 7195 lowlying areas of Greenwich Township (March 2003). 7196 7197 11.3.3 Local Government 7198 A few local governments have considered the im plications of rising sea level for roads, 7199 infrastructure, and floodplain management (see Boxes A1.4 and A1.6 in Appendix 1). 7200 New York City’s plan for the year 2030 in cludes adapting to clim ate change (City of 7201 New York, 2008). The New York City Depart ment of Environmental Protection is 7202CCSP 4.1 January 15, 2009

489 of 784 Final Report looking at ways to decrease the impacts of storm surge by building flood walls to protect 7203 critical infrastructure such as waste plants , and is also examining ways to prevent the 7204 sewer system from backing up more fre quently as sea level rises (Rosenzweig et al ., 7205 2006). The city has also been investigating the possible constructi on of a major tidal 7206 flood gate across the Verizano Na rrows to protect Manhattan ( 

### Velasquez-Manoff, 7207 

### 2006)

. 7208
7209 Outside of the Mid-Atlantic, Miami-Dade County in Florida has been studying its 7210 vulnerability to sea-level rise , including developing maps to indicate which areas are at 7211 greatest risk of inundation. Th e county is hardening facili ties to better withstand 7212 hurricanes, monitoring the salt front, exam ining membrane technology for desalinating 7213 seawater, and creating a climat e advisory task force to advise the county commission 7214 (Yoder, 2007). 7215 Begin box********* 7216 Box 11.1. Jamestown: An Historic Example of Retreat in Response to Sea Level Rise 7217 Established in 1607 along the James River, Jamestown was the capital of Virginia until 1699, when a fire 7218 destroyed the statehouse. Nevertheless, rising sea level was probably a contributing factor in the decision to 7219 move the capital to Williamsburg, because it was making the Jamestown peninsula less habitable than it 7220 had been during the previous century. Fresh water was scarce, especially during droughts (Blanton, 2000). 7221 The James River was brackish, so groundwater was th e only reliable source of freshwater. But the low 7222 elevations on Jamestown limited the thickness of the freshwater table—especially during droughts. As Box 7223 Figure 11.1 shows, a 10 centimeter (cm) rise in sea level can reduce the thickness of the freshwater table by 7224 four meters on a low-lying island where the freshwater lens floats atop the salt water. 7225 7226 Rising sea level has continued to alter Jamestown. Two hundred years ago, the isthmus that connected the 7227 peninsula to the mainland eroded, creating Jamestown Island (Johnson and Hobbs, 1994). Shore erosion 7228 also threatened the location of the historic town its elf, until a stone revetment was constructed (Johnson and 7229 Hobbs, 1994). As the sea rose, the shallow valleys be tween the ridges on the island became freshwater 7230 marsh, and then tidal marsh (Johnson and Hobbs, 1994). Maps from the seventeenth century show 7231 agriculture on lands that today are salt marsh. Havi ng converted mainland to island, the rising sea will 7232 eventually convert the island to open water, unless the National Park Service continues to protect it from 7233 the rising water. 7234 7235 Other shorelines along Chesapeake Bay have also been retreating over the last four centuries. Several bay 7236 island fishing villages have had to relocate to the mainland as the islands on which they were located 7237CCSP 4.1 January 15, 2009

490 of 784 Final Report eroded away (Leatherman et al ., 1995). Today, low-lying farms on the Eastern Shore are converting to 7238 marsh, while the marshes in wildlife refuges convert to open water. 7239

7240 Box Figure 11.1 Impact of sea-level rise on an island freshwater table. ( a) According to the Ghyben7241 Herzberg relation, the freshwater table extends below sea level 40 cm for every 1 cm by which it extends 7242 above sea level (Ghyve [1889] and Herzberg [1901], as c ited by Freeze and Cherry [1979]). (b) For islands 7243 with substantial elevation, a 1-m rise in sea level si mply shifts the entire water table up 1 meter, and the 7244 only problem is that a few wells will have to be repl aced with shallower wells. (c) However, for very low 7245 islands the water table cannot rise because of runoff, evaporation, and transpiration. A rise in sea level 7246 would thus narrow the water table by 40 cm for every 1 cm that the sea level rises, effectively eliminating 7247 groundwater supplies for the lowest islands. 7248 End Box 7249
7250 7251CCSP 4.1 January 15, 2009

491 of 784 Final Report CHAPTER 11 REFERENCES 7252 * Indicates non-peer reviewed literature; available upon request 7253 7254 Blanton , D.B., 2000: Drought as a factor in the Jamestown colony, 1607-1612. 7255 Historical Archaeology , 34(4) , 74-81. 7256
CCSP (Climate Change Science Program), 2007: Stakeholder Meetings Final Report: 7257 Climate Change Science Program Synthesis and Assessment Product 4.1

. 7258 [National Oceanic and Atmospheric Ad ministration, Silver Spring, MD], 81 pp. 7259 <http://www.climatescience.gov/Library/sap/sap4- 7260 1/stakeholdermeetingfinalreport.pdf> 7261 City of New York , 2008: PlaNYC : A Greater, Greener New York

. City of New York, 7262 New York, 155 pp. 7263 <http://home2.nyc.gov/html/planyc2030/dow nloads/pdf/full_report.pdf> 7264 (CSO) Coastal States Organization, 2007: The Role of Coastal Zone Management 7265 Programs in Adaptation to Climate Change

. Coastal States Organization, 7266 Washington, DC, 27 pp. 7267 <http://www.coastalstates.org/documents/CSO%20Climate%20Change%20Final 7268 %20Report.pdf> 7269

Delaware (Delaware Coastal Programs), 2005: Delaware Coastal Programs: Section 309 7270 Enhancement Assessment . Department of Natural Resources and Environmental 7271 Control, Dover, DE, 46 pp. 7272

Freeze , R.A. and J.A. Cherry, 1979: Groundwater . Prentice-Hall, Englewood Cliffs, NJ, 7273 604 pp. 7274

Johnson , G.H. and C.H. Hobbs, 1994: The geol ogical history of Jamestown Island. 7275 Jamestown Archaeological Assessment Newsletter , 1(2/3) , 9-11. 7276
Knuuti , K., 2002: Planning for sea level rise: U.S. Army Corps of Engineers policy. In: 7277 Solutions to Coastal Disasters '02 [Ewing, L. and L. Wallendorf (eds.)]. 7278 American Society of Civil Engineers, Reston, VA, pp. 549-560. 7279CCSP 4.1 January 15, 2009

492 of 784 Final Report * Leatherman , S.P., R. Chalfont, E.C. Pendl eton, and T.L. McCandless, 1995: 7280 Vanishing Lands: Sea Level, Society, and Chesapeake Bay . Laboratory of Coastal 7281 Research, University of Maryland, College Park, and Department of the Interior, 7282 [Washington, DC], 47 pp. 7283 Maryland , 2006: CZMA, Secton 309 Asse ssment and Strategy. Maryland Department of 7284 Natural Resources, Coastal Zone Mana gement Division, Watershed Services 7285 Center, Annapolis, 70 pp. 7286 <http://www.dnr.state.md.us/bay/czm/assessment.html> 7287 New Jersey , 2006: New Jersey Coastal Management Program: Assessment and 7288 Enhancement Strategy, FY2006-2010 . New Jersey Department of Environmental 7289 Protection Coastal Manageme nt Office, Trenton, 84 pp. 7290 <http://www.state.nj.us/dep/cmp/czm_309.html> 7291

New York , 2006: New York State Coastal Managem ent Program: 309 Assessment and 7292 Strategies, July 1, 2006 through June 30, 2010 . Department of State, New York 7293 State, Albany, 98 pp. 7294
North Carolina , 2006: Assessment and Strategy of the North Carolina Coastal 7295 Management Program. North Carolina Department of Environment and Natural 7296 Resources, Raleigh, 90pp. 7297
NOAA (National Oceanic and Atmospheric Administration), 2006: Responses to Section 7298 309 of the Coastal Zone Management Act. Coastal Zone Enhancement Program 7299 compiled by NOAA Office of Ocean and Co astal Resource Management, Silver 7300 Spring, MD. <http://coastalmanag ement.noaa.gov/enhanc.html> 7301

Pearsall , S.H., III, and B. Poulter, 2005: Adapting coastal lowlands to rising seas: a case 7302 study. In: Principles of Conservation Biology [Groom, M.J., G.K. Meffe, and 7303 C.R. Carroll (eds.)]. Sinauer Associ ates, Sunderland, MA, 3rd edition, pp. 366- 7304 370. 7305CCSP 4.1 January 15, 2009

493 of 784 Final Report Pendleton , E.A., S.J. Williams, and E.R. Thieler, 2004: Coastal Vulnerability 7306 Assessment of Assateague Island National Seashore (ASIS) to Sea-level Rise . U.S. 7307 Geological Survey open-file report 2 004-1020. U.S. Geological Survey, Reston, 7308 VA, 20 pp. <http://pubs.usgs.gov/of/2004/1020/> 7309 Pennsylvania , 2006: Section 309 Assessment and St rategy: Pennsylvania’s Coastal 7310 Resources Management Program. Pennsyl vania Department of Environmental 7311 ProtectionWater Planning Office, Harrisburg, 69 pp. 7312 <http://www.dep.state.pa.us/riv er/docs/309_FINAL_June30_06.pdf> 7313 Rosenzweig , C., D. Majors, M. Tults, and K. Demong, 2006: New York City Climate 7314 Change Task Force. In: Adapting to Climate Change: Lessons for London. 7315 Greater London Authority, London, pp. 150-153. 7316 <http://www.london.gov.uk/climatechangepartnership/> 7317

* Scarlett , L., 2007: Testimony of P. Lynn Scarlett, Deputy Secretary Department of the 7318 Interior, before the House Appropriations Subcommittee on Interior, Environment 7319 and Related Agencies Regardi ng Climate Change. April 26, 2007. 7320
Thieler , E.R., S.J. Williams, and R. Beavers, 2002: Vulnerability of U.S. National Parks 7321 to Sea-Level Rise and Coastal Change . U.S. Geological Survey fact sheet FS 095- 7322 02. [U.S. Geological Survey, Reston, VA], 2 pp. <http://pubs.usgs.gov/fs/fs095- 7323 02/> 7324
Titus , J.G., 1998: Rising seas, coastal erosi on, and the takings clause: how to save 7325 wetlands and beaches without hurting property owners. Maryland Law Review, 7326 57(4) , 1376-1378. 7327
Titus , J.G., 2000: Does the US government real ize that the sea is rising? How to 7328 restructure federal programs so that wetlands and beaches survive. Golden Gate 7329 University Law Review, 30(4) , 717-778. 7330CCSP 4.1 January 15, 2009

494 of 784 Final Report * TNC (The Nature Conservancy), 2007: Save of the Week: Climate Change Action on 7331 North Carolina’s Albemarle Peninsula . The Nature Conservancy, Arlington, VA. 7332 <http://www.nature.org/success/art14181.html> 7333
USACE (U.S. Army Corps of Engineers), 2000: Planning Guidance Notebook Appendix 7334 E: Civil Works Missions and Evaluation Procedures . Army Corps of Engineers 7335 document # ER 1105-2-100. Department of the Army, U. S. Army Corps of 7336 Engineers, Washington, DC, 310 pp. 7337 <http://www.usace.army.mil/publications/eng-regs/er1105-2-100/toc.htm> 7338

* Velasquez-Manoff , M., 2006: How to keep New York afloat. The Christian Science 7339 Monitor , November 9, 2006, p. 13. 7340 Virginia , 2006: Virginia Coastal Zone Manageme nt Program: Section 309 Needs 7341 Assessment and Strategy . Virginia Coastal Zone Management Program, 7342 Richmond, 104 pp. <http://www.deq.sta te.va.us/coastal/assess.html> 7343

* Yoder , D., 2007: Miami Dade Water and Sewer Department presentation to American 7344 Water Works Association webcast, Global Climate Impacts , March 14, 2006. 7345

7346CCSP 4.1 January 15, 2009

495 of 784 Final Report 

## Chapter 12. Institutional Barriers 7347 7348 Author: James G. Titus, U.S. EPA 7349
7350 KEY FINDINGS 7351

 Most coastal institutions were designed without considering sea-level rise. 7352

 Some regulatory programs were create d in order to respond to a demand for 7353 hard shoreline structures ( e.g ., bulkheads) to hold the coast in a fixed location, 7354 and have generally not shifted to retreat or soft shore protection ( e.g ., beach 7355 nourishment). 7356

 The interdependence of decisions made by property owners and federal, state, 7357 and local governments creates an institu tional inertia that currently impedes 7358 preparing for sea-level rise, as long as no decision has been made regarding 7359 whether particular locations will be prot ected or yielded to the rising sea. 7360
7361 12.1 INTRODUCTION 7362 Chapter 10 described several categories of deci sions where the risk of sea-level rise can 7363 justify doing things differently today. Ch apter 11, however, suggested that only a few 7364 organizations have started to prepare for ri sing sea level since the 1980s when projections 7365 of accelerated sea-level rise first became widely available. 7366
7367 It takes time to respond to new problems. Mo st coastal institutions were designed before 7368 the 1980s. Therefore, land-use planning, in frastructure, home building, property lines, 7369 wetland protection, and flood insurance all were designed without considering the 7370CCSP 4.1 January 15, 2009

496 of 784 Final Report dynamic nature of the coast (see Chapters 6, 8, 9, 10). A common mi ndset is that sea 7371 level and shores are stab le, or that if they are not then shores should be stabilized (NRC, 7372 2007). Even when a particular institution has been designed to account for shifting 7373 shores, people are reluctant to give up r eal estate to the s ea. Although scientific 7374 information can quickly change what people expect, it takes longe r to change what 7375 people want. 7376
7377 Short-term thinking often prevails. The costs of planning for hazards like sea-level rise 7378 are apparent today, while the benefits may not occur during the tenure of current elected 7379 officials (Mileti, 1999). Local o fficials tend to be responsive to citizen concerns, and the 7380 public is generally less concerned about haza rds and other long-term or low-probability 7381 events than about crime, housi ng, education, traffic, and other issues of day-to-day life 7382 (Mileti, 1999; Depoorter, 2006). Land-use and transportation planners generally have 7383 horizons of 20 to 25 years (TRB, 2008), while th e effects of sea-level rise may emerge 7384 over a period of several decades. Although fe deral law requires transportation plans to 7385 have a time horizon of at least 20 years 53 , some officials view that time horizon as the 7386 maximum (TRB, 2008). Uncertainty about future climate change is a logical reason to 7387 prepare for the range of uncertainty (see Chapter 10) but cognitive dissonance 54 can lead 7388 people to disregard the new information instead (Kunreuther et al., 2004; Bradshaw and 7389

53 23 U.S.C. §135(f)(1) (2008). 54 Cognitive dissonance is a feeling of conflict or anxiety caused by holding two contradictory ideas simultaneously, especially when there is a discrepancy between one’s beliefs or actions and information that contradicts those beliefs or actions. When confronted with information ( e.g. , about risk) that contradicts one’s pre-existing beliefs or self-image ( e.g. , that they are acting reasonably), people often respond by discounting, denying, or ignoring the information ( e.g. , Festinger [1957], Harmon-Jones and Mills, [1999]).CCSP 4.1 January 15, 2009

497 of 784 Final Report Borchers, 2000; Akerlof and Dickens, 1982). So me officials resist changing procedures 7390 unless they are provided guidance (TRB, 2008). 7391 7392 Finally, a phenomenon known as “moral hazar d” can discourage people from preparing 7393 for long-term consequences. Moral hazard refers to a situation in which insurance or the 7394 expectation of a government bailout reduces someone’s incentive to prevent or decrease 7395 the risk of a disaster (Pauly, 1974). The polit ical process tends to sympathize with those 7396 whose property is threatened, ra ther than allowing them to suffer the consequences of the 7397 risk they assumed when they bought the pr operty (Burby, 2006). It can be hard to say 7398 “no” to someone whose home is threat ened (Viscusi and Zeckhauser, 2006). 7399
7400 This Chapter explores some of the institutional barriers that discourage people and 7401 organizations from preparing for the consequenc es of rising sea level. “Institution” refers 7402 to governmental and nongovernmental orga nizations and the programs that they 7403 administer. “Institutiona l barriers” refer to characteristics of an institution that prevent 7404 actions from being taken. This discussion has two general themes. First, institutional 7405 biases are more common than actual barriers . For example, policies that encourage 7406 higher densities in the coasta l zone may be barriers to wetland migration, but they 7407 improve the economics of shore protection. Such a policy might be viewed as creating a 7408 bias in favor of shore protection over wetland migration, but it is not really a barrier to 7409 adaptation from the perspective of a community that prefers protection anyway. A bias 7410 encourages one path over another; a barrier can block a particul ar path entirely. 7411
7412CCSP 4.1 January 15, 2009

498 of 784 Final Report Second, interrelationships between various deci sions tend to reinfor ce institutional inertia 7413 For instance, omission of sea-level rise from a land-use plan may discourage 7414 infrastructure designers from preparing for the rise, and a federal regulatory preference 7415 for hard structures may prevent state official s from encouraging soft structures. Although 7416 inertia has slowed current acts to respond to the risk of sea- level rise, it could just as 7417 easily help to sustain momentum toward a response once key decision makers decide 7418 which path to follow. 7419
7420 The barriers and biases examined in this Chapter mostly concern governmental rather 7421 than private sector institutions. Private inst itutions do not always exhibit foresight. In 7422 fact, their limitations have helped motivat e the creation of government flood insurance 7423 (Kunreuther, 1978), wetland protection (Sc odari, 1997), shore protection, and other 7424 government programs (Bator, 1958; Arrow, 1970). This Chapter omits an analysis of 7425 private institutions for two reasons. First, ther e is little literature available on private 7426 institutional barriers to preparing for sea-leve l rise. It is unclear whether this absence 7427 implies that the private barriers are less impor tant, or simply that private organizations 7428 keep their affairs private. Second, the publishe d literature provides no reason to expect 7429 that private institutions have important barriers different from those of public institutions. 7430 The duty of for-profit corporat ions to maximize shareholde r wealth, for example, may 7431 prevent a business from giving up property to f acilitate future environmental preservation 7432 as sea level rises. At first glance, this duty might appear to be a barrier to responding to 7433 sea-level rise, or at least a bi as in favor of shore protection over retreat. Yet that same 7434 duty would lead a corporation to sell the pr operty to an organizati on willing to offer a 7435CCSP 4.1 January 15, 2009

499 of 784 Final Report profitable price, or invest money for s hore protection. Thus, the duty to maximize 7436 shareholder wealth is a bias in favor of profitable responses over money-losing responses, 7437 but not a barrier to prepar ing for sea level rise. 7438 12.2 SOME SPECIFIC INSTITUT IONAL BARRIERS AND BIASES 7439 Productive institutions are designed to accomplish a mission, and rules and procedures 7440 are designed to help accomplish those obj ectives. These rules and procedures are 7441 inherently biased toward achieving the mi ssion, and against anythi ng that thwarts the 7442 mission. By coincidence more than design, the rules and procedures may facilitate or 7443 thwart the ability of others to achieve other missions. 7444 7445 No catalogue of institutional biases in the coas tal zone is available; but three biases have 7446 been the subject of substantial commentary: (1) shore protection versus retreat; (2) hard 7447

structures versus soft engineering solutions; and (3) coastal development versus 7448 preservation. 7449 7450 12.2.1 Shore Protection versus Retreat 7451 Federal, state, local, and private in stitutions generally have a strong bias favoring shore 7452 protection over retreat in developed areas. Many institutions also have a bias against 7453 shore protection in undeveloped areas. 7454
7455 U.S. Army Corps of Engineers (USACE) Civil Works . Congressional appropriations for 7456 shore protection in coastal communities genera lly provide funds for various engineering 7457 projects to limit erosion and flooding (see Figure 12.1). The planning guidance 7458CCSP 4.1 January 15, 2009

500 of 784 Final Report documents for USACE appear to provide the discretion to relocate or purchase homes if a 7459 policy of retreat is the locally preferred approach and is mo re cost-effective than shore 7460 protection (USACE, 2000). In pa rt because the federal government generally pays for 65 7461 percent of the initial cost 55 , retreat is rarely the locally preferred option (Lead and 7462 Meiners, 2002; NRC, 2004). USACE’s envi ronmental policies discourage its Civil 7463 Works program from seriously considering proj ects to foster the landward migration of 7464 developed barrier islands (see Wetland Protection discussed further below). Finally, the 7465 general mission of this agency, its history (Lockhart and Morang, 2002), staff expertise, 7466 and funding preferences combine to make shore protection far more common than a 7467 retreat from the shore. 7468 7469 State Shore Protection . North Carolina, Virginia, Mary land, Delaware, and New Jersey 7470 all have significant state programs to support beach nourishment along the Atlantic 7471 Ocean (see Figure 12.1 and Sections A1.C .2, A1.E.2, and A1.G.4 in Appendix 1). 7472 Virginia, Maryland, Delaware, and New Jersey have also supported beach nourishment in 7473 residential areas along estuaries (see Figure 12.2). Some agencies in Maryland encourage 7474 private shore protection to a void the environmental effects of shore erosion (see Section 7475 A1.F.2 in Appendix 1), and the state provides interest-free lo ans for up to 75 percent of 7476 the cost of nonstructural er osion control projects on pr ivate property (MD DNR, 2008). 7477 Although a Maryland guidance document for pr operty owners favors retreat over shore 7478 protection structures (MD DNR, 2006), none of these states has a program to support a 7479 retreat in developed areas. 7480

55 33 USC §2213.CCSP 4.1 January 15, 2009

501 of 784 Final Report 7481

7482 Figure 12.1 Recently nourished beach and artif icially created dune in Surf City, New Jersey, with recent 7483 plantings of dune grass. (June 2007). 7484 7485

7486 Figure 12.2 Beach nourishment al ong estuaries. (a) The Department of Natural Resources provided an 7487 interest-free loan to private lan downers for a combined breakwater and beach nourishment project to 7488 preserve the recreational beach and protect homes in Bay Ridge, Maryland (July 2008). (b) The Virginia 7489 Beach Board and Town of Colonial Beach nourishe d the public beach along the Potomac River for 7490 recreation and to protect the road and homes to the left (October 2002). 7491 7492CCSP 4.1 January 15, 2009

502 of 784 Final Report 7493 FEMA Programs. Some aspects of the National Flood Insurance Program (NFIP) 7494 encourage shore protection, while others en courage retreat. The Federal Emergency 7495 Management Agency (FEMA) requires local governments to ensure that new homes 7496 along the ocean are built on pilings sunk far enough into the ground so that the homes 7497 will remain standing even if the dunes and b each are largely washed out from under the 7498 house during a storm 56 . The requirement for construction on pilings can encourage larger 7499 homes; after a significant e xpense for pilings, people rarely build a small, inexpensive 7500 cottage. These larger homes provide a bett er economic justification for government7501 funded shore protection than the smaller homes. 7502 7503 Beaches recover to some extent after storms, but they frequently do not entirely recover. 7504 In the past, before homes were regularly bu ilt to withstand the 100-year storm, retreat 7505 from the shore often occurred after major storms ( i.e., people did not rebuild as far 7506 seaward as homes had been before the stor m). Now, many homes can withstand storms, 7507 and the tendency is for emergency beach nourishment operations to protect oceanfront 7508 homes. A FEMA emergency assistance program often funds such nourishment in areas 7509 where the beach was nourished before the storm 57 (FEMA, 2007a). For example, Topsail 7510 Beach, North Carolina received over $1 milli on for emergency beach nourishment after 7511 Hurricane Ophelia in 2005, even though it is ineligible for USACE shore protection 7512 projects and flood insurance under the Coastal Barrier Resources Act (GAO, 2007a). In 7513 portions of Florida that rece ive frequent hurricanes, thes e projects are a significant 7514

56 44 Code of Federal Regiulations §60.3(e)(4) 57 44 CFR §206.226(j)CCSP 4.1 January 15, 2009

503 of 784 Final Report portion of total beach nourishment (see Table 12.1). They have not yet been a major 7515 source of funding for beach nourishment in the Mid-Atlantic. 7516 7517 Several FEMA programs are either neutral or promote retreat. In the wake of Hurricane 7518 Floyd in 1999, one county in North Carolina used FEMA disaster funds to elevate 7519 structures, while an adjacent county used thos e funds to help people relocate rather than 7520 rebuild (see Section A1.G in Appendix 1.). Repetitively flooded homes have been 7521 eligible for relocation assistance under a num ber of programs. Because of FEMA’s rate 7522 map grandfathering policy (see Section 10.7.3.1 in Chapter 10), a statutory cap on annual 7523 flood insurance rate increases, and limitations of the hazard mapping used to set rates, 7524 some properties have rates that are substantia lly less than the actuarial rate justified by 7525 the risk. As a result, relocation programs assist property owners and save the flood 7526 insurance program money by decreasing cl aims. From 1985 to 1995, the Upton-Jones 7527 Amendment to the National Flood Insurance Ac t helped fund the relo cation of homes in 7528 imminent danger from erosion (Crowell et al. , 2007). FEMA’s Severe Repetitive Loss 7529 Program is authorized to spend $80 million to purchase or elevate homes that have made 7530 either four separate claims or at least tw o claims totaling more than the value of the 7531 structure (FEMA, 2008a). Several other FE MA programs provide grants for reducing 7532 flood damages, which states and communities ca n use for relocating re sidents out of the 7533 flood plain, erecting flood prot ection structures, or flood- proofing homes (FEMA, 2008b, 7534 c, d, e). 7535 7536CCSP 4.1 January 15, 2009

504 of 784 Final Report 7537

Table 12.1 Selected Beach Nourishment Projects in Florid a Authorized by FEMA’s Public Assistance Grant Program Year Location Hurricane Authorized Volume of Sand (cubic meters d ) Obligated Funds a (dollars) 1987 Jupiter Island Floyd 90,000 637,670 1999 Jupiter Island Irene 48,500 343,101 0 2001 Longboat Key Gabrielle 48,253 596,150 2001 Collier County Gabrielle 37,800 452,881 2001 Vanderbilt Beach Gabrielle 61,534 1,592,582 2001 Vanderbilt Beach Gabrielle b 738,821 2004 Manasota Key/Knights Island Charley et al

. c 115,700 2,272,521 2004 Bonita Beach Charley et al

. c 21,652 1,678,221 2004 Lovers Key Charley et al

. c 13,300 102,709 2004 Lido Key Charley et al

. c 67,600 2,319,322 2004 Boca Raton Frances 297,572 3,313,688 2004 Sabastian Inlet Recreation Area Frances 184,755 10,097,507 2004 Hillsboro Beach Frances 83,444 1,947,228 2004 Jupiter Island Frances 871,187 8,317,345 2004 Pensacola Beach Ivan 2,500,000 11,069,943 2004 Bay County Ivan 56,520 1,883,850 2005 Pensacola Beach Dennis 400,000 2,338,248 2005 Naples Beach Katrina 34,988 1,221,038 2005 Pensacola Beach Katrina 482,000 4,141,019 2005 Naples Beach Wilma 44,834 3,415,844 2005 Longboat Key Wilma 66,272 1,093,011 Source: Federal Emergency Management Agency. 2008. “Project Worksheets Involving ‘Beach Nourishment’ Obligated Under FEMA’s Public Assistance Gr ant Program: As of June 19, 2008.”
a For some projects, the figure may include costs other than placing sand into the beach system, such as reconstructing dunes and planting dune vegetation, as well as a ssociated planning and engineering costs. b Supplemental grant. Appli cant lost original sand source and had to go 50 kilometers offshore to collect the sand being used. This increased the cost to $30.82 per cubi c meter ($23.57 per cubic yard), compared with originally assumed cost of $10.80 per cubic meter ($8.25 per cubic yard).
c Cumulative impact of the 2004 hurricanes Charley Frances, Ivan Jeanne. d. Converted from cubic yards, preserving significant digits from the original source, which varies by project. 7538CCSP 4.1 January 15, 2009

505 of 784 Final Report 7539 Flood insurance rates are adjusted downward to reflect the reduced risk of flood damages 7540 if a dike or seawall decreases flood risks during a 100-year storm. Because rates are 7541 based on risk, this adjustment is not a bias toward shore protection, but rather a neutral 7542 reflection of actual risk. 7543 7544 Wetland Protection. The combination of federal and stat e regulatory programs to protect 7545 wetlands in the Mid-Atlantic strongly discourages developm ent from advancing into the 7546 sea, by prohibiting or strongly discouraging the filling or diking of tidal wetlands for 7547 most purposes (see Chapter 9). Within th e Mid-Atlantic, New York promotes the 7548 landward migration of tidal wetlands in so me cases (see Section A1.A.2 in Appendix 1), 7549 and Maryland favors shore protection in so me cases. The federal wetlands regulatory 7550 program has no policy on the question of retreat versus shore protection. Because the 7551 most compelling argument against estuarine shor e protection is often the preservation of 7552 tidal ecosystems ( e.g. , NRC, 2007), a neutral regulatory approach has left the strong 7553 demand for shore protection from property ow ners without an eff ective countervailing 7554 force for allowing wetlands to migrate (Tit us 1998, 2000). Wetlands continue to migrate 7555 inland in many undeveloped areas (see Figure 12.3) but not in de veloped areas, which 7556 account for an increasing portion of the coast. 7557 7558 Neither federal nor most state regulations en courage developers to create buffers that 7559 might enable wetlands to migrate inland, nor do they encourage landward migration in 7560 developed areas (Titus, 2000). In fact, US ACE has issued a nationwide permit for 7561CCSP 4.1 January 15, 2009

506 of 784 Final Report bulkheads and other eros ion-control structures 58 . Titus (2000) conclude d that this permit 7562 often ensures that wetlands will not be able to migrate inland unless the property owner 7563 does not want to control the erosion. For this and other reasons, the State of New York 7564 has decided that bulkheads and erosion st ructures otherwise au thorized under the 7565 nationwide permit will not be allowed w ithout state concurrence (NYDOS 2006; see 7566 Section A1.A.2 in Appendix 1). 7567 7568 Federal statutes appear to di scourage regulatory efforts to promote landward migration of 7569 wetlands. Section 10 of the Rivers and Harbor s Act of 1899 and Section 404 of the Clean 7570 Water Act require a permit to dredge or fill any portion of the navigable waters of the 7571 United States 59 . Courts have long construed this juri sdiction to include lands within the 7572 “ebb and flow of the tides”, ( e.g. , Gibbons v. Ogden; Zabel v. Tabb ; 40 C.F.R. § 7573 230.3[s][1], 2004), but it does not extend inland to lands that are dry today but would 7574 become wet if the sea were to rise one meter (Titus, 2000). The absence of federal 7575 jurisdiction over the dry land immediately inla nd of the wetlands can limit the ability of 7576 federal wetlands programs to anticipate sea-level rise. 7577 7578 Although the federal wetlands re gulatory program generally ha s a neutral effect on the 7579 ability of wetlands to migrate as sea level rises, along the bay sides of barrier islands, 7580 regulatory programs, discourage or prevent wetland migration. Under natural conditions, 7581

58 See 61 Federal Register 65,873, 65,915 (December 13, 1996) (reissuing Nationwide Wetland Permit 13, Bank Stabilization activities nece ssary for erosion prevention). See also Reissuance of Nationwide Permits, 72 Fed. Reg. 11,1108-09, 11183 (March 12, 2007) (reissuing Nationwide Wetland Permit 13 and explaining that construction of erosion control structures along coastal shores is authorized). 59 See The Clean Water Act of 1977, § 404, 33 U.S.C. § 1344; The Rivers and Harbors Act of 1899, § 10, 33 U.S.C. §§ 403, 409 (1994).CCSP 4.1 January 15, 2009

507 of 784 Final Report barrier islands often migrate inland as sea le vel rises (see Chapter 3). Winds and waves 7582 tend to fill the shallow water immediately inla nd of the islands, allowing bayside beaches 7583 and marshes to slowly advance into the ba y toward the mainland (Dean and Dalrymple, 7584 2002; Wolf 1989). Human activities on devel oped islands, however, limit or prevent 7585 wetland migration (Wolf, 1989). Artificial dunes limit the overwash (see Section 6.2 in 7586 Chapter 6). Moreover, when a storm does wash sand from the beach onto other parts of 7587 the island, local governments bulldoze the sand back onto the beach; wetland rules 7588 against filling tidal waters prevent people from artificially imitating the overwash process 7589 by transporting sand directly to the bay si de (see Section 10.3). Although leaving the 7590 sand in place would enable some of it to wash or blow into the ba y and thereby accrete 7591 (build land) toward the mainland, doing so is generally impractical. If regulatory agencies 7592 decided to make wetland migration a prior ity, they would have more authority to 7593 encourage migration along the bay sides of ba rrier islands than el sewhere, because the 7594 federal government has jurisidiction over th e waters onto which those wetlands would 7595 migrate. 7596 7597 In addition to the regulatory programs, the federal government preserves wetlands 7598 directly through acquisition and land manageme nt. Existing statutes give the U.S. Fish 7599 and Wildlife Service and other coastal land mana gement agencies the authority to foster 7600 the landward migration of wetlands (Titus, 2000). A 2001 Department of Interior (DOI) 7601 order directed the Fish and Wildlife Servi ce and the National Park Service to address 7602 climate change 60 . However, resource managers have been unable to implement the order 7603

60 Department of Interior Secretarial Order 3226CCSP 4.1 January 15, 2009

508 of 784 Final Report because (1) they have been given no guidan ce on how to address climate change and (2) 7604 preparing for climate change has not been a priority within their ag encies (GAO, 2007b). 7605
7606

7607 Figure 12.3 Tidal Wetland Migration. (a) Marshes taking over land on Hooper Island (Maryland) that had 7608 been pine forest until recently, with some dead trees standing in the foreground and a stand of trees on 7609 slightly higher ground visible in the rear [October 2004]. (b) Marshes on the mainland opposite 7610 Chintoteague Island, Virginia (June 2007). 7611 7612 Relationship to Coastal Development. Many policies encourage or discourage coastal 7613 development, as discussed in Section 12.2.3. Ev en policies that subs idize relocation may 7614 have the effect of encouraging development, by reducing the risk of an uncompensated 7615 loss of one’s investment. 7616
7617 12.2.2 Shoreline Armoring versus Living Shorelines 7618 The combined effect of federal and stat e wetland protection programs is a general 7619 preference for hard shoreline structures over soft engineering appro aches to stop erosion 7620 along estuarine shores (see Box 12.1). USACE ha s issued nationwide permits to expedite 7621 the ability of property owners to erect bulkheads and revetments 61 , but there are no such 7622

61 Reissuance of Nationwide Permits, 72 Federal Register 11,1108-09, 11183 ((March 12, 2007) (reissuing Nationwide Wetland Permit 13 and explaining that construction of erosion control structures along coastalCCSP 4.1 January 15, 2009

509 of 784 Final Report permits for soft solutions such as rebuilding an eroded marsh or bay beach 62 . The bias in 7623 favor of shoreline armoring results indirectly because the statute focuses on filling 7624 navigable waterways, not on the environmental impact of the shore protection. 7625 Rebuilding a beach or marsh requires more of the land below high water to be filled than 7626 building a bulkhead. 7627
7628 Until recently, state regulatory programs shared the preference for hard structures, but 7629 Maryland now favors “living shorelines” (see Chapter 11), a soft engineering approach 7630 that mitigates coastal erosion while preserving at least some of the features of a natural 7631 shoreline (compare Figure 12.4a with 12.4b). Neve rtheless, federal rules can be a barrier 7632 to these state efforts (see e.g ., Section A1.F.2.2 in Appendix 1), because the living 7633 shoreline approaches generally include some filling of tidal waters or wetlands, which 7634 requires a federal permit (see Section 10.3). 7635
7636 The regulatory barrier to soft solutions app ears to result more from institutional inertia 7637 than from a conscious bias in favor of hard structures. The nationwide permit program is 7638 designed to avoid the administrative burden of issuing a large number of specific but 7639 nearly-identical permits (Copeland, 2007). For decades, many people have bulkheaded 7640 their shores, so in the 1970s USACE issued Nationwide Permit 13 to cover bulkheads 7641 and similar structures. Because few people we re rebuilding their er oding tidal wetlands, 7642

shores is authorized). See also Nationwide Permits 3 (Maintenance), 31 (Maint enance of Existing Flood Control Facilities) and 45 (Repair of Uplands Damaged by Discrete Events). 72 Federal Register 11092- 11198 (March 12, 2007). 62 Reissuance of Nationwide Permits, 72 Federal Register 11, 11183, 11185 ((March 12, 2007) (explaining that permit 13 requires fill to be minimized and that permit 27 does not allow conversion of open to water to another habitat such as beach or tidal wetlands)CCSP 4.1 January 15, 2009

510 of 784 Final Report no nationwide permit was issued for this activ ity. Today, as people become increasingly 7643 interested in more environmentally sensitive shore protection, they must obtain permits 7644 from institutions that were created to respond to requests for hard shoreline structures. 7645 During the last few years however, those institu tions have started to investigate policies 7646 for soft shore protection meas ures along estuarine shores. 7647
7648

7649 Figure 12.4 Hard and Soft Shore Protection. (a) Stone Revetment along Elk River at Port Herman, 7650 Maryland, May 2005 (b) Dynamic Revetment along Swan Creek, at Fort Washington, Maryland, 7651 September 2008. 7652 7653CCSP 4.1 January 15, 2009

511 of 784 Final Report BEGIN BOX: 7654 Box 12.1 The Existing Decision-Making Proce ss for Shoreline Protection on Sheltered Coasts 7655 7656

 There is an incentive to install seawalls, bulkhead s, and revetments on sheltered coastlines because 7657 these structures can be built landward of the federal jurisdiction and thus avoid the need for federal 7658 permits. 7659 7660

 Existing biases of many decision makers in fa vor of bulkheads and revetments with limited 7661 footprints limit options that may provide more ecological benefits. 7662 7663

 The regulatory framework affects choices and outcomes. Regulatory factors include the length of 7664 time required for permit approval, incentives th at the regulatory system creates, [and] general 7665 knowledge of available options and their consequences. 7666 7667

 Traditional structural erosion control techniques may appear to be the most cost-effective. 7668 However, they do not account for the cumulative impacts that result in environmental costs nor the 7669 undervaluation of the environmental benefits of the nonstructural approaches. 7670 7671

 There is a general lack of knowledge and experience among decision makers regarding options for 7672 shoreline erosion mitigation on sheltered coasts, especially options that retain more of the 7673 shorelines’ natural features. 7674 7675

 The regulatory response to shoreline erosion on sh eltered coasts is generally reactive rather than 7676 proactive. Most states have not developed plans for responding to erosion on sheltered shores. 7677 7678 Source: NRC (2007) 7679 7680 END BOX 7681 7682
12.2.3 Coastal Development 7683 Federal, state, local, and private institutions all have a modest bias favoring increased 7684 coastal development in developed areas. The federal government usually discourages 7685 development in undeveloped areas, while st ate and local governments have a more 7686 neutral effect. 7687
7688 Coastal counties often favor coastal development because expensive homes with seasonal 7689 residents can substantially increase propert y taxes without much demand for government 7690 services (GAO, 2007a). Thus, local governments provide services ( e.g. , police, fire, trash 7691 removal) to areas in Delaware and North Carolina that are ineligible for federal funding 7692CCSP 4.1 January 15, 2009

512 of 784 Final Report under the Coastal Barrier Resources Act 63 . The property tax system often encourages 7693 coastal development. A small cottage on a lot that has appreciated to $1 million can have 7694 an annual property tax bill greater than the annual rental value of the cottage. 7695
7696 Governments at all levels facilitate the c ontinued human occupation of low-lying lands 7697 by providing roads, bridges, and other infrastr ucture. As coastal farms are replaced with 7698 development, sewer service is often extended to the new communities—helping to 7699 protect water quality but also making it possibl e to develop these lands at higher densities 7700 than would be permitted by septic tank regulations. 7701
7702 Congressional appropriations for shore pr otection can encourage coastal development 7703 along shores that are protected by reducing the risk that the sea w ill reclaim the land and 7704 structures (NRC, 1995; Wiegel, 1992). This reduced risk increases land values and 7705 property taxes, which may encourage furthe r development In some cases, the induced 7706 development has been a key justification for the shore protection (GAO, 1976; Burby, 7707 2006). Shore protection policies may also en courage increased densities in lightly 7708 developed areas. The benefit-cost formulas us ed to determine eligibility (USACE, 2000) 7709 find greater benefits in the most densely developed areas, making increased density a 7710 possible path toward federal funding for shore protection. Keeping hazardous areas 7711 lightly developed, by contrast, is not a path for federal funding (USACE, 1998; cf

. 7712 Cooper and McKenna, 2008). 7713
7714

63 16 U.S.Code. §3501 et seq

.CCSP 4.1 January 15, 2009

513 of 784 Final Report Several authors have argued that the National Flood Insurance Program (NFIP) 7715 encourages coastal development ( e.g., Tibbetts, 2006; Su ffin, 1981; Simmons, 1988; 7716 USFWS, 1997). Insurance convert s a large risk into a modest annual payment that people 7717 are willing to pay. Without insurance, some people would be reluctant to risk $250,000 64 7718 on a home that could be destroyed in a storm. However, empirical studies suggest that the 7719 NFIP no longer has a substantia l impact on the intensity of coastal development (Evatt, 7720 2000; see Chapter 10). The program provided a significant incentive for construction in 7721 undeveloped areas during the 1970s, when rate s received a substantial subsidy (Cordes 7722 and Yezer, 1998; Shilling et al. , 1989; Evatt, 1999). During the last few decades, 7723 however, premiums on new construction have not been subsidized and hence, the 7724 program has had a marginal impact on cons truction in undeveloped areas (Evatt, 2000; 7725 Leatherman, 1997; Cordes and Yezer, 1998; see Chapter 10). Nevertheless, in the 7726 aftermath of severe storms, the program pr ovides a source of funds for reconstruction— 7727 and subsidized insurance while shore prot ection structures are being repaired (see 7728 Chapter 10). Thus, in developed areas the pr ogram helps rebuild communities that might 7729 be slower to rebuild (or be abandoned) if flood insurance and federal disaster assistance 7730 were unavailable. More broadly, the combina tion of flood insurance and the various post7731 disaster and emergency programs providing relocation assistance, mitigation ( e.g., home 7732 elevation), reconstruction of infrastructu re, and emergency beach nourishment provide 7733 coastal construction with a federal safety net that makes coastal construction a safe 7734 investment. 7735
7736

64 NFIP only covers the first $250,000 in flood losses (44 CFR 61.6) For homes with a construction cost greater than $250,000, federal insurance reduces a property owner’s risk, but to a lesser extent.CCSP 4.1 January 15, 2009

514 of 784 Final Report Flood ordinances have also play ed a role in the creation of three-story homes where local 7737 ordinances once limited homes to two storie s. Flood regulations have induced some 7738 people to build their first floor more than 2.5 meters (8 feet) above the ground (FEMA, 7739 1984, 1994, 2000, 2007b). Local governments have continued to allow a second floor no 7740 matter the elevation of the first floor. Property owners often enclose the area below the 7741 first floor ( e.g. , FEMA, 2002), creating gr ound-level (albeit illegal 65 and uninsurable 66 ) 7742 living space. 7743
7744 The totality of federal programs, in conjuncti on with sea-level rise, creates moral hazard. 7745 Coastal investment is profitabl e but risky. If government assume s much of this risk, then 7746 the investment can be profitable without be ing risky—an ideal situ ation for investors 7747 (Loucks et al ., 2006). The “moral hazard” concern is that when investors make risky 7748 decisions whose risk is part ly borne by someone else, ther e is a chance that they will 7749 create a dangerous situation by taking on too much risk (Pauly, 1974). The government 7750 may then be called upon to take on even the risks that the private investors had 7751 supposedly assumed because the risk of cascad ing losses could harm the larger economy 7752 (Kunreuther and Michel-Kerjant, 2007). Invest ors assume that shore protection is cost7753 effective and governments assume that flood in surance rates reflect the risk in most 7754 cases; however, if sea-level rise accelerates, will taxpayers, coasta l property owners, or 7755 inland flood insurance polic yholders have to pay the increased costs? 7756 7757

65 44 CFR §60.3(c)(2) 66 44 CFR §61.5(a)CCSP 4.1 January 15, 2009

515 of 784 Final Report The Coastal Barrier Resources Act (16 U.S.C. U.S.C. §3501 et seq .) discourages the 7758 development of designated undeveloped barrie r islands and spits, by denying them shore 7759 protection, federal highway funding, mo rtgage funding, flood insurance on new 7760 construction, some forms of federal disaster assistance 67 , and most other forms of federal 7761 spending. Within the Mid-Atlantic, this stat ute applies to approximately 90 square 7762 kilometers of land, most of which is in New York or North Carolina (USFWS, 2002) 68

. 7763 The increased demand for coastal property has led the most developable of these areas to 7764 become developed anyway (GAO, 1992; 2007a). “Where the economic incentive for 7765 development is extremely high, the Act’s f unding limitations can become irrelevant” 7766 (USFWS, 2002). 7767 7768 12.3 INTERDEPENDENCE: A BARRIER OR A SUPPORT NETWORK? 7769 Uncertainty can be a hurdle to preparing for sea-level rise. Uncertainty about sea-level 7770 rise and its precise effects is one problem, but uncertainty about how others will react can 7771 also be a barrier. For environmental stresses such as air pollution, a single federal agency 7772 (U.S. EPA) is charged with developing and coordinating the nation’s response. By 7773 contrast, the response to s ea-level rise would requir e coordination among several 7774 agencies, including U.S. EPA (protecting th e environment), USACE (shore protection), 7775 Department of Interior (managing c onservation lands), FEMA (flood hazard 7776 management), and NOAA (coastal zone ma nagement). State and local governments 7777 generally have comparable agencies that work with their federal counterparts. No single 7778

67 Communities are eligible for emergency beach nourishment after a storm, provided that the beach had been previously nourished (GAO, 2007). 68 The other mid-Atlantic states each have less than 6 square kilomete rs within the CBRA system. A small area within the system in Delaware is intensely developed (see Box 9.2).CCSP 4.1 January 15, 2009

516 of 784 Final Report agency is in charge of developing a response to sea-level rise, which affects the missions 7779 of many agencies. 7780
7781 The decisions that these agencies and the private sector make regarding how to respond 7782 to sea-level rise are interdepe ndent. From the perspective of one decision maker, the fact 7783 that others have not decided on their response can be a barrier to pr eparing his or her own 7784 response. One of the barriers of this type is the uncertainty whet her the response to sea7785 level rise in a particular ar ea will involve shoreline armoring, elevating the land, or retreat 7786 (see Chapter 6 for a discussion of specific mechanisms for each of these pathways). 7787
7788 12.3.1 Three Fundamental Pathways: Armor, Elevate, or Retreat 7789 Long-term approaches for managing low coasta l lands as the sea rises can be broadly 7790 divided into three pathways: 7791

 Protect the dry land with seawalls, dikes, and other structures, eliminating wetlands 7792 and beaches (also known as “ shoreline armoring” ) (see Figure 12.4a and Section 7793 6.1.1). 7794

 Elevate the land , and perhaps the wetlands and beaches as well, enabling them to 7795 survive (see Figures 12.1 and 12.5) 7796

 Retreat by allowing the wetlands and beaches to take over land that is dry today (see 7797 Figure 12.6). 7798 Combinations of these three approaches are also possible. Each approach will be 7799 appropriate in some locations and inappropr iate in others. Shor e protection costs, 7800 property values, the environmental importance of habitat, and the feasibility of protecting 7801CCSP 4.1 January 15, 2009

517 of 784 Final Report shores without harming the habitat all vary by location. Deciding how much of the coast 7802 should be protected may require people to consid er social priorities not easily included in 7803 a cost-benefit analysis of shore protection. 7804 7805 Like land use planning, the purpose of selecting a pathway would be to foster a 7806 coordinated response to sea-leve l rise, not to lock future ge nerations into a particular 7807 approach. Shoreline armoring may be appropr iate over the next few decades to halt 7808 shoreline erosion along neighborhoo ds that are about one mete r above high water; but as 7809 sea level continues to rise, the strategy may switch to elevating land surfaces and homes 7810 rather than erecting dikes, which eventual ly leads to land becoming below sea level. 7811 Some towns may be protected by dikes at first, but eventually have to retreat as shore 7812 protection costs increase beyond the value of th e assets protected. In other cases, retreat 7813 may be viable up to a point, past which the need to protect critical infrastructure and 7814 higher density development ma y justify shore protection. 7815
7816

7817CCSP 4.1 January 15, 2009

518 of 784 Final Report 7818 Figure 12.5 Elevating land and house. (a) Initial elevation of house in Brant Beach (New Jersey). (b) 7819 Structural beams placed under house, which is lifted approximately 1.5 meters by hydraulic jack in blue 7820 truck. (c) Three course of cinder blocks added then house set down onto the blocks. (d) Soil and gravel 7821 brought in to elevate land surf ace. (January through June 2005) 7822 7823

. 7824

7825 Figure 12.6 Retreat. (a) Houses along the shore in Kitty Hawk, North Carolina (June 2002). Geotextile 7826 sand bags protect the septic tank buried in the dunes. (b) October 2002. (c) June 2003 7827 7828 7829CCSP 4.1 January 15, 2009

519 of 784 Final Report 12.3.2 Decisions That Cannot Be Made Until the Pathway Is Chosen 7830 Rising sea level has numerous implications fo r current activities. In most cases, the 7831 appropriate response depends on which of th e three pathways a particular community 7832 intends to follow. This subsection examines the relationship between the three pathways 7833 and six example activities, summarized in Table 12.2. 7834 7835 Table 12.2 The best way to prepa re for sea-level rise depends on whether (and how) a community intends to hold back the sea. Pathways for responding to sea-level rise Activity Shoreline armoring ( e.g., dike or seawall) Elevate land Retreat/wetland migration Rebuild drainage systems Check valves, holding tanks; room for pumps No change needed Install larger pipes, larger rights of way for ditches Replace septics with public sewer Extending sewer helps improve drainage Mounds systems; elevate septic system; extending sewer also acceptable Extending sewer undermines policy; mounds system acceptable Rebuild roads Keep roads at same elevation; owners will not have to elevate lots Rebuild road higher; motivates property owners to elevate lots Elevate roads to facilitate evacuation
Location of roads Shore-parallel road needed for dike maintenance No change needed Shore parallel road will be lost; all must have access to shore-perpendicular road Setbacks/subdivisions Setback from shore to leave room for dike No change needed Erosion-based setbacks
Easements Easement or option to purchase land for dike No change needed Rolling easements to ensure that wetlands and beaches migrate 7836 Coastal Drainage Systems in Urban Areas. Sea-level rise slows natural drainage and the 7837 flow of water through drain pipes that rely on gravity. If an area will not be protected 7838 from increased inundation, then larger pipe s or wider ditches (see Figure 12.7) may be 7839 necessary to increase the speed at which gravity drains the area. If an area will be 7840 protected with a dike, then it will be more important to pump the water out and to ensure 7841 that seawater does not back up into the streets through the drai nage system; so then larger 7842 pipes will be less important than underground st orage, check valves, and ensuring that the 7843CCSP 4.1 January 15, 2009

520 of 784 Final Report system can be retrofitted to allow for pumping (Titus et al., 1987). If land surfaces will be 7844 elevated, then sea-level rise will not impair drainage. 7845
7846 In many newly developed areas, low-impact development attempts to minimize runoff 7847 into the drainage system in favor of on-site recharge. In areas where land surfaces will be 7848 elevated over time, the potential for rechar ge would remain roughly constant as land 7849 surfaces generally rise as much as the water table ( i.e. , groundwater level). In areas that 7850 will ultimately be protected with dikes, by contrast, centralized drainage would 7851 eventually be required because land below sea level can not drain unless artificial 7852 measures keep the water table even father below sea level. 7853 7854

7855

7856CCSP 4.1 January 15, 2009

521 of 784 Final Report Figure 12.7 Tidal Ditches in the Mid-Atlantic. (a) Hoope rs Island, Maryland (October 2004). (b) 7857 Poquoson, Virginia (June 2002). (c) Swan Quarter, North Carolina (October 2002). (d) Sea Level, North 7858 Carolina. (October 2002). The water rises and falls with the tides in all of these ditches, although the 7859 astronomic tide is negligible in (c) Swan Quarter. Wetland vegetation is often found in these ditches. 7860 Bulkheads are necessary to prevent the ditch from caving in and blocking the flow of water in (b). 7861 7862 Septics and Sewer. Rising sea level can elevate the wa ter table (ground water) to the point 7863 where septic systems no longer function properly (U.S. EPA, 2002) 69 . If areas will be 7864 protected with a dike, then all of the land protected must even tually be artificially drained 7865 and sewer lines further extended to facil itate drainage. On the other hand, extending 7866 sewer lines would be entirely incompatible with allowing wetlands to migrate inland, 7867 because the high capital investment tends to encourage coastal protection; a mounds7868 based septic system (see Figure 12.8) is more compatible. If a community’s long-term 7869 plan is to elevate the area, then either a mounds-based system or extended public sewage 7870 will be compatible. 7871
7872 Road Maintenance. As the sea rises, roads flood more frequently. If a community expects 7873 to elevate the land with the sea, then rou tine repaving projects would be a cost-effective 7874 time to elevate the streets. If a dike is exp ected, then repaving projects would consciously 7875 avoid elevating the street above people’s ya rds, lest the projects cause those yards to 7876 flood or prompt people to spend excess resour ces on elevating them, when doing so is not 7877 necessary in the long run. 7878 7879

69 “Most current onsite wastewater system codes require minimum separation distances of at least 18 inches from the seasonally high water table or saturated zone irrespective of soil characteristics. Generally, 2- to 4- foot separation distances have proven to be adequate in removing most fecal coliforms in septic tank effluent” U.S. EPA (2002).CCSP 4.1 January 15, 2009

522 of 784 Final Report 7880

7881 7882 Figure 12.8 Mounds-based septic system for areas with high water tables. For areas with high water 7883 tables, where traditional septic/drainfield systems do no t work, sand mounds are often used. In this system, 7884 a sand mound is contructed on the order of 50 to 100 cm above the ground level, with perforated drainage 7885 pipes in the mound above the level of adjacent ground, on top of a bed of gravel to ensure proper drainage. 7886 Effluent is pumped from the septic tank up to the perforated pipe drainage pipe. Source: Converse and 7887 Tyler (1998). 7888 7889 7890 The Town of Ocean City, Maryland, curren tly has policies in place that could be 7891 appropriate if the long-term plan was to build a dike and pumping system, but not 7892 necessarily cost-effectiv e if land surfaces are elevated as currently expected.the town 7893 expects to elevate instead. Cu rrently, the town has an ordi nance that requires property 7894 owners to maintain a 2 percent grade so that rainwater drains into the street. The town has 7895 interpreted this rule as imposing a recipro cal responsibility on the town itself to not 7896 elevate roadways above the level where yards ca n drain, even if the road is low enough to 7897 flood during minor tidal surges. Thus, the lowest lot in a given area dictates how high the 7898 street can be. As sea level rises, the town will be unable to elevate its streets, unless it 7899 changes this rule. Yet public health reasons require drainage to prevent standing water in 7900 which mosquitoes breed. Therefore, Ocean City has an interest in ensuring that all 7901CCSP 4.1 January 15, 2009

523 of 784 Final Report property owners gradually elevate their yards so that the street s can be elevated as the sea 7902 rises without causing public health problems. The town has developed draft rules that 7903 would require that, during any significant cons truction, yards be elev ated enough to drain 7904 during a 10-year storm surge for the life of th e project, considering pr ojections of future 7905 sea-level rise. The draft rules also state th at Ocean City’s policy is for all lands to 7906 gradually be elevated as the sea rises (see Box A1.5 in Appendix 1). 7907 7908 Locations of Roads. As the shore erodes, any home that is accessed only by a road 7909 seaward of the house could lose access befo re the home itself is threatened. Homes 7910 seaward of the road might also lose access if that road were washed out elsewhere. 7911 Therefore, if the shore is expected to erode, it is important to ensu re that all homes are 7912 accessible by shore-perpendicular roads, a fact that was recognized in the layout of early 7913 beach resorts along the New Jersey and other sh ores. If a dike is expected, then a road 7914 along the shore would be useful for dike cons truction and maintenance. Finally, if all land 7915 is likely to be elevated, then sea-level rise may not have a significant impact on the best 7916 location for new roads. 7917 7918 Subdivision and Setbacks. If a dike is expected, then houses need to be set back enough 7919 from the shore to allow room for the dike a nd associated drainage systems. Setbacks and 7920 larger coastal lot sizes are also desirable in areas where a retreat policy is preferred for 7921 two reasons. First, the setback provides open lands onto which wetlands and beaches can 7922 migrate inland without immediately threateni ng property. Second, larger lots mean lower 7923 density and hence fewer structur es that would need to be mo ved, and less justification for 7924CCSP 4.1 January 15, 2009

524 of 784 Final Report investments in central water and sewer. By cont rast, in areas where the plan is to elevate 7925 the land, sea-level rise does not alter the pr operty available to the homeowner, and hence 7926 would have minor implication for setbacks and lot sizes. 7927 7928 Covenants and Easements Accompanying Subdivision. Although setbacks are the most 7929 common way to anticipate eventual dike construction and the la ndward migration of 7930 wetlands and beaches, a less expensive met hod would often be the purchase of (or 7931 regulatory conditions requiring ) rolling easements, which allow development but prohibit 7932 hard structures that stop the landward migra tion of ecosystems. The primary advantage of 7933 a rolling easement is that society makes th e decision to allow wetla nds to migrate inland 7934 long before the property is threatened, so owners can plan around the assumption of 7935 migrating wetlands, whether that means leaving an area undeveloped or building 7936 structures that can be moved. 7937 7938 Local governments can also obtain easements for future dike construction. This type of 7939 easement, as well as rolling easements, would each have very low market prices in most 7940 areas, because the fair market value is equa l to today’s land value discounted by the rate 7941 of interest compounded over the many decades th at will pass before the easement would 7942 have any effect (Titus, 1998). As with setback s, a large area would ha ve to be covered by 7943 the easements if wetlands are going to migr ate inland; a narrow ar ea would be required 7944 along the shore for a dike; and no easements are needed if the land will be elevated in 7945 place. 7946 7947CCSP 4.1 January 15, 2009

525 of 784 Final Report 12.3.3 Opportunities for Deciding on the Pathway 7948 At the local level, officials make assumptions about which land will be protected in order 7949 to understand which lands will truly b ecome inundated (see Chapter 2) and how 7950 shorelines will actually change (see Chapter 3), which existing wetlands will be lost (see 7951 Chapter 4), whether wetlands will be able to migrate inland (see Chapter 6), and the 7952 potential environmental consequences (s ee Chapter 5); the population whose homes 7953 would be threatened (see Chapter 7) and th e implications of sea-level rise for public 7954 access (see Chapter 8) and floodplain manageme nt (see Chapter 9). Assumptions about 7955 which shores will be protected are also n ecessary in order to estimate the level of 7956 resources that would be needed to fulfill property owners’ current expectations for shore 7957 protection ( e.g ., Titus, 2004). 7958 7959 Improving the ability to projec t the impacts of sea-level rise is not the only for such 7960 analyses utility of data regarding shore prot ection. Another use of such studies has been 7961 to initiate a dialogue about what should be protected, so that state and local governments 7962 can decide upon a plan of what will actually be protected. Just as the lack of a plan can 7963 be a barrier to preparing for sea-level rise , the adoption of a plan could remove an 7964 important barrier and signal to decision makers that it may be possible for them to plan 7965 for sea-level rise as well. 7966
7967 7968CCSP 4.1 January 15, 2009

526 of 784 Final Report CHAPTER 12 REFERENCES 7969 * Indicates non-peer reviewed literature; available upon request 7970 7971 7972 Akerlof , G.A. and W.T. Dickens, 1982: The economic consequences of cognitive 7973 dissonance. American Economic Review , 72 , 307, 309. 7974
Arrow , K.J., 1970: The organization of economic activity: issues pertinent to the choice 7975 of market versus nonm arket allocation. In: Public Expenditures and Policy 7976 Analysis [Margolis, J. (ed.)]. Markham Pub lishing Company, Chicago, pp. 59-73. 7977

Bator , F.M., 1958: The anatomy of market failure. The Quarterly Journal of 7978 Economics, 72(3) , 351-79. 7979

Bradshaw , G.A. and J.G. Borchers, 2000: Uncerta inty as information: narrowing the 7980 science-policy gap. Conservation Ecology , 4(1) , 7. 7981 Burby , R.J., 2006: Hurricane Katrina and the Paradoxes of Government Disaster Policy: 7982 Bringing About Wise Governmental Decisions for Hazardous Areas . The Annals 7983 of the American Academy of Political and Social Science , 604(1) , 171-191. 7984
Converse , J.C. and E.J. Tyler, 1998: Soil treat ment of aerobically treated domestic 7985 wastewater with emphasis on modified mounds. In: On-Site Wastewater 7986 Treatment: Proceedings of the Eigh th National Symposium on Individual and 7987 Small Community Sewage Systems [Sievers, D.M. (ed.)]. American Society of 7988 Agricultural Engin eers, St. Joseph, MI. 7989 Cooper , J.A.G. and J. McKenna, 2008: Social jus tice in coastal erosion management: the 7990 temporal and spatial dimensions. Geoforum , 39(1) , 294-306. 7991 Copeland , C., 2007: The Army Corps of Engineers’ Nationwide Permits Program: Issues 7992 and Regulatory Developments . Congressional Research Service, Washington, DC, 7993 [30 pp.] 7994CCSP 4.1 January 15, 2009

527 of 784 Final Report Cordes , J.J. and A.M.J. Yezer, 1998: In harm's way: does federal spending on beach 7995 enhancement and protection induce excessi ve development in coastal areas? Land 7996 Economics, 74(1) , 128-145. 7997
Crowell , M., E. Hirsch, and T.L. Hayes, 2007: Marine Technology Society Journal , 7998 41(1) , 18-27. 7999

Dean , R.G. and R.A. Dalrymple, 2002: Coastal Processes with Engineering 8000 Applications . Cambridge University Press, Cambridge, UK, and New York, 475 8001 pp. 8002 Depoorter , B., 2006: Horizontal politi cal externalities: the supply and demand of disaster 8003 management. Duke Law Journal, 56(1) , 101-125. 8004

Evatt , D.S., 1999: National Flood Insurance Program: Issues Assessment . Federal 8005 Emergency Management Agency, Washington, DC, 123 pp. 8006

Evatt , D.S., 2000: Does the national flood insura nce program drive floodplain 8007 development? Journal of Insurance Regulation , 18(4) , 497-523. 8008

FEMA (Federal Emergency Management Agency), 1984: Elevated Residential 8009 Structures . FEMA 54. Federal Emergency Management Agency, Washington, 8010 DC, 144 pp. 8011

FEMA (Federal Emergency Management Agency), 1994: Mitigation of Flood and 8012 Erosion Damage to Residential Buildings in Coastal Areas . FEMA 257. Federal 8013 Emergency Management Agency, Washington, DC, 40 pp. 8014

FEMA (Federal Emergency Management Agency), 2000: Above the Flood: Elevating 8015 Your Floodprone House . FEMA 347. Federal Emergency Management Agency, 8016 Washington, DC, 69 pp. 8017

FEMA (Federal Emergency Management Agency), 2002: FEMA Notifies Monroe 8018 County, Florida, of Impending Flood Insurance Probation . Region IV News 8019CCSP 4.1 January 15, 2009

528 of 784 Final Report Release Number: R4-02-15. 8020 <http://www.fema.gov/news/newsrelease.fema?id=4528> 8021

FEMA (Federal Emergency Management Agency), 2007a: Public Assistance Guide

. 8022 FEMA 322. Federal Emergency Mana gement Agency, Washington, DC. 8023 <http://www.fema.gov/government/grant/pa/policy.shtm> 8024

FEMA (Federal Emergency Management Agency), 2007b: Coastal Construction 8025 Manual . Federal Emergency Management Agency, Washington, DC. 8026 <http://www.fema.gov/rebuild/mat/fema55.shtm> 8027

FEMA (Federal Emergency Management Agency), 2008a: Severe Repetitive Loss 8028 Program . [Web site] Federal Emergency Ma nagement Agency, Washington, DC. 8029 <http://www.fema.gov/government/grant/srl/index.shtm> 8030

FEMA (Federal Emergency Management Agency), 2008b: Repetitive Flood Claims 8031 Program: Program Overview . [Web site] Federal Emergency Management 8032 Agency, Washington, DC. 8033 <http://www.fema.gov/government/grant/rfc/index.shtm> 8034

FEMA (Federal Emergency Management Agency), 2008c: Hazard Mitigation Grant 8035 Program . [Web site] Federal Emergency Ma nagement Agency, Washington, DC. 8036 <http://www.fema.gov/government/grant/hmgp/> 8037

FEMA (Federal Emergency Management Agency), 2008d: Flood Mitigation Assistance 8038 Program [Web site] Federal Emergency Ma nagement Agency, Washington, DC. 8039 <http://www.fema.gov/government/grant/fma/index.shtm> 8040

FEMA (Federal Emergency Management Agency), 2008e: Pre-Disaster Mitigation 8041 Program . [Web site] Federal Emergency Ma nagement Agency, Washington, DC. 8042 <http://www.fema.gov/government/grant/pdm/index.shtm> 8043 Festinger , L., 1957: A Theory of Cognitive Dissonance . Stanford University Press, 8044 Stanford, CA, 291 pp. 8045CCSP 4.1 January 15, 2009

529 of 784 Final Report GAO (General Accounting Office), 1976: Cost, Schedule, and Pe rformance Problems of 8046 the Lake Pontchartrain and Vicinity, Louisiana, Hurricane Protection Project

. 8047 PSAD-76-161. General Accounting Office, Washington, DC, 25 pp. 8048
GAO (General Accounting Office), 1992: Coastal Barriers: Development Occurring 8049 Despite Prohibitions Against Federal Assistance . GAO/RCED-92-115. General 8050 Accounting Office, Washington, DC, 71 pp. 8051
GAO (Government Accountability Office), 2007a: Coastal Barriers Resources System: 8052 Status of Development that Has Occurre d and Financial Assistance Provided by 8053 Federal Agencies: Development Occurring De spite Prohibitions Against Federal 8054 Assistance . GAO/07-356. Government Accountab ility Office, Washington, DC, 8055 66 pp. 8056
GAO (Government Accountability Office), 2007b. Climate Change: Agencies Should 8057 Develop Guidance for Addressing the Effects on Federal Land and Water 8058 Resources. GAO-07-863. Government Accountab ility Office, Washington, DC, 8059 179 pp. 8060 Gibbons v. Ogden , 22 U.S. 1, 217-18 (9 Wheat. 1824) 8061

Harmon-Jones , E. and J. Mills, 1999: Cognitive Dissonance: Progress on a Pivotal 8062 Theory in Social Psychology . American Psychological Association, Washington, 8063 DC, 411 pp. 8064

Kunreuther , H., R. Ginsberg, L. Miller, P. Sagi , P. Slovic, B. Borkan, and N. Katz, 8065 1978: Disaster Insurance Protection . John Wiley and Sons, New York, 400 pp. 8066

Kunreuther , H.C. and E.O. Michel-Kerjant, 2007: Climate change, insurability of large8067 scale disasters, and the emerging liability challenge. University of Pennsylvania 8068 Law Review , 155(6) , 1795-1842. 8069 Kunreuther, H., R. Meyer, and C. Van den Bulte, 2004: Risk Analysis for Extreme 8070 Events: Economic Incentives for Reducing Future Losses . National Institute of 8071 Standards and Technology, Gaithersburg, MD, 93 pp. 8072CCSP 4.1 January 15, 2009

530 of 784 Final Report Lead , D. and R.E. Meiners, 2002: Government vs. Environment . Rowan and Littlefield, 8073 Lanham, MD, 207 pp. 8074

Leatherman , S.P., 1997: Flood Insurance Availability in Coastal Areas: The Role It 8075 Plays in Encouraging Development Decisions . Federal Emergency Management 8076 Agency,Washington, DC. 8077

Lockhart , J. and A. Morang, 2002: Histor y of coastal engineering. In: Coastal 8078 Engineering Manual, Part I [Morang, A. (ed.)]. Engineer manual 1110-2-1100. 8079 U.S. Army Corps of Engin eers, Washington, DC, [39 pp.] 8080 <http://chl.erdc.usace.army.mil/cemtoc> 8081

Loucks , D.P., J.R. Stedinger, and E.Z. Stakhi v, 2006: Individual and societal responses 8082 to natural hazards. Journal of Water Resources Planning & Management , 132(5) , 8083 315-319. 8084

MD DNR (Maryland Department of Natural Resources), 2006: Shore Erosion Control 8085 Guidelines for Waterfront Property Owners . Maryland Department of Natural 8086 Resources, Annapolis, 30 pp. 8087 <http://www.dnr.state.md.us/ccws/sec/downl oad/waterfrontpropertyownersguide. 8088 pdf > 8089

MD DNR (Maryland Department of Natural Resources), 2008: Grants and Loans: Shore 8090 Erosion Control . [web site] Maryland Department of Natural Resources, 8091 Annapolis. <http://www.dnr.state.md.us/land/sec/> 8092
Mileti , D.S., 1999: Disasters by Design: A Reassessment of Natural Hazards in the 8093 United States . Joseph Henry Press, Washington, DC, 351 pp. 8094
NRC (National Research Council), 1995: Beach Nourishment and Protection. National 8095 Academy Press, Washington, DC, 334 pp. 8096
NRC (National Research Council), 2004: River Basins and Coastal Systems Planning 8097 Within the U.S. Army Corps of Engineers . National Academies Press, 8098 Washington, DC, 167 pp. 8099CCSP 4.1 January 15, 2009

531 of 784 Final Report NRC (National Research Council), 2007: Mitigating Shore Eros ion along Sheltered 8100 Coasts. National Academies Press, Washington, DC, 174 pp. 8101
NYDOS (New York Department of State), 2006: Department of State review of US 8102 Army Corps of Engineers consistency de termination for reissuance, modification, 8103 and issuance of new nationwide permits and conditions. Letter to USACE Buffalo 8104 and New New York districts, December 8, 2006. New York Division of Coastal 8105 Resources, Albany, 5 pp. 8106 Pauly , M.V., 1974: Overinsurance and public provis ion of insurance: the roles of moral 8107 hazard and adverse selection. Quarterly Journa l of Economics , 88(1) , 44-62. 8108 Scodary , P., 1997: Measuring the Benefits of Federal Wetland Protection Programs

. 8109 Environmental Law Institute, Washington, DC, 103 pp. 8110
Simmons , M., 1988: The Evolving National Flood Insurance Program . 86-641 ENR. 8111 Congressional Research Service Washington, DC. 8112 Shilling , J.D., C.E. Sirmans, and J.D. Benjamin, 1989: Flood insurance, wealth 8113 redistribution, and urban property values. Journal of Urban Economics , 26(1) , 43- 8114 53. 8115
Suffin , W.J., 1981: Bureaucracy, entrepreneurship, and natural resources: witless policy 8116 and barrier islands. Cato Journal, 1(1) , 293-311. 8117
Tibbetts , J.H., 2006: After the storm. Coastal Heritage , 20(4) , 3-11. 8118
Titus , J.G., 1998: Rising seas, coastal erosi on and the taking clause: how to save 8119 wetlands and beaches without hurting property owners. Maryland Law Review, 8120 57(4) , 1277-1399. 8121
Titus , J.G., 2000: Does the U.S. government r ealize that the sea is rising? How to 8122 restructure federal programs so that wetlands and beaches survive. Golden Gate 8123 University Law Review , 30(4) , 717-778. 8124CCSP 4.1 January 15, 2009

532 of 784 Final Report * Titus , J.G., 2004: Maps that depict the business-as-usual res ponse to sea level rise in 8125 the decentralized United States of America. Presented at: Global Forum on 8126 Sustainable Development , Paris, 11-12, November 2004. Organization of 8127 Economic Cooperation and Development, Paris. 8128
Titus , J.G., C.Y. Kuo, M.J. Gibbs, T.B. LaRo che, M.K. Webb, and J.O. Waddell, 1987: 8129 Greenhouse effect, sea level rise, and coastal drainage systems. Journal of Water 8130 Resources Planning and Management , 113(2) , 216-227. 8131

TRB (Transportation Research Board), 2008: Potential Impacts of Climate Change on 8132 U.S. Transportation . National Academies Press, Washington, DC, 234 pp. 8133
USACE (U.S. Army Corps of Engineers), 1998: Atlantic Coast of Long Island, Fire 8134 Island Inlet to Montauk Point: Alternative Screening Report . Draft report. U.S. 8135 Army Corps of Engineers New York District, New York, 118 pp. 8136 <http://www.nan.usace.army.mil/fim p/pdf/montauk/screening.pdf> 8137
USACE (U.S. Army Corps of Engineers), 2000: Planning Guidance Notebook

. 8138 Document ER 1105-2-100. U.S. Army Co rps of Engineers, Washington, DC. 8139 <http://www.usace.army.mil/publications/eng-regs/er1105-2-100/> 8140
U.S. EPA (Environmental Protection Agency), 2002: Onsite Wastewater Treatment 8141 Systems Manual . EPA/625/R-00/008. EPA Office of Water and Office of 8142 Research and Development, Washington, DC, [367 pp.] 8143 <http://purl.access.gpo.gov/GPO/LPS21380> 8144
USFWS (U.S. Fish and Wildlife Service), 1997: Biological Opinion: Administration of 8145 the National Flood Insurance Program in Monroe County, Florida, by the 8146 Federal Emergency Management Agency . U.S. Fish and Wildlife Service, 8147 Atlanta, GA. 8148
USFWS (U.S. Fish and Wildlife Service), 2002: The Coastal Barrier Resources Act: 8149 Harnessing the Power of Market Forces to Conserve America’s Coasts and Save 8150CCSP 4.1 January 15, 2009

533 of 784 Final Report Taxpayers’ Money . U.S. Fish and Wildlife Service, Arlington, VA, 34 pp. 8151 <http://www.fws.gov/habitatconservation/TaxpayerSavingsfromCBRA.pdf> 8152
Viscusi , W.K. and R.J. Zeckhauser, 2006: Natio nal survey evidence on disasters and 8153 relief: risk beliefs, self -interest, and compassion. Journal of Risk & Uncertainty , 8154 33(1/2) , 13-36. 8155
Wolff , F., 1989: Environmental assessment of human interference on the natural 8156 processes affecting the barrier beaches of Long Island, New York. Northeastern 8157 Environmental Science , 8(2) , 119-134. 8158 Wiegel , R.L., 1992: Dade County, Florida b each nourishment and hurricane surge 8159 protection. Shore and Beach, 60(4) , 2-28. 8160 Zabel v. Tabb, 430 F.2d 199, 215 (5th Cir. 1970) 8161

8162CCSP 4.1 January 15, 2009

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## Part IV Overview. National implications and a science 8163 

## strategy for the way forward 8164

8165 Authors: S. Jeffress Williams, USGS; E. Robert Thieler, USGS; Benjamin T. Gutierrez, 8166 USGS; Dean B. Gesch; USGS; Donald R. Cahoon, USGS; K. Eric Anderson, USGS 8167
8168 Climate change and effects such as sea-le vel rise have global implications and will 8169 increasingly affect the en tire nation. While this Product focuses primarily on the mid8170 Atlantic region of the United St ates, many of the issues discussed in earlier chapters are 8171 relevant at the national scale. 8172
8173 Chapter 13 draws on findings from the mid-Atla ntic focus area that have relevance to 8174 other parts of the United States, provides an overview of coastal environments and 8175 landforms in the United States, and describes the issues faced in understanding how these 8176 environments may be impacted and respond to sea-level rise. The diversity of U.S. 8177 coastal settings includes bedrock coasts in Maine, glacial bluffs in New York, barrier 8178 islands in the mid-Atlantic a nd Gulf of Mexico, coral reefs in Florida, the Caribbean, and 8179 Hawaii, one of the world’s major delta system s in Louisiana, a wide variety of pocket 8180 beaches and cliffed coasts along the Pacific coas t, Pacific atolls, and a number of arctic 8181 coastline types in Alaska. In addition, the large bays and es tuaries around the country also 8182 exhibit a diverse range of shoreline types, large wetland systems, and extensive coastal 8183 habitats. 8184CCSP 4.1 January 15, 2009

535 of 784 Final Report 8185 Understanding how the different coastal enviro nments of the United States will respond 8186 to future climate and sea-level change is a major challenge. In addi tion, as highlighted in 8187 earlier Parts of this Produc t, human actions and policy decisions also substantially 8188 influence the evolution of the coast. The knowledge gaps and data limitations identified 8189 in this Product focusing on the mid-Atlantic have broad relevance to the rest of the U.S. 8190 Chapter 14 identifies opportuni ties for increasing th e scientific understanding of future 8191 sea-level rise impacts. This includes basic and applied research in the natural and the 8192 social sciences. A significant emphasis is placed on developing linkages between 8193 scientists, policy makers, and stakeholders at al l levels, so that information can be shared 8194 and utilized efficiently and effectively as sea-level rise mitigation and adaptation plans 8195 evolve. 8196 8197CCSP 4.1 January 15, 2009

536 of 784 Final Report 

## Chapter 13. Implications of Sea-Level Rise to the 8198 

## Nation 8199

8200 Authors: S. Jeffress Williams, USGS; Benjamin T. Gutierrez, USGS; James G. Titus, 8201 USEPA; Eric Anderson, USGS (retired); Stephen K. Gill, NOAA; Donald R. Cahoon, 8202 USGS; E. Robert Thieler, USGS; and Dean B. Gesch, USGS 8203
8204

KEY FINDINGS 8205

 Nationwide, more than one- third of the United States population currently lives in 8206 the coastal zone and movement to the coast and development continues, along 8207 with the current and growing vulnerability to coastal hazards such as storms and 8208 sea-level rise. Fourteen of the 20 larges t U.S. urban centers are located along the 8209 coast. With the very likely accelerated rise in sea level and increased storm 8210 intensity, the conflicts between people and development at the coast and the 8211 natural processes will increase, cau sing economic and societal impacts. 8212

 For much of the U.S., shores comprised of barrier islands, dunes, spits, and sandy 8213 bluffs, erosion processes will dominate at highly variable rates in response to sea8214 level rise and storms over the next cent ury and beyond. Some coastal landforms in 8215 the U.S. may undergo large changes in shap e and location if the rate of sea-level 8216 rise increases as predicted. Increased inundation and more frequent flooding will 8217 affect estuaries and low-lying coastal ar eas. The response to these driving forces 8218 will vary depending on the type of coasta l landform and local conditions, but will 8219CCSP 4.1 January 15, 2009

537 of 784 Final Report be more extreme, more variable and less predictable than the changes observed 8220 over the last century. 8221

 For higher sea-level rise scenarios, some barrier island coasts and wetlands may 8222 cross thresholds and undergo significant and irreversible changes. These changes 8223 include rapid landward migration and segm entation of some barrier islands and 8224 disintegration and dr owning of wetlands. 8225

 Nationally, tidal wetlands already experiencing submergence by sea-level rise and 8226 associated land loss, in concert wi th other factors, will continue to deteriorate in 8227 response to changing climate. 8228

 Coastal change is driven by complex and interrelated processes. Over the next 8229 century and beyond, with an expected acceler ation in sea-level rise, the potential 8230 for coastal change is likely to be greater than has been observed in historic past. 8231 These changes to coastal regions will have especially large impacts on urban 8232 centers and developed areas. Some portions of the U.S. coast, however, will be 8233 subject primarily to inundation from s ea-level rise over th e next century. A 8234 substantial challenge remains to quantify th e various effects of sea-level rise and 8235 to identify the dominant coastal change processes for each region of the U.S. 8236

coast. 8237

 Many coastal areas in the United States will likely experience an increased 8238 frequency and magnitude of storm-surg e flooding and coastal erosion due to 8239 storms over the next century, in response to sea-level rise. The impacts from these 8240 storm events are likely to extend farthe r inland from the coast than those that 8241 would be affected by sea-level rise alone. 8242CCSP 4.1 January 15, 2009

538 of 784 Final Report  Understanding, predicting, and responding to the environmental and societal 8243 effects of sea-level rise would benefit from a national program of integrated 8244 research that includes the natural and social sciences. Research on adaptation, 8245 mitigation, and avoidance-of-risk measur es would enable improved understanding 8246 of the many and varied pote ntial societal impacts of sea-level rise that would 8247 benefit the U.S as well as coas tal nations around the world. 8248 8249 13.1 INTRODUCTION 8250 As defined in the SAP 4.1 Prospectus and di scussed in earlier chapters, this Product 8251 focuses on assessing potential impacts to the mid-Atlantic region; however, some 8252 discussion of impacts to other regions and the nation as a whole is warranted. The mid8253 Atlantic region is highly vulnerable to sea- level rise, but regions like the central Gulf 8254 Coast (Louisiana, Texas) are just as vulnerabl e or more so. The challenge in carrying out 8255 a national assessment is that nationwide data bases and scientific pub lications of national 8256 scale and scope are limited. Modest efforts at monitoring and observations for national8257 scale assessments of coastal change and h azards are underway by various organizations, 8258 but more effort is needed. The discussion in ection 13.3 is largely the expert opinions of 8259 the lead authors, informed by results of the two expert scienc e panel reports (Reed et al. , 8260 2008, Gutierrez, et al ., 2007) and available scientific l iterature. Because of the relative 8261 lack of adequate background literature and high reliance on expert opinion, the likehood 8262 statements as used in other chapters are not included in this discussion of potential 8263 impacts to the nation. 8264 8265CCSP 4.1 January 15, 2009

539 of 784 Final Report A large and expanding proportion of the U.S. population and related urban development 8266 is located along the Atlantic, Gulf of Mexi co, and Pacific coasts and increasingly 8267 conflicts with the natural processes associated with coastal change from storms and sea8268 level rise (see a review in Williams et al., 1991). Development in low-lying regions ( i.e ., 8269 New Orleans) and islands ( e.g ., in the Chesapeake Bay, Caribbean, Pacific Ocean) are 8270 particularly at risk (see Gi bbons and Nicholls, 2006) In th e future, as the effects of 8271 climate change intensify, these interactions will become more frequent and more 8272 challenging to society. Currently, more than one-third of the popul ation lives in the 8273 coastal zone and movement to the coast a nd development continues, along with the 8274 growing vulnerability to coasta l hazards. Fourteen of the 20 largest U.S. urban centers are 8275 located along the coast (Crossett et al ., 2004; Crowell et al. , 2007). With the likely 8276 accelerated rise in sea level and increased st orm intensity, the conflicts between people 8277 and development at the coast and the natural pr ocesses will increase, a ffecting all parts of 8278 society (Leatherman, 2001; FitzGerald et al., 2008). 8279
8280 Global sea-level rise associated with climate ch ange is likely to be in the range of 19 cm 8281 to as much as 1 m over the next century and possibly as much as 4 to 6 m over the next 8282 several centuries (IPCC, 2007; Ra hmstorf, 2007; Rahmstorf, e t al ., 2007; Overpeck et al ., 8283 2006). The expected rise will in crease erosion and the frequency of flooding and coastal 8284 areas will be at increasing risk. For some regions, adaptation using engineering means 8285 may be effective; for other coastal areas , however, adaption by re location landward to 8286 higher elevated ground may be appropriate fo r longer-term sustainability (NRC, 1987). 8287
8288CCSP 4.1 January 15, 2009

540 of 784 Final Report Coastal landforms reflect the complex inter action between the natural physical processes 8289 that act on the coast, the geologic characte ristics of the coast, and human activities. 8290 Spatial and temporal variations in these physical processes and the geology along the 8291 coast are responsible for the wide vari ety of landforms around the United States 8292 (Williams, 2003). With future sea-level rise, porti ons of the U.S. ocean coast are likely to 8293 undergo long-term net erosion, at rates higher than those that have been observed over 8294 the past century (see Chapter 3). The exact manner and rates at which these changes are 8295 likely to occur depend on the character of coastal landforms ( e.g ., barrier islands, cliffs) 8296 and the physical processes ( e.g. , waves and winds) that shape these landforms (see 8297 Chapters 3 and 4). Low-relief coastal regi ons, areas undergoing land subsidence and land 8298 subject to frequent storm landfalls, such as th e northern Gulf of Mexi co, Florida, Hawaii, 8299 Puerto Rico, the San Francisco-Sacramento Delta region, and the Mi d-Atlantic region, 8300 are particularly vulnerable. 8301
8302 13.2 TYPES OF COASTS 8303 Coasts are dynamic junctions of the oceans, atmosphere, and land and differ greatly in 8304 physical character and vulnerability to eros ion, storms, and sea-le vel rise (NRC, 1990). 8305 The principal coastal types are described in Chapters 3 and 4, and summarized below. 8306 With future sea-level rise, all of these landforms will become more dynamic (Nicholls et 8307 al. , 2007), but predicting and quantifying change s that are likely to occur with high 8308 confidence is currently scie ntifically challenging. 8309
8310 13.2.1 Cliff and Bluff Shorelines 8311CCSP 4.1 January 15, 2009

541 of 784 Final Report Substantial portions of the U.S. coast are compri sed of coastal cliffs and bluffs that vary 8312 greatly in height, morphology, and sedimentary composition. These occur predominantly 8313 along the New England and Pacific coasts, Hawa ii, and Alaska. Coastal cliff is a general 8314 term that refers to steep slopes along the shoreline that commonly form in response to 8315 long-term rise in sea-level. The term “bluff” also can refer to escarpments eroded into 8316 unlithified material, such as glacial till, along the shore (Hampton and Griggs, 2004). The 8317 terms “cliff” and “bluff” are often used interc hangeably. Coastal cliffs erode in response 8318 to a variety of both marine and terrestrial processes. Cliff retreat can be fairly constant, 8319 but can also be episodic. In contrast to sandy coasts, wh ich may erode landward or 8320 accrete seaward, cliffs retreat only in a landward direction. B ecause rocky cliff coasts are 8321 composed of resistant materials, erosion can can occur more slowly than for those 8322 comprised of unconsolidated sediments and re sponse times to sea-level rise much longer 8323 than for sandy coasts (NRC, 1987), but land slumping due to wave action or land surface 8324 water runoff can result in rapid retreat. Hamp ton and Griggs (2004) provide a review of 8325 the origin, U.S. distribution, evolution, and regi onal issues associated with coastal cliffs. 8326 Predicting the response of coastal cliffs to future sea-level rise is a topic of active 8327 research (Trenhaile, 2001; Walkden and Hall, 2005; Dickson et al ., 2007; Walkden and 8328 Dickson, 2008) 8329
8330 13.2.2 Sandy Shores, Pocket Beaches, Ba rrier Beaches, Spits, and Dunes 8331 Sandy beaches are often categorized into a few basic types which commonly include 8332 mainland, pocket, and barrier beaches (We lls, 1995; Davis and FitzGerald, 2004). The 8333 sediments that comprise beaches are derived mainly from the erosion of the adjacent 8334CCSP 4.1 January 15, 2009

542 of 784 Final Report mainland and continental shelf, and sometimes from sediments supplied from coastal 8335 rivers. Mainland beaches occur where the land intersects the shore. Some mainland 8336 beaches occur in low-relief settings and are surrounded by coastal dunes, while others 8337 occur along steep portions of the coast and ar e backed by bluffs. Examples of mainland 8338 beaches include the shores of eastern L ong Island, northern New Jersey (Oertel and 8339 Kraft, 1994), and parts of Delaware, (Kraft, 1971). Pocket beaches form in small bays, 8340 often occurring between rocky headlands a nd are common along parts of the southern 8341 New England coast, portions of California and Oregon (Hapke et al., 2006), and in parts 8342 of the Hawaiian Islands. Barrier beaches and spits are the most abundant coastal 8343 landforms along the Atlantic and Gulf of Mexico coasts. In general, it is expected that 8344 accelerations in sea-level rise will enhance beach erosion globally, but on a local scale 8345 this response will depend on the sediment budget (Nicholls et al., 2007). 8346
8347 13.2.3 Coastal Marshes, Mangroves, and Mud Flat Shorelines 8348 Coastal wetlands include swamps and tidal fl ats, salt and brackish marshes, mangroves, 8349 and bayous. They form in low-relief, low-ener gy sheltered coastal e nvironments, often in 8350 conjunction with river deltas, landward of barrier islands , and along the flanks of 8351 estuaries ( e.g. , Delaware Bay, Chesapeake Bay, Ev erglades, Lake Pontchatrain, 8352 Galveston Bay, San Francisco Bay, and Puge t Sound). Most coastal wetlands are in 8353 Louisiana, North and South Ca rolina, south Florida, and Alaska (Dahl, 1990; NRC, 8354 1995a). Wetlands are extremely vulnerable to sea-level rise and can maintain their 8355 elevation and viability only if sediment accumulation (both mineral and organic matter) 8356 keeps pace with sea-level rise (Cahoon et al ., 2006; Nyman et al., 2006; Morris et al., 8357CCSP 4.1 January 15, 2009

543 of 784 Final Report 2002; Rybczyk and Cahoon, 2002). Future wetland area will also be determined, in part, 8358 by the amount of space ( e.g ., mud flat or tidal flat area) available for landward migration 8359 and the rates of lateral erosi on of the seaward edge of the marsh (see Chapter 4; Poulter, 8360 2005). Wetlands will be especially vulnerable to the higher projected rates of future sea8361 level rise ( e.g ., greater than 70 cm by the year 2100), but some will survive a 1 meter rise 8362 (Morris et al., 2002). Even under lower accelerated sea-level rise rates, wetlands may be 8363 sustained only where conditions are optim al for vertical wetland development ( e.g ., 8364 abundant sediment supply and low regi onal subsidence rate ) (Rybczyk and Cahoon, 8365 2002). 8366
8367 Mud flat shorelines represent a relatively sm all portion of U.S. coasts, but are important 8368 in providing the foundation for wetlands and marshes (Mitsch and Gosselink, 1986). 8369 They are frequently associat ed with wetlands, and occur pr edominately in low-energy, 8370 low-relief regions with high inputs of fine -grained river-born sediments and organic 8371 materials and large tidal ranges. These shor eline types are common in western Louisiana 8372 ( i.e ., Chenier Plain) and along nor theastern parts of the Gulf Coast of Florida. Muddy 8373 coasts may be drowned with sea-level rise unless sediment inputs are sufficiently large, 8374 such as the Atchafalaya River delta region of southwestern Louisiana, and the flats are 8375 able to be colonized by plants. 8376
8377 13.2.4 Tropical Coral Reef Coasts 8378 Tropical coral reefs, made up of living organi sms very sensitive to ocean temperature and 8379 chemistry, are found in the U.S. along the s outh coast of Florida; around the Hawaiian 8380CCSP 4.1 January 15, 2009

544 of 784 Final Report Islands, Puerto Rico, the Virgin Islands, and many of the U.S. territories in the Pacific 8381 (Riegl and Dodge, 2008). In tropical environmen ts, living coral organisms build reefs that 8382 are important ecological resources (S mith and Buddemeier, 1992; Boesch et al ., 2000). 8383 Most corals are able to tolerate rates of s ea-level rise of 10 to 20 mm per year or more 8384 (Smith and Buddemeier, 1992; Bird, 1995; Wells, 1995; Hallock, 2005). Nonetheless, 8385 the ability of coral reef systems to survive future sea-level rise will depend heavily on 8386 other climate change impacts such as incr ease in ocean temperature and or acidity, 8387 sediment runoff from the land, as well as epis odic storm erosion (Hallock, 2005; Nicholls 8388 et al ., 2007). In addition, human caused stresses such as over-fishing or pollution can 8389 contribute to the vulnerabili ty of these systems to climate change (Buddemeier et al ., 8390 2004; Mimura et al ., 2007). 8391 8392 13.3 Potential for Future Shoreline Change 8393 Over the next century and beyond, with an e xpected acceleration in sea-level rise, the 8394 potential for coastal change will increase and coastal change is likely to be more 8395 widespread and variable than has been obser ved in historic past (NRC, 1987; Brown and 8396 McLachlan, 2002; Nicholls et al. , 2007). However, it is difficult at present to 8397 quantitatively attribute shoreline changes directly to sea-level rise (Rosenzweig et al ., 8398 2007). The potential changes include increased coastal erosion, more frequent tidal and 8399 storm-surge flooding of low-reli ef areas, and wetland deteri oration and losses. Many of 8400 these changes will occur in all coastal states. These changes to the coastal zone can be 8401 expected to have especially large impacts to developed areas (Nicholls et al ., 2007). 8402 Some portions of the U.S. coast will be subj ect principally to i nundation from sea-level 8403CCSP 4.1 January 15, 2009

545 of 784 Final Report rise over the next centur y, including upper reaches of bays and estuaries ( e.g. , 8404 Chesapeake and Delaware Bays, Tampa Bay, Lake Pontchartrain, San Francisco Bay), 8405 and hardened urban shorelines. Erosion, sedime nt transport, and sediment deposition in 8406 coastal environments are active processes and will drive coastal change in concert with 8407 the combined effects of future sea- level rise and storms (Stive, 2004). 8408 8409 Coastal landforms may become even more dynamic and that erosion will dominate 8410 changes in shoreline position over th e next century a nd beyond (Nicholls et al ., 2007). 8411 Wetlands with sufficient sediment supply and available land for inland migration may be 8412 able to maintain elevation, keeping pace with sea-level rise, but sediment starved 8413 wetlands and those constrained by engineering structures ( e.g. , seawalls, revetments) or 8414 steep uplands are likely to deteriorate and convert to open water through vertical 8415 accretion deficits and lateral erosion (see Chap ter 4). On barrier island shores, erosion is 8416 likely to occur on both the ocean front and th e landward side of the island due to a 8417 combination of storm activity, changes in se diment budget, more fr equent tidal flooding, 8418 and rising water levels (Nicholls et al., 2007). 8419
8420 Sea-level rise is a particular concern for islands (Mimura et al ., 2007). Of particular 8421 concern are islands compri sed of coral atolls ( e.g ., Midway Atoll), which are typically 8422 low-lying and dependent on the health of cora l reefs that fringe the atolls. Populated 8423 islands with higher elevations ( e.g ., the Northern Mariana Islands ) are also frequently at 8424 risk as the infrastructure is frequently located in low- lying coastal regions along the 8425 periphery of the islands. 8426CCSP 4.1 January 15, 2009

546 of 784 Final Report 8427 Many coastal areas in the United States will lik ely experience an increased frequency and 8428 magnitude of storm-surge flooding, greater wave heights, and more erosion due to storms 8429 as part of the response to sea-level ri se (NRC, 1987; Woodworth and Blackman, 2004; 8430 Nicholls et al. , 2007; Gutowski et al. , 2008). Impacts from these storm events may 8431 extend farther inland than those that would be affected by sea-level rise alone. Many 8432 regions may also experience large changes to co astal systems, such as increased rates of 8433 erosion, barrier island and dune landward migration, and potential barrier island collapse 8434 (Nicholls et al ., 2007; see also Chapters 1, 3, a nd 14 for discussion of geomorphic 8435 thresholds). The potential of crossing thre sholds, potentially leading to barrier and 8436 wetland collapse, may increase with higher rates of sea-level rise. 8437
8438 The use of so called “soft” coastal engineering mitigation measures, such as beach 8439 nourishment, usually using sand dredged from offshore Holocene-age sand bodies, may 8440 reduce the risk of storm flooding and co astal erosion temporarily (NRC, 1987, 1995b). 8441 However, an important issue is whether or not these practices are able to be maintained 8442 into the future to provide sustainable and ec onomical shoreline protec tion in the face of 8443 high cost, need for periodic re-nourishment, and limited sand resources of suitable quality 8444 for nourishment for many regions of the country (NRC, 1995b; Magoon et al., 2004). 8445 Results from offshore geologic mapping studies indicate that most continental shelf 8446 regions of the U.S. have relatively limited Holocene-age sediment that can be deemed 8447 available and suitable for uses such as beach nourishment (Schwab et al., 2000; Gayes et 8448 al ., 2003; Pilkey et al ., 1981; Kraft, 1971). In some cas es, potential sand volumes are 8449CCSP 4.1 January 15, 2009

547 of 784 Final Report reduced because of economic and environmen tal factors such as water depth, benthic 8450 environmrntal concerns, and concerns that sand removal may alter sediment exchange 8451 with the adjacent coast (Bliss et al ., 2009). The result is limited volumes of high-quality 8452 offshore sand resources readily available fo r beach nourishment. The issue of relying 8453 long term on using offshore sand for beach nour ishment to mitigate erosion is important 8454 and needs to be addressed. 8455 8456 More widespread implementation of regional sediment or best sediment management 8457 practices to conserve valuable coastal sedi ments from offshore disposal of clean sandy 8458 dredged spoils will enhance the long term sustainability of sandy coastal landforms 8459 (NRC, 2007). The use of so called “hard” engineering structures ( e.g. , seawalls, 8460 breakwaters) to protect property from eros ion and flooding may be justified for urban 8461 coasts, but their use on sandy shores can fu rther exacerbate erosion over time due to 8462 disruption of sediment transport processes. Alternatives, such as relocation landward, 8463 strategic removal of devel opment or limiting redevelopment following storm disasters 8464 from highly vulnerable parts of the coast, ma y provide longer term sustainability of both 8465 coastal landforms and development, especially if the higher rates of sea-level rise are 8466 realized (NRC, 1987). An example of abandonment of an island in Chesapeake Bay due 8467 to sea-level rise is detailed in Gibbons and Nicholls (2006). If coastal development is 8468 relocated, those areas could be converted to marine prot ected areas, public open-space 8469 lands that would serve to buffer sea-leve l rise effects landwar d and also provide 8470 recreation benefits and w ildlife habitat values (s ee Salm and Clark, 2000). 8471
8472CCSP 4.1 January 15, 2009

548 of 784 Final Report 13.4 CONCLUSIONS 8473 Global climate is changing, largely due to car bon emissions from human activities (IPCC, 8474 2001; 2007). Sea-level rise is one of the impact s of climate change that will affect all 8475 coastal regions of the United States ov er the next century and beyond (NRC, 1987; 8476 Nicholls et al., 2007). The scientific tools and tec hniques for assessi ng the effects of 8477 future sea-level rise on coastal systems are improving, but much remains to be done in 8478 order to develop useful forecasts of potential effects. Chapter 14 of this Product identifies 8479 research opportunities that, if implemented, would lead to better understanding and 8480 prediction of sea-level rise effects that are likel y to further impact the United States in the 8481 near future. Planning for accelerating sea-leve l rise should include thorough evaluation of 8482 a number of alternatives, such as cost-eff ective and sustainable shore protection and 8483 strategic relocation of development within ur ban centers. Important decisions like these 8484 should ideally be based on the best available science and careful c onsideration of long8485 term benefits for a sustainable future, and the total economic, social, and environmental 8486 costs of various methods of shore protection, relocation, and adaptation. 8487
8488CCSP 4.1 January 15, 2009

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552 of 784 Final Report Magoon , O.T., S.J. Williams, L.K. Lent, S.L. Douglass, B.L. Edge, J.A. Richmond, D.D 8568 Treadwell, L.C. Ewing, and A.P. Pratt, 2004: Economic impact s of anthropogenic 8569 activities on coastlines of the U.S., In: Coastal Engineering 2004, Proceedings of 8570 the 29th International Conf erence, Lisbon, Portugal. Wo rld Scientific Publishing, 8571 New Jersey and London, pp. 3022-3035. 8572
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Oertel , G.F. and J.C. Kraft, 1994: New Jersey and Delmarva barrier islands. In: Geology 8602 of Holocene Barrier Island Systems [Davis, R.A. (ed.)]. Springer-Verlag, New 8603 York, pp. 207-232. 8604 Overpeck , J.T., B.L. Otto-Bliesner, G.H. Miller, D.R. Muhs, R.B. Alley, and J.T. Keihl, 8605 2006: Paleo-climatic evidence for the futu re ice-sheet instability and rapid sea 8606 level rise. Science , 311(5768) , 1747-1750. 8607 Pilkey , O.H., B.W. Blackwekder, H.J. Knebel , and M.W. Ayers, 1981: The Georgia 8608 Embayment continental shelf: Stratigraphy of a submergence. Geological Society 8609 of America Bulletin , 92(1) , 52-63. 8610
Rahmstorf , S., 2007: A semi-empirical approach to projecting future sea-level rise. 8611 Science , 315(5810) , 368-370. 8612
Rahmstorf , S., A. Cazenave, J.A. Church, J.E. Hansen, R.F. Keeling, D.E. Parker, and 8613 R.C.J. Somerville, 2007: Recent climate observations compared to projections. 8614 Science , 316(5825) , 709. 8615

Reed , D.J., D. Bishara, D. Cahoon, J. Donnell y, M. Kearney, A. Kolker, L. Leonard, 8616 R.A. Orson, and J.C. Stevenson, 2008: Site-specific scenarios for wetlands 8617 accretion as sea level rises in the mid-Atlantic region. Section 2.1 in: Background 8618 Documents Supporting Climate Change Science Program Synthesis and 8619 Assessment Product 4.1: Coastal Elevati ons and Sensitivity to Sea Level Rise 8620CCSP 4.1 January 15, 2009

554 of 784 Final Report [Titus, J.G. and E.M. Strange (eds .)]. EPA 430R07004. U.S. Environmental 8621 Protection Agency, Washington, DC, pp. 134-174. 8622 <http://epa.gov/climatechange/e ffects/coastal/background.html> 8623 Riegl , B. and E. Dodge (eds.), 2008: Coral Reefs of the USA . Coral reefs of the 8624 worldvolume 1. Springer-Verla g, Dordrecht and London, 806 pp. 8625 Rosenzweig , C., G. Casassa, D.J. Karoly, A. Imeson, C. Liu, A. Menzel, S. Rawlins, T.L. 8626 Root, B. Seguin, P. Tryjanowski, and C. E. Hanson, 2007: Assessment of observed 8627 changes and responses in natural and managed systems. In: Climate Change 8628 2007: Impacts, Adaptation and Vulnerabili ty. Contribution of Working Group II 8629 to the Fourth Assessment Report of the Intergovernmental Panel on Climate 8630 Change . [Parry, M.L., O.F. Canziani, J.P. Palutikof, and P.J. van der Linden, 8631 (eds.)]. Cambridge University Press, Cambridge, UK, and New York, pp. 79-131. 8632 Rybczyk , J.M. and D.R. Cahoon, 2002: Estimating the potential for s ubmergence for two 8633 subsiding wetlands in the Mississippi River delta. Estuaries , 25(5) , 985-998. 8634
Salm , R.V. and J.R. Clark, 2000: Marine and Coastal Protected Areas . International 8635 Union for Conservation of Nature an d Natural Resources, Switzerland, 370 pp. 8636
Schwab , W.C., E.R. Thieler, J.R., Allen, D.S., Foster, B.A., Swift, and J.F. Denny, 2000: 8637 Influence of inner-continental shelf geologic framework on the evolution and 8638 behavior of the barrier island system be tween Fire Island inlet and Shinnecock 8639 inlet, Long Island, New York. Journal of Coastal Research , 16(2) , 408-422. 8640
Smith , S.V. and R.W. Buddemeier, 1992: Global change and coral reef ecosystems. 8641 Annual Reviews of Ecological Systematics , 23 , 89-118. 8642
Stive , M.J.F., 2004: How important is global warm ing for coastal erosion? An editorial 8643 comment. Climatic Change , 64(1-2) , 27-39. 8644
Trenhaile , A.S., 2001: Modeling the eff ect of late Quaternary in terglacial sea levels on 8645 wave-cut shore platforms. Marine Geology , 172(3-4) , 205-223. 8646CCSP 4.1 January 15, 2009

555 of 784 Final Report Walkden , M. and M. Dickson, 2008: Equilibrium erosion of so ft rock shores with a 8647 shallow or absent beach unde r increased sea level rise. Marine Geology , 251(1-2) , 8648 75-84. 8649

Walkden , M.J.A. and J.W. Hall, 2005: A predictiv e Mesoscale model of the erosion and 8650 profile development of soft rock shores. Coastal Engineering , 52(6) , 535-563. 8651

Wells , J.T., 1995: Effects of sea level rise on coastal sedimentation and erosion. In: 8652 Climate Change: Impact and Coastal Habitation , [Eisma, D. (ed.)]. CRC Press, 8653 Boca Raton, FL, pp. 111-136. 8654
Williams , S.J., 2003: Coastal and marine processes. Chapter 1.1.3.2. In: Our Fragile 8655 World: Challenges and Opportunitie s for Sustainable Development : Encyclopedia 8656 of Life Support Systems (EOLSS), [C ilek, V. (ed.)]. Developed under the 8657 auspices of the UNESCO, EOLSS Publishers, Oxford, UK, 13 pp. 8658 <http://www.eolss.net> 8659
Williams , S.J., K. Dodd, and K.K. Gohn, 1991: Coasts in Crisis . U.S. Geological Survey 8660 circular 1075. U.S. Geological Survey, [Reston, VA], 30 pp. 8661

Woodworth , P.L and D.L. Blackman, 2004: Evidence for systematic changes in extreme 8662 high waters since the mid-1970s. Journal of Climate, 17(6) , 1190-1197. 8663

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556 of 784 Final Report 

## Chapter 14. A Science Strategy for Improving the 8665 

## Understanding of Sea-Level Rise and its Impacts on 8666 

## U.S. Coasts 8667

8668 Authors: E. Robert. Thieler, USGS; K. Eric Anderson, USGS; Donald R. Cahoon, 8669 USGS; S. Jeffress Williams, USGS ; Benjamin T. Gutierrez, USGS 8670
8671 KEY FINDINGS 8672

 Understanding, predicting, and respondi ng to the environmental and human 8673 effects of sea-level rise requires an inte grated program of research that includes 8674 natural and social sciences. 8675

 Monitoring of modern processes and environments could be improved by 8676 expanding the network of basic observati ons and observing systems, developing 8677 time series data on environmental and landscape changes, and assembling 8678 baseline data for the coastal zone. 8679

 The historic and geologic record of coasta l change should be used to improve the 8680 understanding of natural and human-influenced coastal systems, increase 8681 knowledge of sea-level rise and coasta l change over the past few millennia, 8682 identify thresholds or tipping points in co astal systems, and more closely relate 8683 past changes in climate to coastal change. 8684CCSP 4.1 January 15, 2009

557 of 784 Final Report  Increases in predictive capabilities can be achieved by improving quantitative 8685 assessment methods and integrating studies of the past and present into predictive 8686 models. 8687

 Research on adaptation, mitigation, and avoidance measures will enable better 8688 understanding of the societal impacts of sea-level rise. 8689

 Decision making in the coastal zone can be supported by providing easy access to 8690 data and resources, transferring knowledge of vulnerability and risk that affect 8691 decision making, and educating the public about consequences and alternatives. 8692 8693 14.1 INTRODUCTION 8694 Chapter 14 identifies several major themes that present opportuniti es to improve the 8695 scientific understandi ng of future sea-level rise and its impacts on U.S. coastal regions. 8696 Advances in scientific understanding will enable the development of higher quality and 8697 more reliable information for planners and decision makers at all levels of government, as 8698 well as the public. 8699
8700 A number of recent studies have focused speci fically on research needs in coastal areas. 8701 Two National Research Council (NRC) studies, Science for Decision-making (NRC, 8702 1999) and A Geospatial Framework for the Coastal Zone (NRC, 2004) contain 8703 recommendations for science activities that can be applied to sea-leve l rise studies. Other 8704 relevant NRC reports include Responding to Changes in Sea Level (NRC, 1987), Sea 8705 Level Change (NRC, 1990b) and Abrupt Climate Change (NRC, 2002). The Marine 8706 Board of the European Science Foundation’s Impacts of Climate Change on the European 8707CCSP 4.1 January 15, 2009

558 of 784 Final Report Marine and Coastal Environment (Philippart et al. , 2007) identified numerous research 8708 needs, many of which have application to the United States. Recent studies on global 8709 climate change by the Pew Charitable Trusts also included the coastal zone ( e.g. , 8710
Neumann et al. , 2000, Panetta, 2003; Kennedy et al. , 2002). Other studies by the NRC 8711 (1990a, 1990b, 1990c, 2001, 2006a, 2007) and the Heinz Center (2000, 2002a, 2002b, 8712 2006) have addressed issues rele vant to the impacts of sea-level rise on the coastal zone. 8713 These reports and related publications have he lped guide the development of the potential 8714 research and decision-support activities described in the following sections. 8715
8716 14.2 A SCIENCE STRATEGY TO ADDRESS SEA-LEVEL RISE 8717 An integrated scientific program of sea level studies that seeks to learn from the historic 8718 and geologic past, and monitors ongoing phys ical and environmental changes, will 8719 improve the level of knowledge and reduce th e uncertainty about pot ential responses of 8720 coasts, estuaries, and wetlands to sea-leve l rise. Outcomes of both natural and social 8721 scientific research will support decision making and adap tive management in the coastal 8722 zone. The main elements of a potential scie nce strategy and their interrelationships are 8723 shown in Figure14.1. 8724CCSP 4.1 January 15, 2009

559 of 784 Final Report 8725 Figure 14.1 Schematic flow diagram summarizing a science strategy for improvement of scientific 8726 knowledge and decision-making capability needed to address the impacts of future sea-level rise. 8727 8728 Building on and complementing ongoing efforts at federal agencies and universities, a 8729 research and observation program could in corporate new technologi es to address the 8730 complex scientific and societal issues highlig hted in this Product. These studies could 8731 include further development of a robust monitoring program for all coastal regions, 8732 leveraging the existing network of site observations, as well as the growing array of 8733 coastal observing systems. Resear ch should also include studies of the historic and recent 8734CCSP 4.1 January 15, 2009

560 of 784 Final Report geologic past to understand how coastal system s evolved in response to past changes in 8735 sea level. The availability of higher resoluti on data collected over a ppropriate time spans, 8736 coupled with conceptual and numerical mode ls of coastal evolution, will provide the 8737 basis for improved quantitative assessments a nd the development of predictive models 8738 useful for decision making. Providing ready ac cess to interpretations from scientific 8739 research—as well as the unde rlying data—by means of publi cations, data portals, and 8740 decision-support systems will allow coastal managers to evaluate alternative strategies for 8741 mitigation, develop appropriate responses to sea-level rise, and practice adaptive 8742 management as new information becomes available. 8743
8744 14.2.1 Learn From the Historic and Recent Geologic Past 8745 Studies of the recent geologic and historical record of sea-level rise and coastal and 8746 environmental change are needed to improve the state of knowledge of the key physical 8747 and biological processes i nvolved in coastal change. As described throughout this 8748 Product, particularly in Chapters 1 thr ough 5, significant knowledge gaps exist that 8749 inhibit useful prediction of future changes. The following research activities will help 8750 refine our knowledge of past changes and their causes. 8751
8752 Improve understanding of natural and human-influenced coastal systems 8753 Significant opportunities exist to improve predictions of coasta l response to sea-level rise. 8754 For example, scientists’ understa nding of the processes contro lling rates of sediment flux 8755 in both natural and especially in human-modifi ed coastal systems is still evolving. This is 8756 particularly true at the regional (littoral cell) scale, which is often the same scale at which 8757CCSP 4.1 January 15, 2009

561 of 784 Final Report management decisions are made. As describe d in Chapters 3 and 6, the human impact on 8758 coastal processes at management scales is not well understood. S horeline engineering 8759 such as bulkheads, revetments, seawalls, groins, jetties, and beach nourishment can 8760 fundamentally alter the way a coastal system behaves by changing the transport, storage, 8761 and dispersal of sediment. The same is true of development and infrastructure on mobile 8762 landforms such as the barrier islands that comprise much of the mid-Atlantic coast. 8763
8764 Develop better information on the effects of sea-level rise over the past 5,000 years 8765 The foundation of modern coastal barrier island and wetland systems has evolved over 8766 the past 5,000 years as the rate of sea-leve l rise slowed significantly (see Chapters 1, 3, 8767 and 4). More detailed inves tigation of coastal sediment ary deposits is needed to 8768 understand the rates and patterns of change dur ing this part of the recent geologic past. 8769 Advances in methods to obtain samples of the geologic record, along with improvements 8770 in analytical laboratory tec hniques since the early 1990s, have significantly increased the 8771 resolution of the centennial-to-millennial scale record of sea-level rise and coastal 8772 environmental change ( e.g. , Gehrels, 1994; Gehrels et al. , 1996; van de Plassche et al., 8773 1998; Donnelly et al. , 2001; Horton et al. , 2006) and provide a basis for future work. 8774 Archaeological records of past sea-level cha nge also exist in many locales, and provide 8775 additional opportunities to unde rstand coastal change a nd impacts on human activity. 8776
8777 Understand thresholds in coastal systems that , if crossed, could lead to rapid changes to 8778 coastal and wetland systems 8779CCSP 4.1 January 15, 2009

562 of 784 Final Report Several aspects of climate change studies, such as atmosphere-ocean interactions, 8780 vegetation change, sea ice extent, and glacier and ice cap responses to temperature and 8781 precipitation, involve understa nding the potential for abrupt climate change or “climate 8782 surprises” (NRC, 2002; Meehl et al. , 2007). Coastal systems may also respond abruptly 8783 to changes in sea-level rise or other physical and biological processes (see Chapter 3, Box 8784 3.1). Coastal regions that may respond rapidly to even modest changes in future external 8785 forcing need to be identified, as well as th e important variables dr iving the changes. For 8786 example, limited sediment supply, and/or permanent sand removal from the barrier 8787 system, in combination with an acceleration in the rate of sea-leve l rise, could result in 8788 the development of an unstable stat e for some barrier island systems ( i.e ., a behavioral 8789 threshold or tipping point, as described in Chapters 1 and 3). Coastal responses could 8790 result in landward migrati on or roll-over, or barrier segmentation. Understanding and 8791 communicating the potential for such dramatic changes in the form and rate of coastal 8792 change will be crucial for the development of adaptation, mitigation, and other strategies 8793 for addressing sea-level rise. 8794 8795 The future evolution of low-elevation, narro w barriers will likely depend in part on the 8796 ability of salt marshes in b ack-barrier lagoons and estuaries to keep pace with sea-level 8797 rise (FitzGerald et al. , 2004, 2008; Reed et al. , 2008). It has been suggested that a 8798 reduction of salt marsh in back-barrier regi ons could change the hydrodynamics of back8799 barrier systems, altering local sediment budgets and leading to a reduction in sandy 8800 materials available to sustai n barrier systems (FitzGerald et al. , 2004, 2008). 8801
8802CCSP 4.1 January 15, 2009

563 of 784 Final Report Relate climate proxies to coastal change 8803 Links between paleoclimate proxies ( e.g. , atmospheric gases in ice cores, isotopic 8804 composition of marine microfossils, tree rings), sea-level rise, and coastal change should 8805 be explored. Previous periods of high sea le vel, such as those dur ing the last several 8806 interglacial periods, provide tangible evidence of higher-than-present sea levels that are 8807 broadly illustrative of the potential for future shoreline changes. For example, high stands 8808 of sea level approximately 420,000 and 125,000 y ears ago left distinct shoreline and 8809 other coastal features on the U.S. Atlantic coastal plain (Colquhoun et al. , 1991; Baldwin 8810 et al. , 2006). While the sedimentary record of these high stands is fragmentary, 8811 opportunities exist to relate past shoreline po sitions with climate pr oxies to improve the 8812 state of knowledge of the relationships betw een the atmosphere, sea level, and coastal 8813 evolution. Future studies may also provide insight into how coastal systems respond to 8814 prolonged periods of high sea level and rapid sea-level fluctuations during a high stand. 8815 Examples of both exist in the geologic record and have poten tial application to 8816 understanding and forecasting future coastal evolution. 8817
8818 14.2.2 Monitor Modern Coastal Conditions 8819 The status and trends of sea- level change, and changes in the coastal environment, are 8820 monitored through a network of observation si tes, as well as through coastal and ocean 8821 observing systems. Monitoring of modern processes and environments could be 8822 improved by expanding the network of basic observations, as well as the continued 8823 development of coastal and ocean observing systems. There are numerous ongoing 8824CCSP 4.1 January 15, 2009

564 of 784 Final Report efforts that could be leveraged to contribute to understanding patte rns of sea-level rise 8825 over space and time and the respon se of coastal environments. 8826
8827Expand the network of basic observations 8828 An improvement in the coverage and quality of the U.S. network of basic sea-level 8829 observations could better inform researchers a bout the rate of sea-level rise in various 8830 geographic areas. Tide gauges are a primary sour ce of information for sea-level rise data 8831 at a wide range of time scales, from minutes to centuries. These data contribute to a 8832 multitude of studies on local to global sea-level trends. Tide gauge data from the United 8833 States include some of the longest such data sets in the world and have been especially 8834 valuable for monitoring long-term trends. A denser network of high-resolution gauges 8835 would more rigorously assess re gional trends and effects. The addition of tide gauges 8836 along the open ocean coast of the United States would be valuable in some regions. These 8837 data can be used in concert with satellite altimetry observations. 8838 8839 Tide-gauge observations also provide records of terrestr ial elevation change that 8840 contributes to relative sea-leve l change, and can be coupled with field- or model-based 8841 measurements or estimates of land elevation changes. Existing and new gauges should be 8842 co-located with continuously operating Global Positioning System (GPS) reference 8843 stations (CORS) or surveyed periodically using GPS and other Global Navigation 8844 Satellite System technology. This will enable the coupling of the geodetic (earth-based) 8845 reference frame and the oceanographic refere nce frame at the la nd-sea interface. Long 8846 time series from CORS can provide precise lo cal vertical land movement information in 8847CCSP 4.1 January 15, 2009

565 of 784 Final Report the ellipsoidal frame ( e.g. , Snay et al. , 2007; Woppelmann et al. , 2007). Through a 8848 combined effort of monitoring ellipsoid heig hts and the geoid, as well as through gravity 8849 field monitoring, changes to coastal el evations can be adequately tracked. 8850 8851 Develop and maintain coastal observing systems 8852 Observing systems have become an important tool for examining environmental change. 8853 They can be place-based ( e.g. , specific estuaries or ocean lo cations) or consist of regional 8854 aggregations of data a nd scientific resources ( e.g. , the developing network of coastal 8855 observing systems) that cover an entire regi on. Oceanographic observati ons also need to 8856 be integrated with observations of the physical environment, as well as habitats and 8857 biological processes. 8858 8859 An example of place-based observing systems is the National Estuarine Research 8860 Reserve System (NERRS: <http://www.nerrs.no aa.gov>), a network of 27 reserves for 8861 long-term research, monitoring, educati on, and resource stewardship. Targeted 8862 experiments in such settings can potentially elucidate impacts of sea-level rise on the 8863 physical environment, such as shoreline cha nge or impacts to groundwater systems, or on 8864 biological processes, such as species ch anges or ecosystem impacts. Important 8865 contributions can also be made by th e Long Term Ecological Research sites 8866 (<http://www.lternet.edu>) such as the Virgin ia Coast Reserve in the mid-Atlantic area 8867 (part of the focus of this Pr oduct). The sites combine long-ter m data with current research 8868 to examine ecosystem change over time. In tegration of these ecological monitoring 8869CCSP 4.1 January 15, 2009

566 of 784 Final Report networks with the geodetic a nd tide gauge networks mentione d previously would also be 8870 an important enhancement. 8871
8872 The Integrated Ocean Observing System (IOOS) (<http://www.ocean.us>) will bring 8873 together observing systems and data collecti on efforts to understand and predict changes 8874 in the marine environment. Many of these efforts can contribute to understanding 8875 changes in sea-level rise ove r space and time. These observing systems incorporate a 8876 wide range of data types and sources, and provide an integrated approach to ocean 8877 studies. Such an approach should enable sea-level rise-induced changes to be 8878 distinguished from the diverse processes that drive changes in the coastal and marine 8879 environment. 8880
8881 A new initiative began in 2005 with a worldwide effort to build a Global Earth 8882 Observation System of Systems (GEOSS) (<http://www.earthobservations.org>) over the 8883 next 10 years. GEOSS builds upon existing national, regional, and international systems 8884 to provide comprehensive, c oordinated Earth observations from thousands of instruments 8885 worldwide, which have broad applic ation to sea-level rise studies. 8886
8887 Develop time series data to monito r environmental and landscape changes 8888 Observations of sea level using satellite altimetry ( e.g. , TOPEX/Poseidon and Jason-1) 8889 have provided new and important insights into the patterns of se a-level change across 8890 space and time. Such observations have allowe d scientists to examine sea-level trends 8891 and compare them to the instrumental record (Church et al. , 2001, 2004), as well as 8892CCSP 4.1 January 15, 2009

567 of 784 Final Report predictions made by previous climate ch ange assessments (Rahmstorf, 2007). The 8893 satellite data provide spatial coverage not available with ground-based methods such as 8894 tide gauges, and provide an efficient mean s for making global obser vations. Plans for 8895 future research could include a robust sa tellite observation program to ensure 8896 comprehensive coverage. 8897 8898 Studies of environmental and landscape change can also be expanded across larger spatial 8899 scales and longer time scales. Examples incl ude systematic mapping of shoreline changes 8900 and coastal barriers and dunes around the United States ( e.g. , Morton and Miller, 2005), 8901 and other national mapping efforts to doc ument land-use and land-cover changes ( e.g. , 8902 the NOAA Coastal Change Analysis Program: 8903 <http://www.csc.noaa.gov/crs/lca/ccap.html>). It is also important to undertake a 8904 rigorous study of land movements beyond th e point scale of tide gauges and GPS 8905 networks. For example, the application of an emerging technology—Interferometric 8906 Synthetic Aperture Radar (InSAR)—enables th e development of spatially-detailed maps 8907 of land-surface displacement over broad areas (Brooks et al. , 2007). 8908 8909 Determining wetland sustainability to current a nd future sea-level rise requires a broader 8910 foundation of observations if they are to be applied with high conf idence at regional and 8911 national scales. In addition, there is a signi ficant knowledge gap concerning the viability 8912 or sustainability of human-impacted and rest ored wetlands in a time of accelerating sea8913 level rise. The maintenance of a network of s ites that utilize surface elevation tables and 8914 soil marker horizons for measuring marsh accretion or loss will be essential in 8915CCSP 4.1 January 15, 2009

568 of 784 Final Report understanding the impacts on areas of critical wetland habitat. The addition of sites to the 8916 network would aid in delineati ng regional variations (Cahoon et al. , 2006). Similar long8917 term studies for coastal erosion, habitat cha nge, and water quality are also essential. 8918 8919 Coastal process studies require data to be coll ected over a long period of time in order to 8920 evaluate changes in beach and barrier pr ofiles and track morphological changes over a 8921 time interval where there has been a significan t rise in sea level. These data will also 8922 reflect the effects of storms and the sediment budget that frequently make it difficult to 8923 extract the coastal response to sea-level change. For example, routine lidar mapping 8924 updates to track morphological changes and ch anges in barrier island area above mean 8925 high water ( e.g. , Morton and Sallenger, 2003), as well as dune degradation and recovery, 8926 and shore-face profile and nea r-shore bathymetric evoluti on may provide insight into 8927 how to distinguish various time and space scales of coastal change and their relationship 8928 to sea-level rise. 8929 8930 Time series observations can al so be distributed across the la ndscape and need not be tied 8931 to specific observing systems or data netw orks. They do, however, need a means to have 8932 their data assimilated into a larger contex t. For example, development of new remote 8933 sensing and in-situ technologies and techniques would he lp fill critical data gaps at the 8934 land-water interface. 8935 8936 Assemble and update baseline data for the coastal zone 8937CCSP 4.1 January 15, 2009

569 of 784 Final Report Baseline data for the coastal zone, including elevation, bathymetry, shoreline position, 8938 and geologic composition of the coast, as well as biologic and ecologic parameters such 8939 as vegetation and species distribution, and ecosystem and habitat boundaries, should be 8940 collected at high spatial re solution. As described in Ch apter 2, existing 30-m (100-ft) 8941 digital elevation models are generally inade quate for meaningful ma pping and analyses in 8942 the coastal zone. The use of lid ar data, with much better hor izontal and vertical accuracy, 8943 is essential. While some of these mappi ng data are being colle cted now, there are 8944 substantial areas around the United States that would benefit from higher quality data. 8945 More accurate bathymetric data, especially in the near-shore, is n eeded for site-specific 8946 analyses and to develop a complete topographi c-bathymetric model of the coastal zone to 8947 be able to predict with gr eater confidence wave and curre nt actions, inundation, coastal 8948 erosion, sediment transport, and storm effects. 8949 8950 To improve confidence in model predictions of wetland vulnerability to sea-level rise, 8951 more information is needed on: (1) maximum accretion rates ( i.e. , thresholds) regionally 8952 and among vegetative communities; (2) wetland dynamics across larger landscape scales; 8953 (3) the interaction of feedback controls on flooding with other accretion drivers ( e.g. , 8954 nutrient supply and soil organic matter accumulation); (4) fine-grained, cohesive 8955 sediment supplies; and (5) cha nging land use in the watershed ( i.e. , altered river flows 8956 and accommodation space for landward migra tion of wetlands). In addition, population 8957 data on different species in near shore areas ar e needed to accurately judge the effects of 8958 habitat loss or transformation. More extensiv e and detailed areas of habitat mapping will 8959 enable preservation efforts to be fo cused on the most important areas. 8960CCSP 4.1 January 15, 2009

570 of 784 Final Report 8961 14.2.3 Predict Future Coastal Conditions 8962 Studies of the past history of sea-level rise and coastal response, combined with extensive 8963 monitoring of present conditions , will enable more robust pred ictions of future sea-level 8964 rise impacts. Substantial opportunities exis t to improve methods of coastal impact 8965 assessment and prediction of future changes. 8966 8967 Develop quantitative assessment methods that iden tify high-priority areas needing useful 8968 predictions 8969 Assessment methods are needed to identify both geographic and topical areas most in 8970 need of useful predictions of sea-level rise impacts. For example, an assessment 8971 technique for objectively assessing potential e ffects of sea-level rise on open coasts, the 8972 Coastal Vulnerability Index (CVI), has been employed in the United States and elsewhere 8973 ( e.g. , Gornitz et al ., 1997; Shaw et al. , 1998; Thieler and Hammar-Klose, 1999, 2000a, 8974 2000b). Although the CVI is a fairly simplistic te chnique, it can provide useful insights 8975 and has found application as a coastal planning and ma nagement tool (Thieler et al. , 8976 2002). Such assessments have also been inte grated with socioeconomic vulnerability 8977 criteria to yield a more integrative m easure of community vulnerability (Boruff et al. , 8978 2005). 8979 8980 Projecting long-term wetland sustainability to future sea-level rise requires data on 8981 accretionary events over suffici ently long time scales that include the return periods of 8982 major storms, floods, and droughts, as well as information on the effects of wetland 8983CCSP 4.1 January 15, 2009

571 of 784 Final Report elevation feedback on inundation and sedimentat ion processes that a ffect wetland vertical 8984 accretion. Numerical models can be applied to predict wetland sustainability at the local 8985 scale, but there is no t sufficient data to populate these m odels at the regional or national 8986 scale (see Chapter 4). Given this data constr aint, current numerical modeling approaches 8987 will need to improve or adapt su ch that they can be applied at broader spatial scales with 8988 more confidence. 8989 8990 Integrate studies of past and present coas tal behavior into predictive models 8991 Existing shoreline-change pred iction techniques are typically based on assumptions that 8992 are either difficult to validate or too simp listic to be reliable for many real-world 8993 applications (see Appendix 2). As a result, the usefulness of these modeling approaches 8994 has been debated in the coas tal science community (see Chapter 3). Newer models that 8995 include better representations of r eal-world settings and processes ( e.g. , Cowell et al., 8996 1992; Stolper et al. , 2005; Pietrafesa et al. , 2007) have shown promise in predicting 8997 coastal evolution. Informing these models w ith improved data on past coastal changes 8998 should result in better predictions of future changes. 8999 9000 The process of marine transgre ssion across the continental shelf has left an incomplete 9001 record of sea-level and environmental change . An improved understand ing of the rate and 9002 timing of coastal evolution will need to draw on this incomplete record, however, in order 9003 to improve models of coastal change. Us ing a range of techniques, such as high9004 resolution seafloor and geologic framewor k mapping coupled with geochronologic and 9005 paleoenvironmental studies, the record of coastal evolution duri ng the Pleistocene (1.8 9006CCSP 4.1 January 15, 2009

572 of 784 Final Report million to 11,500 years ago) and the Holocene (t he last 11,500 years) can be explored to 9007 identify the position and timing of former shorelines and coastal environments. 9008 9009 14.2.4 Improve Understanding of Societal Impacts 9010 Research in the social scien ces will be critical to understa nding the potential effects on 9011 society and social systems resulting from sea-level rise. 9012 9013 Increase research on adaptation, mitigation, and avoidance measures 9014 This Product describes a wide variety of poten tial impacts of sea-leve l rise, including the 9015 effects on the physical environment, biologi cal systems, and coastal development and 9016 infrastructure. While the ability to predict future changes is currently inadequate for 9017 many decisions, adaptation, mitigation, and avoidan ce strategies must evolve as scientific 9018 knowledge and predictive abil ity increase. For example, expanded research and 9019 assessments of the economic and environmental costs of present and future actions are 9020 needed to allow a more complete analysis of the tradeoffs involved in sea-level rise 9021 decision making. In addition, opportunities to engage stakeholders such as federal 9022 agencies, states, counties, towns, non-government organizations, and private landowners 9023 in the design and implementation of sea-le vel rise impact and response planning should 9024 be created. 9025 9026 Develop multi-disciplinary groups that in tegrate natural and social sciences 9027 Interdisciplinary research that combines natu ral and social sciences will be crucial to 9028 understanding the interplay of the physical, environmenta l, and societal impacts of sea- 9029CCSP 4.1 January 15, 2009

573 of 784 Final Report level rise. Development of programs that f acilitate such collaborations should be 9030 encouraged. 9031 9032Expand institutional capacity and overcome barriers 9033 Substantial opportunities exist to expand and improve upon the ab ility of institutions to 9034 respond to sea-level rise (see Chapter 10, 11, a nd 12). Research is needed to define the 9035 capacity needed for decision making, as well as the methods that can be best employed 9036 ( e.g. , command and control, economic incentive) to achieve management goals. 9037 Overcoming the institutional barriers described in Chapter 12 is also necessary for 9038 effective response to the management ch allenges presented by sea-level rise. 9039 9040 14.2.5 Develop Coastal Decision Support Syst ems for Planning and Policy Making 9041 For coastal zone managers in all levels of governme nt, there is a pressing need for more 9042 scientific information, a reducti on in the ranges of uncertainty for processes and impacts, 9043 and new methods for assessing options and al ternatives for management strategies. 9044 Geospatial information on a wide range of themes such as topography, bathymetry, land 9045 cover, population, and infrastructure, that is maintained on regular cycle will be a key 9046 component of planning for mitigation and adap tation strategies. For example, specialized 9047 themes of data such as hydric (abundantly mo ist) soils may be cri tical to understanding 9048 the potential for wetland survival in specifi c areas. Developing and maintaining high9049 resolution maps that incor porate changes in hazard type and distribution, coastal 9050 development, and societal risk will be critical. Regularly conducting vulnerability 9051 assessments and reviews will be necessary in order to adapt to changing conditions. 9052CCSP 4.1 January 15, 2009

574 of 784 Final Report 9053Provide easy access to data and information res ources for federal, state, local, academic, 9054 and public users 9055 Understanding and acting on scien tific information about sea-level rise and its impacts 9056 will depend upon common, consistent, shared da tabases for integrating knowledge and 9057 providing a basis for decision making. Thema tic data and other value-added products 9058 should adhere to predetermined standards to make them universally accessible and 9059 transferable through internet portals. All data should be accompanied by appropriate 9060 metadata describing its method of producti on, extent, quality, spatial reference, 9061 limitations of use, and othe r characteristics (NRC, 2004). 9062 9063 An opportunity exists to devel op a national effort to devel op and apply data integration 9064 tools to combine terrestrial and marine data into a seamless geospatial framework. This 9065 would involve the collection of real-time tide data and the development of more 9066 sophisticated hydrodynamic models for the enti re U.S. coastline, as well as the 9067 establishment of protocols and tools for me rging bathymetric and topographic datasets 9068 (NRC, 2004). Modern and updated digital fl ood insurance rate maps (DFIRM) that 9069 incorporate future sea-level rise are need ed in the coastal zone (see Chapter 9). 9070 9071 Transfer scientific knowledge to studies of vulnerability, risk, and societal impacts 9072 In addition to basic scientific research a nd environmental monitoring, a significant need 9073 exists to integrate the results of these effo rts into comprehensive vulnerability and risk 9074 assessments. Tools are needed for mapping, modeling, and communicating risk to help 9075CCSP 4.1 January 15, 2009

575 of 784 Final Report public agencies and communities understand and reduce their vulnerability to, and risk 9076 of, sea-level rise hazards. Social science res earch activities are also needed that examine 9077 societal consequences and economic impacts of sea-level rise, as well as identify 9078 institutional frameworks needed to adapt to changes in the coastal zone. For example, 9079 analyses of the economic costs of armoring s hores at risk of erosion and the expected 9080 lifespan of such efforts will be required, as will studies on the durability of armored 9081 shorefronts under different se a-level rise scenarios. The physical and biological 9082 consequences of armoring shores will need to be quantified and the tradeoffs 9083 communicated. Effective planning for sea-level rise will also require integrated economic 9084 assessments on the impact to fisheries, tourism, and commerce. 9085 9086 Applied research in the development of co astal flooding models for the subsequent study 9087 of ecosystem response to sea-level rise is underway in coastal states such as North 9088 Carolina (Feyen et al. , 2006). There is also a need fo r focused study on the ecological 9089 impacts of sea-level rise and in how the transf er of this knowledge can be made to coastal 9090 managers for decision-making. 9091 9092 Develop decision support systems 9093 County and state planners need tools to anal yze vulnerabilities, expl ore the implications 9094 of alternative response measures, assess the costs and benefits of options, and provide 9095 decision-making support. These might take the fo rm of guidelines, checklists, or software 9096 tools. In addition, there is a need to examin e issues in a landscape or ecosystem context 9097 rather than only administrative boundaries. 9098CCSP 4.1 January 15, 2009

576 of 784 Final Report 9099 In addition to new and maintained data, mode ls, and research, detailed site studies are 9100 needed to assess potential impacts on a site-s pecific basis and provi de information that 9101 allows informed decision making. Appropriate methodologies need to be developed and 9102 made available. These will have to look at a full range of possible impacts including 9103 aquifer loss by saltwater intrusion, wetland lo ss, coastal erosion, and infrastructure 9104 implications, as well as the impact of ad aptation measures themselves. Alternative 9105 strategies of adaptive management will be required. Each locality may need a slightly 9106 different set of responses to provide a balanced policy of preserving ecosystems, 9107 protecting critical infrastructure, and adjusting to property loss or protection. Providing a 9108 science-based set of decision support tools wi ll provide a sound basis for making these 9109 important decisions. 9110 9111Educate the public on conse quences and alternatives 9112 Relative to other natural hazards such as earthquakes, volcanic eruptions, and severe 9113 weather ( e.g. , hurricanes, tornadoes) that typically occur in minutes to days, sea-level rise 9114 has a long time horizon over which effects b ecome clear. Thus, it is often difficult to 9115 communicate the consequences of this sometimes slow process that occurs over many 9116 years. The impacts of sea-level rise, however , are already being felt across the United 9117 States (see Chapter 13). Public education will be crucial for adapting to physical, 9118 environmental, economic, and social changes resulting from sea-level rise. Research 9119 activities that result in effective means to conduct public education and outreach 9120 concerning sea-level rise consequence and alternativ es should be encouraged. 9121 9122CCSP 4.1 January 15, 2009

577 of 784 Final Report CHAPTER 14 REFERENCES 9123 * Indicates non-peer reviewed literature; available upon request 9124

Baldwin , W.E., R.A. Morton, T.R. Putney, M.P. Ka tuna, M.S., Harris, P.T. Gayes, N.W. 9125 Driscoll, J.F. Denny, and W.C. Schwab, 2006: Migration of the Pee Dee River 9126 system inferred from ancestral paleoc hannels underlying the South Carolina 9127 Grand Strand and Long Bay inner shelf. Geological Society of America Bulletin , 9128 118(5/6) , 533-549. 9129
Boruff , B.J., C. Emrich, and S.L. Cutter, 2005 : Erosion hazard vulnerability of US 9130 coastal counties. Journal of Coastal Research , 21(5) , 932-942. 9131

Brooks , B.A., M.A. Merrifield, J. Foster, C.L. We rner, F. Gomez, M. Bevis, and S. Gill, 9132 2007: Space geodetic determination of spa tial variability in relative sea level 9133 change, Los Angeles Basin. Geophysical Research Letters , 34 , L01611, 9134 doi:10.1029/2006GL028171. 9135
Cahoon , D.R., P.F. Hensel, T. Spencer, D.J. R eed, K.L., McKee, and N. Saintilan, 2006: 9136 Coastal wetland vulnerability to relative sea-level rise: wetland elevation trends 9137 and process controls. In: Wetlands and Natural Resource Management 9138 [Verhoeven, J.T.A., B. Beltman, R. Bobbi nk, and D. Whigham (eds.)]. Ecological 9139 studies volume 190. Springer, Berlin and New York, pp. 271-292. 9140
Church , J.A., J.M. Gregory, P. Huybrechts, M. Kuhn, K. Lambeck, M.T. Nhuan, D. Qin, 9141 and P.L. Woodworth, 2001: Changes in sea level. In: Climate Change 2001: The 9142 Scientific Basis. Contribution of Working Group 1 to the Third Assessment 9143 Report of the Intergovernmental Panel on Climate Change [Houghton, J.T., Y. 9144 Ding, D.J. Griggs, M. Noguer, P.J. van de r Linden, X. Dai, K. Maskell, and C.A. 9145 Johnson (eds.)]. Cambridge University Pr ess, Cambridge UK, and New York, pp. 9146 639-693. 9147
Church , J.A., N.J. White, R. Coleman, K. La mbeck, and J.X. Mitrovica, 2004: Estimates 9148 of the regional distribution of sea-level rise over the 1950-2000 period. Journal of 9149 Climate , 17(13) , 2609-2625. 9150CCSP 4.1 January 15, 2009

578 of 784 Final Report Colquhoun , D.J., G.H. Johnson, P.C. Peebles, P.F. Huddlestun, and T. Scott, 1991: 9151 Quaternary geology of the A tlantic coastal plain. In: Quaternary Nonglacial 9152 Geology: Conterminous U.S. [Morrison, R.B. (ed.)]. The Geology of North 9153 America v. K-2. Geological Society of America, Boulder, CO, pp. 629-650. 9154
Cowell , P.J., P.S. Roy, and R.A. Jones, 1992: Shoreface translation model: computer 9155 simulation of coastal-sand-body response to sea-level rise. Mathematics and 9156 Computers in Simulation , 33(5-6) , 603-608. 9157 Donnelly , J.P., S.S. Bryant, J. Butler, J. Dowling, L. Fan, N. Hausmann, P. Newby, B. 9158 Shuman, J. Stern, K. Westover, and T. Webb III, 2001: A 700-year sedimentary 9159 record of intense hurricane landf alls in southern New England. Geological Society 9160 of America Bulletin , 113(6) , 714-727. 9161

* Feyen , J., K. Hess, E. Spargo, A. Wong, S. White, J. Sellars, and S. Gill, 2006: 9162 Development of continuous bathymet ric/topographic unstructured coastal 9163 flooding model to study sea-level rise in North Carolina. In: Proceedings of the 9164 9th International Conference on Estuarine and Coastal Modeling , Charleston, 9165 SC, October 31 – November 2, 2005. [Spauldi ng, M. (ed.)]. American Society of 9166 Civil Engineers, Reston, VA, pp. 338-356. 9167
FitzGerald , D.M., I.V. Buynevich, and B.A. Ar gow, 2004: Model of tidal inlet and 9168 barrier island dynamics in a regi me of accelerated sea-level rise. Journal of 9169 Coastal Research , Special issue 39 , 789-795. 9170
FitzGerald , D.M., M.S. Fenster, B.A. Argow, and I.V. Buynevich, 2008: Coastal 9171 impacts due to sea-level rise. Annual Reviews of Earth and Planetary Sciences , 9172 36, 601-647. 9173
Gehrels , W.R., 1994: Determining relative sea level change from salt-marsh foraminifera 9174 and plant zones on the coast of Maine, U.S.A. Journal of Coastal Research , 9175 10(4) , 990-1009. 9176CCSP 4.1 January 15, 2009

579 of 784 Final Report Gehrels , W.R., D.F. Belknap, and J.T. Kelley, 1 996: Integrated high-precision analyses 9177 of Holocence relative sea level changes: lessons from the coast of Maine. 9178 Geological Society of America Bulletin , 108(9) , 1073-1088. 9179

* Gornitz , V. T.W. Beaty, and R.C. Daniels, 1997: A Coastal Hazards Database for the 9180 U.S. West Coast . ORNL/CDIAC-81, NDP-043C. Oa k Ridge National Laboratory, 9181 Oak Ridge, TN, 162 pp. <http://cd iac.ornl.gov/ndps/ndp043c.html> 9182

* Heinz Center , 2000: Evaluation of Erosion Hazards. The H. John Heinz III Center for 9183 Science, Economics, and the Envi ronment, Washington, DC, 203 pp. 9184

* Heinz Center , 2002a: Human Links to Coastal Disasters . The H. John Heinz III Center 9185 for Science, Economics, and the Environment, Washington, DC, 139 pp. 9186

* Heinz Center , 2002b: The State of the Nation’s Ecosystems: Measuring the Lands, 9187 Waters, and Living Resources of the United States . Cambridge University Press, 9188 New York, 270 pp. 9189

* Heinz Center , 2006: Filling the Gap--Priority Da ta Needs and Key Management 9190 Challenges for National Reporting on Ecosystem Condition . The H. John Heinz 9191 III Center for Science, Economics, and the Environment, Washington, DC, 110 9192 pp. 9193

Horton , B.P., R. Corbett, S.J. Culver, R.J. Ed wards, and C. Hillie r, 2006: Modern salt 9194 marsh diatom distributions of the Outer Banks, North Carolina, and the 9195 development of a transfer function for high resolution reconstructi ons of sea level. 9196 Estuarine, Coastal, and Shelf Science , 69(3-4) , 381-394. 9197

* Kennedy , V.S., R.R. Twilley, J.A. Kleypas, J.H. Cowan, and S.R. Hare, 2002: Coastal 9198 and Marine Ecosystems & Global Clim ate Change: Potentia l Effects on U.S. 9199 Resources . Pew Center on Global Climate Change, Arlington, VA, 52 pp. 9200

Meehl , G.A., T.F. Stocker, W.D. Collins, P. Frie dlingstein, A.T. Gaye, J.M. Gregory, A. 9201 Kitoh, R. Knutti, J.M. Murphy, A. Noda , S.C.B. Raper, I.G. Watterson, A.J. 9202 Weaver, and Z.-C. Zhao, 2007: Global clim ate projections. In: Climate Change 9203CCSP 4.1 January 15, 2009

580 of 784 Final Report 2007: The Physical Science Basis . Contribution of Worki ng Group I to the Fourth 9204 Assessment Report of the Intergovernment al Panel on Climate Change [Solomon, 9205 S., D. Qin, M. Manning, Z. Chen, M. Mar quis, K.B. Averyt, M. Tignor, and H.L. 9206 Miller (eds.)]. Cambridge University Press, Cambridge, UK, and New York, pp. 9207 747-845. 9208

Morton , R.A. and T.L. Miller, 2005: National Assessment of Shoreline Change: Part 2, 9209 Historical Shoreline Changes and Associ ated Coastal Land Loss Along the U.S. 9210 Southeast Atlantic Coast . U.S. Geological Survey open-file report 2005-1401, 9211 U.S. Geological Survey, [St. Petersburg, FL], 35 pp. 9212 <http://pubs.usgs .gov/of/2005/1401> 9213

Morton , R.A. and A.H. Sallenger Jr., 2003: Mo rphological impacts of extreme storms on 9214 sandy beaches and barriers. Journal of Coastal Research , 19(3) , 560-573. 9215

* Neumann , J.E., G. Yohe, R. Nic holls, and M. Manion, 2000: Sea-level Rise and Global 9216 Climate Change: A Review of Impacts to U.S. Coasts . Pew Center on Global 9217 Climate Change, Arlington, VA, 38 pp. <http://www.pewclimate.org/global9218 warming-in-depth/all_reports/sea_level_rise> 9219
NRC (National Research Council), 1987: Responding to Changes in Sea Level: 9220 Engineering Implications

. National Academy Press, Washington, DC, 148 pp. 9221
NRC (National Research Council), 1990a: Managing Coastal Erosion . National 9222 Academy Press, Washington, DC, 182 pp. 9223
NRC (National Research Council), 1990b: Sea Level Change. National Academy Press, 9224 Washington, DC, 256 pp. 9225
NRC (National Research Council), 1990c: Spatial Data Needs: The Future of the 9226 National Mapping Program. National Academy Press, Washington, DC, 78 pp. 9227
NRC (National Research Council), 1999: Science for Decisionmaking: Coastal and 9228 Marine Geology at the U.S. Geological Survey. National Academy Press, 9229 Washington, DC, 113 pp. 9230CCSP 4.1 January 15, 2009

581 of 784 Final Report NRC (National Research Council), 2001: Sea Level Rise and Coastal Disasters: 9231 Summary of a Forum. National Academies Press, Washington, DC, 24 pp. 9232
NRC (National Research Council), 2002: Abrupt Climate Change: Inevitable Surprises

. 9233 National Academy Press, Washington, DC, 230 pp. 9234
NRC (National Research Council), 2004: A Geospatial Framework for the Coastal Zone: 9235 National Needs for Coas tal Mapping and Charting. National Academies Press, 9236 Washington, DC, 149 pp. 9237
NRC (National Research Council), 2006: Beyond Mapping: Meeting National Needs 9238 Through Enhanced Geographic Information Science. National Academies Press, 9239 Washington, DC, 100 pp. 9240
NRC (National Research Council), 2007: Mitigating Shore Erosi on on Sheltered Coasts

. 9241 National Academies Press, Washington, DC, 174 pp. 9242

* Panetta , L.E., 2003: America’s Living Oceans: Charting a Course for Sea Change: A 9243 Report to the Nation: Recommenda tions for a New Ocean Policy. Pew Oceans 9244 Commission, Arli ngton, VA, 145 pp. 9245 <http://www.pewtrusts.org/pdf/env_pew_oceans_final_report.pdf> 9246 Philippart , C.J.M., R. Anadón, R. Danovaro, J.W. Dippner, K.F. Drinkwater, S.J. 9247 Hawkins, G. O’Sullivan, T. Oguz, and P.C. Reid, 2007: Impacts of Climate 9248 Change on the European Marine and Coastal Environment . Marine Board 9249 position paper 9, European Science Foundation, Strasbourg, France, 84 pp. 9250 <http://www.sesame-ip. eu/doc/MB_Climate_Chan ge_VLIZ_05031.pdf> 9251
Pietrafesa , L.J., K. Kelleher, T. Karl, M. Davids on, M. Peng, S. Bao, D. Dickey, L. Xie, 9252 H. Liu, and M. Xia, 2007: A new archite cture for coastal inundation and flood 9253 warning prediction. Marine Technology Society Journal , 40(4) , 71-77. 9254
Rahmstorf , S., 2007: A semi-empirical approach to pr ojecting future sea-level rise. 9255 Science , 315(5810) , 368-370. 9256CCSP 4.1 January 15, 2009

582 of 784 Final Report Reed , D.J., D. Bishara, D. Cahoon, J. Donnell y, M. Kearney, A. Kolker, L. Leonard, 9257 R.A. Orson, and J.C. Stevenson, 2008: Site-specific scenarios for wetlands 9258 accretion as sea level rises in the mid-Atlantic region. Section 2.1 in: Background 9259 Documents Supporting Climate Change Science Program Synthesis and 9260 Assessment Product 4.1: Coastal Elevati ons and Sensitivity to Sea Level Rise 9261 [Titus, J.G. and E.M. Strange (eds .)]. EPA 430R07004. U.S. Environmental 9262 Protection Agency, Washington, DC, pp. 134-174. 9263 <http://epa.gov/climatechange/e ffects/coastal/background.html> 9264
Shaw , J., R.B. Taylor, S. Solomon, H.A. Chri stian, and D.L. Forbes, 1998: Potential 9265 impacts of global sea-level rise on Canadian coasts. The Canadian Geographer , 9266 42(4) , 365-379. 9267 Snay , R., M. Cline, W. Dillinger, R. Foote, S. Hilla, W. Kass, J. Ray, J. Rohde, G. Sella, 9268 and T. Soler, 2007: Using global positioning system-derived crus tal velocities to 9269 estimate rates of absolute sea level ch ange form North American ride gauge 9270 records. Journal of Geophysical Research , 112 , B04409, 9271 doi:10.1029/2006JB004606. 9272 Stolper , D., J.H. List, and E.R. Thieler, 2005: Simulating the evolution of coastal 9273 morphology and stratigraphy with a ne w morphological-behavior model 9274 (GEOMBEST). Marine Geology , 218(1-4) , 17-36. 9275
Thieler , E.R. and E.S. Hammar-Klose, 1999: National Assessment of Coastal 9276 Vulnerability to Sea-Level Rise: Prelimi nary Results for the U.S. Atlantic Coast

. 9277 U.S. Geological Survey open-file repor t 99-593. U.S. Geological Survey, Reston, 9278 VA, 1 sheet. <http://pubs.usgs.gov/of/of99-593/> 9279
Thieler , E.R. and E.S. Hammar-Klose, 2000a: National Assessment of Coastal 9280 Vulnerability to Sea-Level Rise: Prelimi nary Results for the U.S. Pacific Coast

. 9281 U.S. Geological Survey open-file repor t 00-178. U.S. Geological Survey, Reston, 9282 VA, 1 sheet. <http://pubs .usgs.gov/of/2000/of00-178/> 9283CCSP 4.1 January 15, 2009

583 of 784 Final Report Thieler , E.R. and E.S. Hammar-Klose, 2000b: National Assessment of Coastal 9284 Vulnerability to Sea-Level Rise: Prelimi nary Results for the U.S. Gulf of Mexico 9285 Coast . U.S. Geological Survey open-file report 00-179. U.S. Geological Survey, 9286 Reston, VA, 1 sheet. <http: //pubs.usgs.gov/of/2000/of00-179/> 9287
Thieler , E.R., S.J. Williams, and R. Beavers, 2002: Vulnerability of U.S. National Parks 9288 to Sea-Level Rise and Coastal Change . U.S. Geological Survey fact sheet FS 095- 9289 02. [U.S. Geological Survey, Reston, VA], 2 pp. <http://pubs.usgs.gov/fs/fs095- 9290 02/> 9291

van de Plassche , O., K. van der Borg, and A.F.M. de Jong, 1998: Sea level-climate 9292 correlation during the past 1400 years. Geology , 26(4) , 319-322. 9293 Woppelmann , G., B.M. Miguez, M.-N. Bouin, and Z. Altamimi, 2007: Geocentric sea9294 level trend estimates from GPS analyses at relevant tide gauges world wide, 9295 Global and Planetary Change , 57(3-4) , 396-406. 9296

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584 of 784 Final Report 

## Appendix 1. State and Local Information on Vulnerable 9298 

## Species and Coastal Policies in the Mid-Atlantic 9299 9300 9301 

## OVERVIEW 9302 Appendix 1 discusses many of the species that depend on potentially vulnerable habitat in 9303 specific estuaries, providing local elaboration of the general issues examined in Chapter 9304 5. It also describes key statutes, regulations, and other policies that currently define how 9305 state and local governments are responding to sea level rise, providi ng support for some 9306 of the observations made in Part III. This set of information was not developed as a 9307 quantitative nor analytical a ssessment and therefore is not intended as a complete or 9308 authoritative basis for decision-m aking; rather, it is a starti ng point for those seeking to 9309 discuss local impacts and to examine the types of decisions and potential policy 9310 responses related to sea-level rise. 9311 9312 The sections concerning species and habitat are largely derived from a U.S. EPA report 9313 developed in support of this Synthesis and Assessment Product (U.S. EPA, 2008), with 9314 additional input from stakeholde rs as well as expert and public reviewers. That report 9315 synthesized what peer-reviewed literature was available, and augmented that information 9316 with reports by organizations that manage the habitats under discussion, databases, and 9317 direct observations by experts in the field. The sections that concern state and local 9318 policies are based on statutes, regulations, a nd other official documents published by state 9319 and local governments. 9320 9321CCSP 4.1 January 15, 2009

585 of 784 Final Report Characterizations of likelihood in this Product are largely ba sed on the judgment of the 9322 authors and on published peer-reviewed literature and existing policies, rather than a 9323 formal quantification of uncertainty. Da ta on how coastal ecosystems and specific 9324 species may respond to climate change is limited to a small number of site-specific 9325 studies, often carried out for purposes unrelated to efforts to evaluate the potential impact 9326 of sea level rise. Although being able to characterize current understanding

― and the 9327 uncertainty associated with that information

― is important, quantita tive and qualitative 9328 assessments of likelihood are not unavailable fo r the site-specific issues discussed in this 9329 Appendix. Unlike the main body of the Product, any likelihood statements in this 9330 Appendix regarding specific habitat or speci es reflect likelihood as expressed in 9331 particular reports being cited. St atements about the implications of coastal policies in this 9332 Appendix are based on the authors qualitative as sessment of available published literature 9333 and of the governmental policies. Published information, data, and tools are evolving to 9334 further examine sea-level rise at this scale. 9335 9336 The synthesis was compiled by the following au thors for the specific areas of focus and 9337 edited by K. Eric Anderson, USGS; Stephen K. Gill, NOAA; Daniel Hudgens, Industrial 9338 Economics, Inc.; and James G. Titus, U.S. EPA: 9339 9340 A. Long Island page 586 9341 Lead Authors: Daniel Hudgens, Industrial Economics Inc.; Ann 9342 Shellenbarger Jones, Industrial Econ omics Inc.; James G. Titus, EPA. 9343 Contributing Authors: Elizabeth M. Strange, Stratus Consulting Inc.; J. 9344 Tanski, New York Sea Grant; G. Sinha, University of Ohio; 9345 9346 B. New York Metropolitan Area page 598 9347 Lead Author: Elizabeth M. St range, Stratus Consulting Inc; 9348CCSP 4.1 January 15, 2009

586 of 784 Final Report Contributing Authors: Daniel H udgens, Industrial Economics Inc.; Ann 9349 Shellenbarger Jones, Indu strial Economics Inc. 9350 9351 C. New Jersey Shore page 605 9352 Lead Author: James G. Titus, U.S. EPA 9353 Contributing Author: Elizabeth M. Strange, Stratus Consulting Inc. 9354 9355 D. Delaware Estuary page 619 9356 Lead Author: James G. Titus, U.S. EPA 9357 Contributing Authors: Chris Linn, Delaware Valley Regional Planning 9358 Commission; Danielle Kreeger, Partners hip for the Delaware Estuary, Inc.; 9359 Michael Craghan, Middle Atlantic Ce nter for Geography & Environmental 9360 Studies; Michael Weinstein, New Jers ey Marine Sciences Consortium 9361 (NJMSC) and Director, New Jers ey Sea Grant College Program 9362 9363 E. The Atlantic Coast of Virginia, Maryla nd, and Delaware page 634 9364 Lead Author: James G. Titus, U.S. EPA 9365 Contributing Author: Elizabeth M. Strange, Stratus Consulting Inc. 9366 9367 F. Chesapeake Bay page 645 9368 Lead Author: James G. Titus, U.S. EPA 9369 Contributing Authors: Ann Shellenbar ger Jones, Industrial Economics Inc.; 9370 Peter Conrad, City of Baltimore; Elizabeth M. Strange, Stratus Consulting; 9371 Zoe Johnson, Maryland Department of Na tural Resources; Michael Weinstein, 9372 New Jersey Sea Grant 9373 9374 G. North Carolina page 686 9375 Lead Authors: James G. Titus, U. S. EPA; Rebecca L. Feldman, NOAA; Ben 9376 Poulter, Potsdam Institute for Climate Impact Research 9377 Contributing Authors: Jeff DeBlie u, The Nature Conservancy; Ann 9378 Shellenbarger Jones, Indu strial Economics Inc. 9379 9380 

## A1.A. Long Island 9381 The North Shore of Long Island is generally characterized by high bluffs of glacial 9382 origin, making this area less susceptible to problems associated with increased sea level. 9383 The South Shore, by contrast, is generally lo w lying and fronted by barrier islands, except 9384 for the easternmost portion. As a result, there are already major planning efforts 9385 underway in the region to preserve the dr y lands under threat of inundation. A brief 9386CCSP 4.1 January 15, 2009

587 of 784 Final Report discussion of these efforts, especially on th e South Shore, is provided in Section A1.A.2 9387 of this Appendix. Maps and estimates of the ar ea of land close to sea level are provided in 9388 Titus and Richman (2001). Further informa tion on portions of the South Shore can be 9389 found in Gornitz et al. (2002). 9390 9391 A1.A.1 Environmental Implications 9392 North Shore and Peconic Bay. 9393 Of the 8,426 hectares (ha) (20,820 acres [ac]) of tidal wetlands in Long Island Sound, 9394 about 15 percent are in New York, primarily along the shores of Westchester and Bronx 9395 counties (Holst et al. , 2003). Notable areas of ma rsh are in and around Stony Brook 9396 Harbor and West Meadow, bordering th e Nissequogue River and along the Peconic 9397 Estuary (NYS DOS, 2004). In general, tidal wetlands along the North Shore are limited; 9398 the glacial terminal moraine 70 resulted in steep uplands a nd bluffs and more kettle-hole 71 9399 wetlands along the eastern portion (LISHRI, 2003). In the eastern portion, there has 9400 already been a significant loss of the historical area of vege tated tidal wetlands (Holst et 9401 al. , 2003; Hartig and Gornitz, 2004), which some sc ientists partially at tribute to sea-level 9402 rise (Mushacke, 2003). 9403 9404 The loss of vegetated low marsh reduces ha bitat for several ra re bird species ( e.g. , seaside 9405 sparrow) that nest only or primarily in low marsh (see Section 5.2). Low marsh also 9406 provides safe foraging areas for sma ll resident and transient fishes ( e.g. , weakfish, winter 9407 flounder). Diamondback terrapin live in the cr eeks of the low marsh, where they feed on 9408

70 A glacial terminal moraine is a glacial deposit landform that marks the limit of glacial advance. 71 A kettle hole is a depression landform formed in glacial deposit sediments from a time when a large block of glacial ice remained an d melted after a glacial retreat.CCSP 4.1 January 15, 2009

588 of 784 Final Report plants, mollusks, and crustaceans (LISF, 2008). Some wetlands along Long Island Sound 9409 may be allowed to respond naturally to sea- level rise, including some in the Peconic 9410 Estuary. Where migration is possible, preserva tion of local biodiversity as well as some 9411 regionally rare species is possible (Strange et al. , 2008). 9412 9413 Beaches are far more common than tidal wetlands in the Long Island Sound study area. 9414 Several notable barrier beaches exist. Fo r example, the sandy barrier-beach system 9415 fronting Hempstead Harbor supports a typica l community progression from the foreshore 9416 to the bay side, or backshore (LISHRI, 2003) . The abundant inverteb rate fauna provide 9417 forage for sanderling, semipalmated plovers, and other migrating shorebirds (LISHRI, 9418 2003). The maritime beach community between the mean high tide and the primary dune 9419 provides nesting sites for seve ral rare bird species, incl uding piping plover, American 9420 oystercatcher, black skimmer, least tern, comm on tern, roseate tern, the Northeastern 9421 beach tiger beetle, and horseshoe crab (LISHRI, 2003) (see Box A1.1). Diamondback 9422 terrapin use dunes and the upper limit of the backshore beach for nesting (LISHRI, 2003). 9423 9424 Since nearly all of the Long Island Sound shoreline is densely populated and highly 9425 developed, the land may be armored in response to sea-level rise, rais ing the potential for 9426 beach loss. The Long Island Sound Habitat Rest oration Initiative cautions: “Attempts to 9427 alter the natural cycle of deposition and er osion of sand by construction of bulkheads, 9428 seawalls, groins, and jetties interrupt the formation of new beaches” (LISHRI, 2003). 9429 9430CCSP 4.1 January 15, 2009

589 of 784 Final Report Shallow water habitats are a major ecologica l feature in and around the Peconic Estuary. 9431 Eelgrass beds provide food, shelter, and nursery habitats to diverse species, including 9432 worms, shrimp, scallops and other bivalves, crabs, and fish (PEP, 2001). Horseshoe crabs 9433 forage in the eelgrass beds of Cedar Po int/Hedges Bank, where they are prey for 9434 loggerhead turtles (federally lis ted as threatened), crabs, wh elks, and sharks (NYS DOS, 9435 2004). Atlantic silverside spawn here; silver side eggs provide an important food source 9436 for seabirds, waterfowl, and blue crab, wh ile adults are prey for bluefish, summer 9437 flounder, rainbow smelt, white perch, Atla ntic bonito, and striped bass (NYS DOS, 9438 2004). The Cedar Point/Hedges Bank Shallows eelgrass beds are known for supporting a 9439 bay scallop fishery of statewide importance (NYS DOS, 2004). 9440 9441 Other noteworthy habitats that could be affected by sea-leve l rise include the sea-level 9442 fen vegetation community that grows along Flanders Bay (NYS DOS, 2004), and the 9443 Long Island’s north shore tidal flats, where longshore drift carries material that erodes 9444 from bluffs and later deposits it to form flat s and barrier spits or shoals (LISHRI, 2003). 9445 One of the largest areas of tidal mudflats on the North Shore is near Conscience Bay, 9446 Little Bay, and Setauket Harbor west of Po rt Jefferson (NYS DOS, 2004). Large beds of 9447 hard clams, soft clams, American oysters, and ribbed mussels are found in this area (NYS 9448 DOS, 2004). 9449 9450 South Shore

. 9451 Extensive back-barrier salt marshes exist to the west of Great South Bay in southern 9452 Nassau County (USFWS, 1997). These marshe s are particularly notable given 9453CCSP 4.1 January 15, 2009

590 of 784 Final Report widespread marsh loss on the mainland shorel ine of southern Nassau County (NYS DOS 9454 and USFWS, 1998; USFWS, 1997). To the east of Jones Inlet, the extensive back-barrier 9455 and fringing salt marshes are keeping pace with current rates of sea-level rise, but experts 9456 predict that the marshes’ ability to keep pace is likely to be marginal if the rate of sea9457 level rise increases moderately, and that th e marshes are likely to be lost under higher 9458 sea-level rise scenarios (Strange et al. , 2008, interpreting the findings of Reed et al ., 9459 2008). Opportunities for marsh migration al ong Long Island’s South Shore would be 9460 limited if the mainland shores continue to be bulkheaded. Outside of New York City, the 9461 state requires a minimum 22.9-meter (m) (75- foot [ft]) buffer around tidal wetlands to 9462 allow marsh migration, but outsi de of this buffer, additiona l development and shoreline 9463 protection are permitted 72 (NYS DEC, 2006). Numerous wildlife species could be 9464 affected by salt marsh loss. For example, the Dune Road Marsh west of Shinnecock Inlet 9465 provides nesting sites for seve ral species that are already showing significant declines, 9466 including clapper rail, sharp-tailed sparrow, seaside sparrow, willet, and marsh wren 9467 (USFWS, 1997). The salt marshes of Gilgo Stat e Park provide nesting sites for northern 9468 harrier, a species listed by the state as threatened (NYS DOS, 2004). 9469 9470 Of the extensive tidal flats along Long Island ’s southern shoreline, most are found west 9471 of Great South Bay and east of Fire Island Inle t, along the bay side of the barrier islands, 9472 (USFWS, 1997) in the Hempstead Bay–Sout h Oyster Bay complex, (USFWS, 1997) and 9473 around Moriches and Shinnecock Inlets (NYS DOS and USFWS, 1998). These flats 9474 provide habitat for several edible shellfish sp ecies, including soft clam, hard clam, bay 9475

72 The state has jurisdiction up to 300 feet beyond the tidal wetland boundary in most areas (but only 150 feet in New York City).CCSP 4.1 January 15, 2009

591 of 784 Final Report scallop, and blue mussel. The tidal flats around Moriches and Shinnecock Inlets are 9476 particularly important foragi ng areas for migrating shorebir ds. The South Shore Estuary 9477 Reserve Council asserts that “because shorebir ds concentrate in just a few areas during 9478 migration, loss or degradation of key sites could devastate these populations” (NYS DOS 9479 and USFWS, 1998). 9480 9481 The back-barrier beaches of the South Shore also provide nesting sites for the endangered 9482 roseate tern and horsesh oe crabs (USFWS, 1997). Shorebirds, such as the red knot, feed 9483 preferentially on horseshoe crab eg gs during their spring migrations. 9484 9485 Increased flooding and erosion of marsh and dr edge spoil islands w ill reduce habitat for 9486 many bird species that forage and nest th ere, including breeding colonial waterbirds, 9487 migratory shorebirds, and wint ering waterfowl. For example, erosion on Warner Island is 9488 reducing nesting habitat for the federally e ndangered roseate tern and increasing flooding 9489 risk during nesting (NYS DOS and USFWS, 1998). The Hempstead Bay–South Oyster 9490 Bay complex includes a network of salt marsh an d dredge spoil islands that are important 9491 for nesting by herons, egrets, and ibises. Li kewise, Lanes Island and Warner Island in 9492 Shinnecock Bay support colonies of the stat e-listed common tern a nd the roseate tern 9493 (USFWS, 1997). 9494
--START TEXT BOX-- 9495 BOX A1.1: Effects on the Piping Plover 9496 Piping Plover Charadrius melodus 9497 Habitat: The piping plover, federally listed as threatened , is a small migratory shorebird that primarily 9498 inhabits open sandy barrier island beaches on Atlantic coasts (USFWS, 1996). Major contributing factors to 9499 the plover’s status as threatened are beach recreation by pedestrians and vehicles that disturb or destroy 9500 plover nests and habitat, predation by mammals and other birds, and shoreline development that inhibit the 9501 natural renewal of barrier beach and overwash habitats (USFWS, 1996). In some locations, dune 9502CCSP 4.1 January 15, 2009

592 of 784 Final Report maintenance for protection of access roads associated with development appears to be correlated with 9503 absence of piping plover nests from former nesting sites (USFWS, 1996). 9504 9505 Locations: The Atlantic population of piping plovers winters on beaches from the Yucatan Peninsula to 9506 North Carolina. In the summer, they migrate north and breed on beaches from North Carolina to 9507 Newfoundland (CLO, 2004). In the mid-Atlantic region, breeding pairs of plovers can be observed on 9508 coastal beaches and barrier islands, although suitable habitat is limited in some areas. In New York, piping 9509 plovers breed more frequently on Long Island’s sandy beaches, from Queens to the Hamptons, in the 9510 eastern bays and in the harbors of northern Suffolk County. New York’s Breezy Point barrier beach, at the 9511 mouth of Jamaica Bay, consistently supports one of the largest piping plover nesting sites in the entire New 9512 York Bight coastal region (USFWS, 1997). New York ha s seen an increase in pipi ng plover breeding pairs 9513 in the last decade from less than 20 0 in 1989 to near 375 in recent years (2003 to 2005), representing nearly 9514 a quarter of the Atlantic coast’s total breeding population (USFWS, 2004a). Despite this improvement, 9515 piping plovers remain state listed as endangered in New York (NYS DEC, 2007). 9516 9517 Impact of Sea-Level Rise: Where beaches are prevented from migr ating inland by shoreline armoring, 9518 sea-level rise will negatively impact Atlantic coast piping plover populations. To the degree that developed 9519 shorelines result in erosion of o cean beaches, and to the degree that stabilization is undertaken as a 9520 response to sea-level rise, piping plover habitat will be lost. In contrast, where b eaches are able to migrate 9521 landward, plovers may find newly available habitat. For example, on Assateague Island, piping plover 9522 populations increased after a storm ev ent that created an overwash area on the north of the island (Kumer, 9523 2004). This suggests that if barrier beaches are allo wed to migrate in response to sea-level rise, piping 9524 plovers might adapt to occupy new inlets an d beaches created by overwash events. 9525 9526 Beach nourishment, the antic ipated protection response for much of New York’s barrier beaches such as 9527 Breezy Point, can benefit piping plovers and other shor ebirds by increasing availa ble nesting habitat in the 9528 short term, offsetting losses at erod ed beaches, but may also be detr imental, depending on timing and 9529 implementation (USFWS, 1996). For instance, a study in Massachusetts found that plovers foraged on 9530 sandflats created by beach nourishment (Cohen et al ,, 2005). However, once a beach is built and people 9531 spread out to enjoy it, many areas become restricted during nesting season. Overall, throughout the Mid9532 Atlantic, coastal development and shoreline stabilization projects constitute the most serious threats to the 9533 continuing viability of storm-maintained beach habitats and their dependent species, including the piping 9534 plover (USFWS, 1996). 9535 9536 Photograph credit: USFWS, New Jersey Field Office /Gene Nieminen, 2006. 9537 9538 -- END TEXT BOX – 9539 9540 A1.A.2 Development, Shore Protection, and Coastal Policies 9541 New York State does not have written policie s or regulations pert aining specifically to 9542 sea-level rise in relation to coastal zone management, althoug h sea-level rise is becoming 9543 recognized as a factor in coastal erosion and flooding by New York State Department of 9544 State (DOS) in the development of regional management plans. 9545 9546CCSP 4.1 January 15, 2009

593 of 784 Final Report Policies regarding management and development in shoreline areas are primarily based 9547 on three laws. Under the Tidal Wetlands Act pr ogram, the Department of Environmental 9548 Conservation (DEC) classifies various we tland zones and adjacent areas where human 9549 activities may have the potential to impair wetland values or adversely affect their 9550 function; permits are required for most activ ities that take place in these areas. New 9551 construction greater than 9.3 s quare meters (sq m) (100 square feet [sq ft]), excluding 9552 docks, piers, and bulkheads) as well as roads and other infrastructure must be set back 9553 22.9 m (75 ft) from any tidal wetland, except w ithin New York City where the setback is 9554 9.1 m (30 ft) 73

. 9555 9556 The Waterfront Revitalization and Coastal Resources Act (WRCRA) allows the DOS to 9557 address sea-level rise indire ctly through policies regarding flooding and erosion hazards 9558 (NOAA, 1982). Seven out of 44 written policie s related to management, protection, and 9559 use of the coastal zone addre ss flooding and erosion control. These polices endeavor to 9560 move development away from areas threaten ed by coastal erosion and flooding hazards, 9561 to ensure that development activities do not exacerbate erosion or flooding problems and 9562 to preserve natural protective features such as dunes. They also provide guidance for 9563 public funding of coastal hazard mitigati on projects and encourage the use of 9564 nonstructural erosion and fl ood control measures where possible (NYS DOS, 2002). 9565 9566 Under the Coastal Erosion Hazard Areas Act program, the DEC identified areas subject 9567 to erosion and established two types of eros ion hazard areas (structu ral hazard and natural 9568

73 Article 25, Environmental Conservation Law Implementing Regulations-6NYCRR PART 661.CCSP 4.1 January 15, 2009

594 of 784 Final Report protective feature areas) wh ere development and construction activities are regulated 74

. 9569 Permits are required for most activities in designated natural pr otective feature areas. 9570 New development ( e.g. , building, permanent shed, deck, pool, garage) is prohibited in 9571 nearshore areas, beaches, bluffs, and primar y dunes. These regulations, however, do not 9572 extend far inland and therefore do not encompa ss the broader area vulnerable to sea-level 9573 rise. 9574 9575 New York State regulates shore protection st ructures along estuaries and the ocean coast 9576 differently. The state’s Coastal Erosion Hazar d Law defines coastal erosion hazard areas 9577 as those lands with an average erosion ra te of at least 30 cm (1 ft) per year. 75 Within 9578 those erosion hazard areas, the local governme nts administer the programs to grant or 9579 deny permits, generally following state guidelines. 76 Those guidelines requires that 9580 individual property owners first evaluate non-structural approaches; but if they are 9581 unlikely to be effective, hard structures are allowed (New York State, 2002a). 9582 9583 Shoreline structures, which by definition incl ude beach nourishment in New York State, 9584 are permitted only when it can be shown that th e structure can prevent erosion for at least 9585 thirty years and will not cause an increase in erosion or flooding at the local site or 9586 nearby locations (New York State, 2002a). Se tbacks, relocation, and elevated walkways 9587 are also encouraged before hardening. 9588 9589

74 Environmental Conservation Law, Article 34 75 § New York Environmental Conservation Law 34-0103 (3)(a) 76 § New York Environmental Conservation Law 34-0105CCSP 4.1 January 15, 2009

595 of 784 Final Report Currently, all of the erosion hazard areas are along the open coast. Therefore, the state 9590 does not directly regulate shor e protection structures along es tuarine shores. However, 9591 under the federal Coastal Zone Management Act, New York's coastal management 9592 program reviews federal agency permit applica tions, to ensure consistency with policies 9593 of the State's coastal management program (NOAA, 2008; USACE, 2007). The state has 9594 objected to nationwide permit 13 issued by the Corps of Engin eer’s wetlands regulatory 9595 program (see Section 12.2.2 in Chapter 12), wh ich provides a general authorization for 9596 erosion control structures (NYS DOS, 2006). The effect of that objection is that 9597 nationwide permit 13 does not automatically pr ovide a property owner with a permit for 9598 shore protection unless the state concurs w ith such an applica tion (NYS DOS, 2006). 9599 The state has also objected to the application of nationwide permits 3 (which includes 9600 maintenance of existing shore protection st ructures) and 31 (maintenance of existing 9601 flood control activities) within special management areas (NYS DOS, 2006). 9602 9603 Similar to the New York metropolitan area, the policies for Long Island reflect the fact 9604 that the region is intensely developed in the we st and developing fast in the east . Much of 9605 the South Shore, particularly within Nassau County, is already developed and has already 9606 been protected, primarily by bulkheads. The Long Island Sound Management Program 9607 estimates that approximately 50 percent of the Sound’s shoreline is armored (NYS DOS, 9608 1999). 9609 9610 Some of the South Shore’s densely deve loped communities facing flooding problems, 9611 such as Freeport and Hempstead, have al ready implemented programs that call for 9612 elevating buildings and infr astructure in place and installing bulkheads for flood 9613CCSP 4.1 January 15, 2009

596 of 784 Final Report protection. The Town of Hempstead has adopted the provisions of the state’s Coastal 9614 Erosion Hazards Area Act, described in Sect ion A1.B of this Appendix, because erosion 9615 and flooding along Nassau County’s ocean coas t have been a major concern. The Town 9616 of Hempstead has also been actively worki ng with the U.S. Army Corps of Engineers 9617 (USACE) to develop a long-term storm damage reduction plan for the heavily developed 9618 Long Beach barrier island (USACE, 2003). 9619 9620 Beach nourishment and the construction of fl ood and erosion protection structures are 9621 also common on the island. For example, in the early 1990s USACE constructed a 9622 substantial revetment around the Montauk Li ghthouse at the eastern tip of Long Island 9623 and after a new feasibility study has proposed co nstruction of a larger revetment (Bleyer, 9624 2007). USACE is also reformulating a plan for the development of long-term storm 9625 damage prevention projects along the 134 kilo (km) 83 mile [mi]) portion of the South 9626 Shore of Suffolk County. As part of this effort, USACE is assessing at-risk properties 9627 within the 184 square kilome ter (sq km) (71 square miles [sq mi]) floodplain, present and 9628 future sea-level rise, restoration and preser vation of important coastal landforms and 9629 processes, and important public uses of the area (USACE, 2008b). 9630 9631 To obtain state funding for nourishment, comm unities must provide public access every 9632 800 m (0.5 mi) (New York State, 2002b). In 199 4, as terms of a legal settlement between 9633 federal, state, and local agencies cooper ating on the rebuilding of the beach through 9634 nourishment, the community of West Hampton provided six walkways from the 9635 shorefront road to allow public access to the beach (Dean, 1999). In communities that 9636CCSP 4.1 January 15, 2009

597 of 784 Final Report have not had such state-funded projects, however, particularly al ong portions of the bay 9637 shore communities in East Hampton, South Hampton, Brookhaven, and Islip, public 9638 access to tidal waters can be less common (NYS DOS, 1999). 9639 9640 The Comprehensive Coastal Management Pl an (CCMP) of the Peconic Bay National 9641 Estuary Program Management Plan calls for “no net increase of hardened shoreline in the 9642 Peconic Estuary”. The intent of this recomm endation is to discourage individuals from 9643 armoring their coastline; yet th is document is only a management plan and does not have 9644 any legal authority. However, towns such as East Hampton are trying to incorporate the 9645 plan into their own programs. In 2006, the town of East Hampton adopted and is now 9646 enforcing a defined zoning dist rict overlay map that preven ts shore armoring along much 9647 of the town’s coastline (Town of East Hampton, 2006). Despite such regulations, 9648 authorities in East Hampton and elsewhere recognize that there are some areas where 9649 structures will have to be allowed to protect existing development. 9650 9651 The New York Department of State (DOS) is also examining options for managing 9652 erosion and flood risks through land use measur es, such as further land exchanges. For 9653 example, there is currently an attempt to re vise the proposed Fire Island to Montauk Point 9654 Storm Damage Reduction Project to consider a combination of nourishment and land use 9655 measures. One option would be to use beach nourishment to protect structures for the 9656 next few decades, during which time development could gradually be transferred out of 9657 the most hazardous locations. Non-conforming development could eventually be brought 9658CCSP 4.1 January 15, 2009

598 of 784 Final Report into conformance as it is reconstructed, m oved, damaged by storms or flooding, or other 9659 land use management plans are brought into effect. 9660 9661 

## A1.B. New York Metropolitan Area 9662 The New York metropolitan area has a mixtur e of elevated and low-lying coastlines. 9663 Low-lying land within 3 m of mean sea level (Gornitz et al

. , 2002) include the borough 9664 of Queens’ northern and southeastern shore, respectively (where New York’s two major 9665 airports, LaGuardia and John F. Kennedy Interna tional Airport, are lo cated); much of the 9666 recreational lands along Jamaica Bay’s Gateway National Recreation Area ( e.g. , Floyd 9667 Bennett Field, Jamaica Bay Wildlife Refuge, Fo rt Tilden, Riis Park); and the Staten 9668 Island communities of South Beach and Oakwood Beach. In New Jersey, the heavily 9669 developed coast of Hudson County (incl uding Hoboken, Jersey City, and Bayonne) is 9670 also within 3 m, as is much of the ar ea known as the Meadowlands (area around Giants 9671 Stadium). Other areas with sections of lo w-lying lands are found in Elizabeth and 9672 Newark, New Jersey (near Ne wark Airport). The area also includes the ecologically9673 significant Raritan Bay-Sandy H ook habitat complex at the apex of the New York region 9674 (also known as the New York Bight), where the east-west oriented coastline of New 9675 England and Long Island intersects the north-s outh oriented coastline of the mid-Atlantic 9676 at Sandy Hook. 9677 9678 Given its large population, the effects of hurricanes and ot her major storms combined 9679 with higher sea levels could be particularly severe in the New York metropolitan area. 9680 With much of the area’s transportation infras tructure at low elevation (most at 3 m or 9681CCSP 4.1 January 15, 2009

599 of 784 Final Report less), even slight increases in the height of flooding coul d cause extensive damage and 9682 bring the thriving city to a relative sta ndstill until the flood wa ters recede (Gornitz et al. , 9683 2002). 9684 9685 Comprehensive assessments of the vulnerabil ity of the New York City metropolitan area 9686 are found in Jacob et al. (2007) and Gornitz et al. (2002). Jacob et al. summarize 9687 vulnerability, coastal management and adaptation issues. Gornitz et al . details the 9688 methodology and results of a study that summari zes vulnerability to impacts of climate 9689 change, including higher storm surges, s horeline movement, wetland loss, beach 9690 nourishment and some socioeconomic implicatio ns. These assessments use sea-level rise 9691 estimates from global climate models avai lable in 2002. Generalized maps depicting 9692 lands close to sea level are found in Titus and Richman (2001) and Titus and Wang 9693 (2008). 9694 9695 If sea-level rise impairs coastal habitat, ma ny estuarine species would be at risk. This 9696 Section provides additional details on the possible environmental implications of sea9697 level rise for the greater New York metr opolitan area, including New York City, the 9698 lower Hudson River, the East River, Jamai ca Bay, the New Jersey Meadowlands, Raritan 9699 Bay and Sandy Hook Bay. The following subsections discuss tidal wetlands, beaches, 9700 tidal flats, marsh and bay islands, and sh allow waters. (Sections A1.A.2 and A1.D.2 9701 discuss the statewide coastal policie s of New York and New Jersey.) 9702 9703 Tidal Wetlands . Examples of this habitat include: 9704CCSP 4.1 January 15, 2009

600 of 784 Final Report  Staten Island : The Northwest Staten Island/Harbor Herons Special Natural 9705 Waterfront Area is an importa nt nesting and foraging area for herons, ibises, egrets, 9706 gulls, and waterfowl (USFWS, 1997). Seve ral marshes on Staten Island, such as 9707 Arlington Marsh and Saw Mill Creek Marsh, provide foraging areas for the birds of 9708 the island heronries. Hoffman Island and Swinburne Island, east of Staten Island, 9709 provide important nesting habitat for herons and cormorants, respectively (Bernick, 9710 2006). 9711

 Manhattan : In the marsh and mudflat at the m outh of the Harlem River at Inwood 9712 Hill Park (USFWS, 1997) great blue herons are found along the flat in winter, and 9713 snowy and great egrets are common fro m spring through fall (NYC DPR, 2001). 9714

 Lower Hudson River : The Piermont Marsh, a 412 h ectare (ha) (1,017 acre [ac]) 9715 brackish wetland on the western shore of the lower Hudson River has been 9716 designated for conservation management by New York State and the National 9717 Oceanic and Atmospheric Administration (NOAA) (USFWS, 1997). The marsh 9718 supports breeding birds, including relativel y rare species such as Virginia rail, 9719 swamp sparrow, black duck, least bittern, and sora rail. Anadromous and freshwater 9720 fish use the marsh’s tidal creeks as a spawning and nursery area. Diamondback 9721 terrapin reportedly nest in upla nd areas along the marsh (USFWS, 1997). 9722

 Jamaica Bay : Located in Brooklyn and Queens, th is bay is the largest area of 9723 protected wetlands in a majo r metropolitan area along the U.S. Atlantic Coast. The 9724 bay includes the Jamaica Bay Wildlife Re fuge, which has been protected since 1972 9725 as part of the Jamaica Bay Unit of the Gateway National Recreation Area. Despite 9726 extensive disturbance from dredging, filling, and development, Jamaica Bay remains 9727CCSP 4.1 January 15, 2009

601 of 784 Final Report one of the most important migratory shoreb ird stopover sites in the New York Bight 9728 (USFWS, 1997). The bay provides overwint ering habitat for many duck species, and 9729 mudflats support foraging migrant species (Hartig et al. , 2002). The refuge and 9730 Breezy Point, at the tip of the Rockaway Peninsula, support populations of 214 9731 species that are state or federally listed or of special emphasis, including 48 species 9732 of fish and 120 species of birds (USFWS, 1997). Salt marshes such as Four Sparrow 9733 Marsh provide nesting habitat for declining sparrow specie s and serve 326 species of 9734 migrating birds (NYC DPR, undated). Wetlands in some parts of the bay currently 9735 show substantial losses (Hartig et al. , 2002). 9736

 Meadowlands : The Meadowlands contai n the largest single tract of estuarine tidal 9737 wetland remaining in the New York/New Jers ey Harbor Estuary and provide critical 9738 habitat for a diversity of species, including a number of special status species. 9739 Kearney Marsh is a feeding area for the state-listed endangere d least tern, black 9740 skimmer, and pied-billed grebe. Diamondb ack terrapin, the only turtle known to 9741 occur in brackish water, is found in the Sawmill Wildlife Management Area 9742 (USFWS, 1997). 9743

 Raritan Bay-Sandy Hook : The shorelines of southern Raritan Bay include large 9744 tracts of fringing salt marsh at Conas konk Point and from Flat Creek to Thorn’s 9745 Creek. These marshes are critical for larg e numbers of nesting and migrating bird 9746 species. The salt marsh at Conaskonk Point pr ovides breeding areas for bird species 9747 such as green heron, American oystercatcher, seaside sparrow, and saltmarsh sharp9748 tailed sparrow, as well as feeding areas for herons, egrets, common tern, least tern, 9749 and black skimmer. In late May and ear ly June, sanderlings, ruddy turnstones, 9750CCSP 4.1 January 15, 2009

602 of 784 Final Report semipalmated sandpipers, and red knots feed on horseshoe crab eggs near the mouth 9751 of Chingarora Creek. Low marsh along th e backside of Sandy Hook spit provides 9752 forage and protection for the young of mari ne fishes, including winter flounder, 9753 Atlantic menhaden, bluefish, and striped bass, and critical habitat for characteristic 9754 bird species of the low marsh such as cl apper rail, willet, and marsh wren (USFWS, 9755 1997). 9756 9757 Estuarine Beaches. Relatively few areas of estuarine b each remain in the New York City 9758 metropolitan area, and most have been modi fied or degraded (USFWS 1997; Strange 9759 2008a). In Jamaica Bay, remaining estuar ine beaches occur off Belt Parkway ( e.g. , on 9760 Plumb Beach) and on the bay islands (USFWS , 1997). Sandy beaches are still relatively 9761 common along the shores of Staten Island from Tottenville to Ft. Wadsworth. The 9762 southern shoreline of Raritan Bay includes a number of beaches along Sandy Hook 9763 Peninsula and from the Highlands to Sout h Amboy, some of which have been nourished. 9764 There are also beaches on small islands w ithin the Shrewsbury-Navesink River system 9765 (USFWS, 1997). 9766
9767 Although limited in area, the remaining b eaches support an extensive food web. Mud 9768 snails and wrack-based species ( e.g. , insects, isopods, and amphipods) provide food for 9769 shorebirds including the pipi ng plover, federally listed as threatened (USFWS, 1997). 9770 The beaches around Sandy Hook Bay have beco ming important nestling places in winter 9771 for several species of seals (USFWS, 1997) . The New Jersey Audubon Society reports 9772 that its members have observed gulls and tern s at the Raritan Bay beach at Morgan on the 9773CCSP 4.1 January 15, 2009

603 of 784 Final Report southern shore, including some rare speci es such as black-hea ded gull, little gull, 9774 Franklin’s gull, glaucous gulls, black tern, sandwich tern, and Hudsonian godwit. 9775 Horseshoe crabs lay their eggs on area beaches , supplying critical forage for shorebirds 9776 (Botton et al ., 2006). The upper beach is used by nesting diamondback terrapins; human9777 made sandy trails in Jamaica Bay are also an important nest site for terrapins in the 9778 region, although the sites are prone to depr edations by raccoons (Feinberg and Burke, 9779 2003). 9780 9781 Tidal flats

. Like beaches, tidal flats are limited in the New York City metropolitan region, 9782 but the flats that remain provi de important habitat, particul arly for foraging birds. Tidal 9783 flats are also habitat for hard and soft shel l clams, which are important for recreational 9784 and commercial fishermen where not im paired by poor water quality. Large 9785 concentrations of shorebirds, herons, and wa terfowl use the shallows and tidal flats of 9786 Piermont Marsh along the lower Hudson River as staging areas for both spring and fall 9787 migrations (USFWS, 1997). Tida l flats in Jamaica Bay are frequented by shorebirds and 9788 waterfowl, and an intensive survey of shor ebirds in the mid-1980s estimated more than 9789 230,000 birds of 31 species in a single year, mo stly during the fall migration (Burger, 9790 1984). Some 1,460 ha (3,600 ac) of intertidal flats extend offshore an average of 0.4 km 9791 (0.25 mi) from the south shore of the Rarita n and Sandy Hook Bays, from the confluence 9792 of the Shrewsbury and Navesink Rivers, west to the mouth of the Raritan River. These 9793 flats are important foraging and staging areas for migrating shoreb irds, averaging over 9794 20,000 birds, mostly semipalmated plover, sande rling, and ruddy turnst one. The flats at 9795 the mouth of Whale Creek near Pirate’s Cove attract gulls, terns, and shorebirds year 9796CCSP 4.1 January 15, 2009

604 of 784 Final Report round. Midwinter waterfowl surveys indicate that an average of 60,000 birds migrate 9797 through the Raritan Bay-Sandy Hook area in winter (USFWS, 1997). Inundation with 9798 rising seas will eventually make flats unavail able to short-legged shorebirds, unless they 9799 can shift feeding to marsh ponds and pannes (Erwin et al. , 2004). At the same time, 9800 disappearing saltmarsh islands in the area are transforming into intertidal mudflats. This 9801 may increase habitat for shorebirds at low tide, but it leaves less habitat for refuge at high 9802 tide (Strange 2008a). 9803 9804 Shallow water habitat . This habitat is exte nsive in the Hudson River, from Stony Point 9805 south to Piermont Marsh, just below the Tappan Zee Bridge (USF WS, 1997). This area 9806 features the greatest mixing of ocean and fr eshwater, and concentrates nutrients and 9807 plankton, resulting in a high leve l of both primary and secondary productivity. Thus, this 9808 part of the Hudson provides key habitat for numer ous fish and bird species. It is a major 9809 nursery area for striped bass, white perch, to mcod, and Atlantic sturgeon, and a wintering 9810 area for the federally endangere d shortnose sturgeon. Waterfowl also feed and rest here 9811 during spring and fall migrations. Some su bmerged aquatic vegetation (SAV) is also 9812 found here, dominated by water celery, sago pondweed, and horned pondweed (USFWS, 9813 1997). 9814 9815 Marsh and bay islands . Throughout the region, these islands are vulnerable to sea-level 9816 rise (Strange 2008a). Between 1974 and 1994, th e smaller islands of Jamaica Bay lost 9817 nearly 80 percent of their vegetativ e cover (Strange 2008a, citing Hartig et al. , 2002). 9818 Island marsh deterioration in Jamaica Bay has led to a 50 percent decline in area between 9819CCSP 4.1 January 15, 2009

605 of 784 Final Report 1900 and 1994 (Gornitz et al ., 2002). Marsh loss has accelerated, reaching an average 9820 annual rate of 18 ha (45 ac) per year between 1994 and 1999 (Hartig et al. , 2002). The 9821 islands provide specialized habitat for an array of species: 9822

 Regionally important populations of egrets , herons, and ibises are or have been 9823 located on North and South Brother islands in the East River and on Shooter’s 9824 Island, Prall’s Island, and Isle of Meadows in Arthur Kill and Kill van Kull 9825 (USFWS, 1997). 9826

 North and South Brother Islands have the largest black crowned night heron colony 9827 in New York State, along with large numb ers of snowy egret, great egret, cattle 9828 egret, and glossy ibis (USFWS, 1997). 9829

 Since 1984, an average of 1,000 state threaten ed common tern have nested annually 9830 in colonies on seven islands of the Jamaica Bay Wildlife Refuge (USWFS, 1997). 9831

 The heronry on Carnarsie Pol also suppor ts nesting by great black-backed gull, 9832 herring gull, and American oys tercatcher (USFWS, 1997). 9833

 The only colonies of lau ghing gull in New York Stat e, and the northernmost 9834 breeding extent of this species, occur on the islands of East High Meadow, Silver 9835 Hole Marsh, Jo Co Marsh, and West Hempstead Bay (USFWS, 1997). 9836

 Diamondback terrapin nest in large number s along the sandy shor eline areas of the 9837 islands of Jamaica Bay, primarily Ruler’s Bar Hassock (USFWS, 1997). 9838 9839 

## A1.C. New Jersey Shore 9840 The New Jersey shore has three types of ocean coasts (see Chapter 3 of this Product). At 9841 the south end, Cape May and Atlantic Coun ties have short and fairly wide “tide- 9842CCSP 4.1 January 15, 2009

606 of 784 Final Report dominated” barrier islands. Behind the is lands, 253 sq km (97 sq mi) of marshes 9843 dominate the relatively small open water bays. To the north, Ocean County has “wave 9844 dominated” coastal barrier islands and spits . Long Beach Island is 29 km (18 mi) long 9845 and only two to three blocks wide in most pl aces; Island Beach to the north is also long 9846 and narrow. Behind Long Beach Island and Isla nd Beach lie Barnegat and Little Egg 9847 Harbor Bays. These shallow estuaries range fr om 2 to 7 km (about 1 to 4 mi) wide, and 9848 have 167 sq km (64 sq mi) of open water (USFWS, 1997) with extensive eelgrass, but 9849 only 125 sq km (48 sq mi) of tidal mars h (Jones and Wang, 2008). Monmouth County’s 9850 ocean coast is entirely headlands, with the exception of Sandy Hook at the northern tip of 9851 the Jersey Shore. Non-tidal wetlands are im mediately inland of th e tidal wetlands along 9852 most of the mainland shore 77

. 9853 9854 A1.C.1 Environmental Implications 9855 There have been many efforts to conserve and restore species and habi tats in the barrier 9856 island and back-barrier lagoon systems in Ne w Jersey. Some of the larger parks and 9857 wildlife areas in the region in clude Island Beach State Par k, Great Bay Boulevard State 9858 Wildlife Management Area, and the E.B. Fo rsythe National Wildlif e Refuge (Forsythe 9859 Refuge) in Ocean and Atlantic counties. Parts of the Cape May Peninsula are protected 9860 by the Cape May National Wildlife Refuge (USFWS, undated[a]), the Cape May Point 9861 State Park (NJDEP, undated) and The Na ture Conservancy’s (TNC’s) Cape May 9862 Migratory Bird Refuge (TNC, undated). 9863 9864

77 For comprehensive discussions of the New Jersey shore and the implications of sea level rise, see Cooper et al. (2005), Lathrop and Love (2007), Najjar et al. (2000) and Psuty and Ofiara (2002)CCSP 4.1 January 15, 2009

607 of 784 Final Report Tidal and Nearshore Nontidal Marshes. There are 18,440 ha (71 sq mi), 29,344 ha (113 9865 sq mi), and 26,987 ha (104 sq mi) of tidal sa lt marsh in Ocean, Atlantic, and Cape May 9866 counties, respectively (Jones and Wang, 2008). Th e marshes in the study area are keeping 9867 pace with current local rates of sea-level ri se of 4 millimeters (mm) per year, but are 9868 likely to become marginal with a 2 mm per y ear acceleration and be lost with a 7 mm per 9869 year acceleration, except where they ar e near local sources of sediments ( e.g. , rivers such 9870 as the Mullica and Great Harbor rivers in Atlantic County) (Strange 2008b, interpreting 9871 the findings of Reed et al ., 2008). 9872 9873 There is potential for wetland migration in Fors ythe Refuge, and other lands that preserve 9874 the coastal environment such as parks and wildlife management areas. Conservation 9875 lands are also found along parts of the Mullica and Great Egg Harbor Rivers in Atlantic 9876 County. However, many estuarine shorelines in developed areas are hardened, limiting 9877 the potential for wetland migr ation (Strange, 2008b). 9878 9879 As marshes along protected shorelines experi ence increased tidal flooding, there may be 9880 an initial benefit to some species. If tidal cr eeks become wider and deeper fish may have 9881 increased access to forage on the marsh surface (Weinstein, 1979). Sampling of larval 9882 fishes in high salt marsh on Cattus Island, Beach Haven West, and Cedar Run in Ocean 9883 County showed that high marsh is important for mummichog, rainwater killifish, spotfin 9884 killifish, and sheepshead minnow (Talbot and Able, 1984). The flooded marsh surface 9885 and tidal and nontidal ponds and ditches appear to be especially important for the larvae 9886 of these species (Talbot and Able, 1984). However, as sea level rises, and marshes along 9887 hardened shorelines convert to open water, ma rsh fishes will lose access to these marsh 9888CCSP 4.1 January 15, 2009

608 of 784 Final Report features and the protection from predators, nursery habitat, and fo raging areas provided 9889 by the marsh (Strange 2008b). 9890 9891 Loss of marsh area would also have negative implications fo r the dozens of bird species 9892 that forage and nest in the region’s marshes. Initially, d eeper tidal creeks and marsh pools 9893 will become inaccessible to short-legged shorebirds such as plovers (Erwin et al. , 2004). 9894 Long-legged waterbirds such as the yellow-crowned night heron, which forages almost 9895 exclusively on marsh crabs (fi ddler crab and others), will lose important food resources 9896 (Riegner, 1982). Eventually, complete convers ion of marsh to open water will affect the 9897 hundreds of thousands of shorebirds that stop in these areas to feed during their 9898 migrations. The New Jersey Coastal Mana gement Program estimates that some 1.5 9899 million migratory shorebirds stopover on New Jersey’s shores during their annual 9900 migrations (Cooper et al. , 2005). Waterfowl also forage a nd overwinter in area marshes. 9901 Mid-winter aerial waterfowl counts in Barnegat Bay alone average 50,000 birds 9902 (USFWS, 1997). The tidal marshes of the Ca pe May Peninsula provide stopover areas for 9903 hundreds of thousands of shorebirds, songbird s, raptors, and waterfowl during their 9904 seasonal migrations (USFWS, 1997). The peninsul a is also an important staging area and 9905 overwintering area for seab ird populations. Surveys conducted by the U.S. Fish and 9906 Wildlife Service from July through December 1995 in Cape May County recorded more 9907 than 900,000 seabirds migrating along the coast (USFWS, 1997). 9908 9909 As feeding habitats are lost, local bird populations may no l onger be sustainable (Strange, 9910 2008b). For example, avian biologists suggest th at if marsh pannes and pools continue to 9911CCSP 4.1 January 15, 2009

609 of 784 Final Report be lost in Atlantic County as a result of sea-level ri se, the tens of thousands of shorebirds 9912 that feed in these areas may shift to feed ing in impoundments in the nearby Forsythe 9913 Refuge. Such a shift would increase shorebird de nsities in the refuge ten-fold and reduce 9914 population sustainability due to lower per capita food resources and disease from 9915 crowding (Erwin et al. , 2006). 9916 9917 Local populations of marsh nesting bird specie s will also be at risk where marshes drown. 9918 This will have a particularly negative impact on rare species such as seaside and sharp9919 tailed sparrows, which may have difficulty fi nding other suitable nes ting sites. According 9920 to a synthesis of published studies in Greenla w and Rising (1994) and Post and Greenlaw 9921 (1994), densities in the region ranged from 0.3 to 20 singing males pe r hectare and 0.3 to 9922 4.1 females per hectare for the seaside and sh arp-tailed sparrows, respectively (Greenlaw 9923 and Rising, 1994). Loss and alteration of su itable marsh habitats are the primary 9924 conservation concerns for these and other ma rsh-nesting passerine birds (BBNEP, 2001). 9925 9926 Shore protection activities (nourishment and vegetation c ontrol) are underway to protect 9927 the vulnerable freshwater ecosystems of th e Cape May Meadows (The Meadows), which 9928 are located behind the eroding dunes near Cape May Point (USACE, 2008a). Freshwater 9929 coastal ponds in The Meadows are found within about one hundred meters (a few 9930 hundred feet) of the shoreline and therefore could easily be inundated as seas rise. The 9931 ponds provide critical foraging a nd resting habitat for a variety of bird species, primarily 9932 migrating shorebirds (NJDEP, undated). Among the rare birds seen in The Meadows by 9933 local birders are buff-breasted sandpipers, arctic tern, roseate tern, whiskered tern, 9934CCSP 4.1 January 15, 2009

610 of 784 Final Report Wilson’s phalarope, black rail, king rail, Hudsonian godwit, and black-necked stilt 9935 (Kerlinger, undated). The Nature Conserva ncy, the United States Army Corps of 9936 Engineers (USACE), and the New Jersey Department of Environmental Protection 9937 (NJDEP) have undertaken an extensive restor ation project in the Cape May Migratory 9938 Bird Refuge, including beach replenishment to protect a mile-long stretch of sandy beach 9939 that provides nesting habitat for the piping plover (federally li sted as threatened), creation 9940 of plover foraging ponds, and creation of island nesting sites for terns and herons (TNC, 9941 2007). 9942 9943Estuarine Beaches. Estuarine beaches are largely disappearing in developed areas where 9944 shoreline armoring is the preferred method of shore protection. The erosion or inundation 9945 of bay islands would also reduce the am ount of beach habitat. Many species of 9946 invertebrates are found within or on the sandy substrate or beach wrack (seaweed and 9947 other decaying marine plant material left on the shore by the tides) along the tide line of 9948 estuarine beaches (Bertness, 1999). These species provide a rich and abundant food 9949 source for bird species. Small beach invertebrates include isopods and amphipods, blood 9950 worms, and beach hoppers, and beach macroinvert ebrates include soft shell clams, hard 9951 clams, horseshoe crabs, fiddler crabs, a nd sand shrimp (Shellenbarger Jones, 2008a). 9952 9953 Northern diamondback terrapin nest on estuar ine beaches in the Barnegat Bay area 9954 (BBNEP, 2001). Local scientists consider coas tal development, which destroys terrapin 9955 nesting beaches and access to nesting habita t, to be one of the primary threats to 9956 diamondback terrapins, along with predation, ro ad kills, and crab trap bycatch (Strange, 9957CCSP 4.1 January 15, 2009

611 of 784 Final Report 2008b, citing Wetland Institute [undated]). 9958 9959 Loss of estuarine beach could also have nega tive impacts on various beach invertebrates, 9960 including rare tiger beetles (Strange, 2008b). Two sub-species likely exist in coastal New 9961 Jersey: Cicindela dorsalis dorsalis , the northeastern beach ti ger beetle, which is a 9962 federally listed threatened species and a st ate species of special concern and regional 9963 priority, and Cicindela dorsalis media , the southeastern beach tiger beetle, which is state9964 listed as rare (NJDEP, 2001). In the mid- 1990s, the tiger beetle was observed on the 9965 undeveloped ocean beaches of Holgate and Isla nd Beach. Current surveys do not indicate 9966 whether this species is also found on the area’s estuar ine beaches, but it feeds and nests in 9967 a variety of habitats (USFWS, 1997). The current abundance and distribution of the 9968 northeastern beach tiger beetle in the coastal ba ys is a target of research (State of New 9969 Jersey, 2005). At present, there are plans to reintroduce the species in the study region at 9970 locations where natural ocean beaches remain (State of New Jersey, 2005). 9971 9972 Tidal Flats. The tidal flats of New Jersey’s back-ba rrier bays are crit ical foraging areas 9973 for hundreds of species of shorebirds, passeri nes, raptors, and wa terfowl (BBNEP, 2001). 9974 Important shorebird areas in the study regi on include the flats of Great Bay Boulevard 9975 Wildlife Management Area, North Brigantine Natural Area, and the Brigantine Unit of 9976 the Forsythe Refuge (USFWS, 1997). The USFWS estimates that the extensive tidal flats 9977 of the Great Bay alone total 1,358 ha (3,355 ac). Inundation of tid al flats with rising seas 9978 would eliminate critical foraging opportunities for the area’s abundant avifauna. As tidal 9979 flat area declines, increased crowding in remaining areas could lead to exclusion and 9980CCSP 4.1 January 15, 2009

612 of 784 Final Report mortality of many foraging birds (Galbraith et al. , 2002; Erwin et al. , 2004). Some areas 9981 may become potential sea gra ss restoration sites, but whet her or not “enhancing” these 9982 sites as eelgrass areas is feasible will depe nd on their location, acreage, and sediment type 9983 (Strange, 2008b). 9984 9985 Shallow Nearshore Waters and Submer ged Aquatic Vegetation (SAV) . The Barnegat 9986 Estuary is distinguished from the lagoons to the south by more open water and SAV and 9987 less emergent marsh. Within the Barnegat Es tuary, dense beds of eelgrass are found at 9988 depths under 1 m, particularly on sandy shoa ls along the backside of Long Beach Island 9989 and Island Beach, and around Barnegat Inlet, Manahawkin Bay, and Little Egg Inlet. 9990 Eelgrass is relatively uncommon from the mi ddle of Little Egg Harbor south to Cape 9991 May, particularly locations where water depths are more than 1 m, such as portions of 9992 Great South Bay (USFWS, 1997). 9993 9994 Seagrass surveys from the 1960s through the 1990s indicate that there has been an overall 9995 decline in seagrass beds in Barnegat Es tuary, from 6,823 ha (16,847 ac) in 1968 to an 9996 average of 5,677 ha (14,029 ac) duri ng the period 1996 to 1998 (BBNEP, 2001). 9997 Numerous studies indicate th at eelgrass has high ecologica l value as a source of both 9998 primary (Thayer et al. , 1984) and secondary production (Jackson et al. , 2001) in estuarine 9999 food webs. In Barnegat Estuary eelgrass beds pr ovide habitat for invertebrates, birds, and 10000 fish that use the submerged vegetation for spawning, nursery, and feeding (BBNEP, 10001 2001). Shallow water habitat quality may al so be affected by adjacent shoreline 10002 protections. A Barnegat Bay study found that where shorelin es are bulkheaded, SAV, 10003CCSP 4.1 January 15, 2009

613 of 784 Final Report woody debris, and other features of natural sha llow water habitat are ra re or absent, with 10004 a resulting reduction in fish abundance (Byrne, 1995). 10005
10006 Marsh and Bay Islands. Large bird populations are f ound on marsh and dredge spoil 10007 islands of the New Jersey back-barrier bays. These islands include nesting sites protected 10008 from predators for a number species of cons ervation concern, includ ing gull-billed tern, 10009 common tern, Forster’s tern, least tern, bl ack skimmer, American oystercatcher, and 10010 piping plover (USFWS, 1997). Diamondback terr apins are also known to feed on marsh 10011 islands in the bays (USFWS, 1997). 10012
10013 Some of the small islands in Barnegat Bay and Little Egg Harbor extend up to about 1 m 10014 above spring high water (Jones and Wang, 2008), but portions of other islands are very 10015 low, and some low islands are currently disappearing. Mordecai (MLT, undated) and 10016 other islands (Strange, 2008b) used by nes ting common terns, Forster’s terns, black 10017 skimmers, and American oystercatchers are vulnerable to sea-level rise and erosion 10018 (MLT, undated). With the assistance of local governments, the Mordecai Land Trust is 10019 actively seeking grants to halt the gradual erosion of Mordecai Is land, an 18-ha (45-ac) 10020 island just west of Beach Haven on Long B each Island (MLT, undated). Members of the 10021 land trust have documented a 37 percent loss of island area since 1930. The island’s 10022 native salt marsh and surrounding waters and SA V beds provide habitat for a variety of 10023 aquatic and avian species. NOA A National Marine Fisheries Service considers the island 10024 and its waters Essential Fish Habitat for spaw ning and all life stages of winter flounder as 10025 well as juvenile and adult st ages of Atlantic sea herring, bluefish, summer flounder, scup, 10026CCSP 4.1 January 15, 2009

614 of 784 Final Report and black sea bass (MLT, undated). The island is also a strategically-located nesting 10027 island for many of New Jersey ’s threatened and endangere d species, including black 10028 skimmers, least terns, American bitterns, and both yellow-crowned and black-crowned 10029 night herons (MLT, 2003). 10030
10031 Sea-level fens . New Jersey has identified 12 sea-le vel fens, encompassing 126 acres. This 10032 rare ecological community is restricted in distribution to Ocean County, New Jersey, 10033 between Forked River and Tuckerton, in an area of artesian groundwater discharge from 10034 the Kirkwood-Cohansey aquifer. Additional recent field surveys have shown possible 10035 occurrences in the vicinity of Tuckahoe in Cape May and Atlantic counties (Walz et al. , 10036 2004). These communities provide significant we tland functions in the landscape as well 10037 as supporting 18 rare plant species, of which one is state-listed as endangered. (Walz et 10038 al. , 2004). 10039
10040 A1.C.2 Development, Shore Protection, and Coastal Policies 10041 At least five state policies affect the re sponse to sea-level rise along New Jersey’s 10042 Atlantic Coast: the Coastal Facility Review Act, the Wetlands Act, the State Plan, an 10043 unusually strong public trust doctrine, a nd the state’s strong support for beach 10044 nourishment—and opposition to both erosion-cont rol structures and shoreline retreat— 10045 along ocean shores. This section discusses the la tter policy; the first four are discussed in 10046 Section A1.D.2 of this Appendix. 10047
10048CCSP 4.1 January 15, 2009

615 of 784 Final Report In 1997, then-Governor Whitman promised coas tal communities that “there will be no 10049 forced retreat,” and that the government woul d not force people to leave the shoreline. 10050 That policy does not necessarily mean that there will always be government help for 10051 shore protection. Nevertheless, although subseq uent administrations have not expressed 10052 this view so succinctly, they have not withdrawn the policy either. In fact, the primary 10053 debate in New Jersey tends to be about th e level of public acce ss required before a 10054 community is eligible to r eceive beach nourishment, not th e need for shore protection 10055 itself (see Chapter 8 of this Product). 10056
10057 With extensive development and tourism along its shore, New Jersey has a well10058 established policy in favor of shore protection along the ocean 78 . The state generally 10059 prohibits new hard structures along the ocean front; but that was not always the case. A 10060 large portion of the Monmouth County shoreline was once prot ected with seawalls, with 10061 a partial or total loss of beach (Pilkey et al. , 1981). Today, beach nourishment is the 10062 preferred method for reversing beach eros ion and providing ocean front land with 10063 protection from coastal storms (Mauriello, 1991). The entire Monmouth County shoreline 10064 now has a beach in front of the old seawa lls. Beach nourishment has been undertaken or 10065 planned for at least one community in ever y coastal county from Middlesex along Raritan 10066 Bay, to Salem along the Delaware River. Island Beach State Park, a barrier spit along the 10067 central portion of Barnegat Bay just north of Long Beach Island, is heavily used by New 10068 Jersey residents and includes the official b each house of the Governor. Although it is a 10069

78 For example, the primary coastal policy document during the Whitman administration suggested that even mentioning the term “retreat” would divide people and impede meaningful discussion of appropriate policies, in part because retreat can mean government restrictions on de velopment or simply a decision by government not to fund shore protection (see NJDEP, 1997). Governor Whitman promised coastal mayors and residents that “there will be no forced retreat.”CCSP 4.1 January 15, 2009

616 of 784 Final Report state park, it is currently included in the authorized USACE Project for beach 10070 nourishment from Manasquan to Barnegat In let. In the case of Cape May Meadows 79 , 10071 environmental considerations have prompt ed shore protection efforts (USACE, 2008a). 10072 The area’s critical freshwater ecosystem is immediately behind dunes that have eroded 10073 severely as a result of the jetties protec ting the entrance to the Cape May Canal. 10074 10075 Some coastal scientists have suggested the possibility of disintegrating barrier islands 10076 along the New Jersey shore (see Chapter 3). Although the bay sides of these islands are 10077 bulkheaded, communities are unlikely to seriously consider the option of being encircled 10078 by a dike as sea level rises (see Box A1.2). Nevertheless, Avalon us es a combination of 10079 floodwalls and checkvalves to prevent tidal flooding; and Atlantic City’s stormwater 10080 management system includes underground tanks with checkvalves. These systems have 10081 been implemented to address current flooding problems; but they would also be a logical 10082 first step in a strategy to protect low-lying areas with structural solutions as sea level 10083 rises 80 . Other authors have suggested that a gradual elevation of barrier islands is more 10084 likely (see Box A1.2). 10085
10086 Wetlands along the back-barrier bays of New Je rsey’s Atlantic coast are likely to have 10087 some room to migrate inland, because they are adjacent to larg e areas of non-tidal 10088 wetlands. One effort at the state level to preserve such coastal resources is the state’s 10089 Stormwater Management Plan, which establishe s a special water resource protection area 10090 that limits development within 91.4 m (300 ft ) along most of its co astal shore (NJDEP 10091

79 The Meadows are within Cape May Point State Park and the Nature Conservancy’s Cape May Migratory Bird Refuge. 80 See Chapter 5 of this Product for explanation of structural mechanisms to combat flooding.CCSP 4.1 January 15, 2009

617 of 784 Final Report DWM, 2004). Although the primary objective of the regulation is to improve coastal 10092 water quality and reduce potential flood damage , it serves to preserve areas suitable for 10093 the landward migration of wetlands. 10094 10095CCSP 4.1 January 15, 2009

618 of 784 Final Report 10096

10097

10098 BOX A1.2: Shore Protection on Long Beach Island The effects of sea-level rise can be observed on both the ocean and bay sides of this 29-km (18-mi) long barrier island. Along the ocean side, shore erosion has threatened homes in Harvey Cedars and portions of Long Beach township. During the 199 0s, a steady procession of dump tr ucks brought sand onto the beach from inland sources. In 2007, the USACE began to re store the beach at Surf C ity and areas immediately north. The beach had to be closed for a few weeks, however, after officials discovered that munitions (which had been dumped offshore after World War II) had been inadvertently pumped onto the beach. High tides regularly flood the main boulevard in the commercial district of Beach Haven, as well as the southern two blocks of Central Avenue in Ship Bottom. Referring to the flooded parking lot during spring tides, the billboard of a pizza parlor in Beach Haven Crest boasts “Occasional Waterfront Dining.” U.S. EPA’s 1989 Report to Congress used Long Beach Island as a model for analyzing alternative responses to rising sea level, considering four op tions: a dike around the island, beach nourishment and elevating land and st ructures, an engineered retreat which woul d include the creation of new bayside lands as the ocean eroded, and making no effort to mainta in the island’s land area (U.S. EPA, 1989; Titus et al ., 1991). Giving up the island was the most expensive option (Weggel et al ., 1989; Titus, 1990). The study concluded that a dike would be the least expensive in the short run, but unaccepta ble to most residents due to the lost view of the bay and risk of being on a barrier island below sea level (Titus, 1991). In the long run, fostering a landward migration would be the leas t expensive, but it would unsettle the expectations of bay front property owners and hence require a lead time of a few generations between being enacted and new bayside land actually being created. Thus, the combination of beach nourishment and elevating land and structures appeared to be the most realistic, and U.S. EPA used that assumption in its nationwide cost estimate (U.S. EPA, 1989; Titus et al ., 1991). Long Beach Township, Ship Bottom, Harvey Cedars, and Beach Ha ven went through a similar thinking process in considering their preferre d response to sea-level rise. In resolutions enacted by their respective councils, they concluded that a gradual elevation of their communities would be preferable to either dikes or the retreat option. In the last ten years, several structural moving companies have had ongoing operations, continually elevating homes (see Figure 12.5).

. Box Figure A1.2 Street flooding in Long Beach Island, New Jersey at one of the higher tides.CCSP 4.1 January 15, 2009

619 of 784 Final Report 

## A1.D. Delaware Estuary 10099 A1.D.1 Environmenal Implications 10100 On both sides of Delaware Bay, most shores are either tidal wetlands or sandy beaches 10101 with tidal wetlands immediately behind th em. In effect, the sandy beach ridges are 10102 similar to the barrier isla nds along the Atlantic, only on a smaller scale. Several 10103 substantial communities with wide sandy beaches on one side and marsh on the other side 10104 are along Delaware Bay—especially on the Delaware side of the bay. Although these 10105 communities are potentially vulnerable to inund ation, shoreline erosion has been a more 10106 immediate threat to these communities. Detail ed discussions of the dynamics of Delaware 10107 shorelines are found in Kraft and John (1976). 10108 10109 Delaware Bay is home to hundreds of species of ecological, commercial, and recreational 10110 value (Dove and Nyman, 1995). Unlike other estuaries in the Mid-Atlantic, the tidal 10111 range is greater than the ocean tidal range, generally about 2 m. In much of Delaware 10112 Bay, tidal marshes appear to be at the lo w end of their potent ial elevation range, 10113 increasing their vulnerability to sea-level rise (Kearney et al. , 2002). Recent research 10114 indicates that 50 to 60 percent of Delawa re Bay’s tidal marsh has been degraded, 10115 primarily because the surface of the marshes is not rising as fast as the sea (Kearney et 10116 al. , 2002). One possible reason is that channe l deepening projects and consumptive 10117 withdrawals of fresh water have change d the sediment supply to the marshes 10118 (Sommerfield and Walsh, 2005). Many marsh re storation projects are underway in the 10119 Delaware Bay ( cf . Teal and Peterson, 2005): dikes have been removed to restore tidal 10120 flow and natural marsh habitat and biota; however, in some restor ation areas invasion by 10121CCSP 4.1 January 15, 2009

620 of 784 Final Report common reed ( Phragmites australis) has been a problem (Abel and Hagan, 2000; 10122 Weinstein et al. , 2000). 10123
10124 The loss of tidal marsh as sea level rise s would harm species that depend on these 10125 habitats for food and shelter, in cluding invertebrates, finfish, and a variety of bird species 10126 (Kreeger and Titus, 2008). Great blue her ons, black duck, blue and green-winged teal, 10127 Northern harrier, osprey, rails, red winged blackbirds, widgeon, and shovelers all use the 10128 salt marshes in Delaware Bay. Blue crab, killifish, mummichog, perch, weakfish, 10129 flounder, bay anchovy, silverside, herring, and rockfish rely on tidal marshes for feeding 10130 on the mussels, fiddler crabs, and other inve rtebrates and for protection from predators 10131 (Dove and Nyman, 1995). 10132
10133 Delaware Bay is a major stopover area for six species of migratory shorebirds, including 10134 most of the Western Hemisphere’s populat ion of red knot (USFWS, 2003). On their 10135 annual migrations from South America to th e Arctic, nearly a million shorebirds move 10136 through Delaware Bay, where they feed heavil y on invertebrates in tidal mudflats, and 10137 particularly on horseshoe crab eggs on the bay’s sandy beaches and foreshores (Walls et 10138 al. , 2002). Horseshoe crabs have been historic ally abundant on the Delaware Bay shores. 10139 A sea-level rise modeling study estimated that a 6-centimeter (cm) (2-ft) rise in relative 10140 sea level over the next century could reduce shorebird foraging areas in Delaware Bay by 10141 57 percent or more by 2100 (Galbraith et al. , 2002). 10142
10143CCSP 4.1 January 15, 2009

621 of 784 Final Report Invertebrates associated with cordgrass stands in the lo w intertidal zone include grass 10144 shrimp, ribbed mussel, coffee-bean snail, a nd fiddler crabs (Kreamer, 1995). Blue crab, 10145 sea turtles, and shorebirds are among the many species that prey on ribbed mussels; 10146 fiddler crabs are an import ant food source for bay anc hovy and various species of 10147 shorebirds (Kreamer, 1995). Wading birds su ch as the glossy ibis feed on marsh 10148 invertebrates (Dove and Nyma n, 1995). Waterfowl, particul arly dabbling ducks, use low 10149 marsh areas as a wintering ground. 10150
10151 Sandy beaches and foreshores account for the majority of the Delaware and New Jersey 10152 shores of Delaware Bay. As sea level rises, beaches can be lost if either shores are 10153 armored or if the land behind the existing beac h has too little sand to sustain a beach as 10154 the shore retreats (Nordstrom, 2005). As s hown in Table A1.1, so far only 4 percent 10155 (Delaware) and 6 percent (New Jersey) of th e natural shores have been replaced with 10156 shoreline armoring. Another 15 percent (Delaware) and 4 percent (New Jersey) of the 10157 shore is developed. Although conservation ar eas encompass 58 percent of Delaware 10158 Bay’s shores, they include only 32 percent of beaches that are optimal or suitable habitat 10159 for horseshoe crabs (Kreeger and Titus, 2008). 10160
10161 Beach nourishment has been relatively common along the developed beach communities 10162 on the Delaware side of the bay. Although beach nourishment can diminish the quality of 10163 habitat for horseshoe crabs, nourished beaches are more beneficial than an armored 10164 shore; most beach nourishment along the New Jersey shore of Delaware Bay has been 10165 justified by environmental benefits (Kreeger and Titus, 2008; USACE 1998b,, c). 10166CCSP 4.1 January 15, 2009

622 of 784 Final Report 10167

Table A1.1 The shores of Delaware Ba y: Habitat type and conservation stat us of shores suit able for horseshoe crabs. Shoreline length Delaware New Jersey New Jersey and Delaware By Habitat Type (percent of bay shoreline km % km % % Beach 68 74 62 42 54 Armored Shore 3.7 4 8.3 6 5 Organic 20 22 78 53 41 Total Shoreline 91 100 148 100 100 By Indicator of Future Shore Protection (km) Shore Protection Structures 2.7 2.9 5.1 3.4 3 Development 13 15 5.7 3.8 8 By Suitability for Horseshoe Crab (percent of Bay shoreline Optimal Habitat 31.3 34 26.0 18 24 Suitable Habitat 10.5 12 5.1 3.5 6.6 Less Suitable Habitat 29.0 32 49.0 33 33 Unsuitable Habitat 20.0 22 67.0 46 37 Within Conservations Lands by Suitability for Horseshoe Crab (percent of equally suitable lands) Optimal Habitat 12.9 41 9.6 37 39 Optimal and Suitable Habitat 13.6 33 9.8 32 32 Optimal, Suitable, and Less Suitable Habitat 32.2 46 43.3 54 50 All Shores 44.7 49 92.7 63 58 Source: Kreeger and Titus (2008), compiling data developed by Lathrop et al. (2006). 10168 Many Delaware Bay beaches have a relativel y thin layer of sand. Although these small 10169 beaches currently have enough sand to protect the marshes immediately inland from 10170 wave action, some beaches may not be able to survive accelerated sea-level rise even in 10171 areas without shoreline armori ng, unless artificial measures ar e taken to preserve them 10172 ( Kreeger and Titus (2008). For example, Delaware has already nourished beaches with 10173 the primary purpose of restoring horseshoe crab habitat (Smith et al. , 2002) (see Box 10174 A1.3.). 10175
10176
10177
10178CCSP 4.1 January 15, 2009

623 of 784 Final Report 10179
BOX A1.3: Horseshoe Crab s and Estuarine Beaches 10180 10181 The Atlantic horseshoe crab ( Limulus polyphemus) , an ancient species that has survived virtually 10182 unchanged for more than 350 million years, enters estu aries each spring to spawn along sandy beaches. The 10183 species has experienced recent popula tion declines, apparently due to overharvesting as well as habitat loss 10184 and degradation (Berkson and Shuster, 1999). 10185 10186 10187 10188 10189 10190 10191 10192 10193 10194 Population Status and Sea-Level Rise 10195 In Delaware Bay, as elsewhere along its range, horse shoe crabs depend on narr ow sandy beaches and the 10196 alluvial and sand bar deposits at the mouths of tidal creeks for essential spawning habitat. A product of 10197 wave energy, tides, shoreline config uration, and over longer periods, sea-level rise, the narrow sandy 10198 beaches utilized by horseshoe crabs are diminishing at sometimes alarming rates due to beach erosion as a 10199 product of land subsidence and sea-level increases (Nordstrom, 1989; Titus et al. , 1991). At Maurice Cove 10200 in Delaware Bay, for example, portions of the shoreline have eroded at a rate of 4.3 m per year between 10201 1842 and 1992 (Weinstein and Weishar, 2002); an estimate by Chase (1979) suggests that the shoreline 10202 retreated 150 m landward in a 32-year period, exposing ancient peat de posits that are believed to be 10203 suboptimal spawning habitat (Botton et al. , 1988). If human infrastructure along the coast leaves estuarine 10204 beaches little or no room to transg ress inland as sea level rises, concomitant loss of horseshoe crab 10205 spawning habitat is likely (Galbraith et al. , 2002). Kraft et al. (1992) estimated this loss, along with 10206 wetland “drowning”, as greater than 90 percent in Delaware Bay (about 33,000 ha). 10207 10208 Horseshoe Crab Spawning and Shorebird Migrations 10209 Each spring, horseshoe crab spawning coincides with the arrival of hundreds of thousands of shorebirds 10210 migrating from South America to their sub-Arctic nes ting areas. While in Delaware Bay, shorebirds feed 10211 extensively on horseshoe crab eggs to increase their depleted body mass before continuing their migration 10212 (Castro and Myers, 1993; Clark, 1996). Individual birds may increase their body weight by nearly one-third 10213 before leaving the area. There is a known delicate re lationship between the horseshoe crab and red knots 10214 (Baker et al ., 2004). How other shorebirds might be affected by horseshoe crab population decline is 10215 uncertain (Smith et al. , 2002). 10216 Numerous other animals, including diamondback terrapins, and Kemp’s ridley sea turtles, 10217 rely on the sandy beaches of Delaware Bay to la y eggs or forage on invertebrates such as 10218 amphipods and clams. When tides are high, numerous fish also forage along the 10219 submerged sandy beaches, such as killifish, mummichog, rockfish, perch, herring, 10220 silverside, and bay anch ovy (Dove and Nyman, 1995). 10221CCSP 4.1 January 15, 2009

624 of 784 Final Report 10222 A1.D.2 Development, Shore Protection, and Coastal Policies 10223 A1.D.2.1 New Jersey 10224 Policies that may be relevant for adapting to s ea-level rise in New Jersey include policies 10225 related to the Coastal Facil ity Review Act (CAFRA), the (coastal) Wetlands Act of 1970, 10226 the State Plan, an unusually st rong public trust doctrine, a nd strong preference for beach 10227 nourishment along the Atlantic Ocean over hard structures or shoreline retreat. This 10228 Section discusses the first four of these policies (nourishment of ocean beaches is 10229 discussed in Section A1.C of this Appendix). 10230
10231 CAFRA applies to all shores along Delaware Bay and the portion of the Delaware River 10232 south of Killcohook National Wildlife Area, as well as most tidal shores along the 10233 tributaries to Delaware Bay. The act sometimes limits development in the coastal zone, 10234 primarily to reduce runoff of pollution into the state’s waters (State of New Jersey, 2001). 10235 Regulations promulgated under the Wetlands Act of 1970 prohibit development in tidal 10236 wetlands unless the development is water-depe ndent and there is no prudent alternative 10237 (NJAC 7:7E-2.27 [c]). Regulations prohibit development of freshw ater wetlands under 10238 most circumstances (NJAC 7: 7E-2.27 [c]). The regulations also prohibit development 10239 within 91.4 m (300 ft of tidal wetland, unless the development has no significant adverse 10240 impact on the wetlands (NJAC 7:7-3.28 [c]). Th ese regulations, like Maryland’s Critical 10241 Areas Act (see Section A1.E.2), may indirect ly reduce the need for shore protection by 10242 ensuring that homes are set back farther from the shore than would otherwise be the case 10243 (NOAA 2007, see Section 6.2 in Chapter 6). For th e same reason, existing restrictions of 10244CCSP 4.1 January 15, 2009

625 of 784 Final Report development in nontidal wetlands (see Secti on 10.3) may also enable tidal wetlands to 10245 migrate inland. 10246
10247 The New Jersey state plan provides a statewide vision of where growth should be 10248 encouraged, tolerated, and di scouraged—but local government has the final say. In most 10249 areas, lands are divided into fi ve planning areas. The state en courages development in (1) 10250 metropolitan and (2) suburban planning areas, and in those (3) fringe planning areas that 10251 are either already developed or part of a well-designed new development. The state 10252 discourages development in most portions of (4) rural planning areas and (5) land with 10253 valuable ecosystems, geologic features, or wildlife habitat, including coastal wetlands 10254 and barrier spits/islands (State of New Jers ey, 2001). However, even these areas include 10255 developed enclaves, known as “centers” where development is recognized as a reality 10256 (State of New Jersey, 2001). The preservation of rural and natural landscapes in portions 10257 of planning areas (4) and (5) is likely to afford opportuni ties for wetlands to migrate 10258 inland as sea level rises. Ne vertheless, New Jersey has a long history of building dikes 10259 along Delaware Bay and the Delaware River to convert tidal wetlands to agricultural 10260 lands (see Box 5.1) and dikes still protect some undeveloped lands. 10261
10262 10263 10264 10265 10266 10267 10268 10269 10270 --Start text box-- 10271 10272 BOX A1.4: The Gibbstown Levee, New Jersey 10273 10274CCSP 4.1 January 15, 2009

626 of 784 Final Report The Gibbstown Levee along the Delaware River in New Jersey once served a function similar to the dikes 10275 in Cumberland County, preventing tidal inundation and lowering the water table to a level below mean sea 10276 level. When the dike was built 300 years ago (USACE, undated[a]), the tides were 1 m lower and the 10277 combination dike and tide gate kept the water levels low enough to permit cultivation. But rising sea level 10278 and land subsidence have left this land barely above low tide, and many lands drain too slowly to 10279 completely drain during low tide. Hence, farmland has converted to non-tidal wetland. 10280 10281 By keeping the creek a meter or so lower than it wo uld be if it rose and fell with the tides, the levee 10282 improves drainage during rainstorms for Greenwich Township. Nevertheless, it is less effective today than 10283 when the sea was 50 to 100 cm lower. During extreme rainfall, the area can flood fairly easily because the 10284 tide gates have to be closed most of the day. Heavy rain during a storm surge is even more problematic 10285 because for practical purposes there is no low tide to afford the opportunity to get normal drainage by 10286 opening the tide gate. Evacuations were necessary during hurricane Floyd when part of this dike collapsed 10287 as a storm tide brought water levels of more than ten feet above mean low water (NCDC, 1999). 10288 10289 Officials in Greenwich Township are concerned that the dikes in Gl oucester County are in danger of 10290 failing. “The Gibbstown Levee was repaired in many pl aces in 1962 by the U.S. Army Corps of Engineers 10291 under Public Law 84-99” (USACE, 2004). Part of the problem appears to be that most of these dikes are 10292 the responsibility of meadow companies originally chartered in colonial times. These companies were 10293 authorized to create productive agricultural lands from tidal marshes. Although harvests of salt hay once 10294 yielded more than enough revenue to maintain the dikes, this type of farming became less profitable during 10295 the first half of the twentieth century. Moreover, as s ea level has continued to rise, the land protected by the 10296 dikes has mostly reverted to marsh (Weinstein et al ., 2000; Abel et al ., 2000). Revenues from these lands, 10297 if any, are insufficient to cover the cost of maintaining the dikes (DiMuz io, 2006). As a result, the dikes are 10298 deteriorating, leading officials to f ear a possible catastrophic dike failure during storm, or an increase in 10299 flood insurance rates (DELO, 2006). The officials hope to obtain federal funding (DELO, 2006). 10300 10301 Even if these dikes and their associated tide gates ar e fortified, the dry land will gradually be submerged 10302 unless pumping facilities are installed (see Section 6.2 in Chapter 6), because much of the area is barely 10303 above low tide even today (Titus and Wang 2008). Although freshwater marshes in general seem likely to 10304 be able to keep pace with rising sea level (Reed et al. , 2008), wetlands behind dikes do not always fare as 10305 well as those exposed to no rmal tidal currents (Reed et al ., 2008). Over longer periods of time, increases in 10306 salinity of the Delaware River resu lting from rising sea level and reduced river flows during droughts could 10307 enable saltwater to invade these fresh marshes (Hull and Titus, 1986), which would convert them to open 10308 water ponds. 10309 10310 If pumping facilities are not sufficient for a daily pumping of all the very low lands protected by the dikes, 10311 the primary impact of the dikes could be to prevent flooding from storm surges and ordinary tides. For the 10312 isolated settlements along Marsh Dike Road and else where, elevating homes an d land surfaces may be 10313 possible; although property values are less than along th e barrier islands, sources for fill material are closer. 10314 One could envision that Gibbstown, Bridgetown, and other more populated communities could be encircled 10315 with a ring dike with a pumping system that drains only the densely developed area; or they too may 10316 elevate land as the sea rises. 10317 10318
--End box-- 10319 10320CCSP 4.1 January 15, 2009

627 of 784 Final Report In Cumberland County, salt marsh has been recl aimed for agricultural purposes for more 10321 than 200 years (Sebold, 1992 and references ther ein). Over the last few decades, many of 10322 the dikes that were constructed have been dismantled. Some have failed during storms. 10323 Others have been purchased by conservation programs seeking to restore wetlands, most 10324 notably Public Service Enterprise Group ( PSEG) in its efforts to offset possible 10325 environmental effects of a nuclear power plan t. Although the trend is for dike removal, 10326 the fact that diked farms have been part of the landscape for centuries leads one to the 10327 logical inference that dikes may be used to hold back a rising sea once again. Cumberland 10328 County has relatively little coastal developmen t, yet the trend in coastal communities that 10329 have not become part of a conservation progr am has been for a gradual retreat from the 10330 shore. Several small settlements along Dela ware Bay are gradua lly being abandoned. 10331
10332 The state plan contemplates a substantial degree of agricultural and environmental 10333 preservation along the Delaware River and its tidal tributaries in Salem and lower 10334 Gloucester County. An agricultu ral easement program in Gloucester County reinforces 10335 that expectation. Farther up the river, in the industrial and commercial areas, most of the 10336 shoreline is already bulkheaded, to provide the vertical shor e that facilitates docking—but 10337 the effect is also to stop coastal erosion. The eventual fate of existing dikes, which protect 10338 lightly developed areas, is unclear (Box A1.4). 10339
10340 The public trust doctrine in New Jersey has tw o unique aspects. First, the public has an 10341 easement along the dry beach between mean high water and the vegetation line. Although 10342 other states have gradually acquired these easements in most recreational communities, 10343CCSP 4.1 January 15, 2009

628 of 784 Final Report few states have general access along the dry b each. As a result, people are entitled to 10344 walk along river and bay beaches. The laws of Delaware and Pennsylvania, by contrast, 10345 grant less public access along the shore. In mo st states, the public owns the land below 10346 mean high water. In these two states, the publ ic owns the land below mean low water. 10347 The public has an easement along the wet beach between mean low and mean high water, 10348 but only for navigation, fishi ng, and hunting—not for recreati on (see Chapter 8 of this 10349 Product for additional details) 10350 10351 Second, the New Jersey Supreme Court has held that the public is entitled to 10352 perpendicular access to the beach 81 . The holding does not mean that someone can 10353 indiscriminately walk across any landowner’s property to get to the water, but it does 10354 require governments to take prudent measures to ensure that public access to the water 10355 accompanies new subdivisions 82

. 10356 10357 As trustee, the New Jersey Department of Environmental Protection has promulgated 10358 rules preserving the public trust rights to parallel and perpendicular access. The 10359 regulations divide new constr uction (including shore protect ion structures) into three 10360 classes: single family homes (or duplexes); de velopment with two or three homes; and all 10361 other residential and nonresid ential development. Along mo st of the tidal Delaware 10362 River, any development other than a single family home requires a public walkway at 10363 least 3 m (10 ft) wide along the shore. By contrast, along Delaware Bay, areas where one 10364

81 Matthews v Bay Head Improvement Association, 471 A.2d 355. Supreme Court of NJ (1984). 82 Federal law requires similar access before an area is eligible for beach nourishment.CCSP 4.1 January 15, 2009

629 of 784 Final Report might walk along the beach rather than requi re a walkway, the regulations have a more 10365 general requirement for public access. (See Table A1.2). 10366

Table A1.2 New Jersey Regulatory Requirements for (Para llel) Access along, and (Perpendicular) to the Shore for New Development or Shore Prot ection Structures Along Delaware Estuary. Single Family 4 Two or Three Residential Structures 5 All other Development 6 Designated Urban Rivers 1 No requirement Along the shore : 20-ft preservation buffer, including 10-ft wide walkway To the shore : 10-ft wide walkway every half mile. Along the Shore : 30-ft preservation buffer, including 16-ft wide walkway To the Shore : 20-ft wide preservation buffer, including 10-ft wide walkway, every half mile Beaches along Major Bodies of Water 2 Access along and to the beach is required. Access along and to the beach is required. Access along and to the beach is required.

All other coastal areas (except Hudson River) No requirement Alternative access on site or nearby. Access along the beach and shore is required.

1 Within this region, Cohansey River within Bri dgeton, Maurice River within Millville, and Delaware River from the CAFRA boundary upstream to the Trenton Makes Bridge (Trenton). Also applies to Arthur Kill, Kill Van Kull west of Bayonne Bride, Newark Bay, Elizabeth Riber, Hackwnsask River, Rahway River, and Raritan River. 2 Delaware Bay within this region. Also Atlan tic Ocean, Sandy Hook Bay, and Raritan Bay. 3 See Section B of this Appendix for Hudson River requirements. 4 NJAC 7:7E-8.11 (f)(6-7) 5 NJAC 7:7E-8.11 (f)(4-5) 6 NJAC 7:7E-8.11 (d-e) 10367 A1.D.2.2 Delaware 10368 Kent County does not permit subdivisi ons—and generally discourages most 10369 development—in the 100-year coastal floodpl ain, as does New Castle County south of 10370 the Chesapeake and Delaware Canal 83 . Because the 100-year floodplain for storm surge 10371 extends about 2 m above spring high water, which is often more than one kilometer 10372 inland, the floodplain regulations often require a greater setback than the erosion-hazard 10373 (see e.g ., A1.G.2) and environmental ( e.g ., A1.E.2 and A1.F.2) setbacks elsewhere in the 10374 mid-Atlantic. Thus, a greater amount of la nd may be available for potential wetland 10375

83 See Kent County Ordinances § 7.3 and New Castle Ordinance 40.10.313CCSP 4.1 January 15, 2009

630 of 784 Final Report migration (see Section 6.2 in Chapter 6). Nevert heless, if sea level continues to rise, it is 10376 logical to assume that this buffer would not last forever. 10377
10378 Preservation easements and land purchases have also contributed to a major conservation 10379 buffer (DDA, 2004), which would leave room fo r wetlands to migrate inland as sea level 10380 rises (see Chapter 6.2). The state is purchasi ng agricultural preserva tion easements in the 10381 coastal zone, and a significan t portion of the shore is in Prime Hook or Bombay Hook 10382 National Wildlife Refuge. The majority of the shore south of the canal is part of some 10383 form of preservation or conservation land. 10384 10385 A1.D.2.3 Pennsylvania 10386 Pennsylvania 84 is the only state in the nation along tidal water without an ocean coast 85

. 10387 As a result, the state’s sensitivity to sea-level rise is different than other states. Floods in 10388 the tidal Delaware River are as likely to be caused by extrem e rainfall over the watershed 10389 as storm surges. The Delaware River is usua lly fresh along almost all of the Pennsylvania 10390 shore. Because Philadelphia re lies on freshwater intakes in the tidal river, the most 10391 important impact may be the impact of salin ity increases from ri sing sea level on the 10392 city’s water supply (H ull and Titus, 1986). 10393 10394 The state of Pennsylvania has no policies that directly address the issue of sea-level 10395 rise 86 . Nevertheless, the state has several coastal policies that might form the initial basis 10396

84 This section only addresses the Pennsylvania side of the river because Section C in this Appendix addressed the policy context for shore protection in New Jersey. 85 This statement also applies to the District of Columbia. 86 Philadelphia’s flood regulations do consider sea level rise.CCSP 4.1 January 15, 2009

631 of 784 Final Report for a response to sea-level rise, including state policies on tidal wetlands and floodplains, 10397 public access, and redeveloping the shore in response to the decline of water-dependent 10398 industries. 10399
10400 Tidal Wetlands and Floodplains 10401 Pennsylvania’s Dam Safety and Waterway Management Rules and Regulations 87 require 10402 permits for construction in the 100-year fl oodplain or wetlands. The regulations do not 10403 explicitly indicate whether la ndowners have a right to prot ect property from erosion or 10404 rising water level. A permit for a bulkhead or revetment seaward of the high-water mark 10405 can be awarded only if the project will not have a “significant adverse impact” on the 10406 “aerial extent of a wetland” or on a “wetland’s values and functions”. A bulkhead 10407 seaward of the high-water mark, however, elim inates the tidal wetlands on the landward 10408 side. If such long-term impacts were viewed as “significant,” permits for bulkheads could 10409 not be awarded except where the shore was al ready armored. But the state has not viewed 10410 the elimination of mudflats or beaches as “significant” for purposes of these regulations; 10411 hence it is possible to obtain a permit for a bulkhead. 10412
10413 The rules do not restrict construction of bul kheads or revetments landward of the high 10414 water mark. However, they do prohibit permits for any “encroachment located in, along, 10415 across or projecting into a wetland, unless the applicant affirmatively demonstrates 10416 that...the ... encroachment will not have an adverse impact on the wetland...” 88

. 10417

87 These regulations were issued pursuant to the Dam Safety and Encroachment Act of 1978. Laws of Pennsylvania, The Dam Safety and Encroachments Act of November 26, 1978, P.L. 1375, No. 325. 88 Pennsylvania Code, Chapter 105. Dam Safety and Waterway Management, Pennsylvania Department of Environmental Protection, 1997. Subchapter 105.18b.CCSP 4.1 January 15, 2009

632 of 784 Final Report Therefore, shoreline armoring can eliminate co astal wetlands (or at least prevent their 10418 inland expansion 89 ) as sea level rises by preventing their landward migration. Like the 10419 shore protection regulations, Pe nnsylvania’s Chapter 105 floodpl ains regulations consider 10420 only existing floodplains, not the floodplains that would result as the sea rises. 10421
10422 Public Access 10423 Public access for recreation is an objec tive of the Pennsylvania Coastal Zone 10424 Management program. This policy, coupled with ongoing redevelopment trends in 10425 Pennsylvania, may tend to ensure that future development includes access along the 10426 shore. If the public access is created by setting development b ack from the shore, it may 10427 tend to also make a gradual retreat possible. If keeping public acces s is a policy goal of 10428 the governmental authority awarding the perm it for shore protection, then public access 10429 need not be eliminated, even if shores are armored (see Titus, 1998 and Table A1.2). 10430
10431 Development and Redevelopment 10432 Industrial, commercial, residential, recr eational, wooded, vacant, transportation, and 10433 environmental land uses all occupy portions of Pennsylvania’s 100-km coast. Generally 10434 speaking, however, the Pennsylvania coastal z one is consistently and heavily developed. 10435 Only about 18 percent of the coastal area is classified as undeveloped (DVRPC, 2003). 10436 Much of the shoreline has been filled or modified with bul kheads, docks, wharfs, piers, 10437

89 Chapter 3 of this Product concludes that most tidal wetlands in Pennsylvania are likely to keep pace with projected rates of sea level rise. However, that finding does not address erosion of wetlands at their seaward boundary. Even though wetlands can keep vertical p ace with the rising water level, narrow fringing wetlands along rivers can be eliminated by shoreline armoring as their seaward boundaries erode and their landward migration is prevented. Moreover, even where the seaward boundary keeps pace, preventing an expansion of wetlands might be viewed as significant.CCSP 4.1 January 15, 2009

633 of 784 Final Report bulkheads, revetments and other hard struct ures over the past two centuries (DVRPC, 10438 2000). 10439
10440 The Pennsylvania coast is moving from an i ndustrial to a post-indus trial landscape. The 10441 coastal zone is still dominated by manufact uring and industrial la nd uses, but a steady 10442 decline in the industrial econom y over the past 60 years ha s led to the abandonment of 10443 many industrial and manufacturing facilities. So me of these facilities sit empty and idle; 10444 others have been adapted for us es that are not water dependent. 10445
10446 A majority of Pennsylvania’s De laware River shore is classifi ed as developed, but sizable 10447 expanses (especially near the water) are bl ighted and stressed ( DVRPC, 2003). Because 10448 of the decaying industrial base, many reside ntial areas along the Delaware River have 10449 depressed property values, declining population, high vacancy rates, physical 10450 deterioration, and high levels of pove rty and crime (DVRPC, 2003). Many—perhaps 10451 most—of the refineries, chemical processing plants, and other manufacturing facilities 10452 that operate profitably toda y may close in the next 50 to 100 years. (DVRPC, 2003) 10453 10454 New paradigms of waterfront development ha ve emerged that offer fresh visions for 10455 southeastern Pennsylvania’s waterfront. In late 2001, Philadelphia released the 10456 Comprehensive Redevelopment Plan for th e North Delaware Ri verfront—a 25-year 10457 redevelopment vision for a distressed ten-mile stretch of waterfront led by the design firm 10458 Field Operations. Delaware County, m eanwhile, developed its Coastal Zone 10459 Compendium of Waterfront Provisions (1998) to guide re vitalization efforts along its 10460CCSP 4.1 January 15, 2009

634 of 784 Final Report coast. Likewise, Bucks County just finished a national search for a design firm to create a 10461 comprehensive plan outlining the revitali zation of its waterfront. Meanwhile, the 10462 Schuylkill River Development Corporation pr oduced the Tidal Schuylkill River Master 10463 Plan. 10464 10465 All of these plans and visions share co mmon elements. They view the region’s 10466 waterfronts as valuable public amenities that can be capitalized on, and they view the 10467 estuary as something for the region to embrace, not to turn its back on. They emphasize 10468 public access along the water’s edge, the creation of greenways and trails, open spaces, 10469 and the restoration of natural shorelines a nd wetlands where appropr iate (DRCC, 2006). 10470
10471 

## A1.E. The Atlantic Coast of Virginia, Maryland, and 10472 

## Delaware (including coastal bays) 10473 Between Delaware and Chesapeake Bays is the land commonly known as the Delmarva 10474 Peninsula. The Atlantic coast of the Delmarva consists mostly of barrier islands separated 10475 by tidal inlets of various sizes (The iler and Hammar-Klose, 1999; Titus et al. , 1985). 10476 Behind these barrier islands, shallow estuar ies and tidal wetlands are found. The large 10477 area of tidal wetlands behind Virg inia’s barrier islands to the south are mostly mudflats; 10478 marshes and shallow open water are more co mmon in Maryland and adjacent portions of 10479 Virginia and Delaware. The barrier islands th emselves are a small portion of the low land 10480 in this region (Titus and Richman, 2001). The northern portion of the Delaware shore 10481 consists of headlands, rather than barrie r islands (see Chapter 3 of this Product). 10482
10483CCSP 4.1 January 15, 2009

635 of 784 Final Report A1.E.1 Environmental Implications 10484 Tidal Marshes and Marsh Islands . The region’s tidal marshes and marsh-fringed bay 10485 islands provide roosting, nes ting, and foraging areas for a va riety of bird species, both 10486 common and rare, including shorebirds (pipi ng plover, American oystercatcher, spotted 10487 sandpiper), waterbirds (gull-bi lled, royal, sandwich, and least terns and black ducks) and 10488 wading birds such as herons and egrets (C onley, 2004). Particularly at low tide, the 10489 marshes provide forage for shorebirds such as sandpipers, plovers, dunlins, and 10490 sanderlings (Burger et al ., 1997). Ducks and geese, in cluding Atlantic brants, 10491 buffleheads, mergansers, and goldeneyes, overwinter in the ba ys’ marshes (DNREC, 10492 undated). The marshes also provide nesting habitat for many species of concern to federal 10493 and state agencies, including American blackduck, Nelson’s sparrow, salt marsh sharp10494 tailed sparrow, seaside sparrow, coastal plai n swamp sparrow, black rail, Forster’s tern, 10495 gull-billed tern, black skimmers, an d American oystercatchers (Erwin et al. , 2006). 10496 10497 The marshes of the bay islands in particular are key resources for birds, due to their 10498 relative isolation and protecti on from predators and to the proximity to both upland and 10499 intertidal habitat. Fo r example, hundreds of horned greb es prepare for migration at the 10500 north end of Rehoboth Bay near Thompson’s Island (Ednie, undated). Several bird 10501 species of concern in this region nest on shell piles (shellrake) on marsh islands, 10502 including gull-billed terns, common terns, black skimmers, royal tern, and American 10503 oystercatchers (Erwin, 1996; Rounds et al. , 2004). Dredge spoil isla nds in particular are a 10504 favorite nesting spot for the spotted sandpiper, which has a state conservation status of 10505 vulnerable to critically imperiled in Mary land, Delaware, and Virginia (Natureserve, 10506CCSP 4.1 January 15, 2009

636 of 784 Final Report 2008). However, marsh islands are also s ubject to tidal flooding, which reduces the 10507 reproductive success of island-nesting birds (Eyler et al. , 1999). 10508 10509 Sea-level rise is considered a major threat to bird species in the Virginia Barrier 10510 Island/Lagoon Important Bird Area (IBA) (Watts, 2006). Biologists at the Patuxent 10511 Wildlife Research Center suggest that s ubmergence of lagoonal marshes in Virginia 10512 would have a major negative effect on marsh-ne sting birds such as black rails, seaside 10513 sparrows, saltmarsh sharp-tailed sparrows, cl apper rails, and Forster’s terns (Erwin et al. , 10514 2004). The U.S. Fish and Wildlife Service cons iders black rail and both sparrow species 10515 “birds of conservation concern” because popul ations are already d eclining in much of 10516 their range (USFWS, 2002). The number of bi rd species in Virginia marshes was found 10517 to be directly related to marsh size; the minimum marsh size found to support significant 10518 marsh bird communities was 4.1 to 6.7 ha (10 to 15 ac) (Watts, 1993). 10519 10520 The region’s tidal marshes also support a dive rsity of resident and transient estuarine and 10521 marine fish and shellfish species that move in and out of marshes with the tides to take 10522 advantage of the abundance of decomposing pl ants in the marsh, th e availability of 10523 invertebrate prey, and refuge from pred ators (Boesch and Turner, 1984; Kneib, 1997). 10524 Marine transients include recreationally and commercially important species that depend 10525 on the marshes for spawning and nursery habi tat, including black drum, striped bass, 10526 bluefish, Atlantic croaker, sea trout, and summer flounder. Important forage fish that 10527 spawn in local marsh areas include spot, menhaden, silver perch, and bay anchovy. 10528CCSP 4.1 January 15, 2009

637 of 784 Final Report Shellfish species found in the marshes includ e clams, oysters, shrimps, ribbed mussels, 10529 and blue crabs (Casey and Doctor, 2004). 10530 10531 Salt Marsh Adaptation to Sea-level Rise. Salt marshes occupy thousands of acres in 10532 eastern Accomack and Northampton counties (Fleming et al. , 2006). Marsh accretion 10533 experts believe that most of these marshes ar e keeping pace with curr ent rates of sea-level 10534 rise, but are unlikely to continue to do so if the rate of s ea-level rise increases by another 10535 2 mm per year (Strange 2008c, in terpreting the findings of Reed et al ., 2008). However, 10536 some very localized field measurements indica te that accretion rates may be insufficient 10537 to keep pace even with current rates of sea-level rise (Stran ge, 2008d). For instance, 10538 accretion rates as low as 0.9 mm per year (P hillips Creek Marsh) and as high as 2.1 mm 10539 per year (Chimney Pole Marsh) have been reported (Kastler a nd Wiberg, 1996), and the 10540 average relative sea-level rise along the Eastern Shore is es timated as 2.8 to 4.2 mm per 10541 year (May, 2002). 10542 10543 In some areas, marshes may be able to migr ate onto adjoining dr y lands. For instance, 10544 lands in Worcester County that are held fo r the preservation of the coastal environment 10545 might allow for wetland migration. Portions of eastern Accomack County that are 10546 opposite the barrier islands and lagoonal mars hes owned by The Nature Conservancy are 10547 lightly developed today, and in some cases already converting to marsh. In unprotected 10548 areas, marshes may be able to migrate in land in low-lying areas. From 1938 to 1990 10549 mainland salt marshes on the Eastern Shore incr eased in area by 8.2 percent, largely as a 10550 result of encroachment of salt marsh in to upland areas (Kastler and Wiberg, 1996). 10551CCSP 4.1 January 15, 2009

638 of 784 Final Report 10552 The marsh islands of the coastal bays are undergoing rapid erosion; for example, Big 10553 Piney Island in Rehoboth Bay experienced erosio n rates of 10 m (30 ft) per year between 10554 1968 and 1981, and is now gone (Swisher, 1982; Strange et al ., 2008). Seal Island in 10555 Little Assawoman Bay is eroding rapidly after being nearly totally devegetated by greater 10556 snow geese (Strange, 2008c). Island shrinking is also a pparent along the Accomack 10557 County, Virginia shore; from 1949 to 1990, Chimney Pole marsh showed a 10 percent 10558 loss to open water (Kastler and Wiberg, 1996). The United States Army Corps of 10559 Engineers (USACE) has created many small dre dge spoil islands in the region, many of 10560 which are also disappearing as a result of erosion (Federal Register, 2006). 10561 10562 Sea-Level Fens. The rare sea-level fen vegetation community is found in a few locations 10563 along the coastal bays, including the Angol a Neck Natural Area along Rehoboth Bay in 10564 Delaware and the Mutton Hunk Fen Natural Area Preserve fronting Gargathy Bay in 10565 eastern Accomack County (VA DCR, undated [a ][b]). The Division of Natural Heritage 10566 within the Virginia Departme nt of Conservation and Recreat ion believes that chronic sea10567 level rise with intrusions of tidal flooding and salinity poses “a serious threat to the long10568 term viability” of sea-level fens (VA DCR, 2001). 10569 10570 Shallow Waters and Submerged Aquatic Vegetation (SAV). Eelgrass beds are essential 10571 habitat for summer flounder, bay scallop, and blue crab, all of wh ich support substantial 10572 recreational and commercial fisherie s in the coastal bays (MCBP, 1999). Various 10573 waterbirds feed on eelgrass beds, including brant, canvasback duck, and American black 10574CCSP 4.1 January 15, 2009

639 of 784 Final Report duck (Perry and Deller, 1996). Shallow water areas of the coastal bays that can maintain 10575 higher salinities also f eature beds of hard and surf clams (DNREC, 2001). 10576 10577 Tidal Flats . Abundant tidal flats in this region provi de a rich invertebrate food source for 10578 a number of bird species, including whimbrels, dowitche rs, dunlins, black-bellied 10579 plovers, and semi-palmated sandpipers (Watts and Truitt, 2002). Loss of these flats could 10580 have significant impacts. For example, 80 percent of the Northern Hemisphere’s 10581 whimbrel population feeds on area flats, in large part on fiddler crabs (TNC, 2006). The 10582 whimbrel is considered a species “of conserva tion concern” by the United States Fish and 10583 Wildlife Service, Division of Migratory Bird Management (USFWS, 2002). 10584 10585 Beaches. Loss of beach habitat due to sea-leve l rise and erosion below protective 10586 structures could have a numb er of negative consequences for species that use these 10587 beaches: 10588

 Horseshoe crabs rarely spawn unless sand is at least deep enough to nearly cover 10589 their bodies, about 10 cm (4 inches [i n]) (Weber, 2001). Shoreline protection 10590 structures designed to slow beach loss can also block horseshoe crab access to 10591 beaches and can entrap or strand spawning crabs when wave energy is high (Doctor 10592 and Wazniak, 2005). 10593

 The rare northeastern tig er beetle depends on beac h habitat (USFWS, 2004b). 10594

 Photuris bethaniensis is a globally rare firefly loca ted only in interdunal swales on 10595 Delaware barrier be aches (DNREC, 2001). 10596CCSP 4.1 January 15, 2009

640 of 784 Final Report  Erosion and inundation may reduce or elim inate beach wrack communities of the 10597 upper beach, especially in developed areas where shores are protected (Strange, 10598 2008c). Beach wrack contains insects a nd crustaceans that provide food for many 10599 species, including migrating shorebirds (Dugan et al. , 2003). 10600

 Many rare beach-nesting birds, such as piping plover , least tern , common tern, black 10601 skimmer, and American oystercatcher, ne st on the beaches of the coastal bays 10602 (DNREC, 2001) 10603
10604 Coastal Habitat for Migra ting Neotropical Songbirds. Southern Northampton County is 10605 one of the most important bird areas along the Atlantic Coast of North America for 10606 migrating neotropical songbirds such as indi go buntings and ruby-th roated hummingbirds 10607 (Watts, 2006). Not only are these birds valued for their beauty but they also serve 10608 important functions in dispersing seeds and cont rolling insect pests. It is estimated that a 10609 pair of warblers can consume thousands of insects as they raise a brood (Mabey et al. , 10610 undated). Migrating birds concentrate with in the tree canopy and thick understory 10611 vegetation found within the lower 10 km (6 mi) of the penins ula within 200 m (650 ft) of 10612 the shoreline. Loss of this unde rstory vegetation as a result of rising seas would eliminate 10613 this critical stopover area for neotropical mi grants, many of which have shown consistent 10614 population declines since the early 1970s (Mabey et al. , undated) 10615
10616 A1.E.2 Development, Shore Protection, and Coastal Policies 10617 A1.E.2.1 Atlantic Coast 10618CCSP 4.1 January 15, 2009

641 of 784 Final Report Less than one-fifth of the Delmarva’s ocean coast is developed, and the remaining lands 10619 are owned by private conservation organizatio ns or government agencies. Almost all of 10620 the Virginia Eastern Shore’s 124-km (77-mi) ocean coast is owned by the U.S. Fish and 10621 Wildlife Service, NASA, the State, or The Nature Conservancy 90 . Of Maryland’s 51 km 10622 (32 mi) of ocean coast, 36 km (22 mi) are along Assateague Island National Seashore. 10623 The densely populated Ocean City occupies approximately 15 km (9 mi). More than 10624 three-quarters of the barrier islands and spits in Delaware are part of Delaware Seashore 10625 State Park, while the mainland coast is a bout evenly divided between Cape Henlopen 10626 State Park and resort towns such as Rehoboth, Dewey Beach, and Bethany Beach. With 10627 approximately 15 km of developed ocean coast each, Maryland and Delaware have 10628 pursued beach nourishment to protect valuable coastal property and preserve the beaches 10629 that make the property so valuable (Hedrick et al. , 2000). 10630
10631 With development accounting for only 15 to 20 percent of the ocean coast, the natural 10632 shoreline processes are likely to dominate al ong most of these shores. Within developed 10633 areas, counteracting shoreline erosion in de veloped areas with beach nourishment may 10634 continue as the primary activity in the n ear term. A successful alternative to beach 10635 nourishment, as demonstrated by a USACE (200 1a) and National Park Service project to 10636 mitigate jetty impacts along Assa teague Island, is to restore sediment transport rates by 10637 mechanically bypassing sand from the inlet and tidal deltas into the shallow nearshore 10638 areas that have been starve d of their natural sand suppl y. Beginning in 1990, the USACE 10639 and the Assateague Island National Seashor e partnered to develop a comprehensive 10640

90 A few residential structures are on Cedar Island, and Cobbs and Hog Islands have some small private inholdings (Ayers, 2005).CCSP 4.1 January 15, 2009

642 of 784 Final Report restoration plan for the nort hern end of Assateague Isla nd. The “North End Restoration 10641 Project” included two phases. The first phase, completed in 2002, provided a one-time 10642 placement of sand to replace a portion of sa nd lost over the past 60 years due to the 10643 formation of the inlet and subsequent jetty stabilization efforts. The second phase is 10644 focused on re-establishing a natural sedi ment supply by mechanically bypassing sand 10645 from the inlet and tidal deltas into the shallow nearshore areas 91

. 10646
10647 A1.E 2.2 Coastal Bay Shores 10648 The mainland along the back-barrier bays has be en developed to a greater extent than the 10649 respective ocean coast in all three states (MRLCC, 2002; MDP, 2001; DOSP, 1997). 10650 Along the coastal bays, market forces have le d to extensive developm ent at the northern 10651 end of the Delmarva due to the relatively close proximity to Washington, Baltimore, and 10652 Philadelphia. Although connected to the de nsely populated Hampton Roads area by the 10653 Chesapeake Bay Bridge-Tunnel, southern portion s of the Delmarva are not as developed 10654 as the shoreline to the north. Worcester County, Maryland, reflects a balance between 10655 development and environmental protection re sulting from both recognition of existing 10656 market forces and a conscious decision to preserve Chincoteague Bay. Development is 10657 extensive along most shores opposite Ocean Ci ty and along the bay shores near Ocean 10658 City Inlet. In the southern portion of the county, conservation easements or the Critical 10659 Areas Act preclude development along most of the shore. Although the Critical Areas 10660 Act encourages shore protection, and conserva tion easements in Maryland preserve the 10661 right to armor the shore (MET, 2006), these low-lying lands are more vulnerable to 10662

91 See <http://www.nps.gov/asis/naturescien ce/resource-management-documents.htm>CCSP 4.1 January 15, 2009

643 of 784 Final Report inundation than erosion ( e.g. , Titus et al ., 1991) and are therefore possible candidates for 10663 wetland migration. 10664 10665 Of the three states, Maryland has the most stringent policies governing development 10666 along coastal bays Under the Chesapeake a nd Atlantic Coastal Bays Critical Areas 10667 Protection Program, new development must be set back at least 100 ft from tidal wetlands 10668 or open water 92 . In most undeveloped areas, the stat ute also limits future development 10669 density to one home per 20 ac within 305 m (1000 ft) of the shore 93 and requires a 61-m 10670 (200-ft) setback. 94 In Virginia, new development must be set back at least 30 m (100 ft). 10671 (see Section A1.F.2 in this Appendix for additional discussion of the Maryland and 10672 Virginia policies.) The Delaware Department of Natural Resources has proposed a 30-m 10673 (100-ft) setback along the co astal bays (DNREC, 2007); Sussex County currently 10674 requires a 15-m (50-ft) setback 95

. 10675
10676 While shore protection is curren tly more of a priority along th e Atlantic Coast, preventing 10677 the inundation of low-lying lands may eventua lly be necessary as well. Elevating these 10678 low areas appears to be more practical than erecting a dike around a narrow barrier island 10679 (Titus, 1990). Most land surfaces on the baysid e of Ocean City were elevated during the 10680 initial construction of residences (McGea n, 2003). In an appendix for U.S. EPA’s 1989 10681 Report to Congress, Leatherman (1989) conc luded that the only portion of Fenwick 10682

92 Maryland Natural Resources Code §8-1807(a). Code of Maryland Regulations §27.01.09.01 (C); 93 Code of Maryland Regulations §27.01.02.05(C)(4). 94 Maryland Natural Resources Code §8-1808.10 95 Sussex County, DE. 2007. Buffer zones for wetlands and tidal and perennial non-tidal waters. § 115-193, Sussex County Code. Enacted July 19, 1988 by Ord. No. 521.CCSP 4.1 January 15, 2009

644 of 784 Final Report Island where bayside property would have to be elevated with a 50 cm rise in sea level 10683 would be the portion in Delaware ( i.e. , outside of Ocean City). He also concluded that 10684 Wallops Island, South Bethany, Bethany, a nd Rehoboth Beach are high enough to avoid 10685 tidal inundation for the first 50 to 100 cm of sea-level rise. The Town of Ocean City has 10686 begun to consider how to respond to address some of the logistical problems of elevating 10687 a densely developed barrie r island (see Box A1.5). 10688 10689 The Maryland Coastal Bays Program consider s erosion (due to sea-level rise) and 10690 shoreline hardening major fact ors contributing to a decline in natural shoreline habitat 10691 available for estuarine species in the north ern bays (MCBP, 1999). Much of the shoreline 10692 of Maryland’s northern coastal bays is protected using bulkhead s or stone riprap, 10693 resulting in unstable sediments and loss of wetlands and shallow water habitat (MCBP, 10694 1999). Armoring these shorelines will preven t inland migration of marshes, and any 10695 remaining fringing marshes will ultimately be lost (Strange 2008c). The Coastal Bays 10696 Program estimated that more than 600 ha ( 1,500 ac) of salt marshes have already been 10697 lost in the coastal bays as a result of shor eline development and st abilization techniques 10698 (MCBP, 1999). If shores in the southern pa rt of Maryland’s co astal bays remain 10699 unprotected, marshes in low-lying areas would be allowed to potentially (see Chapter 4) 10700 expand inland as sea level rises (Strange 2008c). 10701
10702
10703
10704 10705CCSP 4.1 January 15, 2009

645 of 784 Final Report --Start box-- 10706 10707 BOX A1.5: Elevating Ocean City as Sea Level Rises 10708 10709 Logistically, the easiest time to elevate low land is when it is still vacant, or during a coordinated 10710 rebuilding. Low parts of Ocean City’s bay side were elevated during the initial construction. As sea level 10711 rises, the town of Ocean City has started thinking about how it might ultimately elevate. 10712 Ocean City’s relatively high bay sides make it much less vulnerable to inundation by spring tides than other 10713 barrier islands. Still, some streets are below the 10-year flood plain, and as sea level rises, flooding will 10714 become increasingly frequent. 10715 However, the town cannot elevate the lowest street s without considering the implications for adjacent 10716 properties. A town ordinance requires property owners to maintain a 2 percent grade so that yards drain 10717 into the street. The town construes this rule as imposing a reciprocal responsibility on the town itself to not 10718 elevate roadways above the level where yards can drain, even if the road is low enough to flood during 10719 minor tidal surges. Thus, the lowest lot in a gi ven area dictates how high the street can be. 10720 As sea level rises, failure by a single property owner to elevate could prevent the town from elevating its 10721 streets, unless it changes this rule. Yet public health r easons require drainage, to prevent standing water in 10722 which mosquitoes breed. Therefore, the town has an inte rest in ensuring that all property owners gradually 10723 elevate their yards so that the streets can be elevat ed as the sea rises withou t causing public health 10724 problems. 10725 The Town of Ocean City (2003) has developed draft rules that would re quire that, during any significant 10726 construction, yards be elevated enough to drain durin g a 10-year storm surge fo r the life of the project, 10727 considering projections of future sea- level rise. The draft rules also state that Ocean City’s policy is for all 10728 lands to gradually be elevated as the sea rises. 10729 --End box-- 10730
10731 

## A1.F Chesapeake Bay 10732 The Chesapeake Bay region accounts for more th an one-third of the lowland in the Mid10733 Atlantic (see Titus and Richman 2001). A ccordingly, the first subsection (A1.F.1) on 10734 vulnerable habitat, development, and shore protection) divides th e region into seven 10735 subregions. Starting with Hampton Roads, the subsections proceed clockwise around the 10736 Bay to Virginia’s Middle Peninsula and Nort hern Neck, then up the Potomac River to 10737 Washington, D.C., then up Maryland’s West ern Shore, around to the Upper Eastern 10738 Shore, and finally down to the Lower Easter n Shore. The discussions for Virginia are 10739 largely organized by planning district; the Maryland discussions are organized by major 10740CCSP 4.1 January 15, 2009

646 of 784 Final Report section of shore. The second subsection comp ares the coastal polic ies of Maryland and 10741 Virginia that are most relevant to ho w these states respond to rising sea level 96

. 10742
10743 A1.F.1 Inundation, Development and Sho re Protection, and Vulnerable Habitat 10744 A1.F.1.1 Hampton Roads 10745 Most of the vulnerable dry land in the Hampt on Roads region is located within Virginia 10746 Beach and Chesapeake. These low areas are not , however, in the urban portions of those 10747 jurisdictions. Most of Virginia Beach’s very low land is either along the back-barrier bays 10748 near the North Carolina borde r, or along the North Landing River. Most of Chesapeake’s 10749 low land is around the Northwest River near the North Carolina border, or the along the 10750 Intracoastal Waterway. The localities located farther up the James and York Rivers have 10751 less low land. An important exception is historic Jamestown Island, which has been 10752 gradually submerged by the rising tides sin ce the colony was esta blished 400 years ago 10753 (see Box 10.1 in chapter 10). 10754 10755 Development and Shore Protection 10756 Norfolk is home to the central business district of the Hampton Roads region. 10757 Newport News has similar development to Norf olk along its southern shores, with bluffs 10758 giving rise to less dense resi dential areas further north along the coast. The city of 10759 Hampton is also highly developed, but ove rall has a much smaller percentage of 10760 commercial and industrial development than Norfolk or Newport News. 10761

96 As this report was being finalized, a comprehensive study of the impacts of sea level rise on the Chesapeake Bay region was completed by the National Wildlife Federation (Glick et al., 2008)

.CCSP 4.1 January 15, 2009

647 of 784 Final Report 10762 Outside of the urban core, localities are mo re rural in nature. These localities find 10763 themselves facing mounting development pressures and their comprehensive plans 10764 outline how they plan to respond to these pressures ( e.g ., Suffolk, 1998; York County, 10765 1999; James City County, 2003; Isle of Wi ght County, 2001). Overall, however, the 10766 makeup of these outlying localitie s is a mix of urban and rural development, with historic 10767 towns and residential development dotting the landscape. 10768 10769 Virginia Beach has sandy shores along bot h the Atlantic Ocean and the mouth of 10770 Chesapeake Bay. Dunes dominate the bay shore, but much of the developed ocean shore 10771 is protected by a seawall, and periodic b each nourishment has occurred since the mid10772 1950s (Hardaway et al. , 2005). Along Chesapeake Bay, by c ontrast, the Virginia Beach 10773 shore has substantial dunes, with homes set well back from the shore in some areas. 10774 Although the ground is relatively high, beach nourishment has been required on the bay 10775 beaches at Ocean Park (Hardaway et al. , 2005). Norfolk has maintained its beaches along 10776 Chesapeake Bay mostly with breakwaters and groins. Shores along ot her bodies of water 10777 are being armored. Of Norfolk’ s 269 km (167 mi) of shorelin e, 113 km (70 mi) have been 10778 hardened (Berman et al. , 2000). 10779
10780 Overall trends in the last century show the dunes east of the Lynn Haven inlet advancing 10781 into the Bay (Shellenbarger Jones and Bosc h, 2008c). West from the inlet, erosion, beach 10782 nourishment, and fill operations as well as condominium development and shoreline 10783 armoring have affected the accreti on and erosion patterns (Hardaway et al. , 2005). Along 10784CCSP 4.1 January 15, 2009

648 of 784 Final Report the shores of Norfolk, the rate of erosion is generally low, and beach accretion occurs 10785 along much of the shore (Berman et al. , 2000). Most of the shor e along Chesapeake Bay 10786 is protected by groins and breakwaters, and hence relatively stable (Hardaway et al. , 10787 2005). On the other side of the James River, the bay shoreline is dominated by marshes, 10788 many of which are eroding (Shellenba rger Jones and Bosch, 2008c). . 10789 10790 Since 1979, Virginia Beach has had a “Green Li ne”, south of which the city tries to 10791 maintain the rural agricultural way of life. Because development has continued, Virginia 10792 Beach has also established a “Rural Area Line ,” which coincides with the Green Line in 10793 the eastern part of the city and runs 5 km (3 mi) south of it in the western portion. Below 10794 the Rural Area Line, the city strongly disc ourages development and encourages rural 10795 legacy and conservation easements (VBCP, 2003). In effect, the city’s plan to preserve 10796 rural areas will also serve to preserve th e coastal environment as sea level rises 10797 throughout the coming century and beyond (see Sections 6.1.3, 6.2, 10.3). To the west, by 10798 contrast, the City of Chesapeake is enc ouraging development in the rural areas, 10799 particularly along major corridors. Comprehens ive plans in the more rural counties such 10800 as Isle of Wight and James City tend to focus less on preserving open space and more on 10801 encouraging growth in designated areas (I sle of Wight, 2001; James City County, 2003). 10802 Therefore, these more remote areas may pr esent the best opportunity for long-range 10803 planning to minimize coastal h azards and preserve the ability of ecosystems to migrate 10804 inland. 10805
10806 Vulnerable Habitat 10807CCSP 4.1 January 15, 2009

649 of 784 Final Report Much of the tidal wetlands in the area ar e within Poquoson’s Plum Tree Island National 10808 Wildlife Refuge. Unlike most mid-Atlantic we tlands, these wetlands are unlikely to keep 10809 pace with the current rate of sea-level rise (Shellenbarger Jones and Bosch, 2008c, 10810 interpreting the findings of Reed et al ., 2008). The relative isolati on of the area has made 10811 it a haven for over 100 different species of birds. The refuge has substantial forested dune 10812 hummocks (CPCP, 1999), and a variety of ma mmals use the higher ground of the refuge. 10813 Endangered sea turtles, primarily the logge rhead, use the near shore waters. Oyster, 10814 clams, and blue crabs inhabit the shallow wa ters and mudflats, and striped bass, mullet, 10815 spot, and white perch have been found in the near shore waters and marsh (USFWS, 10816 undated[b]). 10817
10818 The wetlands in York County appear able to ke ep pace with the curren t rate of sea-level 10819 rise. Assuming that they are typical of most wetlands on the western side of Chesapeake 10820 Bay, they are likely to become marginal with a modest acceleration and be lost if sea10821 level rise accelerates to 1 cm per y ear (Shellenbarger Jones and Bosch, 2008c, 10822 interpreting the findings of Reed et al ., 2008). Bald eagles currently nest in the Goodwin 10823 Islands National Estuarine Research Reserv e (Watts and Markham, 2003). This reserve 10824 includes intertidal flats, 1 00 ha (300 ac) of eelgrass and widgeon grass (VIMS, undated), 10825 and salt marshes dominated by salt marsh cordgrass and salt meadow hay. 10826
10827 A1.F.1.2 York River to Potomac River 10828CCSP 4.1 January 15, 2009

650 of 784 Final Report Two planning districts lie between the York and Potomac rivers. The Middle Peninsula 10829 Planning District includes the land betw een the York and Rappahannock rivers. The 10830 Northern Neck is between the Rappahannock and Potomac rivers. 10831
10832 Development and Shore Protection 10833 A large portion of the necks along Mobjack Ba y has a conservation zoning that allows 10834 only low-density residential development “in a manner which protects natural resources 10835 in a sensitive environment 97. The intent is to preserve contiguous open spaces and protect 10836 the surrounding wetlands 98 . The county also seeks to maintain coastal ecosystems 10837 important for crabbing and fishing. As a re sult, existing land use would not prevent 10838 wetlands and beaches along Mobjack Bay from migrating inland as sea level rises. 10839
10840 Gloucester County also has suburban country side zoning, which allows for low density 10841 residential development, includ ing clustered sub-developments 99 along part of the Guinea 10842 Neck and along the York River between Ca rter Creek and the Catlett islands. These 10843 developments often leave some open space that might convert to wetlands as sea level 10844 rises even if the development itself is prot ected. The county plan anticipates development 10845 along most of the York River. Nevertheless, a number of areas are off limits to 10846

97 Gloucester County Code of Ordinances, accessed through Municode Online Codes: <http://livepublish.municode.com/22/lpext.dll?f = templates&fn = main-j.htm&vid = 10843>: “The intent of the SC-1 district is to allow low density residential development....Cluster development is encouraged in order to protect environmental and scenic resources.” 98 Gloucester County Code of Ordinances, accessed through Municode Online Codes; <http://livepublish.municode.com/22/lpext.dll?f = templates&fn = main-j.htm&vid = 10843> 99 Definition of suburban countryside in Gloucest er County Code of Or dinances, accessed throughMunicode Online Codes: <http://livepublish.municode.com/22/lpext.dll?f = templates&fn = mainj.htm&vid = 10843>: “The intent of the SC-1 district is to allow low density residential development....Cluster development is encouraged in order to protect environmental and scenic resources.”CCSP 4.1 January 15, 2009

651 of 784 Final Report development. For example, the Catlett isla nds are part of the Chesapeake Bay National 10847 Estuarine Research Reserve in Virginia, managed as a conservation area 100

. 10848 10849 Along the Northern Neck, shoreline armoring is already very comm on, especially along 10850 Chesapeake Bay and the Rappahannock Rivers shores of Lancaster County. Above 10851 Lancaster County, however, development is relatively sparse along the Rappahannock 10852 River and shoreline armoring is not comm on. Development and shoreline armoring are 10853 proceeding along the Potomac River. 10854 10855 Vulnerable Habitat 10856 Like the marshes of Poquoson to the south, th e marshes of the Guinea Neck and adjacent 10857 islands are not keeping pace with the current ra tes of sea-level rise (Shellenbarger Jones 10858 and Bosch, 2008a, interpreting the findings of Reed et al ., 2008). For more than three 10859 decades, scientists have documented their migration onto farms and forests (Moore, 10860 1976). Thus, the continued survival of th ese marshes depends on land-use and shore 10861 protection decisions. 10862
10863 Upstream from the Guinea Neck, sea-level rise is evident in the York River’s tributaries, 10864 not because wetlands are converting to ope n water but because the composition of 10865 wetlands is changing. Along the Pamunkey and Ma ttaponi Rivers, dead trees reveal that 10866 tidal hardwood swamps are converting to brackis h or freshwater marsh as the water level 10867 rises (Rheinhardt, 2007). Tida l hardwood swamps provide ne sting sites for piscivorous 10868

100 See the Research Reserve’s web page at <http://www.vims.edu/cbnerr/about/index.htm>.CCSP 4.1 January 15, 2009

652 of 784 Final Report (fish eating) species such as ospreys, bald eagles, and double-crested cormorants 10869 (Robbins and Blom, 1996). 10870
10871 In Mathews County, Bethel Beach (a natural area preserve separating Winter Harbor 10872 from Chesapeake Bay) is currently migrati ng inland over an extens ive salt marsh area 10873 (Shellenbarger Jones and Bosch, 2008a). The beach is currently undergoing high erosion 10874 (Berman et al. , 2000), and is home to a population of th e Northeastern beach tiger beetle 10875 (federally listed as threatened) and a nesting site for rare least terns, which scour shallow 10876 nests in the sand (VA DCR, 1999). In the ove rwash zone extending toward the marsh, a 10877 rare plant is present, the sea-beach knotweed ( Polygonum glaucum ) (VA DCR, 1999). 10878 The marsh is also one of few Chesapeake Bay nesting sites for northern harriers ( Circus 10879

cyaneus ), a hawk that is more commonly found in regions further north (VA DCR, 1999). 10880 As long as the shore is able to migrate, thes e habitats will remain intact; but eventually, 10881 overwash and inundation of the marsh could reduce habitat populat ions (Shellenbarger 10882 Jones and Bosch, 2008a). 10883
10884 A1.F.1.3 The Potomac River 10885 Virginia Side . Many coastal homes are along blu ffs, some of which are eroding (Bernd10886 Cohen and Gordon, 1999). Lewisetta is one of the larger vulnerable communities along 10887 the Potomac. Water in some ditches rise a nd fall with the tides, and some areas drain 10888 through tide gates. With a fairly modest rise in sea level, one coul d predict that wetlands 10889 may begin to take over portions of people’s ya rds, the tide gates could close more often, 10890 and flooding could become more frequent. So mewhat higher in elevation than Lewisetta, 10891CCSP 4.1 January 15, 2009

653 of 784 Final Report Old Town Alexandria and Belle Haven (Fai rfax County) both fl ood occasionally from 10892 high levels in the Potomac River. 10893 10894 Maryland Side. Much of the low-lying land is con centrated around St. George Island and 10895 Piney Point in St. Mary’s County, and along the Wicomico River and along Neal Sound 10896 opposite Cobb Island in Charles County. Rela tively steep bluffs, however, are also 10897

common. 10898 10899 Development and Shore Protection 10900 West of Chesapeake Bay, the southwestern s horeline of the Potomac River is the border 10901 between Maryland and Virginia 101 . As a result, islands in the Potomac River, no matter 10902 how close they are to the Virginia side of the river, are part of Maryland or the District of 10903 Columbia. Moreover, most efforts to contro l erosion along the Virginia shore take place 10904 partly in Maryland (or the Dist rict of Columbia) and thus c ould potentially be subject to 10905 Maryland (or Washington, D.C.) policies 102

. 10906 10907 Development is proceeding along approximately two-thirds of the Potomac River shore. 10908 Nevertheless, most shores in Charles Count y, Maryland are in the resource conservation 10909 area defined by the state’s Critical Areas Act (and hence limited to one home per 20 ac) 10910 (MD DNR, 2007). A significant portion of Prin ce George’s County’s shoreline along the 10911 Potomac and its tributaries are owned by the National Park Service and other 10912 conservation entities that s eek to preserve the coastal environment (MD DNR, 2000). 10913

101 See Maryland v. Virginia, 540 US (2003) 102 The Virginia Shore across from Washington, D.C. is mostly owned by the federal government, which would be exempt from District of Columbia policies.CCSP 4.1 January 15, 2009

654 of 784 Final Report 10914 In Virginia, parks also acc ount for a significant portion of the shore (ESRI, 1999). In 10915 King George County, several developers have set development back from low-lying 10916 marsh areas, which avoids problems associat ed with flooding and poor drainage. Water 10917 and sewer regulations that only apply for lo t sizes less than 10 acres may provide an 10918 incentive for larger lot sizes. In Stafford C ounty, the CSX railroad line follows the river 10919 for several miles, and is set back to allow shor es to erode, but not so far back as to allow 10920 for development between the railro ad and the shore (ADC, 2008a). 10921 10922 Vulnerable Habitat 10923 The Lower Potomac River includes a diverse mix of land uses and habitat types. 10924 Freshwater tidal marshes in the Lower Potomac are found in the upper reaches of tidal 10925 tributaries. In general, freshwater tidal ma rshes in the Lower Potomac are keeping pace 10926 with sea-level rise through sediment and peat accumulation, and are li kely to continue to 10927 do so, even under higher sea-level rise scen arios (Strange and Shellenbarger Jones, 10928 2008a, interpreting the findings of Reed et al ., 2008). 10929 10930 Brackish tidal marshes are a major feature of the dow nstream portions of the region’s 10931 rivers. In general, these marshes are keeping pace with sea-level ri se today, but are likely 10932 to be marginal if sea level rise accelerates by 2 mm per year, and be lost if sea level 10933 accelerates 7 mm per year (Strange and Shellenbarger Jones 2008a, interpreting the 10934 findings of Reed et al ., 2008). Loss of brackish tidal mars hes would eliminate nesting, 10935 foraging, roosting, and stopover areas for migr ating birds (Strange and Shellenbarger 10936CCSP 4.1 January 15, 2009

655 of 784 Final Report Jones, 2008a). Significant concentrations of migrating waterfowl forage and overwinter 10937 in these marshes in fall and winter. Rails, coots, and migrant shor ebirds are transient 10938 species that feed on fish a nd invertebrates in and around th e marshes and tidal creeks. 10939 (Strange and Shellenbarger Jones, 2008a). The rich food resources of the tidal marshes 10940 also support rare bird species such as ba ld eagle and northern harrier (White, 1989). 10941 10942 Unnourished beaches and tidal flats of the Lower Potomac are likely to erode as sea 10943 levels rise. Impacts on beaches are highly depe ndent on the nature of shoreline protection 10944 measures selected for a specific area. For example, the developed areas of Wicomico 10945 Beach and Cobb Island are at the mouth of the Wicomico River in Maryland. Assuming 10946 that the shores of Cobb Island continue to be protected, s ea-level rise is likely to 10947 eliminate most of the island’s remaini ng beaches and tidal flats (Strange and 10948 Shellenbarger Jones, 2008a). 10949 10950 Finally, where the cliffs and bluffs along the Lower Potomac are not protected ( e.g. , 10951 Westmoreland State Park, Caledon Natural Ar ea), natural erosional processes will 10952 generally continue, helping to maintain th e beaches below (Strange and Shellenbarger 10953 Jones, 2008a). 10954 10955 Above Indian Head, the Potomac River is fres h. Tidal wetlands are likely to generally 10956 keep pace with rising sea level in these areas (see Chapter 4 of this Product). 10957 Nevertheless, the Dyke Marsh Preserve faces an uncertain future. Its freshwater tidal 10958 marsh and adjacent mud flats are one of the la st major remnants of the freshwater tidal 10959CCSP 4.1 January 15, 2009

656 of 784 Final Report marshes of the Upper Potomac River (Johnston, 2000). A recent survey found 62 species 10960 of fish, nine species of amphibians, seven spec ies of turtles, two species of lizards, three 10961 species of snakes, 34 species of mammals, and 76 species of birds in Dyke Marsh 10962 (Engelhardt et al. , 2005). Many of the fi sh species present ( e.g. , striped bass, American 10963 shad, yellow perch, blueback herring) are important for commercial and recreational 10964 fisheries in the area (Mangold et al. , 2004). 10965 10966 Parklands on the Mason Neck Peninsula are managed for conservation, but shoreline 10967 protection on adjacent lands may result in ma rsh loss and reduced abundance of key bird 10968 species (Strange and Shelle nbarger Jones, 2008b). The Ma son Neck National Wildlife 10969 Refuge hosts seven nesting bald eagle pairs and up to 100 bald eagles during winter, has 10970 one of the largest great blue heron colonies in Virginia, pr ovides nesting areas for hawks 10971 and waterfowl, and is a st opover for migratory birds. 10972 10973 A1.F.1.4 District of Columbia 10974 Within the downtown area, most of the lowe st land is the area filled during the 1870s, 10975 such as Hains Point and the location of the fo rmer Tiber and James Creeks, as well as the 10976 Washington City Canal that join ed them (See Box 5.2 in Chapte r 5). The largest low area 10977 is the former Naval Air Station, now part of Bolling Air Force Base, just south of the 10978 mouth of the Anacostia River, which was part of the mouth of the Anacostia River during 10979 colonial times. A dike protects this area, wh ere most of the low land between Interstate10980 295 and the Anacostia River was open water when the city of Washington was originally 10981 planned. 10982CCSP 4.1 January 15, 2009

657 of 784 Final Report 10983 Development and Shore Protection 10984 The central city is not likely to be given up to rising sea level; city officials are currently 10985 discussing the flood control infrastructure n ecessary to avoid portions of the downtown 10986 area from being classified as part of the 100-year floodplain. Nevert heless, natural areas 10987 in the city account for a substa ntial portion of the city’s shor e, such as Roosevelt Island 10988 and the shores of the Potomac River w ithin C&O Canal National Historic Park. 10989 10990 As part of the city’s efforts to restore th e Anacostia River, Dist rict officials have 10991 proposed a series of environmental protec tion buffers along the Anacostia River with 10992 widths between 15 and 90 m (50 and 300 ft). Bulkheads are being removed except where 10993 they are needed for navigation, in favor of natu ral shores in the upper part of the river and 10994 bioengineered “living sh orelines” in the lower portion (DCOP, 2003). 10995 10996 Vulnerable Habitat 10997 The Washington, D.C. area features sensitive wetland habitats potentially vulnerable to 10998 sea-level rise. Several major areas are mana ged for conservation or are the target of 10999 restoration efforts, making ultimate impacts uncertain. The wetlands around the 11000 Anacostia River are an example. Local organizations have been working to reverse 11001 historical modifications and restore some of the wetlands around several heavily altered 11002 lakes. Restoration of the 13-ha (32-ac) Kenilworth Marsh was completed in 1993; 11003 restoration of the Kingman Lake marshes be gan in 2000 (USGS, undated). Monitoring of 11004 the restored habitats demonstrates that th ese marshes can be very productive. A recent 11005CCSP 4.1 January 15, 2009

658 of 784 Final Report survey identified 177 bird species in the ma rshes, including shorebirds, gulls, terns, 11006 passerines, and raptors as well as marsh nes ting species such as marsh wren and swamp 11007 sparrow (Paul et al. , 2004). 11008 11009 Roosevelt Island is another ar ea where sea-level rise effect s are uncertain. Fish in the 11010 Roosevelt Island marsh provide food for her ons, egrets, and other marsh birds (NPS, 11011 undated). The ability of the tidal marshes of th e island to keep pace with sea-level rise 11012 will depend on the supply of sediment, and increased inundation of the swamp forest 11013 could result in crown dieback and tree mortality (Fleming et al ., 2006). 11014 11015 A1.F.1.5 Western Shore: Potomac River to Susquehanna River 11016 The Western Shore counties have relatively little low land, unlike the low counties across 11017 the Bay. The Deal/Shady Side peninsula (A nne Arundel County) and Aberdeen Proving 11018 Grounds (Harford County) are the only areas with substantial amounts of low-lying land. 11019 The block closest to the water, however, is similarly low in many of the older 11020 communities, including parts of Baltimore County, Fells Point in Baltimore (see Box 11021 A1.6), downtown Annapolis, North Beach, a nd Chesapeake Beach, all of which flooded 11022 during Hurricane Isabel. 11023
11024 Between the Potomac and the Patuxent Rivers , the bay shore is usually a sandy beach in 11025 front of a bank less than 3 m (10 ft) high. Cli ffs and bluffs up to 35 m (115 ft) above the 11026 water dominate the shores of Calvert C ounty (Shellenbarger Jones and Bosch, 2008b). 11027CCSP 4.1 January 15, 2009

659 of 784 Final Report The shores north of Calvert County tend to be beaches; but these beaches become 11028 narrower as one proceeds north, where the wave climate is milder. 11029CCSP 4.1 January 15, 2009

660 of 784 Final Report BOX A1.6: Planning for Sea- level Rise in Baltimore 11030 Only 3.2 percent of the City of Baltimore’s 210 sq km (81 sq mi) of land is cu rrently within the coastal 11031 floodplain. This land, however, includes popular tour ist destinations such as Inner Harbor and the Fells 11032 Point Historic District, as well as industrial areas, some of which are being redeveloped into mixed use 11033 developments with residential, commercial, and retail land uses. The map below depicts the areas that the 11034 city expects to be flooded by category 1, 2, 3 and 4 hurricanes, which roughly correspond to water levels of 11035 1.78 m (6 ft), 3.0 m (10 ft), 4.2 m (14 ft), and 5.5 m (18 ft) above North Amercan Vertical Datum 11036 (NAVD88). Approximately 250 homes are vulnerable to a category 1, while 700 homes could be flooded 11037 by a category 2 hurricane (Baltimore, 2006). As Hurr icane Isabel passed in September 2003, water levels 11038 in Baltimore Harbor generally reached approximately 2.4 m (8 ft) above NAVD, flooding streets and 11039 basements, but resulting in only 16 flood insurance claims (Baltimore, 2006). 11040 11041 The city’s All Hazards Plan explicitly in cludes rising sea level as one of th e factors to be considered in land 11042 use and infrastructure planning 103 . The All Hazards Plan has as an objec tive to “develop up-to-date research 11043 about hazards” and a strategy under that objective to “study the thr eat, possible mitigation and policy 11044 changes for sea-level rise.” As a first step toward acc urate mapping of possible sea-level rise scenarios, the 11045 city is exploring options for acquiring lidar. Policies developed for floodplain management foreshadow the 11046 broad methods the city is likely to use in its response. 11047 11048 11049 11050 11051 11052 11053 11054 11055 11056 11057 11058 11059 11060 11061 11062 11063 11064 11065 11066 Box Figure A1.6 Inundation Zone for Baltimore Harbor under category 1,2,3, and 4 hurricanes. 11067 11068 Property values are high, and there is a long-standing practice of armori ng shores to facilitate port-related 11069 activities and more recently, protect wate rfront structures from shore eros ion. In most areas, there is not 11070 enough room between the harbor and waterfront buildings to fit a dike. Even where there is room, the loss 11071 of waterfront views would be unacceptable in tourist and residential areas (see Section 6.5 in Chapter 6; 11072 Titus, 1990). In addition, storm sewers, which drain by gravity into the harbor, would have to be fit with 11073 pumping systems. 11074 11075 Fells Point Historic District This historic community has 24 ha (60 ac) within the 100-year flood plain. 11076 Fells Point is a Federal Historic District and pending approval as a Local Historic District. The row houses 11077 here were built predominantly in the early to mid- nineteenth century and cannot be easily elevated. 11078 Elevating brick and stone structures is always more difficult than elevating a wood frame structure. But 11079 because row houses are, by definition, attached to each other, elevating them one at a time is not feasible. 11080

103 Baltimore (City of Baltimore Department of Planning) 2006 “All Hazards Plan for Baltimore City” Adopted by Baltimore City Planning Commission April 20, 2006 at 6, 10-11.CCSP 4.1 January 15, 2009

661 of 784 Final Report Many of these homes have basements, which already flood. FEMA regulations do not permit basements in 11081 new construction in the floodplain and treats (44 CFR §60.3[c] [2]) existing basements as requiring 11082 mitigation. Possible mitigation for basements includes relocation of utilities, reinforcement of walls, and 11083 filling. 11084 11085 In theory, homes could be remodeled to add stairways and doors to convert what is now the second floor to 11086 a first floor and convert the first floors to base ments. But doing so would reduce the livable space. 11087 Moreover, federal and local preser vation laws, as well as community sensibilities, preclude adding third 11088 stories to these homes. Elevating streets is also problematic because below-grade utilities need to be 11089 elevated. In the last decade only one street (one block of Caroline Street ) has been elevated specifically to 11090 reduce flooding. 11091 11092 FEMA Flood Hazard Mapping and Sea-level Rise 11093 11094 Baltimore City is a participating jurisdiction in the National Flood Insurance Program through its regulation 11095 of development in the floodplain and through overall floodplain management. The city is currently funded 11096 through the Cooperative Technical Partnership (CTP) to update its flood maps. Federal flood mapping 11097 policies require that Flood Insurance Rate Maps be based on existing conditions (see Section 10.7.5.3 in 11098 Chapter 10). Therefore, the floodplain maps do not cons ider future sea level rise. As a result, the city will 11099 be permitting new structures with effective functional lifespan of 50 to 100 years but elevated only to 11100 current flood elevations. One strate gy to surmount this limitation is to add “freeboard,” or additional 11101 elevation to the effective BFE. Baltimore alread y requires one additional foot of freeboard. 11102 11103 The City of Baltimore is concerned, however, that 0.3 to 0.6 additional meters of freeboard is inequitable 11104 and inefficient. If flood levels will be, for example, 1 meter higher than the flood maps currently assume, 11105 then lands just outside the current flood boundary are also potentially vulnerable. If the city were to add 1 11106 meter of freeboard to property in the floodplain, without addressing adjacent properties outside the 11107 floodplain, then adjacent property owners would have divergent requirements that city officials would find 11108 difficult to justify. (see Figure 10.6.) 11109 11110 11111 11112 Baltimore has two regional sewerage plants. One of th em, the Patapsco Wastewater Treatment Plant, sits 11113 on ground that is less than two meters above mean s ea level and floods occasionally (see Box Figure A1.6). 11114 The facility itself is elevated and currently drains by gravity into the Patapsco River (USGS 7.5-minute 11115 map series). With a significant rise in sea level, however, pumping will be needed and possibly additional 11116 protections against storms (Smith, 1998: Titus et al ., 1987, . Numerous streets, with associated conduits and 11117 utility piping, are within the existing coatal floodplain and would potentially be a ffected by sea-level rise 11118 (see Box Figure A1.6). 11119 11120 --End box-- 11121 11122 Development and Shore Protection 11123 The Western Shore was largely developed befo re the Maryland’s Critical Areas Act was 11124 passed. Stone revetments are common along the mostly developed shores of Anne 11125 Arundel and Baltimore Counties. Yet Calvert County has one of the only shore protection 11126 policies in the nation that pr ohibits shore protection along an estuary, even when the 11127 InfrastructureCCSP 4.1 January 15, 2009

662 of 784 Final Report prohibition means that homes will be lost. Calv ert County’s erosion policy is designed to 11128 preserve unique cliff areas that border Chesapeake Bay. 11129
11130 The county allows shoreline armoring in cer tain developed areas to protect property 11131 interests, but also bans armoring in other areas to protect endangered species and the 11132 unique landscape 104 . Cliffs in Calvert County are sepa rated into categories according to 11133 the priority for preservation of the lan d. Although a county policy prohibiting shore 11134 protection would appear to run counter to the state law gran ting riparian owner the right 11135 to shore protection, to date no legal challeng es to the cliff policy have been made. The 11136 state has accepted the county’ s policy, which is embodied in the county’s critical areas 11137 plan submitted to the stat e under the Critical Areas Act. Recognizing the potential 11138 environmental implications , living shoreline protecti on is becoming increasingly 11139 commonplace along the Western Shore. 11140
11141 Vulnerable Habitat 11142 A range of sea-level rise impacts are possi ble along the western shore of Chesapeake 11143 Bay, including potential loss of key habitats. Fi rst, marshes are expected to be marginal 11144 with mid-range increases in sea-level rise, and to be lost with high -range increases in sea11145 level rise (Shellenbarger Jones and Bosc h, 2008b, interpreting the findings of Reed et al ., 11146 2008). The ability to migrate is likely to dete rmine coastal marsh surv ival as well as the 11147 survival of the crustaceans, mollusks, turtle s, and birds that depend on the marshes. In 11148 upper reaches of tributaries, how ever, marsh accretion is likely to be sufficient to counter 11149

104 See also Nationwide Permits 3 (Maintenance), 31 (Maintenance of Existing Flood Control Facilities) and 45 (Repair of Uplands Damaged by Discrete Events). 72 Federal Register 11092-11198 (March 12, 2007).CCSP 4.1 January 15, 2009

663 of 784 Final Report sea-level rise (Shellenbarger Jones and Bosch, 2008b, interpreting the findings of Reed et 11150 al ., 2008). Several key locations warrant attention: 11151

 In the Jug Bay Sanctuary, along the upper Patuxent River, marsh inundation is 11152 causing vegetation changes, compou nding stress on local bird species 11153 (Shellenbarger Jones and Bosch, 2008b). 11154

 Cove Point Marsh in Calvert County is a 60-ha (150-ac) freshw ater, barrier-beach 11155 marsh. Numerous state-defined rare plant species are present, including American 11156 frog’s-bit, silver plumegrass, various ferns, and unique wetland communities 11157 (Steury, 2002), as well as several rare or threatened beetle species. With current 11158 rates of sea-level rise, the marsh is co ntinuing to migrate, but will soon hit the 11159 northern edge of local residential development. 11160

 The potential loss of the wide mudflats at Hart-Miller Island would eliminate 11161 major foraging and nesting areas for seve ral high conservation priority species 11162 (Shellenbarger Jones and Bosch, 2008b). 11163

 Given the extent of development and s horeline armoring in Anne Arundel County 11164 and Baltimore City/County, both intertidal areas and wetlands are likely to be lost 11165 with even a modest accelera tion in sea-level rise (Shellenbarger Jones and Bosch, 11166 2008b). 11167
11168 Beach loss, particularly in St. Mary’s , Calvert, and Anne Arundel Counties along 11169 Chesapeake Bay, may occur in areas without nourishment. In general, beach loss will 11170 lead to habitat loss for resident insects (i ncluding the Northeastern beach tiger beetle, 11171CCSP 4.1 January 15, 2009

664 of 784 Final Report federally listed as threatened) and other inverteb rates, as well as forage loss for larger 11172 predators such as shorebirds (Lippson and Lippson, 2006) 105

. 11173
11174 The Calvert County cliffs represent unique ha bitat that could be degraded by sea-level 11175 rise; however, the cliffs are not likely to be lost entirely. The Puritan tiger beetle and 11176 Northeastern beach tiger beetle, both fe derally listed, are present in the area 11177 (Shellenbarger Jones and Bosch, 2008b). While natural erosion proce sses are allowed to 11178 continue in the protected c liff areas in the southern por tion of the county, shoreline 11179 protections in the more northern developed areas are increasing erosion rates in adjacent 11180 areas (Wilcock et al. , 1998). 11181
11182 A1.F.1.6 Upper Eastern Shore 11183 The Eastern Shore above Rock Hall is dominat ed by bluffs and steep slopes rising to 11184 above 6 m (20 ft). Tolchester Beach, Bettert on Beach, and Crystal Beach are typical in 11185 that regard. From Rock Hall south to around the middle of Kent Is land, all of the land 11186 within a few kilometers of the Chesapeake Bay or its major tributaries consists of low11187 lying land. 11188 11189 Between the Choptank River and Ocohannoc k Creek along the Eastern Shore of 11190 Chesapeake Bay lies one of the largest concentr ations of land close to sea level. Water 11191 levels in roadside ditches rise and fall with the tides in the areas west of Golden Hill in 11192 Dorchester County and several necks in Somerset County. Many farms abut tidal 11193 wetlands, which are gradually encroaching onto those farms. Some landowners have 11194

105 For more detail on beach habitats and the species that occur in the mid-Atlantic region, see Shellenbarger Jones (2008a).CCSP 4.1 January 15, 2009

665 of 784 Final Report responded by inserting makeshift tide gates over culverts, decrea sing their own flooding 11195 but increasing it elsewhere. Throughout Hoope rs Island, as well as the mainland nearby, 11196 there are: numerous abandoned driveways th at once led to a home but are now ridges 11197 flooded at high tide and surrounded by low marsh or open water; recently abandoned 11198 homes that are still standing but surrounded by marsh; and dead trees still standing in 11199 areas where marsh has invaded a forest. 11200
11201 Development and Shore Protection 11202 Along the Chesapeake Bay, recent coastal development has not placed a high value on 11203 the beach. The new bayfront subdivisions of ten provide no public access to the beach, 11204 and as shores erode, people erect shore-protec tion structures that eventually eliminate the 11205 beach (see Chapter 6 of this Product; Titus, 1998). Some traditional access points have 11206 been closed (Titus, 1998). Maintaining a beach remains important to some of the older 11207 bay resort communities where residents ha ve long had a public beach—but even 11208 communities with “beach” in the name are seeing their beaches replaced with shore 11209 protection structures. 11210
11211 Maryland’s Critical Areas Act, however, is lik ely to restrict the extent of additional 11212 development along the Eastern Shore of Chesap eake Bay to a greater extent than along 11213 the Western Shore. The resource conservati on areas where development is discouraged 11214 include half of the Chesapeake Bay shoreline between the Susquehanna and Choptank 11215 Rivers. Among the major tributaries, most of the Sassafras, Chester, and Choptank Rivers 11216 are similarly preserved; the Act did not prevent development along most of the Wye, Elk, 11217CCSP 4.1 January 15, 2009

666 of 784 Final Report and North East Rivers. Existing development is most concentrated in the northern areas 11218 near Interstate-95, Kent Is land, and the various necks n ear Easton and St. Michaels. 11219
11220 Vulnerable Habitat 11221 Above Kent Island . The environmental implications of sea-level rise effects in the upper 11222 Chesapeake Bay are likely to be relativel y limited. The Susquehanna River provides a 11223 large (though variable) influx of sediment to the upper Chesapeake Bay, as well as almost 11224 half of Chesapeake Bay’s freshwater input (CBP, 2002). This sediment generally is 11225 retained above the Chesapeake Bay Bridge and provides material for accretion in the tidal 11226 wetlands of the region (CBP, 2002). The other upper Chesapeak e Bay tributaries 11227 characteristically have large sediment load s as well, and currently receive sufficient 11228 sediment to maintain wetlands and thei r ecological function. As such, the upper 11229 Chesapeake Bay will continue to provide spawni ng and nursery habitat for crabs and fish, 11230 as well as nesting and foraging habitat for migr atory and residential bi rds, including bald 11231 eagles and large numbers of waterfowl. Likewi se, while some of the beaches may require 11232 nourishment for retention, the general lack of shorelin e protections will minimize 11233 interferences with longshore se diment transport. Hence, b eaches are likely to remain 11234 intact throughout much of the re gion (Shellenbarger Jones, 2008b). 11235
11236 Two areas in the upper bay—Eastern Neck and Elk Neck—appear most vulnerable to 11237 sea-level rise effects. First, Eastern Neck Wildlife Refuge lies at the southern tip of 11238 Maryland’s Kent County. Ongoing shoreline prot ection efforts seek to reduce erosion of 11239 habitats supporting many migrat ory waterfowl and residential birds, as well as turtles, 11240CCSP 4.1 January 15, 2009

667 of 784 Final Report invertebrates, and the Delmarva fox squirr el, federally listed as endangered. In many 11241 marsh locations, stands of i nvasive common reed are the onl y areas retaining sufficient 11242 sediment (Shellenbarger Jones, 2008b). Lo cal managers have observed common reed 11243 migrating upland into forested areas as inundation at marsh edges increases, although 11244 widespread marsh migration of other species has not been observed (S hellenbarger Jones, 11245 2008b). The three-square bulrush marshes on Ea stern Neck have been largely inundated, 11246 as have the black needle ru sh marshes on Smith Island and other locations, likely causes 11247 of reductions in black duck counts (Shellenbarger Jones, 2008b). 11248 11249 Other sea-level rise impacts are possible in Cecil County, in and around the Northeast 11250 and Elk Rivers. The headwaters of the rivers are tidal freshwater wetlands and tidal flats, 11251 spawning and nursery areas for striped bass and a nursery area for alewife, blueback 11252 herring, hickory shad, and white perch, as well as a wintering and breeding area for 11253 waterfowl (USFWS, 1980). Accret ion is likely to be sufficient in some areas due to the 11254 large sediment inputs in the Upper Bay. Where accretion rates are not sufficient, wetland 11255 migration would be difficult due to the upland elevation adjacent to the shorelines. These 11256 conditions increase the chances of large tida l fresh marsh losses (Shellenbarger Jones, 11257 2008b). Other sensitive Cecil Count y habitats exist such as the cliffs at Elk Neck State 11258 Park and the Sassafras River Natural Resource Management Area, which will be left to 11259 erode naturally losses (Shellenbarger Jones, 2008b). Finally, marsh loss is possible in and 11260 around the Aberdeen Proving Ground in Harford County. The Proving Ground is 11261 primarily within 5 m of sea level and cont ains 8000 ha (20,000 ac) of tidal wetlands. 11262
11263CCSP 4.1 January 15, 2009

668 of 784 Final Report Kent Island to Choptank River. The central Eastern Shore region of Chesapeake Bay 11264 contains diverse habitats, and sea-level rise holds equally diverse implications, varying 11265 greatly between subregions. Larg e expanses of marsh and tidal flats are likely to be lost, 11266 affecting shellfish, fish, and waterfowl populations (Shellenba rger Jones, 2008c). Several 11267 subregions merit consideration: 11268

 Marshes along the Chester River are likely to be marginal with moderate sea-level 11269 rise rate increases (Shellenbarger Jone s, 2008c, interpreting the findings of Reed 11270 et al ., 2008; see Chapter 4 of this Product). 11271

 Loss of the large tidal flats exist at th e mouth of the Chester River (Tiner and 11272 Burke, 1995) may result in a decline in the resident invertebrate s and fish that use 11273 the shallow waters as well as the birds that feed on the flats (Shellenbarger Jones, 11274 2008c; Robbins and Blom, 1996). 11275

 The Eastern Bay side of nearby Kent Is land has several tidal creeks, extensive 11276 tidal flats, and wetlands. Existing marshes and tidal flats are likely to be lost (see 11277 Chapter 4) (although some marsh may conve rt to tidal flat). Increasing water 11278 depths are likely to reduce the rema ining SAV; a landward migration onto 11279 existing flats and marshes will depend on sediment type and choice of shoreline 11280 structure (Shellenbar ger Jones, 2008c). 11281

 Portions of the Wye River shore are being developed. If these s hores are protected 11282 and the marshes and tidal flats in these ar eas are lost, the juve nile fish nurseries 11283 will be affected and species that feed in the marshes and SAV will lose an 11284 important food source (MD DNR, 2004). 11285
11286CCSP 4.1 January 15, 2009

669 of 784 Final Report Certain key marsh areas are li kely to be retained. The uppe r reaches of tributaries, 11287 including the Chester an d Choptank Rivers, are likely to retain current marshes and the 11288 associated ecological services. Likewise, Popl ar Island will provide a large, isolated 11289 marsh and tidal flat area (USACE, undated[ b]). In addition, the marshes of the Wye 11290 Island Natural Resource Management Area support a large wate rfowl population (MD 11291 DNR, 2004). Maryland DNR will manage Wye Island to protect its biological diversity 11292 and structural integrity, such that detrimenta l effects from sea-level rise acceleration are 11293 minimized (MD DNR, 2004). 11294 11295 Beach loss is also possible in some areas. The Chesapeake Bay shore of Kent Island 11296 historically had narrow sandy beaches with some pebbles along low bluffs, as well as 11297 some wider beaches and dune areas ( e.g. , Terrapin Park). As development continues, 11298 however, privately owned shores are gradually being replaced with stone revetments. The 11299 beaches will be unable to migrate inland, lead ing to habitat loss for the various resident 11300 invertebrates, including tiger beetles, sand fleas, and numerous crab species 11301 (Shellenbarger Jones, 2008c). Shorebirds that rely on beaches for forage and nesting will 11302 face more limited resources (Lippson and Lippson, 2006). Likewise, on the bay side of 11303 Tilghman Island, the high erosion rates w ill tend to encourage shoreline protection 11304 measures, particularly following constructi on of waterfront homes (MD DNR, undated). 11305 Beach loss, combined with anticipated marsh loss in the area, will eliminate the worms, 11306 snails, amphipods, sand fleas, and other invertebrates that live in the beach and intertidal 11307 areas and reduce forage for their predators (Shellenbarger Jones, 2008c). 11308 11309CCSP 4.1 January 15, 2009

670 of 784 Final Report A1.F.1.7. Lower Eastern Shore 11310 Approximately halfway between Crisfield on the Eastern Shore and the mouth of the 11311 Potomac River on the Western Shore, are the last two inhabited islands in Chesapeake 11312 Bay unconnected by bridges to the mainland: Smith (Maryland) and Tangier (Virginia). 11313 Both islands are entirely below the 5-ft el evation contour on a US GS topographic map. 11314 Along the Eastern Shore of Northampton County, by contrast, elevati ons are higher, often 11315 with bluffs of a few meters. 11316
11317 Development and Shore Protection 11318 Along Chesapeake Bay, islands are threaten ed by a combination of erosion and 11319 inundation. Wetlands are taking ov er portions of Hoopers and Deal Islands, but shore 11320 erosion is the more serious threat. During th e middle of the nineteenth century, watermen 11321 who made their living by fishing Chesapeake Bay made their homes on various islands in 11322 this region. Today, Bloodsworth and Lower H oopers Islands are uninhabitable marsh, 11323 and the erosion of Barren and Poplar Islands led people to move their homes to the 11324 mainland (Leatherman, 1992). Smith Island is now several islands, and has a declining 11325 population. Hoopers and Deal Is lands are becoming gentrified, as small houses owned by 11326 watermen are replaced with larger houses ow ned by wealthier retirees and professionals. 11327
11328 Virtually all of the beaches along Chesapeake Bay are eroding. Shore erosion of beaches 11329 and clay shores along the Chester, Nanticoke, and Chester Rivers is slower than along the 11330 Bay but enough to induce shoreline armori ng along most developed portions. The lower 11331CCSP 4.1 January 15, 2009

671 of 784 Final Report Eastern Shore has a history of abandoning lowl ands to shore erosion and rising sea level 11332 to a greater extent than other pa rts of the state (Leatherman, 1992). 11333
11334 Today, Smith and Tangier are the only inhab ited islands without a bridge connection to 11335 the mainland. Government officials at all levels are pursuing efforts to prevent the loss of 11336 these lands, partly because of their unique cu ltural status and—in the case of Tangier—a 11337 town government that works hard to ensure that the state continues to reinvest in schools 11338 and infrastructure. The USACE has several plan ned projects for halting shore erosion, but 11339 to date, no efforts are underway to elevate the land (USACE, 2001b; Johnson, 2000). The 11340 replacement of traditional lifestyles with gentrified second homes may increase the 11341 resources available to preserve these islands. 11342
11343 The mainland of Somerset County vulnerable to sea-level rise is mostly along three 11344 necks. Until recently, a key indicator of the cost-effectiveness of s hore protection was the 11345 availability of a sewer line 106 . As sea level rises, ho mes without sewer may be 11346 condemned as septic systems fail. The in corporated town of Crisfield, in the 11347 southernmost neck, has long had sewer service, which has been recently expanded to 11348 nearby areas. The town itself is largely enci rcled by an aging dike. Deal Island, no longer 11349 the thriving fishing port of cen turies gone by, still has modera te density housing on most 11350 of the dry land. 11351 11352 Wicomico County’s low-lying areas are along both the Wicomico and Nanticoke Rivers. 11353 Unlike Somerset, Wicomico has a large ur ban/suburban populati on, with the Eastern 11354

106 The mounds systems have made it possible to inhabit low areas with high water tables.CCSP 4.1 January 15, 2009

672 of 784 Final Report Shore’s largest city, Salisbury. Planners accep t the general principa ls of the state’s 11355 Critical Areas Act, which discourag es development along the shore. 11356 11357 Much of coastal Dorchester County is already part of Blackwater Wildlife Refuge. The 11358 very low land south of Cambridge that is not already part of th e refuge is farmland. 11359 Because most of the low-lying lands we st of Cambridge are within Resource 11360 Conservation Areas (CBCAC, 2001), signifi cant development would be unlikely under 11361 the state's Critical Areas Act (see Sec tion A1.F.2). On the higher ground along the 11362 Choptank River, by contrast, many waterfront parcels are being deve loped. In July 2008, 11363 the State of Maryland Board of Public Works approved the purchase of 295 ha (729 ac) 11364 of land along the Little Blackwater River, ne ar the town to Cambridge in Dorchester 11365 County. Funded by the state’s Program Open Space, the purchase will allow for the 11366 preservation and restoration of more than two-thirds of a 434-ha (1,072-ac) parcel that 11367 was previously slated for development 107

. 11368 11369 Vulnerable Habitat 11370 On the lower Eastern Shore of Chesapeake Bay in Maryland, habitats vulnerable to sea11371 level rise are diverse and include beache s, various types of tidal marsh, non-tidal 11372 marshes, and upland pine forests. 11373
11374 Narrow sandy beaches exist along discrete segm ents of shoreline throughout the region, 11375 particularly in Somerset County. Given the grad ual slope of the shoreline, one might infer 11376

107 See <http://www.dnr.state.md.us/dnrnews/pressrelease2007/041807.html>CCSP 4.1 January 15, 2009

673 of 784 Final Report that these habitats could accommodate mode rate sea-level rise by migrating upslope, 11377 assuming no armoring or other barriers exis t. Many of the beaches provide critical 11378 nesting habitat for the diamondback terrapin ( Malaclemys terrapin ), and proximity of 11379 these nesting beaches to nearby marshes provides habitat for new hatchlings (see Box 11380 A1.7) 11381 Start Box******* 11382 11383 BOX A1.7: The Diamondback Terrapin, Malaclemys terrapin 11384 The diamondback terrapin, Malaclemys terrapin , comprising seven subspecies, is the only turtle that is 11385 fully adapted to life in the brackish salt marshes of estuarine embayments, lagoons, and impoundments 11386 (Ernst and Barbour, 1972). Its range extends from Massachusetts to Texas in the narrowest of coastal strips 11387 along the Atlantic and Gulf coasts of the United States (Palmer and Cordes , 1988). Extreme fishing 11388 pressure on the species resulted in population crashes over much of their range so that by 1920 the catch in 11389 Chesapeake Bay had fallen to less than 900 pounds. The Great Depression put a halt to the fishery, and 11390 during the mid-twentieth century, populations began to recover (CBP, 2006). Although a modest fishery 11391 has been reestablished in some areas, stringent harves t regulations are in place in several states. In some 11392 instances, states have listed the species as endangered (Rhode Island), threatened (Massachusetts), or as a 11393 “species of concern” (Georgia, Delaware, New Jers ey, Louisiana, North Carolina, and Virginia). In 11394 Maryland, the status of the northern diamondback subpopulation is under review (MD DNR, 2006). 11395 11396 Effects of Sea-level Rise 11397 The prospect of sea-level rise, along with land su bsidence at many coastal locations, increasing human 11398 habitation of the shore zone and shoreline stabilization, places the habitat of terrapins at increasing risk. 11399 Loss of prime nesting beaches remains a major threat to the diamondback terrapin population in 11400 Chesapeake Bay (MD DTTF, 2001). Because human infrastructure ( i.e. , roadways, buildings, and 11401 impervious surfaces) leaves tidal salt marshes with little or no room to transgress inland, one can infer that 11402 the ecosystem that terrapins depend on may be lost with concomitant extirpation of the species. 11403 End Box******** 11404 11405 Of the 87,000 ha (340 sq mi) of tidal marsh in the Chesapeake Bay, a majority is located 11406 in the three-county lower Eastern Shore region (Darmondy and Foss, 1979). The marshes 11407 are critical nursery grounds for commercially important fisheries ( e.g. , crabs and 11408 rockfish); critical f eeding grounds for migratory waterf owl; and home to furbearers ( e.g. , 11409 muskrat and nutria). 11410
11411 Areas of Virginia’s Eastern Shore are uniquely vulnerable to sea-level rise since large 11412 portions of Northampton and Accomack counties lie near sea level. Because most of the 11413CCSP 4.1 January 15, 2009

674 of 784 Final Report land in the two counties is undeveloped or agri cultural, the area also has a high potential 11414 for wetland creation relative to other Virginia shorelines. 11415
11416 Most notably, the bay side of northern Acco mack County is primarily tidal salt marsh, 11417 with low-lying lands extending several ki lometers inland. Unprotected marshes are 11418 already migrating inland in response to sea-level rise, creating new wetlands in 11419 agricultural areas at a rate of 16 ha (40 ac) per year (Strange, 2008e). Given the 11420 anticipated lack of shorelin e protection and insufficient sediment input, the seaward 11421 boundaries of these tidal wetla nds are likely to continue retreating (Strange, 2008e, 11422 interpreting the findings of Reed et al ., 2008). The upland eleva tions are higher in 11423 southern than northern Accomack Count y, however, making wetland migration more 11424 difficult. 11425
11426 The salt marshes of Accomack County support a variety of species, in cluding rare bird 11427 species such as the seaside sparrow, shar p-tailed sparrow, and peregrine falcon (VA 11428 DCR, undated [a][b]). Growth and survival of these species may be reduced where shores 11429 are hardened, unless alternativ e suitable habitat is available nearby. Furthermore, long11430 term tidal flooding will decrea se the ability of nekton ( i.e. , free-swimming finfish and 11431 decapod crustaceans such as shrimps and crabs) to access coastal marshes. 11432
11433 A1.F.2 Baywide Policy Context 11434 Chesapeake Bay’s watershed has tidal shores in Virginia, Maryland, the District of 11435 Columbia, and Delaware. Because the shores of Delaware and the District of Columbia. 11436CCSP 4.1 January 15, 2009

675 of 784 Final Report account for a small portion of the total, this subsection focuses on Virginia and Maryland. 11437 (The federal Coastal Zone Management Act’s definition of “coastal state” excludes the 11438 District of Columbia 108 .) 11439
11440 Coastal management officials of Maryland ha ve cooperated with the U.S. EPA since the 11441 1980s in efforts to learn the ramifications of accelerated sea-level rise for their activities 11442 (AP, 1985). Increased erosion from sea-level rise was one of the factors cited for the 11443 state’s decision in 1985 to shift its erosion cont rol strategy at Ocean City from groins to 11444 beach nourishment (AP, 1985). The state also developed a planning document for rising 11445 sea level (Johnson, 2000), and sea-level rise was a key factor motivating Maryland to 11446 become the second mid-Atlantic state to obtain lidar elevation data fo r the entire coastal 11447 floodplain. 11448 11449 Neither Maryland nor Virginia has adopted a comprehensive policy to explicitly address 11450 the consequences of rising sea level. Neve rtheless, the policies designed to protect 11451 wetlands, beaches, and private shorefront prope rties are collectively an implicit policy. 11452 Both states prevent new buildings within 30.5 m (100 ft) of most tidal shores; Maryland 11453 also limits the density of new development in most areas to one home per 8 ha (20 ac) 11454 within 305 m (1,000 ft) of the shore. Virginia allows most forms of shore protection. 11455 Maryland encourages shore protection 109 , but discourages new bulkheads in favor of 11456 revetments or nonstructural measures (MD DNR, 2006). Both states have programs to 11457 inform property owners of nonstructural options and have created programs and 11458

108 16 USC §1453 (4) 109 Code of Maryland Regulations§ 27.01.04.02.02-03CCSP 4.1 January 15, 2009

676 of 784 Final Report educational outreach efforts to train marine contractors on “livi ng shoreline” design and 11459 installation techniques. Both states work w ith the federal government to obtain federal 11460 funds for beach nourishment along their resp ective ocean resorts (Ocean City and 11461 Virginia Beach); Virginia also assists local governments in efforts to nourish public 11462 beaches along Chesapeake Bay and its tributar ies. Summaries of these land use, wetlands, 11463 and beach nourishment policies follow. 11464 11465 During 2007, both states established climate change commissions to inform policy 11466 makers about options for responding to sea leve l rise and other consequences of changing 11467 climate 110 . The Maryland Commission on Climate Ch ange is charged with developing a 11468 climate action plan to address both the cau ses and consequences of climate change 111 . Its 11469 interim report (MCCC, 2008) recommends that th e state (1) protect and restore natural 11470 shoreline features ( e.g. , wetlands) and (2) re duce growth and development in areas 11471 vulnerable to sea-level rise a nd its ensuing coastal hazards. The Virginia commission has 11472 an Adaptation Subgroup. 11473
11474 A1.F.2.1 Land Use 11475 The primary state policies related to land us e are Maryland’s Ches apeake and Atlantic 11476 Coastal Bays Critical Area Protection Act, Vi rginia’s Chesapeake Bay Preservation Act, 11477 and Virginia’s Coastal Primary Sand Dunes & Beaches Act. 11478 11479

110 Maryland Executive Order (01.01.2007.07) ; Virginia Executive Order 59 (2007). 111 Maryland Executive Order (01.01.2007.07).CCSP 4.1 January 15, 2009

677 of 784 Final Report Maryland Chesapeake Bay and Atlantic Coas tal Bays Critical Ar ea Protection Act. The 11480 Maryland General Assembly enacted the Chesapeake Bay Critical Area Protection Act in 11481 1984 to reverse the deterioration of the Bay 112 . (The statute now applies to Atlantic 11482 coastal bays as well; see Section A1.E.2) Th e law seeks to control development in the 11483 coastal zone and preserve a healthy bay eco system. The jurisdictional boundary of the 11484 Critical Area includes all waters of Ches apeake and Atlantic Coastal Bays, adjacent 11485 wetlands 113 , dry land within 305 m (1,000 ft) of open water 114 , and in some cases dry land 11486 within 305 m inland of wetlands that ar e hydraulically connected to the bays 115

. 11487
11488 The act created a Critical Areas Commissi on to set criteria and approve local plans 116

. 11489 The commission has divided land in the cri tical area into three classes: intensely 11490 developed areas (IDAs), limited development areas (LDAs), and resource conservation 11491 areas (RCAs) 117 . Within the RCAs, new development is limited to an average density of 11492 one home per 8 ha (20 ac) 118 and set back at least 61 m (200 ft) 119 , and the regulations 11493 encourage communities to “consider cluster development, transfer of development rights, 11494 maximum lot size provisions, and/ or additional means to maintain the land area necessary 11495 to support the protective uses” 120 . The program limits future intense development 11496

112 Chesapeake Bay Critical Areas Protection Act, Maryland Code Natural Resources §8-1807. 113 i.e. all state and private wetlands designated under Na tural Resources Article, Title 9 (now Title 16 of the Environment Article). 114 Maryland Code Natural Resources §8-1807(c)(1)(i)(2). 115 Lands that are less than 1,000 ft from open water may be excluded from jurisdiction if the lands are more than 1,000 ft from open water, and the wetland s between that land and th e open water are highly functional and able to protect the water from adverse effects of developing the land. Maryland Code Natural Resources §8-1807(c)(1)(i)(2) and §8-1807(a)(2). 116 Maryland Code Natural Resources §8-1808. 117 Code of Maryland Regulations §27.01.02.02(A). 118 Code of Maryland Regulations §27.01.02.05(C)(4). 119 Maryland Code Natural Resources §8-1808.10 The required setback is only 100 feet for new construction on pre-existing lots. 120 Code of Maryland Regulations §27.01.02.05(C)(4).CCSP 4.1 January 15, 2009

678 of 784 Final Report activities to lands within the IDAs, and permits some additional low-intensity 11497 development in the LDAs. However, the statut e allows up to 5 percent of the RCAs in a 11498 county to be converted to an IDA 121 , although a 61-m (200-ft) buffer applies in those 11499 locations. 11500 11501 The three categories were orig inally delineated based on the land uses of 1985. Areas that 11502 were dominated by either agriculture, forest, or other open space, as well as residential 11503 areas with densities less than one home in 2 ha (5 acres), were defined as RCAs 122 . Thus, 11504 the greatest preservation occurs in the area s that had little development when the act was 11505 passed, typically lands that are far from population centers and major transportation 11506 corridors—particularly along tr ibutaries (as opposed to the Bay itself). The boundary of 11507 the critical area was based on wetland maps created in 1972. MCCC (2008) pointed out 11508 that rising sea level and shoreline erosion had made that boundary obsolete in some 11509 locations. As a result, the Le gislature directed the Critical Areas Commission to update 11510 the maps based on 2007 to 2008 imagery, and thereafter at least once every 12 years 123

. 11511 11512 The Critical Areas Program also established a 30.5-m (100-ft) natural buffer adjacent to 11513 tidal waters, which applies to all three land categories 124 . No new development activities 11514 are allowed within the buffer 125 , except water-dependent facilities. By limiting 11515 development in the buffer, the program prev ents additional infrastructure from being 11516 located in the areas most vulnerable to sea- level rise. In some cases, the 30.5-m buffer 11517

121 Code of Maryland Regulations §27.01.02.06. 122 Code of Maryland Regulations §27.01.02.05. 123 Maryland House Bill 1253 (2008) §3. 124 Code of Maryland Regulations §27.01.00.01 (C)(1). 125 Code of Maryland Regulations §27.01.00.01 (C)(2).CCSP 4.1 January 15, 2009

679 of 784 Final Report provides a first line of defense against coas tal erosion and flooding induced by sea-level 11518 rise. But the regulations also encourag e property owners to halt shore erosion 126

. 11519 Nonstructural measures are prefe rred, followed by structural measures 127 , with an eroding 11520 shore the least prefer able (Titus, 1998). 11521 11522 Virginia Chesapeake Bay Preservation Act. The Chesapeake Bay Preservation Act 128 11523 seeks to limit runoff into the bay by creati ng a class of land known as Chesapeake Bay 11524 Preservation Areas. The act also created the Chesapeake Bay Local Assistance Board to 11525 implement 129 and enforce 130 its provisions. Although the act defers most site-specific 11526 development decisions to local governments 131 , it lays out the broad framework for the 11527 preservation areas 132 and provides the Board with rulemaking authority to set overall 11528 criteria 133 . The Board has issued regulations 134 defining the programs that local 11529 governments must develop to comply with the act 135

. 11530 11531 All localities must create maps that define the locations of the preservation areas, which 11532 are subdivided into resource management areas 136 and resource protection areas 11533

126 Code of Maryland Regulations§ 27.01.04.02. 02 127 Code of Maryland Regulations§ 27.01.04.02. 03. 128 Code VA §10.1-2100 et seq. As of August 8, 2003, the Act was posted on the Virginia Legislative Information System website as part of the C ode of Virginia at: <http://leg1.state.va.us/cgibin/legp504.exe?000+cod+TOC10010000021000000000000>. 129 Code VA §10.1-2102. 130 Code VA §10.1-2104. 131 Code VA §10.1-2109. 132 Code VA §10.1-2107(B). 133 Code VA §10.1-2107(A). 134 Chesapeake Bay Preservation Area Designation and Management Regulations (9 VAC 10-20-10 et. seq.). 135 9 Virginia Administrative Code §10-20-50. 136 The act also provides for Resource Management Areas (RMAs) which are lands that, if improperly used or developed, have the potential to diminish the functional value of RPAs. Finally, areas in which development is concentrated or redevelopment effo rts are taking place may be designated as IntenselyCCSP 4.1 January 15, 2009

680 of 784 Final Report (RPAs) 137 . RPAs include areas flooded by the tide s, as well as a 30.5 m (100-ft) buffer 11534 inland of the tidal shores and wetlands 138 . Within the buffer, development is generally 11535 limited to water dependent uses, redevelopment, and some water management facilities. 11536 Roads may be allowed if there is no practical alternative. Similarly, for lots subdivided 11537 before 2002, new buildings may encroach into the 30.5 m buffer if necessary to preserve 11538 the owner’s right to build; but any building mu st still be at least 15.2 m (50 ft) from the 11539 shore 139 . Property owners, however, may still co nstruct shoreline defense structures 11540 within the RPA. The type of shoreline defe nse installed is not regulated (beyond certain 11541 engineering considerations). Consequently, hard structures can be installed anywhere 11542 along Virginia’s shoreline. 11543 11544 Virginia Coastal Primary Sand Dunes & Beaches Act. Virginia’s Dunes and Beaches Act 11545 preserves and protects coastal primar y sand dunes while accommodating shoreline 11546 development. The act identifies eight counties and cities that can adopt a coastal primary 11547 sand dune zoning ordinance, somewhat anal ogous to a Tidal Wetlands ordinance: 11548 Accomack, Northampton, Virginia Beach, No rfolk, Hampton, Mathews, Lancaster, and 11549 Northumberland (Hardaway et al. , 2001); all but Hampton and Accomack have done so. 11550 The act defines beaches as (1) the shoreline zone of unconsolidated sandy material; (2) 11551 the land extending from mean low water landw ard to a marked change in material 11552 composition or in physiographic form ( e.g. , a dune, marsh, or bluff); and (3) if a marked 11553

Developed Areas (IDAs) and become subject to certa in performance criteria for redevelopment. Private landowners are free to develop IDA and RMA lands, but must undergo a permitting process as well to prove that these actions will not harm the RPAs. 137 9 Virginia Administrative Code §10-20-70. 138 9 Virginia Administrative Code §10-20-80 (B). 139 9 Virginia Administrative Code §10-20-130 (4).CCSP 4.1 January 15, 2009

681 of 784 Final Report change does not occur, then a line of woody ve getation or the nearest seawall, revetment, 11554 bulkhead or other si milar structure. 11555 11556 A1.F.2.2 Wetlands and Erosion Control Permits 11557 Virginia. The Tidal Wetlands Act seeks to “...pres erve and prevent th e despoliation and 11558 destruction of wetlands while accommodati ng necessary economic development in a 11559 manner consistent with wetlands preservati on” (VA Code 28.2-1302) . It provides for a 11560 Wetlands Zoning ordinance that any county, ci ty, or town in Virginia may adopt to 11561 regulate the use and development of local wetla nds. Under the ordinan ce, localities create 11562 a wetlands board consisting of five to seven citizen volunteers. The jurisdiction of these 11563 local boards extends from mean low wate r (the Marine Resources Commission has 11564 jurisdiction over bottom lands seaward of mean low water) to mean high water where no 11565 emergent vegetation exists, and slightly above spring high water 140 where marsh is 11566 present. The board grants or denies perm its for shoreline alterations within their 11567 jurisdiction (Trono, 2003). The Virginia Marine Resources Commission has jurisdiction 11568 over the permitting of projects within state-ow ned subaqueous lands and reviews projects 11569 in localities that have no local wetlands boa rd by virtue of not having adopted a wetland 11570 zoning ordinance 141

. 11571 11572 Maryland. The Wetlands and Riparian Rights Act 142 gives the owner of land bounding on 11573 navigable water the right to pr otect their property from the effects of shore erosion. For 11574 example, property owners who erect an eros ion control structure in Maryland can obtain 11575

140 The act grants jurisdiction to an elevation equal to 1.5 times the mean tide range, above mean low water. 141 Virginia Administrative Code §28.2. 142 Maryland Environmental Code §16-101 to §16-503.CCSP 4.1 January 15, 2009

682 of 784 Final Report a permit to fill vegetated wetlands 143 and fill beaches and tidal waters up to 3 m (10 ft) 11576 seaward of mean high water 144 . In addition, Maryland’s stat ute allows anyone whose 11577 property has eroded to fill wetlands and other tidal waters to reclaim any land that the 11578 owner has lost since the early 1970s 145 . (USACE has delegated most wetland permit 11579 approval to the state 146 .) Although the state has long disc ouraged bulkheads, much of the 11580 shore has been armored with stone revetments (Titus, 1998). 11581 11582 Shore protection structures tend to be initially constructed la ndward of mean high water, 11583 but neither Virginia nor Maryland 147 require their removal once the shore erodes to the 11584 point where the structures are flooded by th e tides. Nor has either state prevented 11585 construction of replacement bulkheads within state waters, although Maryland 11586 encourages revetments. 11587 11588 For the last several years, Maryland has enc ouraged the “living shorelines” approach to 11589 halting erosion ( e.g. , marsh planting and beach nourishment) over hard structures and 11590 revetments over bulkheads 148 . Few new bulkheads are built for erosion control, and 11591 existing bulkheads are often replaced with revetments. Nevertheless, obtaining permits 11592 for structural options has of ten been easier (NRC, 2007; J ohnson and Luscher, 2004). For 11593

143 See MD. CODE ANN., ENVIR. § 16-201 (1996); See Baltimore District (1996), app. at I-24, I-31. Along sheltered waters, the state enc ourages property owners to control erosion by planting vegetation. For this purpose, one can fill up to 35 feet seaward of mean high water. See MD. CODE ANN., ENVIR. § 16- 202(c)(3)(iii) (Supp. 1997). Along Ch esapeake Bay and other waters with significant waves, hard structures are generally employed. 144 MD. CODE ANN., ENVIR. § 16-202(c)(2). 145 MD. CODE ANN., ENVIR. § 16-201. 146 See Baltimore District (1996) §§ 1-5 147 The Maryland/Virginia border along the Potomac River is the low water mark. Courts have not ruled whether Maryland or Virginia environmental rules woul d govern a structure in Maryland waters attached to Virginia land. 148 Maryland General Permit at 56, § A1(A)(1)(g).CCSP 4.1 January 15, 2009

683 of 784 Final Report example, in the aftermath of Hurricane Is abel, many property owners sought expedited 11594 permits to replace shore protection structur es that had been destroyed by storms. 11595 Maryland wanted to make obtaining a permit to replace a destroye d bulkhead with a 11596 living shoreline as easy as obtaining a perm it to rebuild the bulkhead; but the state was 11597 unable to obtain federal approval. The perm its issued by USACE authorized replacement 11598 of the damaged structures with new struct ures of the same kind, but they did not 11599 authorize owners to replace lost revetments and bulkheads with living shoreslines, or 11600 even to replace lost bulkheads with revetments (Johnson and Luscher, 2004). 11601
11602 Recognizing the environmental consequen ces of continued sh oreline armoring, the 11603 Living Shoreline Protection Act of 2008 149 . Under the act, the Department of 11604 Environment will designate certain areas as appropriate for structural shoreline measures 11605 ( e.g. , bulkheads and revetments). Outside of those areas, only nonstructural measures 11606 ( e.g. , marsh creation, beach nourishment) will be allowed unless the property owner can 11607 demonstrate that nonstructural measures are infeasible 150

. 11608 11609 A1.F.2.3 Beach Nourishment and Other Sho re Protection Activities 11610 Virginia. Until 2003, the Board on Conservation a nd Development of Public Beaches 11611 promoted maintenance, access, and developm ent along the public beaches of Virginia. 11612 The largest beach nourishment projects have been along the 21 km (13 mi) of public 11613 beach along the Atlantic Ocean in Virginia B each. During the last 50 years, the state has 11614

149 MD H.B. 273 (2008). 150 MD Code Environment §16-201(c)CCSP 4.1 January 15, 2009

684 of 784 Final Report provided three percent of the funding for beach nourishment at Virginia Beach, with the 11615 local and federal shares being 67 percent a nd 30 percent, respectiv ely (VA PBB, 2000). 11616
11617 Virginia has made substantial efforts to promote beach nourishmen t (and public use of 11618 beaches) along Chesapeake Bay and its tributar ies. Norfolk’s four guarded beaches serve 11619 160,000 visitors each summer (VA PBB, 2000). Wh en shore erosion threatened property, 11620 the tourist economy, and local recreation, the Beach Board helped the city construct a 11621 series of breakwaters with beachfill and a term inal groin at a cost of $5 million (VA PBB, 11622 2000). State and local partnerships have also promoted beach restoration projects in 11623 several other locations along Chesapeake Bay and the Potomac and York rivers. (see 11624 Table A1.3). 11625
11626 Maryland. Maryland’s primary effo rt to protect shores along the bay is through the 11627 Department of Natural Resource’s Shor e Erosion Control Program. Until 2008, the 11628 program provided interest-free loans and t echnical assistance to Maryland property 11629 owners to resolve erosion problems through th e use of both structur al and nonstructural 11630 shore erosion control projects; the program is now limited to “living shoreline” (see Box 11631 5.3 in Chapter 5) approaches. The program provides contractor and homeowner training 11632 to support the installatio n of “living shorelines”. The De partment of Natural Resources 11633 has been involved in several beach nourishment projects along Chesapeake Bay (see 11634 Table A1.3), many of which incl ude breakwaters or groins to retain sand w ithin the area 11635 nourished. 11636
11637CCSP 4.1 January 15, 2009

685 of 784 Final Report The Maryland Port Administration and the US ACE have also used dredge spoils to 11638 restore Poplar and Smith Islands (USACE, 2001b). Preliminary examinations are under 11639 way to see if dredged materials can be used to restore other Chesapeake Bay islands such 11640 as James and Barren Islands (Federal Re gister, 2006), or to protect valuable 11641 environmental resources such as the eroding la nds of the U.S. Fish and Wildlife Service 11642 (USFWS) Blackwater National W ildlife Refuge (USFWS, 2008). 11643
11644 Table A1.3. Selected State Funded Beach Nourishment Projects Along Estuarine Shores in Maryland and Virginia
Location City or County $Cost (Millions) Maryland (2001 to 2008) North Beach Calvert n.a. Sandy Point Anne Arundel n.a. PT Lookout State Park St Mary’s n.a. Choptank River Fishing Pier Talbot n.a. Jefferson Island. St. Mary's n.a. Tanners Creek St. Mary's n.a. Bay Ridge Anne Arundel n.a. Hart and Mlllers Island. Baltimore County Co. n.a. Rock Hall Town Park Kent n.a. Claiborne Landing Talbot n.a. Terrapin Beach, Queen Anne’s n.a. Jefferson Is. Club - St Catherine Island St. Mary's n.a.
Elms Power Plant Site St. Mary's n.a.
Virginia (1995 to 2005) Bay Shore Norfolk 5.0 Parks along James River Newport News 1.0 Buckroe Beach Hampton 1.3 Cape Charles Northampton 0.3 Colonial Beach Westmoreland 0.3 Aquia Landing Stafford 0.2 Source: Maryland Department of Natural Resources; Virginia Board on Conservation and Development of Public BeachesCCSP 4.1 January 15, 2009

686 of 784 Final Report 11645 

## A1.G North Caroina 11646 A1.G.1 Introduction 11647 North Carolina’s coastline is outlined by a barrier island sy stem, with approximately 500 11648 km (300 mi) of shoreline along the Atlantic Ocean. North Carolina’ s winding estuarine 11649 shorelines extend a total of approximate ly 10,000 linear km (6,000 mi) (Feldman, 2008). 11650 There are three well-known capes along the coastline: Cape Hatteras, Cape Lookout, and 11651 Cape Fear, in order from north to south. The “Outer Banks” of North Carolina include the 11652 barrier islands and barrier spits from Cape L ookout north to the Virgin ia state line. Much 11653 of this land is owned by the federal g overnment, including Cape Lookout National 11654 Seashore, Cape Hatteras National Seashore, Pea Island National Wildlife Refuge, and 11655 Currituck National Wildlife Refuge. The Outer Banks also include several towns, 11656 including Kitty Hawk, Nags Head, Rodant he, and Ocracoke (see Section A1.G.4.2). 11657 North and east of Cape Lookout, four rive rs empty into the Albemarle and Pamlico 11658 Sounds. Albemarle Sound, Pamlico Sound, and their tidal tribut aries, sometimes 11659 collectively called the Albemarle-Pamlico Estu arine System, comprise the second largest 11660 estuarine system in the United States. 11661
11662 Previous assessments of North Carolina's es tuarine regions have divided the state’s 11663 coastal regions into two principal provinces (geological zones), each with different 11664 characteristics ( e.g. , Riggs and Ames, 2003)

. The zone northeast of a line drawn between 11665 Cape Lookout and Raleigh (locat ed about 260 km west of the cape) is called the Northern 11666 Coastal Province, which includes the Outer Banks and most of the land bordering the 11667CCSP 4.1 January 15, 2009

687 of 784 Final Report Albemarle and Pamlico Sounds

. It has gentle slopes, three major and three minor inlets, 11668 and long barrier islands with a moderately low sediment supply, compared to barrier 11669 islands worldwide (Riggs and Ames, 2003)

. The rest of the state’s coastal zone

― the 11670 Southern Coastal Province

― has steeper slopes, an even lower sediment supply, short 11671 barrier islands, and many inlets. 11672
11673 The Albemarle-Pamlico Peninsula is the land between Albemarle and Pamlico Sounds, to 11674 the west of Roanoke Island. The potential vulne rability of this 5,500 sq km (2,100 sq mi) 11675 peninsula (Henman and Poulter, 2008) is de scribed in Box A1.8. The majority of Dare 11676 and Hyde counties are less than 1 m (approximate ly 3 ft) above sea level, as is a large 11677 portion of Tyrell County (Poulter and Halpi n, 2007). Along the estuarine shorelines of 11678 North Carolina, wetlands are widespread, partic ularly in Hyde, Tyrell, and Dare counties. 11679 North Carolina’s Division of Coastal Manage ment mapped a total of more than 11,000 sq 11680 km (4,400 sq mi) of wetlands in the 20 coasta l counties in North Ca rolina (Sutter, 1999). 11681 Wetlands types present include marshes, sw amps, forested wetlands, pocosins (where 11682 evergreen shrubs and wetland trees occupy p eat deposits), and many other types (Sutter, 11683 1999). 11684 11685 Where the land is flat, areas a few meters a bove sea level drain slowly—so slowly that 11686 most of the lowest land is nontidal wetland (Richardson, 2003). Because rising sea level 11687 decreases the average slope between nearby co astal areas and the sea, it slows the speed 11688 at which these areas drain. Some of the dr y land within a few meters above the tides 11689 could convert to wetland from even a small rise in sea level; and nontidal wetlands at 11690CCSP 4.1 January 15, 2009

688 of 784 Final Report these elevations would be saturated more of the time (McFadden et al ., 2007; Moorhead 11691 and Brinson, 1995). Wetland loss could occur if dikes and drainage systems are built to 11692 prevent dry land from becoming wet (McFadden et al ., 2007). 11693 11694 The very low tide range in some of the sounds is another possible source of vulnerability. 11695 Albemarle Sound, Currituck Sound, and much of Pamlico Sound have a very small tide 11696 range because inlets to the ocean are few and far between (NOAA, 2008b). Some of the 11697 inlets are narrow and shallow as well. A lthough Oregon and Ocracoke inlets are more 11698 than 10 m (over 30 ft) deep, the inlets are characterized by extens ive shoals on both the 11699 ebb and flood sides, and the channels do not maintain depth for long distances before 11700 they break into shallower finger channels. Li ke narrow channels, this configuration limits 11701 the flow of water between the ocean a nd sounds (NOAA, 2008c). Thus, although the 11702 astronomic tide range at the ocean entrances is approximately 90 cm (3 ft), it decreases to 11703 30 cm (1 ft) just inside the inlets, and a few cen timeters in the centers of the estuaries. It 11704 is possible that rising sea level combined w ith storm-induced erosion will cause more, 11705 wider, and/or deeper inlets in the future (Riggs and Ames, 2003; see Chapter 3 of this 11706 Product)

. If greater tide ranges resulted, more lands would be tidally inundated. 11707
11708 The configuration of the few inlets within the Northern Coastal Province reduces tidal 11709 flushing and keeps salinity levels relatively low in most of the estuaries in this area 11710 (Riggs and Ames, 2003). Salinity is relatively high at the in lets, but declines as one 11711 proceeds upstream or away from the inlets. Also, there can be a st rong seasonal variation 11712 with lower salinities during the periods of maximum river discharge and higher salinities 11713CCSP 4.1 January 15, 2009

689 of 784 Final Report during periods of drought (Buzzelli et al ., 2003)

. The salinity in Albemarle-Pamlico 11714 Sound generally ranges from 0 to 20 parts per thousand (ppt), with the upper reaches of 11715 the Neuse and Pamlico Rivers, Albemarle Sound and Currituck Sound having salinities 11716 usually below 5 ppt (Caldwell, 2001; Tenore, 1972). (The typical salinity of the ocean is 11717 35 ppt [Caldwell, 2001]). Some tidal marshes (which are irregularly flooded by the winds 11718 rather than regularly flooded by astronomical tides) are thus unable to tolerate salt water 11719 (Bridgham and Richardson, 1993; Poulter, 2005)

. In some areas, the flow of shallow 11720 groundwater to the sea is also fresh, so th e soils are unaccustomed to salt water, and 11721 hence potentially vulnerable to increased salinity. 11722
11723 BOX A1.8: Vulnerability of the Albemarle-Pamlic o Peninsula and Emerging Stakeholder Response 11724 11725 Vulnerability to sea-level rise on the diverse Albemarle-Pamlico Peninsula is very high: about two-thirds of 11726 the peninsula is less than 1.5 m (5 ft) above sea level (Heath, 1975), and approximately 30 percent is less 11727 than 0.9 m (3 ft) above sea level (Poulter, 2005). Shoreline retreat rates in parts of the peninsula are already 11728 high, up to 7.6 m (25 ft) per year (Riggs and Ames, 2003). The ecosystems of the Albemarle-Pamlico 11729 Peninsula have long been recognized for their biological and ecological value. The peninsula is home to 11730 four national wildlife refuges, the first of which was established in 1932. In all, about one-third of the 11731 peninsula has been set aside for conservation purposes. 11732 11733 The Albemarle-Pamlico Peninsula is among North Carolina’s poorest areas. Four of its five counties are 11734 classified as economically distressed by the state, with high unemploym ent rates, along with low average 11735 household incomes (NC Department of Commerce, 2008). However, now that undeveloped waterfront 11736 property on the Outer Banks is very expensive and very scarce, developers have discovered the small 11737 fishing villages on the peninsula and begun acquiring property in several areas—including Columbia 11738 (Tyrrell County), Engelhard (Hyde County) and Bath (Beaufort County). The peninsula is being marketed 11739 as the “Inner Banks” (Washington County, 2008) . Communities across the peninsula are planning 11740 infrastructure, including wastewater treatment facilitie s and desalination plants for drinking water, to 11741 enable new development. Columbia and Plymouth (Washington County) have become demonstration sites 11742 in the North Carolina Rural Economic Development Center’s STEP (Small Towns Economic Prosperity) 11743 Program, which is designed to support revitalization and provide information vital to developing public 11744 policies that support long-term investment in small towns (NC REDC, 2006). 11745 11746 There are already signs that sea-level rise is causin g ecosystems on the Albemarle-Pamlico Peninsula to 11747 change. For example, at the Buckridge Coastal Reserve, a 7,547-ha (18,650-ac) area owned by the North 11748 Carolina Division of Coastal Management, dieback is occurring in several areas of Atlantic white cedar. 11749 Other parts of the cedar community are beginning to sh ow signs of stress. Initial investigations suggest the 11750 dieback is associated with altered hydrologic conditions , due to canals and ditches serving as conduits that 11751 bring salt and brackish water into the peat soils where cedar usually grows. Storms have pushed estuarine 11752 water into areas that are naturally fresh, affecting water chemistry, peatland soils, and vegetation intolerant 11753 of saline conditions (Poulter and Pederson, 2006). There is growing awareness on the part of residents and 11754 local officials about potential vulnerabilities across the landscape (Poulter, et al ., 2009). Some farmers 11755CCSP 4.1 January 15, 2009

690 of 784 Final Report acknowledge that salt intrusion and sea- level rise are affecting their fields (Moorhead and Brinson, 1995). 11756 Researchers at North Carolina State University are using Hyde County farms to experiment with the 11757 development of new varieties of salt-tolerant soybeans (Lee et al ., 2004). Hyde County is building a dike 11758 around Swan Quarter, the county seat (Hyde Country, 2008). 11759 11760 A variety of evidence has suggested to some stakeholde rs that the risks to the Albemarle-Pamlico Peninsula 11761 merit special management responses. In fact, becaus e so much of the landscape across the peninsula has 11762 been transformed by humans, some have expressed c oncern that the ecosystem may be less resilient and 11763 less likely to be able to adapt when exposed to mounting stresses (Pearsall et al ., 2005). Thus far, no 11764 comprehensive long-term response to the effects of sea-level rise on the peninsula has been proposed. In 11765 2007, The Nature Conservancy, U.S. Fish and Wildlife Service, National Audubon Society, Environmental 11766 Defense, Ducks Unlimited, the North Carolina Coastal Federation and others began working to build an 11767 Albemarle-Pamlico Conservation and Communities Collabo rative (AP3C) to develop a long-term strategic 11768 vision for the peninsula. Although this initiative is only in its infancy, sea-level rise will be one of the first 11769 and most important issues the partnershi p will address (Nature Conservancy, 2008). 11770 The Nature Conservancy and other stakeholders have already identified several adaptive responses to sea11771 level rise on the Peninsula. Many of these approa ches require community participation in conservation 11772 efforts, land protection, and adaptive management (Pearsall and Poulter, 2005). Specific management 11773 strategies that The Nature Conservancy and others have recommended include: plugging drainage ditches 11774 and installing tide gates in agricultural fields so that sea water does not flow inland through them, 11775 establishing cypress trees where land has been cleared in areas that are expected to become wetlands in the 11776 future, reestablishing brackish marshes in hospitable ar eas that are likely to beco me wetlands in the future, 11777 creating conservation corridors that run from the shore line inland to facilitate habitat migration, reducing 11778 habitat fragmentation, banning or restricting hardened structures along the estuarine shoreline, and 11779 establishing oyster reefs and submerged aquatic vegetation beds offshore to help buffer shorelines (Pearsall 11780 and DeBlieu, 2005; Pearsa ll and Poulter, 2005). 11781 End box*** 11782 11783 More than other areas in the Mid-Atlantic , the Albemarle-Pamlico Sound region appears 11784 to be potentially vulnerable to the possibility that several impacts of sea-level rise might 11785 compound to produce an impact larger than th e sum of the individua l effects (Poulter and 11786 Halpin, 2007; Poulter et al ., 2008). If a major inlet opened, increasing the tide range and 11787 salinity levels, it is possible that some freshwat er wetlands that are ot herwise able to keep 11788 pace with rising sea level would be poisone d by excessive salinity and convert to open 11789

water

. Similarly, if a pulse of salt water penetrated into the groundwater, sulfate reduction 11790 of the organic-rich soil and peat that underlies parts of the region could cause the land 11791 surfaces to subside (Hackney and Yelverton, 1990; Henman and Poulter, 2008; Mitsch 11792 and Gosselink, 2000; Portnoy and Giblin, 1997). Moreover, a substantial acceleration in 11793CCSP 4.1 January 15, 2009

691 of 784 Final Report the rate of sea-level rise stor ms of the type described below could cause barrier islands to 11794 be breached (see Chapter 3)

. Pamlico Sound (and potentially Albemarle Sound) could be 11795 transformed from a protected estuary into a semi-open embayment with saltier waters, 11796 regular astronomical tides, and larger waves (Riggs and Ames, 2003)

. 11797 11798 A1.G.2 Shore Processes 11799 A1.G.2.1 Ocean Coasts 11800 North Carolina receives the highest wave ener gy along the entire east coast of the United 11801 States and the northwest Atlantic margin (Riggs and Ames 2003). The coast of North 11802 Carolina has shifted significantly over time due to storms, waves, tides, currents, rising 11803 sea level, and other natural and human activ ities. These factors have caused variable 11804 sediment transport, erosion, and accretion, al ong with the opening and closing of inlets 11805 (see, e.g. , Everts et al. , 1983). 11806
11807 The North Carolina Division of Coastal Ma nagement (NCDCM) has calculated long-term 11808 erosion rates along the coastline adjacent to the ocean by comparing the location of 11809 shorelines in 1998 with the oldest available maps of shoreline location, mostly from the 11810 1940s. The average erosion rate was 0.8 m (2.6 ft) per year. Approximately 18 percent of 11811 the ocean coastline retreated by more than 1.5 m per year (5 ft per year), 20 percent 11812 eroded at an annual rate of 0.6 to 1.5 m (2 to 5 ft) per year, and 30 percent of the 11813 coastaline eroded by 0.6 m (2 ft) per year or less. However, 32 percent of the coastline 11814 accreted (NC DCM, 2003)

. The NCDCM recalculates long-term erosion rates about 11815CCSP 4.1 January 15, 2009

692 of 784 Final Report every five years to better track the dynamic shoreline trends and establish the setback line 11816 that determines where structures may be permitted on the oceanfront (NC DCM, 2005). 11817
11818 An analysis of shoreline change betw een approximately 1850 and 1980 in the area 11819 between the northern border of North Carolina and the point 8 km west of Cape Hatteras 11820 has been published. Data were averaged over 2 km reaches (stretches of coastline). 11821 Across the areas where data were availabl e during this time period, approximately 68 11822 percent of the ocean shoreline retreated towards the mainland, while approximately 28 11823 percent advanced (or accreted) away from the mainland, a nd 4 percent did not change 11824 position (Everts et al. , 1983). On average, the parts of the coastline between Ocracoke 11825 Inlet and Cape Hatteras erode d an average of 4.5 m (14.8 ft) per year over 1852 to 1917, 11826 8.3 m (27.2 ft) per year over 1917 to 1949, and 2.0 m (6.6 ft) per year over 1949 to 1980. 11827 The average erosion rate over the study period along the parts of the coastline facing east 11828 (between Cape Hatteras and Cape Henry, in Virginia) was 0.8 m (2.6 ft) per year. 11829 However, the study indicates that the coas tline from Cape Hatteras to Oregon Inlet 11830 accreted slightly (an average of 0.4 m [1.3 ft] per year) over 1852 to 1917, eroded an 11831 average of 2.9 m (9.5 ft) per year over 1917 to 1949, and eroded an average of 1.3 m (4.3 11832 ft) per year over 1949 to 1980. North of Oregon Inlet, the coastline was stable, on 11833 average, over 1852 to 1917; however, there wa s an average of 1.2 m (3.9 ft) per year of 11834 erosion over 1917 to 1949 and an average of 0.3 m (1.0 ft) per year of erosion in 1949 11835 to1980 (Everts et al ., 1983). 11836
11837CCSP 4.1 January 15, 2009

693 of 784 Final Report The report cautions against predicting future shoreline change based on the limited data 11838 available from surveys conducted since 1850. Th e authors observe that shoreline change 11839 can be influenced by local features, such as inlets, capes, and shoals (Everts et al. , 1983). 11840 For example, shorelines north of the ridges of three offshore shoals intersecting North 11841 Carolina’s ocean coast have retreated, wher eas shorelines south of the ridges have 11842 generally advanced (Everts et al. , 1983). Everts et al . also point out that while geological 11843 evidence indicates that the ba rrier islands have migrated landward over thousands of 11844 years, the islands are presently narrowing fr om both sides, in part because overwash 11845 processes cannot carry sand to the estuarine side due to is land width and development 11846 (Everts et al. , 1983). 11847
11848 More recently, researchers have used models to predict th e amount of shoreline change 11849 that might result from future sea-level rise, above and beyond the shoreline change 11850 caused by other factors. For example, one analys is of statewide erosi on rates over the past 11851 100 years led researchers to estimate that a 1 m sea-level rise woul d cause the shore to 11852 retreat an average of 88 m (289 ft), in a ddition to the erosion caused by other factors 11853 (excluding inlets) (Leatherman et al. , 2000a)

. Another study estimated that a rise in sea 11854 level of 0.52 m between 1996 and 2050 would cause the shoreline at Nags Head to retreat 11855 between 33 and 43 m, or between 108 and 144 ft (Daniels, 1996). 11856 11857 Some researchers are concerned that the barrie r islands themselves ma y be in jeopardy if 11858 sea-level rise accelerates. According to Ri ggs and Ames (2003), about 40 km (25 mi) of 11859 the Outer Banks are so sediment-starved th at they are already in the process of 11860CCSP 4.1 January 15, 2009

694 of 784 Final Report “collapsing”. Within a few decades, they es timate, portions of Cape Hatteras National 11861 Seashore could be destroyed by: (1) sea-level ri se (at current rates or higher); (2) storms 11862 of the magnitude experienced in the 1990s; or (3) one or more Category 4 or 5 hurricanes 11863 hitting the Outer Banks (Riggs and Ames, 2003) . Most of the Outer Banks between Nags 11864 Head and Ocracoke is vulnerable to barrier island segmentation and disintegration over 11865 the next century if the rate of sea-level rise accelerates by 2 mm per year—and portions 11866 may be vulnerable even at the cu rrent trend (see Chapter 3.) 11867
11868 A1.G.3 Vulnerable Habitats and Species 11869 Some wetland systems are already at the limit of their ability to ver tically keep pace with 11870 rising sea level, such as the remnants of the tidal marshes that connected Roanoke Island 11871 to the mainland of Dare Count y until the nineteenth century

. The pocosin wetlands can 11872 vertically accrete by about 1 to 2 mm per ye ar with or without rising sea level—when 11873 they are in their natural state (Craft and Richardson, 1998; Moorhead and Brinson, 1995)

. 11874 The human-altered drainage patterns, however , appear to be limiting their vertical 11875 accretion—and saltwater intrusi on could cause subsidence and conversion to open water 11876 (Pearsall and P oulter, 2005)

. 11877
11878 A1.G.3.1 Estuarine Shoreline Retreat 11879 The Pamlico and Albemarle Sounds, North Carolina’s smaller sounds, and the lower 11880 reaches of the Chowan, Roanoke, Tar, and Ne use Rivers are affect ed by rising sea level 11881 (Brinson et al. , 1985). Rising sea level is not the prim ary cause of shoreline retreat along 11882 estuarine shores in North Carolina. Storm wa ves cause shorelines to recede whether or 11883CCSP 4.1 January 15, 2009

695 of 784 Final Report not the sea is rising. A study of 21 sites estima ted that shoreline retreat—caused by “the 11884 intimately coupled processes of wave action and rising sea level”—i s already eliminating 11885 wetlands at a rate of about 3 sq km (800 ac) per year, mostly in zones of brackish marsh 11886 habitat, such as on the Albemarle-Pa mlico Peninsula (Riggs and Ames, 2003). 11887
11888 Riggs and Ames (2003) compiled data collec ted across North Carolina shorelines, both 11889 those that are adjacent to wetlands and those that are not. These data show that the vast 11890 majority of estuarine shores in the regi on are eroding, except for the sound sides of 11891 barrier islands (which one might expect to advance toward the mainland). Shores have 11892 retreated almost 2 m (7 ft) per year, over periods as long as 30 years. Annual averages for 11893 most shoreline types are less than 1 m per y ear, (Table A1.4) but annual maxima exceed 11894 the average many-fold and can reach 8 m ( 26 ft) per year where the shoreline is 11895 characterized by sediment bluffs or high ba nks. One or a few individual storm events 11896 contribute disproportionately to average a nnual shoreline recessi on rates (Riggs and 11897 Ames, 2003). 11898
Table A1.4 Estuarine shoreline erosion rates by shoreline type and the percent of total shoreline for each type. From Riggs and Ames (2003). Shoreline type Percent of shoreline Maximum rate per year (m) Average rate per year (m) Sediment Bank 38 Low bank 30 2.7 1.0 Bluff/high bank 8 8.0 0.8 Back-barrier strandplain beach <1 0.6 -0.2 1 Organic Shoreline 62 Mainland marsh 55 5.6 0.9 Back-barrier marsh <1 5.8 0.4 Swamp forest 7 1.8 0.7 Human Modified Unknown 2.0 0.2 Weighted Average 2 2.7 1 The negative erosion rate listed refers to this shoreline type, on average, accreting. 2 This weighted average excludes strandplain beaches and human-modified shorelines. 11899 11900CCSP 4.1 January 15, 2009

696 of 784 Final Report An analysis of estuarine shoreline change is also included in Everts et al. (1983). The 11901 authors calculated average erosion rates for the periods around 1850 to 1915 and 1915 to 11902 1980. Between Nags Head and Oregon Inlet, th e estuarine points analyzed between 1850 11903 and 1915 showed both advance rates greater than 4 m (13 ft) per year and retreat rates of 11904 close to 3 m (10 ft) per year. However, between 1915 and 1980, the estuarine points 11905 analyzed in this region showed a range of a pproximately 1 m per yearof retreat to less 11906 than 1 m per year of advance. Study author s did not analyze the area adjacent to Oregon 11907 Inlet or along most of Pea Island. Just nor th of Rodanthe, the earlier dataset shows 11908 dramatic shoreline advance averaging 4 m per year, but the la ter dataset shows a 11909 relatively stable shoreline. Just south of Rodanthe, there was slow advance during the 11910 earlier period and slow retreat (of approximate ly 1 m per year or le ss) in the later period. 11911 Between Avon and Salvo, both datasets show sh oreline retreat at rates not exceeding 2 m 11912 per year, with a slightly higher average rate of retreat in the later period than the earlier 11913 period (taken from Figure 34, Everts et al ., 1983). 11914 11915 The study indicates that the average retreat ra te across all the estu arine points analyzed 11916 from 1852 to 1980 was 0.1 m (4 in) per year. Ho wever, this average masks an important 11917 trend seen both north and south of Oregon Inle t. The rate of shorel ine change gradually 11918 changed from shoreline advance (movement towards the sounds) to shore retreat. The 11919 rate of advance was almost 2.0 m per year from 1852 to 1917. Shores were generally 11920 stable from 1917 to 1949, but they retreate d over the period from 1949 to 1980. Erosion 11921 was greater along estuarine shores facing west (an average of 1.2 m per year over 1852 to 11922 1980) than those facing north or south (ave raging 0.1 m per year over 1852 to 1980). The 11923CCSP 4.1 January 15, 2009

697 of 784 Final Report authors observed that these data indicate th at the North Carolina ba rrier islands in the 11924 study region did not appear to be migrati ng landward during the study period, but instead 11925 they narrowed from both sides. The present rate of island narrowing averages 0.9 m (3.0 11926 ft) per year. Available data indicate that sand washed over the barrier islands to the 11927 estuarine side of islands (ove rwash) did not significantly a ffect shoreline change along 11928 the estuary, particularly afte r the artificial dunes were cons tructed, a process that might 11929 itself have caused erosion from the sound side because it removed sand from the 11930 estuarine system (Everts et al ., 1983). Away from the inlets connecting the Albemarle11931 Pamlico Estuarine System to the ocean, the authors conclude that the retreat of the 11932
estuarine shoreline “ can be accounted for mostly by sea level rise ” (Everts et al ., 11933 1983). 11934 11935 A1.G.3.2 Potential for Wetlands to K eep Pace with Rising Sea Level 11936 Sections 4.3, 4.4, and 4.6 in Chapter 4 di scuss wetland vertical and horizontal 11937 development. In North Carolina, vertical accr etion rates have, for the most part, matched 11938 the rate of sea-level ri se (see Section 4.6.2 in Chap ter 4; Cahoon, 2003; Erlich, 1980; 11939 Riggs et al. , 2000). Vertical accretion ra tes as high as 2.4 to 3.6 mm per year have been 11940 measured, but the maximum rate at which wetlands can accrete is not well understood 11941 (Craft e t al. , 1993). Further, relative s ea-level rise in North Caro lina in recent years has 11942 ranged from approximately 1.8 to 4.3 mm per year at different poi nts along the North 11943 Carolina coast (Zervas, 2004). As discu ssed in Section 4.6.2.2, wetland drowning could 11944 result in some areas if rates of global sea- level rise increase by 2 mm per year and is 11945 likely if rates increase by 7 mm per year. Day et al. (2005) suggest that brackish marshes 11946CCSP 4.1 January 15, 2009

698 of 784 Final Report in the Mississippi Delta region cannot survive 10 mm per year of rela tive sea-level rise. 11947 Under this scenario, fringe wetlands of North Carolina’s lower coastal plain would 11948 drown. However, swamp forest wetlands along th e piedmont-draining rivers are likely to 11949 sustain themselves where there is an abundant supply of mineral sediments ( e.g. , river 11950 floodplains, but not river m ouths) (Kuhn and Mendelssohn, 1999). As sea level rises 11951 further and waters with highe r salt content reach the Albema rle-Pamlico peninsula, the 11952 ability of peat-based wetlands to keep up is doubtful, where the peat, root map, and 11953 vegetation would first be killed by brackish water (Poulter, 2005; Portnoy and Giblin, 11954 1997; Pearsall and Poulter, 2005). 11955 11956 Finally, as described in Chapter 3, in a scen ario where there are high rates of sea-level 11957 rise, more inlets would likely be created a nd segmentation or disintegration of some of 11958 the barrier islands is possible . This would cause a state chan ge from a non-tidal to tidal 11959 regime as additional inlets open, causing the Albemarle and Pamlico Sounds to have a 11960 significant tide range and increased salinit y, which would greatly disrupt current 11961 ecosystems. In this scenario, wave activity in the sounds could cha nge erosion patterns 11962 and could impact wetlands (Riggs and Ames, 2003). 11963 11964 A1.G.3.3 Environmental Implications of Habitat Loss and Shore Protection 11965 Ecological/habitat processes and patterns . Some wetland functions are proportional to 11966 size. Other functions depend on the wetland’s edges, that is, the borders between open 11967 water and wetland. Many irregularly flooded ma rshes in coastal North Carolina are quite 11968 large. In the absence of tida l creeks and astronomical tidal cu rrents, pathways for fish and 11969CCSP 4.1 January 15, 2009

699 of 784 Final Report invertebrate movement are se verely restricted, except when wind tides are unusually high 11970 or during storm events. By contrast, the twice-daily inundation of tidal marshes by 11971 astronomical tides increases connections acr oss the aquatic-wetland edge, as does the 11972 presence of tidal creeks, which allow fish a nd aquatic invertebrates to exploit intertidal 11973 areas (Kneib and Wagner, 1994) . Mobility across ecosystem boundaries is less prevalent 11974 in irregularly flooded marshes, where some fish species become marsh “residents” 11975 because of the long distances required to na vigate from marshes to subtidal habitats 11976 (Marraro et al. , 1991). Where irregularly flooded mars hes are inundated for weeks at a 11977 time, little is known about how resident species adapt. These include, among other 11978 species, several types of fish ( e.g. , killifish and mummichogs), brown water snakes, 11979 crustaceans (various species of crabs), bird s (yellowthroat, marsh wren, harrier, swamp 11980 sparrow, and five species of rails), and seve ral species of mammals (nutria, cotton rat, 11981 and raccoon)

. North Carolina’s coastal marshes are also home to a reintroduced 11982 population of red wolves, and sea-level rise co uld affect this population (see Box A1.9). 11983 11984Effects of human activities. Levees associated with waterfowl impoundments have 11985 isolated large marsh areas in the southern Pamlico Sound from any connection with 11986 estuarine waters. Impoundments were built to create a fres hwater environment conducive 11987 to migratory duck populations and thus e liminated most other habitat functions 11988 mentioned above for brackish marshes. Furthe r, isolation from sea level influences has 11989 likely disconnected the impoundments from pr e-existing hydrologic gr adients that would 11990 promote vertical accretion of marsh soil. If the impoundments were opened to an 11991CCSP 4.1 January 15, 2009

700 of 784 Final Report estuarine connection after decades of isolati on, they would likely become shallow, open11992 water areas incapable of re verting to wetlands (Day et al. , 1990). 11993 11994 Drainage ditches, installed to drain land so that it would be suitable for agriculture and 11995 timber harvesting, are prevalent in North Carolina. By the 19 70s, on the Albemarle11996 Pamlico Peninsula, there were an estimate d 32 km (20 mi) of streams and artificial 11997 drainage channels per square mile of land, wh ile the ratio in other parts of North Carolina 11998 ranged from 1.4:1 to 2.8:1 (Heath, 1975). In Dare County, there are currently an 11999 estimated 4 km of drainage ditc h features per sq km (Poulter et al. , 2008). In many cases, 12000 ditches, some of which were dug more than a century ago to drain farmland (Lilly, 1981), 12001 now serve to transport brackish water landward, a problem that could become 12002 increasingly prevalent as sea level rises. Saltwater intrusion into agricultural soils and 12003 peat collapse are major cons equences of this process. 12004 12005 A number of tide gates have been installed on the Albemarle-Pamlico Peninsula to reduce 12006 brackish water intrusion, but these will serve their pur pose only temporarily, given 12007 continued sea-level rise. One an alysis indicates that plugging ditches in selected places to 12008 reduce saltwater flow inland would be effectiv e for local stakeholde rs. Another option is 12009 to install new water control structures, such as tide gates, in selected locations (Poulter et 12010 al ., 2008). Plugging ditches would also help restore natural drainage patterns to the 12011 marshes. 12012
12013 A1.G.4 Development, Shore Protection, and Coastal Policies 12014CCSP 4.1 January 15, 2009

701 of 784 Final Report A1.G.4.1 Statewide Policy Context 12015 Several North Carolina laws and regulations ha ve an impact on response to sea-level rise 12016 within the state. First, setback rules en courage retreat by requiring buildings being 12017 constructed or reconstructed to be set back a certain distance from where the shoreline is 12018 located when construction permits are issu ed. Second, North Carolina does not allow 12019 “hard” shoreline armoring 151 such as seawalls and revetments on oceanfront 12020 shorelines 152 , preventing property owners from employing one possible method of 12021 holding back the sea to protect property 153 . Along estuarine shores , however, shoreline 12022 armoring is allowed landward of any wetlands

. The North Carolina Coastal Resources 12023 Commission (CRC) is preparing new state re gulations for the location and type of 12024 estuarine shoreline stabilizati on structures to help encour age alternatives to bulkheads 12025 (NC CRC, 2008b; Feldman, 2008). The goals ar e similar to the “ living shorelines” 12026 legislation recently enacted in Maryland (s ee Section A1.F.2.2). Adding sand to beaches 12027 ( i.e. , beach nourishment) is the preferred method in North Carolina to protect buildings 12028 and roads along the ocean coastline. 12029
12030 The state’s Coastal Area Management Act (C AMA) has fostered la nd use planning in the 12031 20 coastal counties to which it applies. Re gulations authorized by CAMA require local 12032 land use plans to “[d]evelop policies that mi nimize threats to life, property, and natural 12033 resources resulting from development located in or adjacent to hazard areas, such as those 12034

151 See Chapter 6 for an explanation of various shore protection options. 152 15A NCAC 07H.0101. 153 Some hard structures exist along North Carolina’s oceanfront shoreline ( e.g ., adjacent to inlets). Many were built before 1985 when the statute was enacted to ban new hard structures, or were covered by exception in the rules. The Legislature regularly consid ers additional exceptions, such as terminal groins for beach nourishment projects and jetties for stabilizing inlets. e.g. North Carolina SB599 (2007-2008).CCSP 4.1 January 15, 2009

702 of 784 Final Report subject to erosion, high winds, storm surge, flowing, or sea level rise”. However, the 12035 state’s technical manual for coastal land us e planning (NC DCM, 2002) does not mention 12036 sea-level rise. Accordingly, loca l land use plans either do not mention sea-level rise at all, 12037 mention it only in passing, or explicitly defe r decisions about vulnerable areas until more 12038 information is available in the future (Feldman, 2008; Poulter et al. , 2009). Nevertheless, 12039 the regulatory requirement to consider sea-level rise may eventually encourage local 12040 jurisdictions to consider how the communities most vulnerable to sea-level rise should 12041 prepare and respond (Feldman, 2008). Land-use plans are updated regularly and are an 12042 important tool for increasing public awareness about coastal hazards. 12043
12044 CAMA and the state’s Dredge and Fill Law au thorize the CRC to regulate certain aspects 12045 of development within Nort h Carolina’s 20 coastal count ies. For example, the CRC 12046 issues permits for development and classifies certain regions as Areas of Environmental 12047 Concern (AECs, e.g. , ocean hazard zones and coastal wetlands) where special rules 12048 governing development apply. Land use plans are binding in AECs. In response to the 12049 threat of damage to coastal structures from the waves, since 1980 North Carolina has 12050 required new development to be set back from the oceanfront

. The setbacks are measured 12051 from the first line of stable natural vegetation 154

. Single-family homes of any size—as 12052 well as multi-family homes and non-residential structures with less than 5,000 sq ft of 12053 floor area—must be set back by 60 ft or 30 times the long-term rate of erosion as 12054 calculated by the state, whichever is greater

. Larger multi-family homes and non12055 residential structures must be set back by 120 ft or the erosion-based setback distance, 12056

154 Local governments can request that an alternative vegetation line be established under certain conditions. Additional rules also apply when there is a sand dune between the home and the shoreline, to protect the integrity of the dune.CCSP 4.1 January 15, 2009

703 of 784 Final Report whichever is greater

. The setback distance for these larger structures is set as either 60 12057 times the annual erosion rate or 105 ft plus 30 times the erosion rate, whichever is less 155

. 12058 North Carolina is considering changes to its oceanfront setback rules, including 12059 progressively larger setback factors for build ings with 10,000 sq ft of floor area or more 12060 (NC CRC, 2008a)

. Along estuarine shorelines, No rth Carolina has a 30-ft setback 156 and 12061 restricts development between 30 and 75 ft from the shore 157

. As the shore moves inland, 12062 these setback lines move inland as well. 12063
12064 As of 2000, the U.S. Army Corps of Engi neers (USACE) participated in beach 12065 nourishment projects along more than 51 km (32 mi) of North Carolina’s shoreline 12066 (including some nourishment projects that occurred as a result of nearby dredging 12067 projects), and nourishment along an additiona l 137 km (85 mi) of coastline had been 12068 proposed (USACE, 2000) 158

. If necessary, property owners can place large geotextile 12069 sandbags in front of buildings to atte mpt to protect them from the waves

. Standards apply 12070 to the placement of sandbags, which is suppos ed to be temporary (t o protect structures 12071 during and after a major storm or other short- term event that causes erosion, or to allow 12072 time for relocation) 159

. Buildings are supposed to be move d or removed within two years 12073 of becoming “imminently threatened” by shoreline changes 160

. 12074 12075

155 15A NCAC 07H. 0305 - 0306. 156 15A NCAC 07H.0306. 157 15A NCAC 07H.0209 158 Although beach nourishment has been a common response to sea level rise in many areas along the coast, there has been a decline in the availability of suitable sand sources for nourishment, particularly along portions of the coast (Bruun, 2002). In addition, the availability of substantial federal funds allocated for beach nourishment has become increasingly questiona ble in certain areas, particularly in Dare County (Dare County, 2007; Coastal Scie nce and Engineering, 2004). 159 15A NCAC 07H.0308 160 15A NCAC 7H.0306 (l)CCSP 4.1 January 15, 2009

704 of 784 Final Report North Carolina officials are in the process of reassessing certain state policies in light of 12076 the forces of shoreline change and climate change

. Policy considerations have been 12077 affected by numerous studies that research ers have published on the potential effects of 12078 sea-level rise on North Carolina (Poulter et al. , 2009)

. The state legislature appointed a 12079 Legislative Commission on Globa l Climate Change to study and report on potential 12080 climate change effects and potential mitigation strategies, including providing 12081 recommendations that address impacts on the coastal zone 161

. The Commission’s 12082 recommendations have not yet been finalized, but an initial draft version offered such 12083 suggestions as creating a mechanism to purch ase land or conservation easements in low12084 lying areas at great risk from sea-level rise; providing incentives for controlling erosion 12085 along estuarine shorelines using ecologically beneficial methods; creating a commission 12086 to study adaptation to climate change and make recommendations about controversial 12087 issues; and inventorying, mapping, and monitoring the physical and biological 12088 characteristics of the entire shoreline (Feldman, 2008; Riggs et al ., 2007). 12089 12090 The CRC is also considering the potential e ffects of sea-level rise and whether to 12091 recommend any changes to its rules affecti ng development in coastal areas (Feldman, 12092 2008)

. In addition, NCDCM is developing a Beach and Inlet Management Plan to define 12093 beach and inlet management zones and propose preliminary management strategies given 12094 natural forces, economic factors, limitations to the supply of beach-quality sand, and 12095 other constraints (Moffatt and Nichol, 2007). 12096 12097 A1.G.4.2 Current Land Use 12098

161 See the “North Carolin a Global Warming Act,” Session Law 2005-442.CCSP 4.1 January 15, 2009

705 of 784 Final Report Ocean Coast (from north to south). North Carolina’s ocean coast, like the coasts of most 12099 states, includes moderate and densely de veloped communities, as well as undeveloped 12100 roadless barrier islands. Unlike other mid-Atla ntic states, North Carolina’s coast also 12101 includes a major lighthouse (at Cape Hattera s) that has been relocated landward, a 12102 roadless coastal barrier that is neverthe less being developed (described below), and 12103 densely populated areas where storms, erosion, and sea-level rise have caused homes to 12104 become abandoned or relocated. 12105
12106 The northern 23 km (14 mi) of the state’s co astline is a designated undeveloped coastal 12107 barrier under the Coastal Barrier Resources Ac t (CBRA) and hence ineligible for most 12108 federal programs (USFWS, undated[c]) This stretch of barrier island includes two 12109 sections of Currituck National Wildlife Ref uge, each about 2 km (1 mi) long, which are 12110 both off-limits to development. Nevertheless, the privately owned areas are gradually 12111 being developed, even though they are acces sible only by boat or four-wheel drive 12112 vehicles traveling along the beach. The CBRA zones are ineligible for federal beach 12113 nourishment and flood insurance (USFWS, undated[c]). 12114 12115 Along the Dare County coast from Kitty Hawk south to Nags Head, federal legislation 12116 has authorized shore protection, and USAC E (2006b) has concluded that the proposed 12117 project would be cost-effective. In some areas, homes have been lost to shoreline erosion 12118 (Pilkey et al. , 1998) (see Figure 12.6). Continued shor e erosion has threatened some of 12119 the through-streets parallel to the shore, wh ich had been landward of the lost homes. 12120 Given the importance of those roads to en tire communities (see Section 12.2 in Chapter 12121CCSP 4.1 January 15, 2009

706 of 784 Final Report 12) small sand replenishment projects have b een undertaken to protect the roads (Town 12122 of Kitty Hawk, 2005)

. The planned beach nourishment project does not extend along the 12123 coast to the north of Kitty Hawk. Those beaches are genera lly not open to the public and 12124 are currently ineligible for publicly funded beach nourishment. 12125
12126 From Nags Head to the southwestern end of Hatteras Island, most of the coast is part of 12127 Cape Hatteras National Seashore. A coastal hi ghway runs the entire length, from which 12128 one can catch a ferry to Ocracoke Island, car rying through traffic to both Ocracoke and 12129 Carteret County. Therefore, the National Park Service must balance its general 12130 commitment to allowing natural shoreline processes to function (see Chapter 12.1; NRC 12131 1988) with the needs to manage an important transportation artery. In most cases, the 12132 approach is a managed retreat, in which shor es generally migrate but assets are relocated 12133 rather than simply abandoned to the sea. Congress appropriated $9.8 million to move the 12134 Cape Hatteras Lighthouse 1,600 ft (468 m) inland in 1999 (NPS, 2000) (see Figure 12135 11.1a). The coastal highway has been relocate d inland in places. Because it is essential 12136 infrastructure, its protection would probably re quire maintaining the barrier island itself, 12137 for example, by filling inlets after severe storms. A possible exception is where the 12138 highway runs through Pea Island National Wildlife Refuge on the northern end of 12139 Hatteras Island, just south of the bridge over Oregon Inlet. The federal and state 12140 governments are considering the possibility th at when a new bridge is built over Oregon 12141 Inlet, it would bypass the Nati onal Wildlife Refuge and ex tend over Pamlico Sound just 12142 west of Hatteras Island as far as Rodanthe (USDOI, 2007)

. 12143
12144CCSP 4.1 January 15, 2009

707 of 784 Final Report The undeveloped Portsmouth Island and Core Banks constitute Cape Lookout National 12145 Sea Shore and lack road access. Cape Lookout is located on Core Banks. Shackleford 12146 Banks, immediately adjacent to the southwest, is also roadless and uninhabited. 12147 Southwest of Cape Lookout, the coast consis ts mostly of developed barrier islands, 12148 conservation lands, and designated “undevelope d coastal barriers” that are nevertheless 12149 being developed. Bogue Banks includes five large communities with high dunes and 12150 dense forests (Pilkey et al. , 1998). Bogue Banks also receives fill to widen its beaches 12151 regularly. 12152 12153 To the west of Bogue Banks are the barrier islands of Onslow County and then Pender 12154 County. Some islands are only accessible by bo at, and most of these are undeveloped. 12155 North Topsail Beach, on Topsa il Island, has been devastated by multiple hurricanes, in 12156 part due to its low elevation and the isla nd’s narrow width. Erosion has forced multiple 12157 roads on the island to be moved. While some pa rts of North Topsail Beach are part of a 12158 unit under the CBRA system, making them inelig ible for federal subsidies, development 12159 has occurred within th em nonetheless (Pilkey et al. , 1998). 12160
12161 Further to the southwest are the barrier islands of New Ha nover County, including Figure 12162 Eight Island, which is entirely privately- owned with no public access to the beach, and 12163 hence ineligible for public funding for beach nourishment (see Chapter 8). Wrightsville 12164 Beach, like many other communities southwest of Cape Lookout, has an inlet on each 12165 side. It is the site of a dispute to protect a hotel from being washed away due to inlet 12166 migration (Pilkey et al. , 1998). The USACE has made a long-term commitment to regular 12167CCSP 4.1 January 15, 2009

708 of 784 Final Report beach renourishment to maintain the place of the shoreline in Wrightsville Beach and 12168 Carolina Beach (USACE, 2006a). An excepti on to North Carolina’s rules forbidding 12169 hardened structures has been granted in Ku re Beach, west of Carolina Beach, where stone 12170 revetments have been placed on the oceanfront to protect Fort Fisher (which dates back to 12171 the Civil War). These structures also protec t a highway that provides access to the area 12172 (Pilkey et al. , 1998). Most of the beach communities in New Hanover County are 12173 extensively developed. 12174 12175 Some of the barrier islands in Brunswick C ounty, close to the South Carolina state line, 12176 are heavily forested with high elevations, making them more resilient to coastal hazards 12177 (Pilkey et al. , 1998). Holden Beach and Ocean Isle Beach, however, contain many 12178 dredge-and-fill finger canals. Historically, at least two inlets ran through Holden Beach; 12179 and storms could create new inlets wh ere there are currently canals (Pilkey et al. , 1998). 12180
12181Estuarine Shores . Significant urbanization was slow to come to this region for many 12182 reasons. Most of the area is farther from population centers than the Delaware and 12183 Chesapeake Estuaries. The Outer Banks were developed more slowly than the barrier 12184 islands of New Jersey, Delaware, and Marylan d. Most importantly, the land is mostly low 12185 and wet. 12186
12187 Unlike the Delaware Estuary, North Carolina do es not have a long hi story of diking tidal 12188 wetlands to reclaim land from th e sea for agricultural purposes 162 . However, the state is 12189

162 Nevertheless, it has had a few short-lived projects, most notably Lake Matamuskeet.CCSP 4.1 January 15, 2009

709 of 784 Final Report starting to gain experience w ith dikes to protect agricu ltural lands from flooding. In 12190 Tyrrell County, the Gum Neck has been protected with a dike for four decades. A dike is 12191 under construction for the town and farms around Swan Quarter (Allegood, 2007), the 12192 county seat of Hyde County (which includes Ocracoke Is land). Hurricanes Fran and 12193 Floyd led to federally-sponsored purchases of thousands of pr operties across North 12194 Carolina’s eastern counties, facilitating th e demolition or relocation of associated 12195 structures. Pamlico County has encouraged people to gradually abandon Goose Creek 12196 Island in the eastern portion of the county, by working with FEMA to relocate people 12197 rather than rebuild damaged homes and businesses (Barnes, 2001)

. By contrast, in other 12198 areas ( e.g ., parts of Carteret County), people t ook the opposite approach and elevated 12199 homes

. 12200
12201 Geography, coastal features, and community characteristics vary greatly along North 12202 Carolina’s coast. Thus, one can assume that a variety of different pl anning and adaptation 12203 strategies related to shorelin e change and sea-level rise w ould be needed, particularly 12204 over the long term. Scientists, managers, and community members in North Carolina 12205 have undertaken a variety of efforts to bette r understand and begin to address potential 12206 sea-level rise vulnerabilities and impacts. These research and collaborative efforts may 12207 increase awareness, receptivity, and readine ss to make informed coastal management 12208 decisions in the future (Poulter et al ., 2009). 12209
12210
12211CCSP 4.1 January 15, 2009

710 of 784 Final Report APPENDIX 1 REFERENCES 12212 * Indicates non-peer reviewed literature; available upon request 12213 12214 12215 Abel , K.W. and S.M. Hagan, 2000: Effects of common reed ( Phragmites australis ) 12216 invasion on marsh surface macrofauna : Response of fishes and decapod 12217 crustaceans. Estuaries, 23(5), 633-646. 12218
Abel , K.W., D.M. Nemerson, P.R. Light, and R.O. Bush, 2000: Initial response of fishes 12219 to marsh restoration at a former sa lt hay farm bordering Delaware Bay. In: 12220 Concepts and Controversies in Tidal Marsh Ecology , [Weinstein, M.P. and D.A. 12221 Kreeger (eds.)]. Kluwer Academic P ublishers, Dordrecht, the Netherlands, 12222

* Allegood , J., 2007: Dike to protect Swan Quarte r: Battered coastal village hopes to 12223 hold back flooding from the next hurricane. Raleigh News and Observer , May 29, 12224 2007. 12225
ADC (Alexandria Drafting Company), 2008: Stafford County, VA Street Atlas. 12226 Langennscheldt Publishing Group, Duncan, SC, 60 pp. 12227

* AP (Associated Press), 1985: Doubled erosion seen for Ocean City. Washington Post , 12228 November 14th. (Maryland Section). 12229 Ayers , R.A., 2005 : Human Impacts to Sensitive Natu ral Resources on the Atlantic 12230 Barrier Islands on the Eastern Shore of Virginia . Virginia Department of 12231 Environmental Quality, Coastal Zone Management Program, Richmond, 14 pp. 12232 <http://www.deq.state.va.us/coastal/documents/task11-07-04b.pdf> 12233

Baker , A.J., P.M. Gonzalez, T. Piersma, L.J. Niles, and I. de Lima Serrano do 12234 Nacimento, 2004: Rapid population decline in Red Knots: fitness consequences of 12235 decreased refueling rates and late arrival in Delaware Bay. Proceedings of the 12236 Royal Society of London, B , 271 , 875-882. 12237

Barnes , J., 2001: North Carolina's Hurricane History . University of North Carolina 12238 Press, Chapel Hill, NC, 336 pp. 12239CCSP 4.1 January 15, 2009

711 of 784 Final Report BBNEP (Barnegat Bay National Estuary Program, Scientific and Technical Advisory 12240 Committee), 2001: Chapter 7 of The Barnegat Bay Estuary Program 12241 Characterization Report. 12242 <http://www.bbep.org/Char_Rpt/Ch7/Chapter%207.htm> 12243
Baltimore District , 1996: Maryland State Programmatic General Permit (MDSPGP)

. 12244 U.S. Army Corps of Engineers, Baltimore. 12245

Berkson , J. and C.N. Shuster Jr., 1999: The horseshoe crab: the battle for a true multiple12246

use resource. Fisheries , 24 , 6-10. 12247

Berman , M.R., H. Berquist, S. Dewing, J. Glover, C.H. Hershner, T. Rudnicky, D.E. 12248 Schatt, and K. Skunda, 2000: Mathews County Shorelin e Situation Report

. 12249 Special report in applied marine science and ocean engineering no. 364. 12250 Comprehensive Coastal Inventory Program, Vi rginia Institute of Marine Science, 12251 College of William and Mary, Gloucester Point, VA. 12252
Bernd-Cohen , T. and M. Gordon, 1999: State co astal program effectiveness in 12253 protecting natural beaches, dunes, bluffs, and rock shores. Coastal Management, 12254 27 , 187-217. 12255
Bernick , A.J., 2006: New York City Audubon’s Harbor Herons Project: 2006 Interim 12256 Nesting Survey . Report prepared for New York City Audubon, New York, 22 pp. 12257

Bertness , M.D., 1999: The Ecology of A tlantic Shorelines . Sinauer Associates, 12258 Sunderland, MA, 417 pp. 12259 * Bleyer , B., 2007: Erosion protection for M ontauk lighthouse creates waves. Lighthouse 12260 Digest. 12261 <http://www.lighthousedigest.com/Digest/StoryPage.cfm?StoryKey=2636> 12262

Boesch , D.F. and R.E. Turner, 1984: Dependence of fishery species on salt marshes: the 12263 role of food and refuge. Estuaries , 7(4A) , 460-468. 12264CCSP 4.1 January 15, 2009

712 of 784 Final Report Botton , M.L., R.E. Loveland, and T.R. Jacobsen, 1988: Beach erosion and geochemical 12265 factors: influence on spawning success of horseshoe crabs ( Limulus polyphemus ) 12266 in Delaware Bay. Marine Biology , 99(3), 325-332. 12267

Botton , M.L., R.E. Loveland, J.T. Tanacredi, and T. Itow, 2006: Horseshoe crabs 12268 ( Limulus polyphemus ) in an urban estuary (Jamaica Bay, New York) and the 12269 potential for ecol ogical restoration. Estuaries and Coasts , 29(5) , 820-830. 12270 Bridgham , S. D., and C. J. Richardson, 1993: H ydrology and nutrient gradients in North 12271 Carolina peatlands. Wetlands , 13 , 207-218. 12272
Brinson , M.M., H.D. Bradshaw, and M.N. Jones, 1985: Transitions in forested wetlands 12273 along gradients of salinity and hydroperiod. Journal of the Elisha Mitchell 12274 Scientific Society , 101, 76-94. 12275 Burger , J., 1984: Cited in New York State Depart ment of State and the U.S. Fish and 12276 Wildlife Service, Southern New England–New York Bight Coastal Ecosystems 12277 Program. 1998. Shorebirds . South Shore Estuary Reserve, Technical Report 12278 Series. 12279 <http://www.nyswaterfronts.com/Final_Draft_HTML/Tech_Report_HTM/PDFs/ 12280 C8A_Index_pdf.htm> 12281 Burger , J., L. Niles, and K.E. Clark, 1997: Importance of beach, mudflat, and marsh 12282 habitats to migrant shorebirds in Delaware Bay. Biological Conservation 79(2) , 12283 283-292. 12284
Buzzelli , C. ., J.R. Ramus, and H.W. Paerl, 2003: Ferry-based monitoring of surface 12285 water quality in North Carolina estuaries. Estuaries , 26 , 975-984. 12286

* Byrne , D.M., 1995: The effect of bulkheads on es tuarine fauna: a comparison of littoral 12287 fish and macroinvertebrate assemblage s at bulkheaded and non-bulkheaded 12288 shorelines in a Barnegat Bay Lagoon. In: Second Annual Marine Estuarine 12289 Shallow Water Science and Management Conference, Atlantic City, NJ. 12290 Environm ental Protection Agen cy, Philadelphia, PA, pp. 53-56. 12291CCSP 4.1 January 15, 2009

713 of 784 Final Report Cahoon , D.R., 2003: Storms as agents of we tland elevation change: their impact on 12292 surface and subsurface sediment processes. Proceedings of the International 12293 Conference on Coastal Sediments 2003 , May 18-23, 2003, Clearwater Beach, 12294 Florida. World Scientific Publishing Corporation, Corpus Christi TX. 12295
Caldwell , W.S., 2001: Hydrologic and Salinity Characte ristics of Currituck Sound and 12296 Selected Tributaries in No rth Carolina and Virginia, 1998-99 . USGS water 12297 resources investigation report 01-4097. U. S. Geological Survey, Raleigh, NC, 36 12298 pp. 12299 Casey , J. and S. Doctor, 2004: Status of finf ish populations in the Maryland Coastal 12300 Bays. In: Maryland’s Coastal Bays: Ecosystem Health Assessment 2004 12301 [Wazniak, C.E. and M.R. Hall (eds.)]. DNR-12-1202-0009. Maryland Department 12302 of Natural Resources, Tidewater Ecosystem Assessment, Annapolis, chapter 8.4. 12303

Castro , G. and J.P. Myers, 1993: Shorebird pred ation on eggs of horseshoe crabs during 12304 spring stopover on Delaware Bay. Auk , 110(4) , 927-930. 12305
CBCAC ( Chesapeake Bay Critical Area Commissi on, Maryland Department of Natural 12306 Resources), 2001: Chesapeake Bay Critical Area Line. 12307
< http://www.marylandgis.net/metadataexplorer/full_metadata.jsp?docId=%7B480 12308 9747B-1DF0-4635-92D1-CE99AA1A84C1%7D&loggedIn=false> 12309

* CBP (Chesapeake Bay Program), 2002: The Impact of Susquehanna Sediments on the 12310 Chesapeake Bay . Scientific and Technical Advisory Committee Workshop 12311 Report. May 2002 12312

* CBP (Chesapeake Bay Program), 2006: Diamondback Terrapin . [web site] 12313 <http://www.chesapeakebay.net/diamondback_terrapin.htm> 12314
* Chase , C.M., 1979: The Holocene Geologic History of the Maurice River Cove and its 12315 Marshes, Eastern Delaware Bay, New Jersey . MS Thesis, University of 12316 Delaware, Newark, 129 pp. 12317CCSP 4.1 January 15, 2009

714 of 784 Final Report Clark , K., 1996: Horseshoe crabs an d the shorebird connection. In: Proceedings of the 12318 Horseshoe Crab Forum: Status of the Resource [Farrell, J. and C. Martin 12319 (eds.)].University of Delaware Sea Grant College Program, Lewes, pp. 23-25. 12320

* CLO (Cornell Laboratory for Ornithology), 2004: All About Birds: Piping Plover . [web 12321 site] 12322 <http://www.birds.cornell.edu/AllAboutBi rds/BirdGuide/Piping_Plover_dtl.html 12323
> 12324
Cohen , J.B., E.H. Wunker, J.D. Fraser, 2005: Substrate and vegetation selection by 12325 piping plovers. Wilson Journal of Ornithology , 120(2) , 404-407 12326 Conley, M., 2004: Maryland Coastal Bays Aquatic Se nsitive Areas Ini tiative Technical 12327 Report . Prepared by the Maryland Department of Natural Resources, Coastal 12328 Zone Management Division. 12329 Cooper , M.J.P., M.D. Beevers, and M. Oppenheimer, 2005: Future Sea-level Rise and 12330 the New Jersey Coast . Science, Technology, and Envi ronmental Policy Program, 12331 Woodrow Wilson School of Public a nd International Affairs, Princeton 12332 University, Princeton, NJ, 37 pp. 12333 <http://www.princeton.edu/~step/people/Oppenheimer%20Future%20of%20Sea 12334 %20Level%20Rise.pdf> 12335
CPCP (City of Poquoson Comprehensive Plan), 1999: Environmental Element

. 12336 Poquoson, VA. <http://www.ci.poquoson.va.us/> 12337
Craft , C.B. and C.J. Richardson, 1998: Recent and long-term organic soil accretion and 12338 nutrient accumulation in the everglades. Soil Science Society of America Journal , 12339 62, 834-843. 12340
Craft , C.B., E.D. Seneca, and S.W. Broome, 1993: Vertical accretion in microtidal 12341 regularly and irregularly flooded estuarine marshes. Estuarine, Coastal, and Shelf 12342 Science, 37, 371-386. 12343CCSP 4.1 January 15, 2009

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716 of 784 Final Report DNREC (Delaware Department of Natural Reso urces and Environmental Control), 2007: 12370 Inland Bays Pollution Control Strategy and Proposed Regulations. April 2007. 12371 DNREC, Division of Water Resources, Dover, DE. 12372

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718 of 784 Final Report Feinberg , J.A. and R.L. Burke, 2003: Nesti ng Ecology and Predation of Diamondback 12421 Terrapins, Malaclemys terrapin , at Gateway National Recreation Area, New 12422 York. Journal of Herpetology , 37(3), 517-526. 12423

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Henman , J. and B. Poulter, 2008: Inundation of freshwater peatlands by sea level rise: 12477 uncertainty and potential carbon cycle feedbacks. Journal of Geophysical 12478 Research , 113 , G01011, doi:10.1029/2006JG000395. 12479

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721 of 784 Final Report Jackson , E.L., A.S. Rowden, M.J. Attrill, S. Bossey, and M. Jones, 2001: The 12500 importance of seagrass beds as habitat for fishery species. Oceanography and 12501 Marine Biology Annual Review, 39, 269-303. 12502 James City County , 2003: James City County Comprehensive Plan. Land Use (pp. 101- 12503 141) and Environment (pp. 42-67) Chapters. Williamsburg, Virginia. 12504

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USACE (United States Army Corps of Engineers), 1998b: Delaware Bay Coastline: 13051 Reeds Beach and Pierces Poit, NJ. final integrated feas ibility report and 13052CCSP 4.1 January 15, 2009

742 of 784 Final Report Environmental Impact Statement . United States Army Corps of Engineers, 13053 Philadelphia District. Addendum 1999. 13054
USACE (United States Army Corps of E ngineers), 2000: Wilmington District. 13055 Attachment D: Dare County Beaches (Bodi e Island Portion) Hurricane Protection 13056 and Beach Erosion Control Project, Da re County, North Carolina. Preliminary 13057 Compilation of Disposal/Nourishment Zone s and Borrow Areas in Recovery from 13058 5-Year Running Total. 13059 <www.saw.usace.army.mil/Dare%20C ounty/Dare%20County%20Bodie%20Is.% 13060 20%20FEIS%20Attachment%20D.pdf> 13061
USACE (United States Army Corps of Engineers), 2001a: Final Finding of No 13062 Significant Impact and Environmental A ssessment, Assateague Island Short-term 13063 Restoration: Modifications to Proposed Project and Development of a Dredging 13064 Plan. Worcester County, MD. Baltimore District, July 2001. 13065

USACE (United States Army Corps of E ngineers), 2001b: Smith Island, Maryland. 13066 Environmental Restoration a nd Protection. Final Integrat ed Feasibility Report and 13067 Environmental Assessment. Submitte d by USACE Baltimore District in 13068 cooperation with Somerset County, Mary land, Maryland Department of Natural 13069 Resources, and Maryland Department of the Environment. 13070
USACE (United States Army Corps of Engineers), 2003: Regional Sediment 13071 Management (RSM) Demonstration Program Project Brief, New York District: 13072 Town of Hempstead, Long Island, New York

. 13073 <http://www.wes.army.mil/rsm/pubs/pdfs/rsm-db9.pdf> 13074
USACE (United States Army Corps of Engineers), 2006a: Annual Report, Fiscal Year 13075 2006 of the Secretary of the Army on Civil Works Activities . South Atlantic 13076 Division, Wilmington, N.C. District. 13077
USACE (United States Army Corps of Engineers), 2006b: Revised Record of Decision: 13078 Dare County Beaches (Bodie Island Por tion), Hurricane Protection and Beach 13079 Erosion Control Project, Dare County, North Carolina . U.S. Army Corps of 13080CCSP 4.1 January 15, 2009

743 of 784 Final ReportEngineers. <http://www.saw.usace.army.mil/Dare%20County/Yelverton-ROD13081 DareCo.pdf> 13082
USACE (United States Army Corps of Engi neers), 2007: Activities Authorized by 13083 Nationwide Permit. 13084 <http://www.lrb.usace.army.mil/regulatory/nwp/NYNWP2007/NY NWP03.doc> 13085
USACE (United States Army Corps of E ngineers), 2008a: Project Fact Sheet: New 13086 Jersey Shore Protection, Lower Cape May Meadows – Cape May Point, NJ

. 13087 <http://www.nap.usace.army/mil/cenap-dp/projects/factsheets/NJLowe Cape May 13088 Meadows.pdf> 13089
USACE (United States Army Corps of Engineers), 2008b: Fire island Inlet to Montauk 13090 Point Reformulation Study, DRAFT . <http://www.nan.usace.army.mil/fimp/> 13091
USDOI (United States Department of the Inte rior), 2007: Letter from Willie Taylor, 13092 Director, Office of Environmental Policy and Compliance, DOI, to Gregory J. 13093 Thorpe, Ph.D., Manager, Project Development and Environmental Analysis 13094 Division, North Carolina Department of Transportation, re: Dr aft Environmental 13095 Impact Statement for NC-12 Replacement of Herbert C. Bonner Bridge (No. 11) 13096 Over Oregon Inlet, Dare County, North Carolina. 13097 <http://www.fws.gov/peaisland/images/doiletter-4-17-07.pdf> 13098
U.S. EPA (Environmental Protection Agency), 1989: The Potential Effects of Global 13099 Climate Change on the United States. EPA 230-05-89-052. U.S. Environmental 13100 Protection Agency, Washington, DC. 13101
U.S. EPA (Environmental Protection Agency), 2008: Background Documents 13102 Supporting Climate Change Science Progr am Synthesis and Assessment Product 13103 4.1: Coastal Elevations and Sens itivity to Sea Level Rise [Titus, J.G. and E.M. 13104 Strange (eds.)]. EPA 430R07004. U.S. Environmental Protection Agency, 13105 Washington, DC, 354 pp. 13106 <http://epa.gov/climatechange/e ffects/coastal/background.html> 13107CCSP 4.1 January 15, 2009

744 of 784 Final Report USFWS (United States Fish and Wildlife Serv ice), Undated(a): Cape May National 13108 Wildlife Refuge. < http:// www.fws.gov/northeast/capemay/> 13109
USFWS (United States Fish and Wi ldlife Service), Undated(b): Profile of the Plum Tree 13110 Island National Wildlife Refuge

. 13111 <http://www.fws.gov/refuges/profiles/index.cfm?id = 51512> 13112
USFWS (United States Fish and Wildlife Service), Undated©: John H. Chafee Coastal 13113 Barrier Resource System

. 13114 <http://www.fws.gov/habitatconservation/coastal_barrier.htm> 13115
USFWS (United States Fish a nd Wildlife Service), 1980: Atlantic coast ecological 13116 inventory: Wilmington . Washington, D.C.: No. 39074-A1-EI-250. 13117
USFWS (United States Fish a nd Wildlife Service), 1993: Species Account for the Red 13118 Wolf . ><http://www.fws.gov/cookeville/ docs/endspec/rwolfsa.html> 13119
USFWS (United States Fish a nd Wildlife Service), 1996: Piping Plover (Charadrius 13120 melodus) Atlantic Coast Population Revised Recovery Plan . Prepared by the 13121 Atlantic Coast Piping Plover Recovery T eam. U.S. Fish and Wildlife Service, 13122 Hadley, MA, 245 pp. 13123
USFWS (United States Fish a nd Wildlife Service), 1997: Significant Habitats and 13124 Habitat Complexes of the New York Bight Watershed . U.S. Fish and Wildlife 13125 Service, Charlestown, RI. <http://training.fws.gov/library/pubs5/begin.htm> 13126
USFWS (United States Fish and Wildlife Serv ice), 2002: Birds of Conservation Concern 13127 2002. Division of Migratory Bird Ma nagement, Arlington, VA. Table 30. 13128 <http://www.fws.gov/migratorybirds/reports/reports.html> 13129

USFWS (United States Fish a nd Wildlife Service), 2004a: 2002-2003 Status Update: 13130 U.S. Atlantic Coast Piping Plover Population . U.S. Fish and Wildlife Service, 13131 Sudbury, MA, 8 pp. 13132 <http://www.fws.gov/northeast/pipingplover/status/index.html> 13133CCSP 4.1 January 15, 2009

745 of 784 Final Report USFWS (United States Fish and Wildlife Servic e), 2004b: Eastern Shore of Virginia and 13134 Fisherman Island National Wildlife Ref uges Comprehensive Conservation Plan. 13135 Chapter 3: Refuge and Resource Descri ptions of Northeast Regional Office, 13136 Hadley, MA. <http://library.fws .gov/CCPs/eastshoreVA_index.htm> 13137

USFWS (United States Fish and Wildlife Serv ice), 2008: Blackwater National Wildlife 13138 Refuge. Wetland Restoration. <http:// www.fws.gov/blackwater/restore.html>. 13139 Last updated January 22, 2008. 13140
USGS (United States Geological Survey), Undated: Anacostia Freshwater Tidal 13141 Reconstructed Wetlands

. 13142 <http://www.pwrc.usgs.gov/resshow/hammerschlag/anacostia.cfm> 13143
VA DCR (Virginia Department of Conservation and Recreation), Undated(a): Parkers 13144 Marsh Natural Area Preserve Fact 13145 Sheet.<http://www.dcr.virgin ia.gov/natural_heritage/natur al_area_preserves/parke 13146 rs.shtml> 13147
VA DCR (Virginia Department of Conservation and Recreation), Undated(b) : Mutton 13148 Hunk Fen Natural Area Preserve. 13149 <http://www.dcr.virginia.gov/natural_her itage/natural_area_preserves/muttonhun 13150 k.shtml> 13151

VA DCR (Virginia Department of Conservati on and Recreation), 1999: Bethel Beach 13152 Natural Area Preserve, fact sheet. 13153 <http://www.dcr.virginia.gov/natural _heritage/documents/pgbethel.pdf> 13154
VA DCR (Virginia Department of Conservati on and Recreation), 2001: The Natural 13155 Communities of Virginia. Ecological Cl assification of Ecological Community 13156 Groups. First Approximation. Division of Natural Heritage Natural Heritage 13157 Technical Report 01-1, January 2001. 13158

VA PBB (Virginia Public Beach Board), 2000: 20 Years of Coastal Management. 13159 Richmond, Virginia: Board on Conservation and Development of Public Beaches. 13160CCSP 4.1 January 15, 2009

746 of 784 Final Report VBCP (Virginia Beach Comprehensive Plan), 2003: Introduction and General Strategy: 13161 Policy Document. 13162

* VIMS (Virginia Institute for Marine Scie nce), Undated: Chesapeake Bay National 13163 Estuarine Research Reserve in Virginia. Goodwin Islands. 13164 <http://www.vims.edu/cbnerr/reservesites/goodwin.htm> 13165

Walls , E.A., J. Berkson, and S.A. Smith, 2002: The horseshoe crab, Limulus polyphemus : 13166 200 million years of existence, 100 years of study. Reviews in Fisheries Science , 13167 10(1) , 39-73. 13168

Walz , K., E. Cronan, S. Domber, M. Serf es, L. Kelly, and K. Anderson, 2004: The 13169 Potential Impacts of Open Marsh Management (OMWM) on a Globally Imperiled 13170 Sea-level Fen in Ocean County, New Jersey . Prepared for the New Jersey 13171 Department of Environmental Protec tion, Coastal Management Office, 18 pp. 13172 Washington County , 2008: Return to the Heart of the Inner Banks. 13173 <http://www.originalwashington.com/> 13174

Watts , B.D., 1993: Effects of Marsh Size on Inci dence Rates and Avian Community 13175 Organization within the Lower Chesapeake Bay . Technical report CCBTR-93-03. 13176 Center for Conservation Biology, Colle ge of William and Mary, Williamsburg, 13177 VA, 53 pp. 13178

Watts , B.D., 2006: Synthesizing Information Resources for the Virginia Important Bird 13179 Area Program: Phase I, Delmarva Peninsula and Tidewater . Technical Report 13180 CCBTR-06-05. Center for Conservation Bi ology, College of William and Mary, 13181 Williamsburg, VA. 13182

Watts , B.D. and C. Markham, 2003: The Influence of Salinity on Diet, Prey Delivery, 13183 and Nestling Growth in Bald Eagles in the Lower Chesapeake Bay: Progress 13184 Report . Technical Report CCBTR-03-06. Ce nter for Conservation Biology, 13185 College of William and Mary, Williamsburg, VA, 5pp. 13186CCSP 4.1 January 15, 2009

747 of 784 Final Report Watts , B.D. and B.R. Truitt, 2002: Abundance of shorebirds along the Virginia barrier 13187 islands during spring migration. The Raven , 71(2), 33-39. 13188

* Weber , R.G., 2001: Preconstruction horseshoe crab egg density monitoring and habitat 13189 availability at Kelly Island, Port Mahon, and Broadkill Beach Study areas. 13190 Prepared for the Philadelphia District Corps of Engineers, Philadelphia, PA. 13191 December 2001. 13192 Weggel , J.R., S. Brown, J. Escajadillo, P. Br een, and E. L. Doheny, 1989: The cost of 13193 defending developed shorelines along shelte red water of the United States from a 13194 two meter rise in mean sea level. In: The Potential Effects of Global Climate 13195 Change on the United States. Appendix: B, Sea Level Rise . EPA 230-05-89-052. 13196 Environmental Protection Agency, Washington, DC, pp. 3-1 to 3-90. 13197 <http://epa.gov/climatechange/effects/coastal/appB.html> 13198
Weinstein , M.P., 1979: Shallow marsh habitats as primary nurseries for fishes and 13199 shellfish, Cape Fear River, North Carolina, United States. Fisheries Bulletin, 13200 77(2) , 339-357. 13201
Weinstein , M.P. and L.L. Weishar, 2002: Beneficial use of dredged material to enhance 13202 the restoration trajectories of formerly diked lands. Ecological Engineering , 13203 19(3) , 187-201. 13204
Weinstein , M.P., K.R. Phillip, and P. Goodwin, 2000: Catastrophes, near-catastrophes, 13205 and the bounds of expectation: Success criteria for macroscale marsh restoration. 13206 In: Concepts and Controversies in Tidal Marsh Ecology [Weinstein, M.P. and 13207 D.A. Kreeger (eds.)]. Kluwer Academic Publishers, Dordrecht, the Netherlands, 13208 pp. 777-804. 13209

* Wetlands Institute , Undated: Terrapin Conservation Program. 13210 <http://www.terrapinconservation.org>. 13211
White , C.P., 1989: Chesapeake Bay: Nature of the Estuary: A Field Guide . Tidewater 13212 Publishers, Centreville, MD, 212 pp. 13213CCSP 4.1 January 15, 2009

748 of 784 Final Report Wilcock , P.R., D.S. Miller, R.H. Shea, and R.T. Kerhin, 1998: Frequency of effective 13214 wave activity and the recession of coas tal bluffs: Calvert Cliffs, Maryland. 13215 Journal of Coastal Research , 14(1) , 256-268. 13216

York (York County, Virginia), 1999: Charting the Course to 2015: The York County 13217 Comprehensive Plan. Yorktown, VA. 13218

Zervas , C., 2004: North Carolina Bathymetry/To pography Sea Level Rise Project: 13219 Determination of Sea Level Trends . NOAA technical re port NOS CO-OPS 041. 13220 NOAA National Ocean Service, Silver Spring, MD, 31 pp. 13221 <http://tidesandcurre nts.noaa.gov/publica tions/techrpt41.pdf> 13222

13223 13224CCSP 4.1 January 15, 2009

749 of 784 Final Report 

## Appendix 2. Basic Approaches for Shoreline Change 13225 

## Projections 13226

Lead Author: Benjamin T. Gutierrez, USGS 13227 Contributing Authors: S. Jeffress Williams, USGS; E. Robert Thieler, USGS 13228 13229 While the factors that influen ce changes in shoreline position in response to sea-level rise 13230 are well known, it has been difficult to inco rporate this understa nding into quantitative 13231 approaches that can be used to as sess land loss over long time periods ( e.g. , 50 to 100 13232 years). The validity of some of the more common approaches discussed in this Appendix 13233 has been a source of debate in the scientif ic community (see Secti on 3.1). This Appendix 13234 reviews some basic approaches that have b een applied to evalua te the potential for 13235 shoreline changes over these time scales. 13236
13237 The Bruun Model. One of the most widely known models developed for predicting 13238 shoreline change driven by sea-level rise on sandy coas ts was formulated by Bruun 13239 (1962, 1988). This model is often referred to as the ‘Bruun rule’ and considers the two13240 dimensional shoreline response (vertical a nd horizontal) to a rise in sea level. A 13241 fundamental assumption of this model is th at over time the cross-shore shape of the 13242 beach, or beach profile, assumes an equili brium shape that translates upward and 13243 landward as sea level rises. Four additional assumptions of this model are that: 13244
1. The upper beach is eroded due to la ndward translation of the profile. 13245CCSP 4.1 January 15, 2009

750 of 784 Final Report 2. The material eroded from the upper beach is transported offshore and deposited 13246 such that the volume eroded from the upper beach equals the volume deposited 13247 seaward of the shoreline. 13248
3. The rise in the nearshore seabed as a result of deposition is equal to the rise in sea 13249 level, maintaining a constant water depth. 13250
4. Gradients in longshore tr ansport are negligible. 13251 Mathematically, the model is depicted as: 13252

S hB

L R   

* * (A2.1) 13253

where R is the horizontal re treat of the shore, h * is the depth of closure or depth where 13254 sediment exchange between the shore face and inner shelf is assumed to be minimal, B is 13255 the height of the berm, L * is the length of the beach profile to h * , and S is the vertical rise 13256 in sea level (Figure A2.1). This relationship can also be evaluated based on the slope of 13257 the shore face,  , as: 13258

S R    tan 1 (A2.2) 13259
For most sites, it has been found that general values of  and R are approximately 0.01 to 13260 0.02 and 50*S to 100*S, respectively (Wright, 1995; Komar, 1998; Zhang, 1998). 13261
13262 A few studies have been conducted to veri fy the Bruun Model (Schwartz, 1967; Hands, 13263 1980; also reviewed in SCOR , 1991; Komar, 1998; and Dean and Dalrymple, 2002). In 13264 other cases, some researchers have advocated th at there are several uncertainties with this 13265 approach, which limit its use in re al-world applications (Thieler et al. , 2000; Cooper and 13266 Pilkey, 2004, also reviewed in Dubois, 2002). Fi eld evaluations have also shown that the 13267CCSP 4.1 January 15, 2009

751 of 784 Final Report assumption of profile equilibrium can be difficult to meet (Riggs et al. , 1995; List et al. , 13268 1997). Moreover, the Bruun relationship neglects the contribution of longshore transport, 13269 which is a primary mechanism of sediment tr ansport in the beach environment (Thieler et 13270 al. , 2000) and there have been relatively few a ttempts to incorporat e longshore transport 13271 rates into this approach (Everts, 1985). 13272
13273 A number of investigators have expanded upon the Bruun rule or developed other models 13274 that simulate sea-level rise driven shoreline changes. Dean and Maurmeyer (1983) 13275 adapted and modified the Bruun rule to apply to barrier islands ( e.g. , the Generalized 13276 Bruun Rule). Cowell et al. (1992) developed the Shorelin e Translation Model (STM), 13277 which incorporated several parameters that characterize the influence of the geological 13278 framework into sea-level rise driven shor eline change for barr ier islands. Stolper et al. 13279 (2005) developed a rules-based geomorphic sh oreline change mode l (GEOMBEST) that 13280 simulates barrier island evolution in response to sea-level rise. While these models can 13281 achieve results consistent with the current und erstanding of sea-level rise driven changes 13282 to barrier island systems, there is still need for more research and testing against both the 13283 geologic record and present- day observations to advance scientific understanding and 13284 inform management. 13285CCSP 4.1 January 15, 2009

752 of 784 Final Report 13286 Figure A2.1 Illustration showing the Bruun Model and the basic dimensions of the shore that are used as 13287 model inputs. 13288 13289 Historical Trend Extrapolation. Another commonly used approach to evaluate potential 13290 shoreline change in the future relies on the calculation of shorelin e change rates based on 13291 changes in shoreline position over time. In th is approach, a series of shorelines from 13292 different time periods are assembled from maps for a particular area. In most cases, these 13293 shorelines are derived from either National Ocean Service T-sheets, aerial photographs, 13294 from Global Positioning System (GPS) surv eys, or lidar surveys (Shalowitz, 1964; 13295 Leatherman, 1983; Dolan et al. , 1991; Anders and Byrnes, 1991; Stockdon et al ., 2002). 13296 The historical shorelines are then used to estimate rates of change over the time period 13297 covered by the different shorelin es (Figure A2.2). Several sta tistical methods are used to 13298CCSP 4.1 January 15, 2009

753 of 784 Final Report calculate the shoreline change rates with th e most commonly used being end-point rate 13299 calculations or linear regression (Dolan et al. , 1991; Crowell et al. , 1997). The shoreline 13300 change rates can then be used to extra polate future changes in the shoreline by 13301 multiplying the observed rate of change by a sp ecific amount of time, typically in terms 13302 of years (Leatherman, 1990; Crowell et al. , 1997). More specific assumptions can be 13303 incorporated that include othe r factors such as the rate of sea-level rise or geological 13304 characteristics of an area (Leatherman, 1990; Komar et al. , 1999). 13305
13306 Because past shoreline positions are readily available from maps that have been produced 13307 over time, the extrapolation of historical tr ends to predict future shoreline position has 13308 been applied widely for coastal manageme nt and planning (Crowell and Leatherman, 13309 1999). In particular, this method is used to estimate building se tbacks (Fenster, 2005). 13310 Despite this, relatively few studies have inco rporated shoreline change rates into long13311 term shoreline change predictions to evaluate sea-level rise impacts, particularly for cases 13312 involving accelerated rates of sea-level rise (Kana et al ., 1984; Leatherman, 1984). 13313 13314 Historical trend analysis has evolved over the last few decades based on earlier efforts to 13315 investigate shoreline change (described in Crowell et al. , 2005). Since the early 1980s, 13316 computer based Geographical Information Syst em (GIS) software has been developed to 13317 digitally catalog shoreline data and facilitate the quantificati on of shoreline change rates 13318 (May et al. , 1982; Leatherman, 1983; Thieler et al. , 2005). At the same time, thorough 13319 review and critique of the procedures that are employed to make these estimates have 13320 been conducted (Dolan et al. , 1991; Crowell et al. , 1991, 1993, 1997; Douglas et al. , 13321CCSP 4.1 January 15, 2009

754 of 784 Final Report 1998; Douglas and Crowell, 2000; Honeycutt et al ., 2001; Fenster et al. , 2001; Ruggiero 13322 et al. , 2003; Moore et al. , 2006; Genz et al. , 2007). 13323
13324 Recently, a national scale assessment of shoreline changes that have occurred over the 13325 last century has been carr ied out by the U.S. Geologica l Survey (Gulf Coast: Morton et 13326 al. , 2004; southeastern U.S. coast: Morton and Miller, 2005; California coast: Hapke et 13327 al. , 2006). In addition, efforts are ongoing to complete similar analyses for the 13328 northeastern, mid-Atlantic, Pacific Northwest, and Alaskan coasts. 13329
13330

13331 Figure A2.2 Aerial photograph of Fire Island, New York showing former shoreline positions and how 13332 these positions are used to calculate long-term shorelin e change rates using linear regression. The inset box 13333 shows the shoreline positions at several points in time over the last 170 years. From the change in position 13334 with time, an average rate of re treat can be calculated. This is noted by the slope of the line, m . The red line 13335 in the inset box indicates the best fit line while the dashed lines specify the 95 percent confidence interval 13336 for this fit. Photo source: State of New York GIS. 13337 13338CCSP 4.1 January 15, 2009

755 of 784 Final Report The Sediment Budget. Another approach to shorel ine change assessment involves 13339 evaluating the sediment mass balance, or se diment budget, for a given portion of the 13340 coast (Bowen and Inman, 1966; Komar, 1996; List, 2005; Rosati, 2005), as shown in 13341 Figure A2.3. Using this method, the gains a nd losses of sediment to a portion of the 13342 shore, often referred to as a control vo lume, are quantified and evaluated based on 13343 estimates of beach volume change. Changes in the volume of sand for a particular setting 13344 can be identified and evaluated with respect to adjacent portions of the shore and to 13345 changes in shoreline position ov er time. One challenge related to this method is obtaining 13346 precise measurements that minimize error since small vertical changes over these 13347 relatively low gradient shoreline areas can result in large volumes of material (NRC, 13348 1987). To apply this approach, accurate measurements of coastal landforms, such as 13349 beach profiles, dunes, or cliff positions, are needed. Collection of such data, especially 13350 those on the underwater portions of the beach profile, is difficult. In addition, high13351 density measurements are needed to evaluate changes from one section of the beach to 13352 the next. While the results ca n be useful to understand where sediment volume changes 13353 occur, the lack of quality data and the expens e of collecting the data limit the application 13354 of this method in many areas. 13355CCSP 4.1 January 15, 2009

756 of 784 Final Report 13356 13357 Figure A2.3 Schematic of the coastal sediment budget (modified from Komar, 1996). Using the sediment 13358 budget approach, the gains and losse s of sediment from the beach and nearshore regions are evaluated to 13359 identify possible underlying causes for shoreline changes. In this schematic the main sediment gains are 13360 from: cliff erosion, coastal rivers, longshore transport, and cross-shore sediment transport from the 13361 continental shelf. The main sediment losses are due to: offshore transport from the beach to the shelf and 13362 wind transport from the beach to coastal dunes. 13363 13364 The Coastal Vulnerability Index. One approach that has been developed to evaluate the 13365 potential for coastal changes is through the development of a Coastal Vulnerability Index 13366 (CVI, Gornitz and Kanciruk, 1989; Gornitz, 1990; Gornitz et al ., 1994; Thieler and 13367 Hammar-Klose, 1999). Recently, the U.S. Geologi cal Survey (USGS) used this approach 13368 to evaluate the potential vulnerability of th e U.S. coastline on a national scale (Thieler 13369 and Hammar-Klose, 1999) and on a more deta iled scale for the U.S. National Park 13370 Service (Thieler et al. , 2002). The USGS approach redu ced the index to include six 13371 variables (geomorphology, shor eline change, coastal slope, relative sea-level change, 13372 significant wave height, and tidal range) which were consid ered to be the most important 13373CCSP 4.1 January 15, 2009

757 of 784 Final Report in determining a shoreline’s susceptibility to sea-level rise (Thiel er and Hammar-Klose, 13374 1999). The CVI is calculated as: 13375

6 fedcba CVI   (A2.3) 13376

where a is the geomorphology, b is the rate of shoreline change, c is the coastal slope, d 13377 is the relative sea-level change, e is the mean significant wave height, and f is the mean 13378 tidal range. 13379
13380 The CVI provides a relatively simple numerical basis for ranking sections of coastline in 13381 terms of their potential for change that can be used by managers to identify regions where 13382 risks may be relatively high. The CVI results are displayed on maps to highlight regions 13383 where the factors that contribute to shorel ine changes may have the greatest potential to 13384 contribute to changes to shor eline retreat (Figure A2.4). 13385CCSP 4.1 January 15, 2009

758 of 784 Final Report 13386 Figure A2.4 Coastal Vulnerability Index (CVI) calculated fo r Assateague Island National Seashore in 13387 Maryland. The inner most color-coded bar is the CVI estimate based on the other input factors (1 through 13388 6). From Pendleton et al . (2004). 13389 13390CCSP 4.1 January 15, 2009

759 of 784 Final Report APPENDIX 2 REFERENCES 13391 * Indicates non-peer reviewed literature; available upon request 13392 13393
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Bowen , A.J. and D.L. Inman, 1966: Budget of Littoral Sands in the Vicinity of Point 13396 Arguello, California . Coastal Engineering Research Center technical memoradum 13397 no. 19. [U.S. Army Corps of Engi neers, Washington, DC], 56 pp. 13398

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Bruun , P., 1988: The Bruun rule of erosion by se a-level rise: a discussion on large scale 13401 two- and three-dimensional usages. Journal of Coastal Research , 4(4) , 627-648. 13402 Cooper , J.A.G. and O.H. Pilkey, 2004: Sea-leve l rise and shoreline retreat: time to 13403 abandon the Bruun Rule. Global and Planetary Change , 43(3-4) , 157-171. 13404
Cowell , P.J., P.S. Roy, and R.A. Jones, 1992: Shoreface translation model: computer 13405 simulation of coastal-sand-body response to sea level rise. Mathematics and 13406 Computers in Simulation , 33(5-6) , 603-608. 13407
Crowell , M. and S.P. Leatherman (eds.) , 1999: Coastal erosion mapping and 13408 management. Journal of Coastal Research , Special issue 28 , 196 pp. 13409
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760 of 784 Final Report Crowell , M., S.P. Leatherman, and B. Douglas, 2005: Erosion: histor ical analysis a 13417 forecasting. In: Encyclopedia of Coastal Science [Schwartz, M.L. (ed.).] Springer, 13418 the Netherlands, pp. 846-850. 13419

Dean , R.G. and R.A. Dalrymple, 2002: Coastal Processes with Engineering 13420 Applications . Cambridge University Press, New York, 475 pp. 13421

Dean , R.G. and E.M. Maurmeyer, 1983: Mode ls of beach profile response. In: CRC 13422 Handbook of Coastal Processes [Komar, P.D. (ed.)]. CRC Press, Boca Raton, FL, 13423 pp. 151-165. 13424

Dolan , R., M.S. Fenster, and S.J. Holme, 1991: Temporal analysis of shoreline recession 13425 and accretion. Journal of Coastal Research , 7(3) , 723-744. 13426 Douglas , B.C. and M. Crowell, 2000: Long-term shoreline position prediction and error 13427 propagation. Journal of Coastal Research , 16(1), 145-152. 13428 Douglas , B.C., M. Crowell, and S.P. Leathe rman, 1998: Consideration for shoreline 13429 position prediction. Journal of Coastal Research , 14(3) , 1025-1033. 13430
Dubois , R.N., 2002: How does a barrier shor eface respond to a sea-level rise? Journal of 13431 Coastal Research , 18(2) , iii-v. 13432

Everts , C.H., 1985: Sea-level rise e ffects on shoreline position. Journal of Waterway, 13433 Port, and Coastal Engineering , 111(6) , 985-999. 13434

Fenster , M.S., 2005: Setbacks. In: Encyclopedia of Coastal Science [Schwartz, M.L. 13435 (ed.)]. Springer, Dordrecht, the Netherlands, pp. 863-866. 13436

Fenster , M.S., R. Dolan, and R.A. Morton, 2001: Coastal storms and shoreline change: 13437 signal or noise? Journal of Coastal Research , 17(3) , 714-720. 13438
Genz , A.S., C.H. Fletcher, R.A. Dunn, L. N. Frazer, and J.J. Rooney, 2007: The 13439 predictive accuracy of s horeline change rate methods and alongshore beach 13440 variation on Maui, Hawaii. Journal of Coastal Research , 23(1) , 87-105. 13441CCSP 4.1 January 15, 2009

761 of 784 Final Report Gornitz , V.M., 1990: Vulnerability of the east co ast, USA to future sea-level rise. 13442 Journal of Coastal Research , Special issue 9 , 201-237. 13443

* Gornitz , V.M. and P. Kanciruk, 1989: Assessment of global coastal hazards from sea 13444 level rise. In: Coastal Zone ’89: Proceedings of the Sixth Symposium on Coastal 13445 and Ocean Management , July 11-14, 1989, Charleston, SC. American Society of 13446 Civil Engineers, New York, pp. 1345-1359. 13447
Gornitz , V.M., R.C. Daniels, T.W. White, and K.R. Birdwell, 1994: The development of 13448 a coastal risk assessment database: vulner ability to sea-level rise in the U.S. 13449 southeast. Journal of Coastal Research , Special issue 12 , 327-338. 13450

Hands , E.B., 1980: Prediction of Shore Retreat and Ne arshore Profile Adjustments to 13451 Rising Water Levels on the Great Lakes. Coastal Engineering Research Center 13452 technical paper TP 80-7. U.S. Army Corp s of Engineers, Ft. Belvoir, VA, 199 pp. 13453 Hapke , C.J., D. Reid, B.M. Richmond, P. Ruggiero, and J. List, 2006: National 13454 Assessment of Shoreline Change: Part 3 Historical Shoreline Change and 13455 Associated Land Loss along Sandy Shore lines of the California Coast. U.S. 13456 Geological Survey open-file report 2 006-1219. U.S. Geological Survey, Reston 13457 VA, 72 pp. <http://purl.access.gpo.gov/GPO/LPS86269> 13458 Honeycutt , M.G., M. Crowell, and B.C. Douglas , 2001: Shoreline position forecasting: 13459 impacts of storms, rate-calculation methodologies, and temporal scales. Journal of 13460 Coastal Research , 17(3) , 721-730. 13461

Kana , T.W., J Michel, M.O. Hayes, and J.R. Jensen, 1984: The physical impact of sea 13462 level rise in the area of Ch arleston, South Carolina. In: Greenhouse Effect and 13463 Sea-level Rise: A Challenge for this Generation [Barth, M.C. and J.G. Titus 13464 (eds.)]. Van Nostrand Reinhold, New York, pp. 105-150. 13465

Komar , P.D., 1996: The budget of littoral sedi ments concepts and applications. Shore 13466 and Beach , 64(3) , 18-26. 13467CCSP 4.1 January 15, 2009

762 of 784 Final Report Komar , P.D., 1998: Beach Processes and Sedimentation . Prentice Hall, Upper Saddle 13468 River, NJ, 2nd edition, 544 pp. 13469

Komar , P.D., W.G. McDougal, J.J. Marra, and P. Ruggiero, 1999: The rational analysis 13470 of setback distances: applica tions to the Oregon coast. Shore and Beach , 67(1) , 13471 41-49. 13472

Leatherman , S.P., 1983: Shoreline mapping: a comparison of techniques. Shore and 13473 Beach , 51(3) , 28-33. 13474

Leatherman , S.P., 1984: Coastal geomorphic responses to sea level rise: Galveston Bay, 13475 Texas. In: Greenhouse Effect and Sea-level Rise: A Challenge for This 13476 Generation [Barth, M.C. and J.G. Titus (e ds.)]. Van Nostrand Reinhold, New 13477 York, pp. 151-178. 13478

Leatherman , S.P., 1990: Modeling shore response to sea-level rise on sedimentary 13479 coasts. Progress in Physical Geography , 14(4) , 447-464. 13480
List , J.H., 2005: The sediment budget. In: Encyclopedia of Coastal Science [Schwartz, 13481 M.L. (ed.)]. Springer, Dordrecht, the Netherlands, pp. 846-850. 13482
List , J.H., A.H. Sallenger, M.E. Hansen, and B.E. Jaffe, 1997: Accelerated relative sea13483 level rise and rapid coastal erosion: testing a causal re lationship for the Louisiana 13484 barrier islands. Marine Geology, 140(3-4) , 347-365. 13485 May , S., W. Kimball, N. Grandy, and R. Do lan, 1982: The coastal erosion information 13486 system (CEIS). Shore and Beach , 50(1) , 19-25. 13487

Moore , L., P. Ruggiero, and J. List, 2006: Comparing mean high water and high water 13488 line shorelines: Should proxy-datum offsets be incorporated in shoreline change 13489 analysis? Journal of Coastal Research , 22(4) , 894-905. 13490

Morton , R.A. and T.L. Miller, 2005: National Assessment of Shoreline Change: Part 2, 13491 Historical Shoreline Changes and Associ ated Coastal Land Loss along the U.S. 13492 Southeast Atlantic Coast. U.S. Geological Survey open-file report 2005-1401. 13493CCSP 4.1 January 15, 2009

763 of 784 Final Report U.S. Geological Survey, St. Petersburg, FL, 35 pp. 13494 <http://pubs.usgs.gov/of/2005/1401/> 13495

Morton , R.A., T.L. Miller, and L.J. Moore, 2004: National Assessment of Shoreline 13496 Change: Part 1, Historical Shoreline Changes and Associated Coastal Land Loss 13497 along the U.S. Gulf of Mexico . U.S. Geological Survey open file report 2004- 13498 1043. U.S. Geological Survey, St. Petersburg, FL, 44 pp. 13499 <http://pubs.usgs.gov/of/2004/1043/> 13500
NRC (National Research Council), 1987: Responding to Changes in Sea Level: 13501 Engineering Implications . National Academy Press, Washington DC, 148 pp. 13502

Pendleton , E.A., S.J. Williams, and E.R. Thieler, 2004: Coastal Vulnerability 13503 Assessment of Fire Island National Seashore (ASIS) to Sea-level Rise . U.S. 13504 Geological Survey open-file report 04- 1020. [U.S. Geological Survey, Reston, 13505 VA], 20 pp. <http://pubs. usgs.gov/of/2004/1020/> 13506 Riggs , S.R., W.J. Cleary, and S.W. Snyder, 1995: Influence of inherited geologic 13507 framework upon barrier beach morphology and shoreface dynamics. Marine 13508 Geology , 126(1-4) , 213-234. 13509
Rosati , J.D., 2005: Concepts in sediment budgets. Journal of Coastal Research, 21(2) , 13510 307-322. 13511 Ruggiero , P., G.M. Kaminsky, and G. Gelf enbaum, 2003: Linking proxy-based and 13512 datum-based shorelines on a high-energy coastline: Implications for shoreline 13513 change analyses. Journal of Coastal Research , Special issue 38 , 57-82. 13514
Schwartz , M.L., 1967: The Bruun theory of sea-leve l rise as a cause of shore erosion. 13515 Journal of Geology , 75(1) , 76-92. 13516
SCOR (Scientific Committee on Ocean Research) Working Group 89, 1991: The 13517 response of beaches to s ea level changes: a review of predictive models. Journal 13518 of Coastal Research , 7(3) , 895-921. 13519CCSP 4.1 January 15, 2009

764 of 784 Final Report Shalowitz , A.L., 1964: Shore and Sea Boundaries; With Special Reference to the 13520 Interpretation and Use of Coast and Geodetic Survey Data . Publication 10-1. 13521 U.S. Department of Commerce, Coast and Geodetic Survey, Washington, DC, 13522 749 pp. 13523
Stockdon , H.F., A.H. Sallenger, J.H. List, and R.A. Holman, 2002: Estimation of 13524 shoreline position and change using airborne topographic Lidar data. Journal of 13525 Coastal Research , 18(3) , 502-513. 13526 Stolper , D., J.H. List, and E.R. Thieler, 2005: Simulating the evolution of coastal 13527 morphology and stratigraphy with a ne w morphological-behavior model 13528 (GEOMBEST). Marine Geology , 218(1-4) , 17-36. 13529
Thieler , E.R. and E. Hammar-Klose, 1999: National Assessment of Coastal Vulnerability 13530 to Sea-level Rise--Preliminary Re sults for U.S. Atlantic Coast. U.S. Geological 13531 Survey open-file report 99-593. U.S. Geological Survey, Reston, VA, 1 sheet. 13532 <http://purl.usgs.gov/of/1999/of99-593/> 13533
Thieler , E.R., O.H. Pilkey, R.S. Young, D.M. Bush, and F. Chai, 2000: The use of the 13534 mathematical models to predict beach behavior for U.S. coastal engineering: a 13535 critical review. Journal of Coastal Research , 16(1) , 48-70. 13536
Thieler , E.R., S.J. Williams, and R. Beavers, 2002: Vulnerability of U.S. National Parks 13537 to Sea-Level Rise and Coastal Change . U.S. Geological Survey fact sheet FS 095- 13538 02. [U.S. Geological Survey, Reston, VA], 2 pp. <http://pub s.usgs.gov/fs/fs095- 13539 02/> 13540
Thieler , E.R., E.A. Himmelstoss, J.L. Zichichi, and T.L. Miller, 2005: Digital Shoreline 13541 Analysis System (DSAS) Version 3.0; An ArcGIS© Extension for Calculating 13542 Shoreline Change . U.S. Geological Survey ope n-file report 2005-1304. U.S. 13543 Geological Survey, Reston, VA. <http://pubs.usgs.gov/of/2005/1304/> 13544 Wright , L.D., 1995: Morphodynamics of Inner Continental Shelves . CRC Press, Boca 13545 Raton, FL, 241 pp. 13546CCSP 4.1 January 15, 2009

765 of 784 Final Report * Zhang , K., 1998: Twentieth Century Storm Activity and Sea Level Rise along the U.S. 13547 East Coast and Their Impact on Shoreline Position . Ph.D. dissertation, 13548 Department of Geography. University of Maryland, College Park, 266 leaves. 13549

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## Glossary 13551
access, lateral 13552 the right to walk or otherwise move along a shore, once someone has reached the shore 13553 13554 access, perpendicular 13555 a legally permissible means of reaching the shore from dry land 13556 13557 access point 13558 a place where anyone may legally gain access to the shore; usually a park, the end of a 13559 public street, or a public path; a place where perpendicular access is provided 13560 13561 accretion, lateral 13562 the extension of land by natural forces acting over a long period of time, as on a beach by 13563 the washing-up of sand from the sea or on a floodplain by the accumulation of sediment 13564 deposited by a stream 13565 13566 accretion, vertical 13567 the vertical accumulation of a sedimentar y deposit; the increase in thickness of a 13568 sediment body as a result of sediment accumulation 13569 13570 active margin 13571 a continental margin character ized by volcanic activity and earthquakes occurring where 13572 the edges of lithospheric plates are colliding; because these margins are largely confined 13573 to the rim of the Pacific, this type of margin is also referred to as a Pacific margin; 13574 compare with passive margin 13575 13576 armoring 13577 the placement of fixed engineering structures , typically rock or c oncrete, on or along the 13578 shoreline to mitigate the effects of coastal er osion and protect structures; such structures 13579 include seawalls , revetments , bulkheads , and rip-rap (loose boulders) 13580 13581 astronomical tides 13582 the alternating rise and fall of the ocean su rface and connected waters, such as estuaries 13583 and gulfs, that result from the gravita tional forces of the moon and sun 13584 13585 avulsion 13586 a sudden cutting off or separation of land by a flood or by and abrupt change in the 13587 course of a stream, as by a stream breaking through a meander or by a sudden change in 13588 current whereby a stream deserts its old cha nnel for a new one; OR rapid erosion of the 13589 shore by waves during a storm 13590 13591 barrier island, (or sometimes just barrier) 13592CCSP 4.1 January 15, 2009

767 of 784 Final Report a long, narrow coastal sandy island that is a bove high tide and parallel to the shore, and 13593 that commonly has dunes, vegetated zone s, and swampy terraces extending landward 13594 from the beach 13595 13596 barrier island roll-over 13597 the landward migration or la ndward transgre ssion of a barrier island , accomplished 13598 primarily over decadal or longer time scal es through the process of storm overwash, 13599 periodic inlet formation, and wind-blown transport of sand 13600 barrier migration 13601 refers to the movement of an entire barrier island or barrier spit in response to sea-level 13602 rise, changes in sediment supply, storm surges or waves, or some combination of these 13603 factors 13604 13605 barrier raising 13606 adding sediment to a barrier island or spit to increase its elevation; it is rarely done on a 13607 large scale ( e.g ., the Galveston, Texas barrier island was raised after the hurricane of 13608 1900) but individual lot owners so metimes import sediment to add elevation to their land, 13609 especially if the land is prone to flooding 13610 13611 barrier spit 13612 a barrier island that is connect ed at one end to the mainland 13613 13614 bathymetry 13615 the measurement of ocean depths and the mapping of the topography of the seafloor 13616 13617 beach 13618 the unconsolidated material that covers a gently sloping zone extending landward from 13619 the low water line to the pl ace where there is a definite change in material or 13620 physiographic form (such as a cliff), or to the line of permanent ve getation (usually the 13621 effective limit of the highest storm waves) 13622 13623 beach nourishment 13624 the addition of sand, often dre dged from offshore, to an erod ing shoreline to enlarge or 13625 create a beach area, offering both tem porary shore protection and recreational 13626 opportunities 13627 13628 berm 13629 a commonly occurring, low, impermanent, ne arly horizontal ledge or narrow terrace on 13630 the backshore of a beach, formed of materi al thrown up and deposited by storm waves 13631 13632 bluff 13633 a high bank or bold headland with a broad, precipitous, sometimes rounded cliff face 13634 overlooking a plain or body of water 13635 13636 breakwater 13637CCSP 4.1 January 15, 2009

768 of 784 Final Report an offshore structure (such as a wall or jetty) that, by break ing the force of the waves, 13638 protects a harbor, anchorage, beach or shore area 13639 13640 breach 13641 (n.) a channel through a barrier spit or island typically formed by storm waves, tidal 13642 action, or river flow; breaches commonly occur during high storm surge cause by a 13643 hurricane or extra-tropical storm; (v.) to cut a deep ope ning in a landform 13644 13645 bulkhead 13646 a structure or partition to retain or prevent sliding of the land; a secondary purpose is to 13647 protect uplands against da mage from wave action 13648 13649 coastal plain 13650 any lowland area bordering a sea or ocean, exte nding inland to the nearest elevated land, 13651 and sloping very gently seaward 13652 13653 coastal squeeze 13654 the narrowing, potentially to the point of failure or elimination, of an environmental 13655 system (typically a beach or marsh) that is trapped between the transgressing sea on one 13656 side and an impassable barrier ( e.g ., a sea wall or bulkhead) on the other 13657 13658 coastal zone 13659 the area extending from the ocean inland across the region directly influenced by marine 13660 processes 13661 13662 coastline 13663 the line that forms the boundary between the coast and the shore or the line that forms the 13664 boundary between the land and the water 13665 13666 continental shelf 13667 the gently sloping underwater region at the e dge of the continent th at extends from the 13668 beach to where the steep continental slope begi ns, usually at depths greater than 300 feet 13669 13670 contour interval 13671 the difference in elevations of ad jacent contours on a topographic map 13672 13673 datum 13674 a quantity, or a set of quantities, that se rves as a basis for the calculation of other 13675 quantities; in terms of surveying and mapping, a datum is a point, line or surface used as 13676 a reference in measuring locations or elevations 13677 13678 delta 13679 a low relief landform composed of sediment s deposited at the mouth of a river that 13680 commonly forms a triangular or fan-shaped plain of considerable area crossed by many 13681 channels from the main river; forms as the result of accumulation of sediment supplied by 13682 the river in such quantity that it is not removed by tidal or wave-driven currents 13683CCSP 4.1 January 15, 2009

769 of 784 Final Report 13684 DEM (digital elevation model) 13685 the digital representation of the ground surf ace or terrain using a set of elevation data 13686 13687 deposition 13688 the laying, placing, or throwing down of any material; typically re fers to sediment 13689 13690 depth of closure 13691 a theoretical depth below which sediment exchange between the nearshore (beach and 13692 shoreface) and the continental shel f is deemed to be negligible 13693 13694 dike 13695 a wall generally of earthen ma terials designed to prevent the permanent submergence of 13696 lands below sea level, tidal flooding of lands between sea level and spring high water, or 13697 storm-surge flooding of the coastal floodplain 13698 13699 discount rate 13700 13701 downdrift 13702 refers to the location of one s ection or feature along the coast in relation to another; often 13703 used to refer to the direction of net longs hore sediment transport between two or more 13704 locations ( i.e ., downstream) 13705 13706 dredge and fill 13707 a process by which channels are dredged through wetlands or uplands to allow small boat 13708 navigation, and dredge spoil is placed on the adjacent land area to raise the land high 13709 enough to allow development; sometimes referred to as “lagoon development” or “canal 13710 estates”; used extens ively before the 1970s 13711 13712 dredge spoil disposal (d redged material placement) 13713 dredged material, or spoil, is material c onsisting of sediment or rock, excavated or 13714 dredged from an underwater location and removed to a placement site or disposal area; in 13715 the United States, designated areas must be coordinated with the Environmental 13716 Protection Agency and resource agencies such as the U.S. Fish and Wildlife Service and 13717 the National Marine Fisheries Service for environmental compliance, and with local 13718 interests for capacity and acceptability 13719 13720 dune 13721 a low mound, ridge, bank or hill of loose, wind blown material (gen erally sand) either 13722 bare or covered with vegetation, capable of movement from place to place but typically 13723 retaining a characteristic shape 13724 13725 ebb current 13726 the tidal current associated with the decrea se in height of the tide, generally moving 13727 seaward or down a tidal river or estuary 13728 13729CCSP 4.1 January 15, 2009

770 of 784 Final Report ebb-tide delta 13730 a large sand shoal commonly deposited at the mouths of tidal inlets formed by ebbing 13731 tidal currents and modified in shape by waves 13732 13733 erosion 13734 the mechanical removal of sedimentary mate rial by gravity, runni ng water, moving ice, 13735 or wind; in the context of coastal settings erosion refers to the landward retreat of a 13736 shoreline indicator such as the water line, th e berm crest, or the vegetation line; the loss 13737 occurs when sediments are entrained into the water column and transported from the 13738 source 13739 13740 erosion-based setback 13741 a setback equal to an estimated annual eros ion rate multiplied by a number of years set by 13742 statute or regulation ( e.g. , 30 years) 13743 13744 estuary 13745 a semi-enclosed coastal body of water which has a free connection with the open sea and 13746 within which sea water is measurably diluted with freshwater from land drainage; an inlet 13747 of the sea reaching into a river valley as far as the upper limit of tidal rise, usually being 13748 divisible into three sectors; (a) a marine or lower estuary, in free connection with the 13749 open sea; (b) a middle estuary subject to st rong salt and freshwater mixing; and (c) an 13750 upper or fluvial estuary, characterized by fres h water but subject to daily tidal action; 13751 limits between these sectors are variable, and subject to constant changes in the river 13752 discharge 13753 13754 eustatic sea-level rise 13755 refers to worldwide rise of sea level that affects all oceans; eustatic rise has various 13756 causes, but typically result from thermal e xpansion of ocean waters, and additions of 13757 water from glaciers, ice caps, and ice sheets 13758 13759 extra-tropical storm 13760 refers to cyclonic weather systems, occurring in the middle or high latitudes ( e.g ., 13761 poleward of the tropics) that are generated by colliding airmasses; these weather systems 13762 often spawn large storms occurring between late fall and early spring 13763 13764 fetch 13765 the area of the open ocean over the surface of which the winds blow with constant speed 13766 and direction, generating waves 13767  13768 flood current 13769 the tidal current associated with the increas e in height of the tide, generally moving 13770 landward or up a tidal river or estuary 13771 13772 flood-tide delta 13773 a large sand shoal commonly deposited on the landward si de of a tidal inlet formed by 13774 flooding tidal currents 13775CCSP 4.1 January 15, 2009

771 of 784 Final Report 13776 floodproofing 13777 a technique that is intended to limit the amount of damage that will occur to a building or 13778 its contents during a flood (see also dry floodproofing and wet floodproofing ) 13779 13780 geologic framework 13781 refers to the underlying geologi cal setting, structure, and lithology (rock/sediment type) 13782 in a given area 13783 13784 geomorphic or geomorphology 13785 the external structure, form, and arrangement of rocks or sediments in relation to the 13786 development of the su rface of the earth 13787 13788 glacial rebound 13789 uplift of land following deglaciation due to the mass of the ice be ing removed from the 13790 land surface which causes an isostatic response of the lithosphere 13791 13792 global sea-level rise 13793 the worldwide average rise in mean sea level (see eustatic sea level ) 13794 13795 groin 13796 an engineering structure oriented perpendicular to the coast, used to accumulate littoral 13797 sand by interrupting longshore transport proc esses; often constructed of concrete, 13798 timbers, steel, or rock 13799 13800 high marsh 13801 the part of a marsh that lies between the low marsh and the marsh’s upland border; this 13802 area can be expansive, extendi ng hundreds of yards inland from the low marsh area; soils 13803 here are mostly saturated but only fl ooded during higher-than-average tides 13804 13805 hydrodynamic climate 13806 the characteristics of nearshore or continental shelf currents in an area that typically result 13807 from waves, tides, and weather systems 13808 13809 inlet 13810 a small, narrow opening, recess, indentation, or other entrance into a coastline or shore of 13811 a lake or river through which water penetrates landward, commonly refers to a waterway 13812 between two barrier islands that connects the sea and a lagoon 13813 13814 intertidal zone 13815 see littoral 13816 13817 inundation 13818 refers to the submergence of land by water 13819 13820 isostasy 13821CCSP 4.1 January 15, 2009

772 of 784 Final Report equilibrium condition whereby portions of the Earth’s crust are comp ensated (floating) 13822 by denser material below 13823 13824 jetty 13825 an engineering structure built at the mouth of a river or tidal inlet stabilize a channel for 13826 navigation; designed to prevent shoaling of a channel by littoral materials and to direct 13827 and confine the stream or tidal flow 13828 13829 lagoon 13830 a shallow coastal body of seawater that is se parated form the open ocean by a barrier or 13831 coral reef; the term is commonly used to define the s hore-parallel body of water behind a 13832 barrier island or barrier spit 13833 13834 levee 13835 a wall, generally of earthen materials, designe d to prevent riverine flooding after periods 13836 of exceptional rainfall 13837 13838 lidar (LIght Detection And Ranging) 13839 a remote sensing instrument that uses laser light pulses to measure the elevation of the 13840 land surface with a high degree of accuracy and precision 13841 13842 lithology 13843 the description of rocks on the basis of charact eristics such as color, mineral composition, 13844 and grain size 13845 13846 lithosphere 13847 the solid portion of the Earth, including the crust and part of the upper mantle 13848 13849 littoral 13850 zone between high and low tide in coastal waters or the shoreline of a freshwater lake 13851 13852 littoral cell 13853 a section of coast for which sediment tran sport processes can be isolated from the 13854 adjacent coast; within each littoral cell, a se diment budget can be defined that describes 13855 sinks, sources, and internal fluxes 13856 13857 littoral drift 13858 the sedimentary material moved in the litto ral zone under the influence of waves and 13859 currents 13860 13861 littoral transport 13862 the movement of littoral drif t in the littoral zone by waves and currents; includes 13863 movement parallel and pe rpendicular to the shore 13864 13865 littoral zone 13866 a term describing the region on the shore o ccurring between high a nd low water marks 13867CCSP 4.1 January 15, 2009

773 of 784 Final Report 13868 living shoreline 13869 refers to a shore protection concept wh ere some or all of the environmental 13870 characteristics of a natural shoreline are re tained as the position of the shore changes 13871 13872 long lived 13873 having a long lifetime or a long expected lifetime; long-lived infrastructure means 13874 infrastructure that is likely to be in service for a long time 13875 13876 longshore current 13877 an ocean current in the littoral zone that moves parallel to the shoreline, produced by 13878 waves approaching at an angle to the shoreline 13879 longshore transport 13880 movement of sediment parallel to the shoreline in the surf zone by wave suspension and 13881 the longshore current 13882 13883 low marsh 13884 the seaward edge of a salt marsh, usually a narrow band along a creek or ditch which is 13885 flooded at every high tide and e xposed at low tide (also see high marsh for comparison) 13886 13887 marsh 13888 a frequently or continually inundated wetla nd characterized by herbaceous vegetation 13889 adapted to saturated soil conditions (see also salt marsh ) 13890 13891 mean high water 13892 a tidal datum; the average height of high water levels observed over a 19-year period 13893 13894 mean higher high water 13895 the average of the higher high water height of each tidal day observed over the national 13896 tidal datum epoch (see national tidal datum epoch 13897 13898 mean sea level 13899 the 'still water level' ( i.e. , the level of the sea with high frequency motions such as wind 13900 waves averaged out) averaged over a period of ti me such as a month or a year, such that 13901 periodic changes in sea level ( e.g ., due to the tides) are also averaged out; the values of 13902 MSL are measured with respec t to the level of marks on land (called 'benchmarks') 13903 13904 metadata 13905 a file of information which captures the basi c characteristics of a data or information 13906 resource; representing the who, what, when, where, why and how of the data resource; 13907 geospatial metadata are used to documen t geographic digital resources such as 13908 Geographic Information System (GIS) files, geospatial databases, and earth imagery 13909 13910 metes and bounds 13911 the boundary lines and limits of a tract that is described and char acterized by placing all 13912 data in the tract description as opposed to other references such as maps or plats 13913CCSP 4.1 January 15, 2009

774 of 784 Final Report 13914 mixed energy coast 13915 a coast in which the coastal landforms are shaped by a combination of wave and tidal 13916 currents 13917 13918 moral hazard 13919 a circumstance in which insurance, lending pr actices, or subsidies designed to protect 13920 against a specified hazard induce people to ta ke measures that increase the risk of that 13921 hazard 13922 13923 mudflat 13924 a level area of fine silt and clay along a shore alternately covered and uncovered by the 13925 tide or covered by shallow water 13926 13927 national geodetic vertical datum of 1929 (NGVD29) 13928 a fixed reference adopted as a standard geode tic datum for elevations; it was determined 13929 by leveling networks across the United States and sea-level measurements at 26 coastal 13930 tide stations; this reference is now supersed ed by the North American vertical datum of 13931 1988 (NAVD88) 13932 13933 national tidal datum epoch (NTDE) 13934 the latest 19-year time pe riod over which NOAA has comput ed and published official 13935 tidal datums and local mean sea-level elevatio ns from tide station r ecords; currently, the 13936 latest NTDE is 1983-2001 13937 13938 nearshore zone 13939 refers to the zone extending fr om the shoreline seaward to a short, but indefinite distance 13940 offshore, typically confined to dept hs less than 5 meters (16.5 feet) 13941 13942 nontidal wetlands 13943 wetlands that are not exposed to the periodic change in water level that occurs due to 13944 astronomical tides 13945 13946 nor’easter (northeaster) 13947 name given to the strong northeasterly winds a ssociated with extra-tropical cyclones that 13948 occur along East Coast of the United States and Canada; these storms often cause beach 13949 erosion and structural damage; wind gusts associated with these storms can approach and 13950 sometimes exceed hurricane force in intensity 13951 13952 North American vertical datum of 1988 (NAVD88) 13953 a fixed reference for elevations determined by geodetic leveling, derived from a general 13954 adjustment of the first-order terrestrial le veling networks of the United States, Canada, 13955 and Mexico; NAVD88 supersedes NGVD29 13956 13957 100-year flood 13958CCSP 4.1 January 15, 2009

775 of 784 Final Report the standard used by the National Flood Insurance Program (NFIP) for floodplain 13959 management purposes and to determine the n eed for flood insurance; a structure located 13960 within a special flood hazard area shown on an NFIP map ha s a 26 percent chance of 13961 suffering flood damage during the term of a 30-year mortgage 13962 13963 ordinary high water mark 13964 a demarcation between the publicly owned la nd along the water and privately owned land 13965 which has legal implications regarding public access to th e shore; generally based on 13966 mean high water, the definition varies by stat e; along beaches with significant waves, it 13967 may be based on the line of vegetation, the water mark caused by wave runup, surveys of 13968 the elevation of mean high wa ter, or other procedures 13969 13970 overwash 13971 sediment that is transported from the beach ac ross a barrier, and is deposited in an apron13972 like accumulation along the backside of the barrier; overwash usually occurs during 13973 storms when waves break through the frontal dune ridge and flow landward toward the 13974 marsh or lagoon 13975 13976 outwash plain 13977 braided stream deposit beyond the margin of a glacier; it is form ed from meltwater 13978 flowing away from the glacier, depositing mostly sand and fine gravel in a broad plain 13979 13980 passive margin 13981 type of continental margin occurring in th e middle of a tectonic plate, consequently 13982 tectonic activity is minimal; these margins ar e typified along the marg ins of the Atlantic 13983 Ocean and often so it is often termed an Atlantic margin 13984 13985 pocket beach 13986 a typically small, narrow beach formed betw een two littoral obstacl es, such as between 13987 rocky headlands or promontorie s that occur at the shore 13988 13989 Public Trust Doctrine 13990 a legal principle derived from English Common Law; the esse nce of the doctrine is that 13991 the waters of the state are a public resource owned by and available to all citizens equally 13992 for the purposes of navigation, hunting, fowling, and fishing, and that this trust is not 13993 invalidated by private owners hip of the underlying land 13994 13995 relative sea-level rise 13996 the rise in sea level measured with respect to a specified vertical datum relative to the 13997 land, which may also be changing elevation over time; typically measured using a tide 13998 gauge 13999 14000 retreat 14001 the act of moving inland 14002 14003 revetment 14004CCSP 4.1 January 15, 2009

776 of 784 Final Report a sloped facing of stone, concrete, etc., built to protect a scarp, embankment, or shore 14005 structure against erosion by wave action or currents 14006 14007 river diversion 14008 engineering approaches used to redirect the flow of water from its natural course 14009 for a range of purposes; commonly used to by-pass water during dam construction, for 14010 flood control, for navigation, or for wetland and floodpl ain restoration 14011 14012 rip-rap 14013 loose boulders placed on or along the shoreline as a form of armoring 14014 14015 riverine flooding 14016 flooding of lands caused by the elevation of nont idal or tidal waters resulting from the 14017 drainage of upstream areas, usually af ter periods of exceptional rainfall 14018 14019 roll-over 14020 see barrier island roll-over 14021 14022 rolling easement 14023 an interest in land (by title or interpretation of the Public Trust Doctrine ) in which a 14024 property owner’s interest in preventing real estate from eroding or being submerged 14025 yields to the public or environmental interest in allowing wetlands or beaches to migrate 14026 inland 14027 14028 root mean square error 14029 a measure of statistical error calculated as the square root of the sum of squared errors, 14030 where error is the difference between an estima te and the actual value; if the mean error 14031 is zero, it also equals the st andard deviation of the error 14032 14033 salt marsh 14034 a grassland containing salt to lerant vegetation establishe d on sediments bordering saline 14035 water bodies where water leve l fluctuates either tidally or nontidally (see also marsh ) 14036 14037 saltwater intrusion 14038 displacement of fresh or ground water by the advance of salt water due to its greater 14039 density, usually in coastal and estuarine areas 14040 14041 sand bypassing 14042 hydraulic or mechanical movement of sand from the accreting updrift side to the eroding 14043 downdrift side of an inlet or harbor en trance; the hydraulic movement may include 14044 natural movement as well as movement caused by man 14045 14046 seawall 14047 a structure, often concrete or stone, built al ong a portion of a coast to prevent erosion and 14048 other damage by wave action, often it retains earth against its shorew ard face; a seawall is 14049 typically more massive and capable of resisting greater wave forces than a bulkhead 14050CCSP 4.1 January 15, 2009

777 of 784 Final Report 14051 sediment(s) 14052 solid materials or fragments that originates fr om the break up of rock and is transported 14053 by air, water or ice, or that accumulates by other natural agents such as chemical 14054 precipitation or biological secretions; solid ma terial that has settled from being suspended 14055 as in moving water or air 14056 14057 sediment broadcasting 14058 a technique in which sediment from an exte rnal source is spread onto salt marshes to 14059 supply mineral material to enhance their growth 14060 14061 sediment supply 14062 refers to the abundance or lack of sediment in a coastal sy stem that is available to 14063 contribute to the maintenance or evolution of coastal landforms including both exposed 14064 features such as beaches and barrier islands, and underwater features such as the seabed 14065 14066 setback 14067 the requirement that construction be locat ed a minimum distance inland from tidal 14068 wetlands, tidal water, the primary dune line, or some other definition of the shore 14069 14070 shoal 14071 a relatively shallow place in a stream, lake , sea, or other body of water; a submerged 14072 ridge, bank, or bar consisti ng of or covered by sand 14073 14074 shore 14075 the narrow strip of land imme diately bordering any body of wa ter, especially a sea or 14076 large lake; the zone over which the ground is alternately exposed and covered by the tides 14077 or waves, or the zone between high and low water 14078 14079 shoreface 14080 the narrow relatively steep surface that exte nds seaward from the beach, often to a depth 14081 of 30 to 60 feet, at which point the slope flattens and merges with the continental shelf 14082 14083 shoreline 14084 the intersection of a specified plane of wate r with the shore or beach; on National Ocean 14085 Service nautical charts and surveys, the lin e representing the shoreline approximates the 14086 mean high water line 14087 14088 shoreline armoring (see armoring ) 14089 a method of shore protection that prevents shore erosion through th e use of hardened 14090 structures such as seawalls , bulkheads, and revetments 14091 14092 shore protection 14093 refers to a range of activitie s that focus on protecting land from inundation, erosion, or 14094 storm-induced flooding through the construction of various structures such as jetties, 14095 groins, or seawalls, or the addi tion of sediments to the shore ( e.g ., beach nourishment) 14096CCSP 4.1 January 15, 2009

778 of 784 Final Report 14097 significant wave height 14098 the average height of the highest on e-third of waves in a given area 14099 14100 sill 14101 semicontinuous structures placed along the edge of a marsh in order to diminish wave 14102 erosion of the marsh, usually made of stone; similar to breakwaters, except that 14103 breakwaters are generally farther from the shore and have larger open spaces between 14104 them 14105 14106 soft shore protection 14107 a method of shore protection that prevents shore erosion through th e use of materials 14108 similar to those already found in a given lo cation, such as adding sand to an eroding 14109 beach or planting vegetation whose roots will retain soils along the shore 14110 14111 spit 14112 a fingerlike extension of the beach that wa s formed by longshore sediment transport; 14113 typically, it is a curved or hook-li ke sandbar extending into an inlet 14114 14115 spring high water 14116 the average height of the high waters dur ing the semi-monthly times of spring tides 14117 (occurs at the full and new moons) 14118 14119 storm surge 14120 an abnormal rise in sea level accompanying a hurricane or other in tense storm, whose 14121 height is the difference between the observed level of the sea surface and the level that 14122 would have occurred in the absence of the cyclone 14123 14124 subsidence 14125 the downward settling of material with little horizontal movemen t; the downwarping of 14126 the earth’s crust relative to the surroundings 14127 14128 submergence 14129 a rise of the water level relative to the land, so that areas that were formerly dry land 14130 become inundated; it is the result either of the sinking of the la nd or a net rise in sea level 14131 14132 supratidal zone 14133 the shore area just a bove the high-tide level 14134 14135 surf zone 14136 the zone of the nearshore region where bor e-like waves occur following breaking waves, 14137 extending from the point where waves break to the wet beach 14138 14139 taxon (plural, taxa) 14140 a general term applied to any taxonomic element, populati on, or group irrrespective 14141 of its classification level 14142CCSP 4.1 January 15, 2009

779 of 784 Final Report 14143 threshold 14144 in climate change studies, a threshold generally refers to the point at which the climate 14145 system begins to change in a marked way because of increased forcing; crossing a 14146 climate threshold triggers a transition to a ne w state of the system at a generally faster 14147 rate 14148 14149 tidal datum 14150 a base elevation used as a vertic al from which to reckon heights 14151 or depths; called a tidal datum when defined in terms of a certain phase of the tide 14152 14153 tidal freshwater marsh 14154 marsh along rivers and estuaries close enough to the coastline to e xperience significant 14155 tides by nonsaline water, vegeta tion is often similar to nontidal freshwater marshes 14156 14157 tidal inlet 14158 an opening in the shoreline through which wate r penetrates the land, thereby providing a 14159 connection between the ocean and bays, lagoons , and marsh and tidal creek systems; the 14160 main channel of a tidal inlet is maintained by tidal currents 14161 14162 tidal range 14163 the vertical difference between normal hi gh and low tides often computed as the 14164 elevation difference between mean high water and mean low water; spring tide range is 14165 the elevation difference between spri ng high water and spring low water 14166 14167 tidal wetlands 14168 wetlands that are exposed to the peri odic rise and fall of the tides (see wetlands ) 14169 14170 tide-dominated coast 14171 coast where the morphology is primar ily a product of tidal processes 14172 14173 tide gauge 14174 the geographic location where tidal observations are conducte d and consisting of a water 14175 level sensor, data collection and transmission equipment, and local bench marks that are 14176 routinely surveyed into the sensors 14177 14178 tidelands 14179 lands that are flooded during ordinary high wate r, and hence available to the public under 14180 the Public Trust Doctrine 14181 14182 tipping point 14183 a critical point in the evolution of a system that leads to new and potentially irreversible 14184 effects at a rate that can either be mu ch faster or much slower than forcing 14185 14186 transgression 14187CCSP 4.1 January 15, 2009

780 of 784 Final Report the spread or extension of the sea over land areas, and the consequent evidence of such 14188 advance; also, any change such as a rise in sea level that brings offshore deep-water 14189 environments to areas formerly occupied by nearshore, shallow-water environments or 14190 that shifts the boundary between marine and nonmarine deposition away from deep water 14191 regions 14192 14193 updrift 14194 refers to the location of one s ection or feature along the coast in relation to another; often 14195 used to refer to the direction of net longs hore sediment transport between two or more 14196 locations ( i.e ., upstream) 14197 14198 wave-dominated coast 14199 coast where the morphology is primar ily a product of wave processes 14200 14201 wave refraction 14202 the process by which a water wave, moving in sh allow water as it approaches the shore at 14203 an angle, tends to be turned from its origin al direction so that the wave crest is more 14204 parallel to shore; also can refer to the bending of wave crests by currents 14205 14206 wave run-up 14207 the upper levels reached by a wave on a beach or coastal structure, relative to still-water 14208 level 14209 14210 wet floodproofing 14211 14212 wetlands 14213 specifies those areas that are inundated or saturated by surface or ground water at a 14214 frequency and duration suffici ent to support, and that under normal circumstances do 14215 support, a prevalence of vegetation typically adapted for life in satu rated soils; wetlands 14216 generally include swamps, mars hes, bogs, and similar areas 14217 14218 wetland accretion 14219 a process by which the surface of wetlands increases in elevation; see also accretion, 14220 vertical 14221 14222 wetland migration 14223 a process by which tidal wetlands adjust to rising sea level by advanc ing inland into areas 14224 previously above the ebb and flow of the tides 14225 14226CCSP 4.1 January 15, 2009

781 of 784 Final Report 

## Scientific Names—Chapter 5 Species 14227 American black duck Anas rubripes American oystercatcher Haematopus palliatus Atlantic menhaden Brevoortia tyrannus Atlantic silverside Menidia spp. bald eagle Haliaeetus leucocephalus bay anchovy Anchoa mitchilli belted kingfisher Ceryle alcyon black rail Laterallus jamaicensis black skimmer Rynchops niger bladderwort Utricularia spp. blue crab Callinectes sapidus bluefish Pomatomus saltatrix brant Branta bernicla canvasback duck Aythya valisineria carp Family Cyprinidae catfish Order Siluriformes clapper rail Rallus longirostris common tern Sterna hirundo crappie Pomoxis spp. diamondback terrapin Malaclemys terrapin eastern mud turtle Kinosternum subrubrum elfin skimmer (dragonfly) Nannothemis bella fiddler crab Uca spp. Forster’s tern Sterna forsteri fourspine stickleback Apeltes quadracus grass shrimp Hippolyte pleuracanthus great blue heron Ardea herodias gull-billed tern Sterna nilotica herring Clupea harengus horseshoe crab Limulus polyphemus Kemp’s ridley sea turtle Lepidochelys kempii laughing gull Larus atricilla least bittern Ixobrychus exilis meadow vole Microtus pennsylvanicus minnows Family Cyprinidae mummichog Fundulus herteroclitus naked goby Gobiosoma bosci northern pipefish Syngnathus fuscus piping plover Charadrius melodus red drum Sciaenops ocellatus red knot Calidris canutus red-winged blackbird Agelaius phoeniceus ribbed mussel Geukensia demissaCCSP 4.1 January 15, 2009

782 of 784 Final Report sand digger Neohaustorius schmitzi sand flea Talorchestia spp. sandpiper Family Scolopacidae sea lettuce Ulva lactuca sea trout Salvelinus fontinalis shad Alosa sapidissima sheepshead minnow Cyprinodon variegatus shiners Family Cyprinidae spot Leiostomus xanthurus striped anchovy Anchoa hepsetus striped bass Morone saxatilis striped killifish Fundulus majalis sundew Drosera spp. sunfish Family Centrarchidae threespine stickleback Gasterosteus aculeatus tiger beetle Cicindela spp. weakfish Cynoscion regalis white croaker Genyonemus lineatus white perch Morone americana widgeon grass Ruppia maritima willet Catoptrophorus semipalmatus 14228

14229CCSP 4.1 January 15, 2009

783 of 784 Final Report ACRONYMS AND ABBREVIATIONS 14230 14231 A–P Albemarle–Pamlico 14232 ABFE Advisory Base Flood Elevations 14233 AEC Areas of Environmental Concern ( 14234 ASFPM Association of State Floodplain Managers 14235 BFE base flood elevation 14236 CAFRA Coastal Facility Review Act 14237 CAMA Coastal Area Management Act 14238 CBRA Coastal Barrier Resources Act 14239 CCMP Comprehensive Coastal Management Plan 14240 CCSP Climate Change Science Program 14241 CORS continuously operating reference stations 14242 CRC Coastal Resources Commission 14243 CTP Cooperative Technical Partnership 14244 CVI Coastal Vulnerability Index 14245 CZM Coastal Zone Management 14246 CZMA Coastal Zone Management Act 14247 DDFW Delaware Division of Fish and Wildlife 14248 DEC Department of Environmental Conservation 14249 DEM Digital elevation Model 14250 DFIRM digital flood insurance rate maps 14251 FEMA Federal Emergency Management Agency 14252 FGDC Federal Geographic Data Committee 14253 FIRM Flood Insurance Rate Maps 14254 FIS Flood Insurance Studies 14255 GAO General Accounting Office (1982) 14256 GAO General Accountability Office (2007) 14257 GEOSS Global Earth Observation System of Systems 14258 GIS geographic information system 14259 GCN greatest conservation need 14260 GPS Global Positioning System 14261 HOWL highest observed water levels 14262 IDA intensely developed area 14263 IOOS Integrated Ocean Observing System 14264 IPCC Intergovernmental Panel on Climate Change 14265 IPCC CZMS Intergovernmental Panel on Climate Change Coastal Zone Management 14266 Subgroup 14267 LDA limited development area 14268 LMSL local mean sea level 14269 MHHW Mean Higher High Water 14270 MHW Mean High Water 14271 MLW Mean Low Water 14272 MLLW Mean Lower Low Water 14273 MSL mean sea level 14274 NAI No Adverse Impact 14275CCSP 4.1 January 15, 2009

784 of 784 Final Report NAS National Academy of Sciences 14276 NAVD North American Vertical Datum 14277 NCDC National Climatic Data Center 14278 NERRS National Estuarine Research Reserve System 14279 NDEP National Digital Elevation Program 14280 NED National Elevation Dataset 14281 NFIP National Flood Insurance Program 14282 NGVD National Geodetic Vertical Datum 14283 NHP National Heritage Program 14284 NHS National Highway System 14285 NLCD National Land Cover Data 14286 NMAS National Map Accuracy Standards 14287 NOAA National Oceanic and At mospheric Administration 14288 NPS National Park Service 14289 NRC National Research Council 14290 NSSDA National Standard for Spatial Data Accuracy 14291 NTDE National Tidal Datum Epoch 14292 NWR National Wildlife Refuge 14293 NWS National Weather Service 14294 PORTS Physical Oceanographic Real-Time System 14295 RCA resource conservation area 14296 RMSE root mean square error 14297 RPA resource protection area 14298 SAV submerged aquatic vegetation 14299 SFHA Special Flood Hazard Area 14300 SRTM Shuttle Radar Topography Mission 14301 SWFL still water flood level 14302 TNC The Nature Conservancy 14303 USACE United States Army Corps of Engineers 14304 U.S. EPA United States Environmental Protection Agency 14305 U.S. FWS United States Fish and Wildlife Service 14306 U.S. DOT United States Department of Transportation 14307 USGS United States Geological Survey 14308 VA PBB Virginia Public Beach Board 14309 WRCRA Waterfront Revitalization and Coastal Resources Act 14310 Box 9.1 Ecological Effects of Sea Level Rise–NOAA North Box 9.2 1991 FEMA Study: Projected Impact of Relative Sea The study notes that these numbers differ slightly from a Box 9.3 A Maryland Case Study– Implicationsfor Decisionmakers: Adult and juvenile piping plover foraging on a sandy beach near the Piping plover nest BOX A1.9: Reintrod uced populati on of red