National Park Service

U.S. Department of the Interior

Natural Resource Program Center

Coastal Geomorphology of the Ocean Shoreline, Gateway 

National Recreation Area

Natural Evolution and Cultural Modifications, a Synthesis

Natural Resource Report NPS/NERO/NRR—2010/184
ON THE COVER

Upper left: Recreational beach, parking lot D, Sandy Hook.Upper right: Bathhouse, Riis Park. 

Lower left: Erosional scarp at location of former bathhouse, Great Kills. Lower right: 

Impinging scarp at bike path, Plumb Beach.

Photography by: Norbert P. Psuty 
Coastal Geomorphology of the Ocean Shoreline,

Gateway National Recreation Area

Natural Evolution and Cultural Modifications, a Synthesis

Natural Resource Report NPS/NERO/NRR—2010/184

NORBERT P. PSUTY1, PETER DENNEHY1, TANYA SILVEIRA1, NATALYA 

APOSTOLOU2

1Rutgers University

Institute of Marine and Coastal Sciences

Sandy Hook Cooperative Research Programs

Highlands, NJ 07732

2National Park Service

Gateway National Recreation Area

210 New York Ave

Staten Island, NY 10305

March 2010

U.S. Department of the Interior

National Park Service

Natural Resource Program Center

Fort Collins, Colorado
ii

The National Park Service, Natural Resource Program Center publishes a range of reports that 

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This report is available from http://www.nps.gov/nero/science and the Natural Resource 

Publications Management website (http://www.nature.nps.gov/publications/NRPM).

Please cite this publication as:

Psuty, N. P., P. Dennehy, T. Silveira, and N. Apostolou. 2010. Coastal geomorphology of the 

ocean shoreline, Gateway National Recreation Area: natural evolution and cultural 

modifications, a synthesis. Natural Resource Report NPS/NERO/NRR—2010/184. Fort Collins, 

Colorado.

Contents

NPS 646/101463, March 2010
iii

Page

Figures............................................................................................................................................. v

Tables............................................................................................................................................. vi

Acknowledgements....................................................................................................................... vii

Introduction and Rationale.............................................................................................................. 1

Methodology................................................................................................................................... 2

Basic Geomorphological Controls.................................................................................................. 3

 Tides........................................................................................................................................ 3

 Wave Climate.......................................................................................................................... 3

 Storm History.......................................................................................................................... 3

 Sea-Level Rise ........................................................................................................................ 5

 Sediment Supply..................................................................................................................... 6

 Sediment Budget................................................................................................................... 10

 Human Manipulation ............................................................................................................ 11

Landform Responses..................................................................................................................... 13

 Sandy Hook........................................................................................................................... 13

 Staten Island.......................................................................................................................... 18

Great Kills............................................................................................................. 18

Miller Field ........................................................................................................... 22

Fort Wadsworth .................................................................................................... 22

 Breezy Point.......................................................................................................................... 22

 Plumb Beach ......................................................................................................................... 27

Sediment Management.................................................................................................................. 35

Areas for Future Inquiry ............................................................................................................... 36

Literature Cited ............................................................................................................................. 37

v

Figures

Page

Figure 1. The coastal units of Gateway and the ocean shorelines incorporated herein. ................. 2

Figure 2. Wave roses incorporating frequency and magnitude of incident significant waves at 

two offshore station locations, 1980-1999...................................................................................... 4

Figure 3. The beach-dune system exchanges sediment among the foredune, the beach, and the 

offshore bar feature during the seasonal variation of wave and current energies. ........................ 4

Figure 4. The mean sea level trend is 3.90 millimeters/year with a 95% confidence interval of 

+/- 0.25 mm/yr based on monthly mean sea level data from 1932 to 2006, equivalent to a change 

of 0.39 m (1.28 ft) in 100 years.. .................................................................................................... 8

Figure 5. The mean sea level trend is 2.77 millimeters/year with a 95% confidence interval of 

+/- 0.09 mm/yr based on monthly mean sea level data from 1856 to 2006, equivalent to a change 

of 0.28 m (0.91 ft) in 100 years. .................................................................................................... 8

Figure 6. Statistical comparison of linear rate of SLR to exponential rate, derived from Sandy 

Hook tide gauge data, 1933-2008.. ................................................................................................. 9

Figure 7. Natural beach-dune configuration with adequate sediment budget, incorporating a 

foredune, an upper berm reached during storm conditions, and a lower surface that is affected by 

the normal tidal variations and incident waves...........................................................11

Figure 8. Coastal topography and engineering structures on the Sandy Hook Unit..................... 14

Figure 9. The artificially wide beach following beach nourishment at the Park entrance........... 16

Figure 10. Coastal topography of Sandy Hook derived from first-return LiDAR data................ 17

Figure 11. Inland offset of shoreline downdrift of terminus of seawall, the Critical Zone, 

September 11, 2008. ..................................................................................................................... 19

Figure 12. Great Kills Park Staten Island Unit ............................................................................. 21

Figure 13. Comparison of topography from 1891 topographic map and location of existing park 

shoreline on 2002 aerial photograph at Great Kills (Mellander, 2007). ....................................... 21

Figure 14. Severe erosion downdrift of projecting headland. Pilings are at site of demolished bath 

house. March 31, 2009.......................................................................................22

Figure 15. Miller Field, Staten Island Unit, with coastal features and structures........................ 23

Figure 16. Beach seaward of constructed sand dike at Miller Field, March 31, 2009. ................ 24

Figure 17. Fort Wadsworth, Staten Island Unit, coastal topography and structures. .................. 24

Figure 18. Beach-dune profile seaward of constructed sand dike, Fort Wadsworth.. ................. 25
vi

Figures (Continued)

Page

Figure 19. Ocean coast extends from the jettied Rockaway Inlet updrift to the eastern margin of 

Riis Park. ..................................................................................................................................... 28

Figure 20. Portions of the wooden bulkhead and riprap wall exposed at base of foredune in Ft. 

Tilden. March 31, 2009................................................................................................................. 28

Figure 21. Coastal topography of Breezy Point spit, derived from first-return measurements 

collected in 2005 using the NASA Experimental Advanced Airborne Research LiDAR 

(EAARL); part of a collaborative effort among the USGS, NASA, and NPS.. ........................... 29

Figure 22. Topography and structures at Plumb Beach............................................................... 31

Figure 23. Small foredune developing at eastern margin of Plumb Beach, migrating inland over 

wetland and tidal channel. April 10, 2008. .................................................................................. 31

Figure 24. Coastal topography of Plumb Beach, derived from first-return measurements collected 

in 2005 using the NASA Experimental Advanced Airborne Research LiDAR (EAARL); part of a 

collaborative effort among the USGS, NASA, and NPS.............................................................. 32

Figure 25. Riprap exposed at eroding sector, central Plumb Beach, March 31, 2009................. 33

Tables

Page

Table 1. Storm Water Elevations................................................................................................... 7
vii

Acknowledgements

Conducting a literature review and digesting a vast suite of information required the able 

participation of people in various offices and agencies where data are stored. This is especially 

true for this product because much of the material was in the gray literature housed on shelves 

and files rather than in the traditional scientific journals. The following people were especially 

helpful and contributed both their knowledge of the park as well as information contained in the 

dusty reports: Kathyryn Mellander, Mark Christiano, Bruce Lane, Tom Hoffman and Felice 

Ciccione of the Gateway National Recreation Area; Annette Baden, Rita Fisher, and Christina 

Rasmussen of the New York District, U.S. Army Corps of Engineers; David Robinson, New 

Jersey State Climatologist, Rutgers University; Barry Pendergrass, New York State Department 

of State, W. Frank Bohlen, Department of marine Science, University of Connecticut; June 

Gallegos, National Park Service Technical Information Center; and Chris Shafer, Sandy Hook 

Cooperative Research Programs, Rutgers University. Their inputs contributed immensely to the 

breadth of resources involved in the production of this paper. Dennis Skidds of the national Park 

Service, Northeast Coastal and Barrier Network , provided the LiDAR data used in the creation 

of the coastal topography maps for the Gateway units. A special note of appreciation is extended 

to Dr. Charles T. Roman for his constructive review of the draft of this document and to the 

anonymous reviewers for their very helpful comments. The resulting product is truly a team 

effort. 

1

Introduction and Rationale

Coastal geomorphology is a basic component of the environmental system at the Gateway

National Recreation Area. The evolution of the physical characteristics of the coastal system is 

based in the geologically-recent history of a rising sea level interacting with the sediments 

occurring on and supplied to portions of the continental shelf (Walker and Coleman, 1987). The 

product of that interaction and the natural processes drive the continuing development of the 

ambient coastal morphology with its variety of barrier island forms and the variable dimensions 

and sequences of beaches and dunes. Further, knowledge of the natural vectors of development, 

direction, and magnitude of morphological change is an important element in the consideration 

of any strategy directed at the shepherding of the existing natural and cultural resources in the 

park (Sherman, et al., 1979). Working within the limits imposed by the natural system and 

incorporating the myriad of cultural modifications offers an opportunity to address issues of 

sustainability and resilience in this dynamic area. An understanding of the vectors of the 

geomorphological evolution and the dimensions of the human modifications provides 

perspective to the impacts of future management decisions.

This paper is a synthesis of the scientific literature pertaining to the geomorphological evolution 

of the ocean shoreline of the units of Gateway National Recreation Area (GNRA). It is a 

description of the studies that have been undertaken within the Park and it also brings together a 

suite of data that pertain to the environs of the Park, such as the wave climate, the measures of 

sea-level rise, and some of the storm history. In addition, this paper incorporates aspects of the 

human manipulation of the Park’s shoreline, both within the confines of the Park and adjacent to 

the Park. The history of inquiry into the physical processes and the resulting landforms is quite 

uneven for the several units of Gateway. The Sandy Hook area has been the subject of study for 

over a century, including Johnson (1919, p. 296) through Psuty, et al. (2009), whereas the 

remainder of the Gateway ocean shoreline is largely unstudied, or certainly not the subject of 

continuous inquiry. Information pertaining to components of Gateway has been included in 

many US Army Corps of Engineers (USACOE) reports (Taney, 1951: through USACOE, 2002) 

and they are sources of observations and histories of change, especially data regarding storm 

events and engineering modifications to the shore environment.

In addition to the natural evolution of the coastal system within the boundary of Gateway, there 

are many human interventions that have altered the processes that create elements of the 

topography and there are alterations of the forms that exist on-site. The presence of engineering 

structures, both within and external to the Park, produce positive and negative modifications. 

Further, episodes of dredging and subsequent discharge of the excavated sediment have adjusted 

the availability and transport pathways of the local materials. Together, the natural conditions 

and the human alterations have created the coastal products in Gateway. The results of this 

combination of processes, sediments, and manipulations are the focus of this paper.
2

Methodology

GNRA is a fairly large geographical area with considerable variety in processes and forms. The 

approach to presentation of the information will be to establish the general condition of the 

coastal system and then to describe the specifics of portions of Gateway NRA, incorporating the 

human modification of the particular sites. The central theme of this paper will be the oceanfacing shoreline of the several units of GNRA. These components are identified on Figure 1. 

They consist of the ocean side and northern coast of Sandy Hook, the coastal stretch from Riis 

Park to the terminus of Breezy Point, a small section of beach exposed to ocean waves at Plumb 

Beach, and three seaward-facing beaches on Staten Island: Fort Wadsworth, Miller Field, and 

Great Kills. Each of these sites incorporates a mixture of natural system modified to varying 

degrees by human factors. An outcome of this synthesis will be an improved understanding of 

the existing balance achieved at each site and an appreciation of the possibilities at future times.

Figure 1. The coastal units of Gateway and the ocean shorelines incorporated herein.
3

Basic Geomorphological Controls 

Tides 

This portion of the coast has a semi-diurnal tide (two highs per day) with a mean spring tidal 

range of 1.59 m (5.22 ft) at the Sandy Hook tide gauge (this value is derived from the tidal epoch 

of 1983-20011). The tidal range has an influence on the beach profile by defining the vertical 

dimension of the beach face. Also, the tidal range generates current flows through coastal inlets 

or entrances. These tidal currents have the capacity to transport sediment and to create tidal 

deltaic deposits on the baysides or ocean sides of inlets/entrances, thereby sequestering sediment 

that would otherwise be transported alongshore to the next downdrift portion of the shore. 

Wave Climate

Waves are the basic drivers of coastal development and coastal change. They supply most of the 

energy to mobilize and transport sediment. The direction of wave approach dictates the direction 

of sediment transport. Therefore, a fundamental data set is the magnitude and direction of 

oncoming waves throughout this coastal area. Wave roses of significant wave heights (mean of 

the highest one-third) have been generated for a range of sites in the offshore by the Wave 

Information Studies of the US Army Corps of Engineers for the entire Eastern Seaboard 

(USACOE, 2009). The application of these data depict the dominance of the incident waves 

arriving from the southeast quadrant (Fig. 2). This spatial limitation is not surprising. This is the 

only quadrant for effective wave generation in the New York Bight. Other directions have much 

shorter fetch distances for wave generation and therefore create much smaller and shorter waves 

(less ambient energy to mobilize and transport sediment). Importantly, under conditions of strong 

winds out of the northeast, the sheltering function of New England causes the winter storm 

waves to wrap around New England (refract) and arrive from the east-southeast in both New 

Jersey and New York. As a result, the wave action and the local currents transport sediments 

toward the entrance to New York Harbor, westerly along the Long Island shore and northerly 

along the New Jersey shore. The transport direction is essentially unidirectional and leads to a 

downdrift extension of the coastal topography toward New York Harbor.

Storm History

Stormy periods are the times of large waves and abundant energy to move sediment on the beach 

profile. The waves operate on the offshore as well as beach portion. Storm winds add another 

component of sediment mobilization and tend to move material on the beach berm and foredune 

(Fig. 3). Much of the erosion and sediment loss occurs during the stormy fall, winter, and spring 

seasons when traveling low pressure cells spur cyclonic storms referred to as nor’easters. The 

summer season tends to be a time of lower winds and waves, and consequently there is a 

recovery of sediment and an accumulation on the dune-beach profile (Fig. 3). Occasionally, the 

summer is a time for hurricane development and locally intense erosion and sediment 

mobilization. Hurricanes tend to be more intense but of shorter duration than nor’easters. The 

nor’easters tend to have impacts over several days (several tidal cycles) and cause considerable

 

1 The tidal epoch is a 19-year cycle of earth-sun-moon interaction that affects the tidal variations and the range of 

tide at the recording station. Each NOAA tide gauge station uses a tidal epoch as a means of calculating the range of 

tide during one complete 19-year cycle (the 1983-2001 tidal epoch is the most recent calculated for Sandy Hook).
4

Fi

Figure 2. Wave roses incorporating frequency and magnitude of incident significant waves at two 

offshore station locations, 1980-1999. Values on the perimeter of the roses pertain to annual percentage 

of waves from that direction. (USACOE, 2009).

Figure 3. The beach-dune system exchanges sediment among the foredune, the beach, and the offshore 

bar feature during the seasonal variation of wave and current energies. The foredune tends to store sand 

high on the profile during low energy periods, whereas the offshore bar stores sand offshore during high 

energy periods. A similar exchange occurs with each storm. The stormy season does not permit recovery 

between storms. 
5

change because of their duration as well as severe winds and waves.

Storms happen. Each year there will be some severe weather that will cause change to the 

coastal topography. Past storm events have produced major changes to the coastal systems 

(Coch, 1993). The potential for storm impacts at Gateway are addressed in a report produced by 

the U.S. Geological Survey (Pendleton, et al., 2005) that relates local inundation vulnerability to 

exposure and physical characteristics. A brief history of storm events and their associated water 

elevation (impact on the beach-dune system) is presented in Table 1. Storm water elevations 

above 1.12 m NAVD88 will cause changes to the upper beach (based on monitoring program at 

Sandy Hook, summarized in Psuty, et al., 2009). Storm water elevations above 1.27 m NAVD88 

will scarp the foredune and lower the beach berm (see Fig. 3). Each of the storm water 

elevations has been adjusted to the NAVD88 datum for comparative purposes. According to 

USACOE and Coastal Planning & Engineering, Inc. (CPE) (1994) and the Federal Emergency 

Management Agency (FEMA) website, the hundred-year recurrence interval storm at the Sandy 

Hook tide gauge will reach 2.95 m (10.8 ft) NAVD88, the fifty-year storm will be at 2.77 m 

(10.2 ft), and the 20-year storm will be at 2.16 m (8.2 ft).

Sea-Level Rise

The issue of sea-level rise (SLR) is important to all coastal locations because of the likely inland 

displacement of the shoreline as the global water-level rises. As a driver, SLR may cause an 

inland shift of the beach-dune system by the simple drowning of the existing beach position, 

thereby causing a re-location of the zone of wave and current processes interacting with available 

sediment. Furthermore, an ancillary effect of SLR will be to hasten the exposure of inland 

features to the effects of storm surge and sediment mobilization and to exacerbate the rates of 

sediment loss in areas of negative sediment budget.

There is a very good record of SLR in Gateway NRA because of the presence of two long-term 

tidal gauges, Sandy Hook (Fig. 4) and The Battery (Fig. 5). These gauges record the recent 

history of water level in and near the Park and offer a means to appreciate the effects. The Sandy 

Hook record of 3.9 mm/yr rise is appropriate for the ocean shoreline of Gateway because of the 

similarity of geomorphological heritage of the ocean shoreline in the Park (a barrier island 

development with relatively thick accumulations of modern sediment). The Battery rate of rise 

is a bit lower (2.77 mm/yr) because it is at a location that is not in a barrier island setting and the 

depth of modern sediment undergoing compaction is much less. The Battery record is probably 

a better model for rate of inundation along portions of Staten Island. 

The importance of any SLR calculation is the subsequent impact of a higher water level (storm 

surge) during low-frequency, high-magnitude storm events. As the local sea level rises during 

the next decades, storm events will reach higher on the beach profile and will penetrate farther

inland to mobilize portions of the topography that heretofore were above the reach of these 

storms. Among the results will be an increase in sediment removal and shoreline displacement 

related to sea-level rise (Buttner, 1987; Nicholls, et al., 2007). Therefore, natural and cultural 

resources will be increasingly exposed to the impacts of storm events and changes in coastal 

topography will be accelerated. Further, the rates of SLR may be escalating into the future. 

Evidence summarized in the recent Intergovernmental Panel on Climate Change report (Bindoff, 

et al., 2007) indicates that sea level will rise at an increasing rate. Statistical analysis of data from 
6

the Sandy Hook tide gauge (Fig. 6) and other local gauge data (Psuty and Ofiara, 2002) show 

that the increasing rate is recognized in the present-day trends. As further evidence of the 

current trend, the absolute elevation of mean sea-level at Sandy Hook and other tidal reference 

marks related to mean water levels at this site have increased by 79.25 mm (0.26 ft) from the 

previous tidal epoch to the tidal epoch of 1983-2001 (NOAA, 2009).

Sediment Supply

The availability of sediment to supply the coastal topography in GNRA is derived from several 

sources. The source provided to the Breezy Point unit is part of the barrier island chain along the 

southern shore of Long Island that receives sediment from eastern Long Island via alongshore 

transport as well as some onshore transport (Taney, 1961; Fairchild, 1966; Williams, 1976; 

Williams and Meisburger, 1987, Williams and Morgan, 1993). Breezy Point and Plumb Beach 

are at the far western end of the barrier-island sediment chain and there are numerous 

interruptions in the continuity of transport created by inlets. Many of the inlets have been sites 

of sediment sequestration as large flood tide deltaic deposits have reduced the sediment flows 

along the westerly pathway. Much of this sediment was originally deposited as glacial outwash 

at the eastern margin of Long Island (Williams and Meisburger, 1987). It is likely that the 

glacially-derived supply is nearly exhausted and there is inadequate natural erosion of that source 

to continue to sustain the present barrier island system in central and eastern Long Island (Kana, 

1995, 1999; Wolff, 1989: Rosati, et al., 1999). A part of the deficit is currently being met by 

beach nourishment and transfers from sediment sequestered in the tidal deltas at the various 

inlets. However, the many Corps of Engineer reports offer testimony to the long-term erosional 

trend of the shoreline and the narrowing of the barrier island system (USACOE, 1965a, 1973, 

1979, 1992: USACOE & CPE, 1994).

The Sandy Hook unit derives its sediment from northerly transport along the New Jersey 

shoreline (USACOE, 1954; McMaster, 1954; Minard, 1969). There may have been more sand in 

the past, but the current sources of eroding headlands immediately updrift from the Hook are 

insufficient to maintain the shoreline position. A seawall constructed about one century ago plus 

several episodes of beach nourishment are supporting the continuity of the Hook.

The eastern shore of Staten Island has a natural sediment supply in the form of glacial deposits 

that form a large terminal moraine near the Verrazano-Narrows Bridge and a large glacial 

outwash plain that extends southeasterly into the harbor from the moraine (Multer, et al., 1984). 

These deposits are easily eroded and supply sediment that is transported to the southwest to form 

a short spit extending to Crooke’s Point. This source contributes an inadequate quantity of 

sediment to maintain this southeastern shore of Staten Island (USACOE, 1995).
7

Table 1. Storm Water Elevations. H = hurricane; NE = nor’easter; 1data from NOAA (2009) 

Date Storm

Type

Elevation

m NAVD88

Reference 

Station Source

Published reports 

3 Sept 1821 H ca. 2.3-2.6 Ft Hamilton (?) USACOE 1979

24 Nov 1901 NE 1.49 Ft Hamilton USACOE/CPE 94

16-17 Sept 1903 H 1.09 Ft Hamilton USACOE/CPE 94

7 Dec 1914 NE 1.25 Ft Hamilton USACOE/CPE 94

11-12 April 1918 NE 1.74 Battery USACOE 1979

5 Feb 1920 NE 1.61 Ft Hamilton USACOE/CPE 94

20 Feb 1927 NE 1.77 Battery USACOE 1979

3 Mar 1931 NE Govs Task Force 1994

17 Nov 1935 Govs Task Force 1994

21 Sept 1938 H 1.67 Battery USACOE/CPE 94

1.65 Sandy Hook UASCOE 1954

14 Sept 1944 H 1.67 Battery USACOE/CPE 94

1.98 Sandy Hook Pore & Barrientos 1976

25 Nov 1950 NE 1.95 Battery USACOE/CPE 94

2.04 Sandy Hook USACOE 1954

6-7 Nov 1953 NE 2.07 Battery USACOE/CPE 94

2.62 Sandy Hook USACOE 1954

31 Aug 1954 (Carol) H 1.58 Battery Govs Task Force 1994

1.61 Sandy Hook Pore & Barrientos 1976

14-16 Oct 1955 NE 1.58 Battery USACOE/CPE 94

12 Sept 1960 (Donna) H 2.22 Battery USACOE/CPE 94

2.28 Ft. Hamilton USACOE 1992

2.29 Sandy Hook USACOE SPM 1973

2.28 Sandy Hook Pore & Barrientos 1976

6-8 March 1962 NE 1.89 Battery USACOE/CPE 94

23 January 1966 NE 1.46 no datum Sandy Hook Pore & Barrientos 1976

12 Nov 1968 NE 1.40 no datum Sandy Hook Pore & Barrientos 1976

3 Feb 1972 NE 1.16 no datum Sandy Hook Pore & Barrientos 1976

19 Feb 1972 NE 1.22 no datum Sandy Hook Pore & Barrientos 1976

6 Aug 1976 (Belle) H

6 Feb 1978 NE Govs Task Force 1994

6 Sep 1979 (David) H 1.41 Sandy Hook NOAA1

28-29 March 1984 NE 1.83 Sandy Hook USACOE/CPE 94

27 Sept 1985 (Gloria) H 1.67 Battery USACOE/CPE 94

31 Oct 1991 NE 1.75 Sandy Hook Govs Task Force 1994

NOAA

11 Dec 1992 NE 2.31 Sandy Hook Schubert & Busciolano 1994

2.10 Battery Schubert & Busciolano 1994

NOAA data

March 2001 NE 1.41 Sandy Hook NOAA1

25 Dec 2002 NE 1.61 Sandy Hook NOAA1

3 Jan 2003 NE 1.50 Sandy Hook NOAA1

10 Dec 2004 NE 1.41 Sandy Hook NOAA1

25 May 2005 NE 1.42 Sandy Hook NOAA1

31 Jan 2006 NE 1.56 Sandy Hook NOAA1

16 April 2007 NE 1.61 Sandy Hook NOAA1

12 Dec 2008 NE 1.50 Sandy Hook NOAA1
8

Figure 4. The mean sea level trend is 3.90 millimeters/year with a 95% confidence interval of +/- 0.25 

mm/yr based on monthly mean sea level data from 1932 to 2006, equivalent to a change of 0.39 m (1.28 

ft) in 100 years. The vertical datum base value is MSL, 1995. NOAA, 2009.

Figure 5. The mean sea level trend is 2.77 millimeters/year with a 95% confidence interval of +/- 0.09 

mm/yr based on monthly mean sea level data from 1856 to 2006, equivalent to a change of 0.28 m 

(0.91 ft) in 100 years. The vertical datum base value is MSL, 1995. NOAA, 2009.
9

Figure 6. Statistical comparison of linear rate of SLR to exponential rate, derived from Sandy Hook tide 

gauge data, 1933-2008. The correlation value (R2) assigned to the exponential increase is nearly 

identical to the correlation value assigned to the linear increase. The base value for the vertical scale is 

MSL, 1995. NOAA, 2009.
10

Sediment Budget

Whether a shoreline erodes or builds seaward is a function of the local sediment budget, a 

comparison of the amount of incoming sediment compared to the outflows of sediment. It does 

not matter if the sediment is lost to an offshore sink, inland to a bay, or whether it is transported 

to the next unit downdrift. It is a comparative measure that applies to a geographical area for 

some duration of time. Usually, sediment budget is expressed in terms of some volume of sand 

per year. As an example, Plumb Beach in the Jamaica Bay Unit may have a negative sediment 

budget of -1,000 m3/yr. However, that value may be composed of some parts of Plumb Beach 

losing 2,000 m3/yr and another part gaining 1,000 m3/yr. At Plumb Beach, as well as at other 

coastal portions of GNRA, there is an alongshore compartmentalization of the shoreline that 

incorporates gradations of sediment budget that often passes from zones of negative sediment 

budget to positive sediment budget, each with their characteristic features and vectors of change. 

In a general application of the concept, most of GNRA is undergoing a long-term negative 

sediment budget. However, there are gradients of sediment availability that affect local sediment 

budgets and their characteristics and trends. Thus, portions of Gateway may be accreting and 

extending laterally while, in general, the units are experiencing net loss. Further, there is a 

cultural component to the sediment budget because of the physical emplacement of sediment on 

the beaches by dredging or trucking. In the short-term, the cultural contribution to sediment 

availability affects the sediment budget.

The natural configuration of the topography at the shoreline is a broad free-sand beach backed by 

a vegetated foredune-ridge (Fig. 7). With adequate sand, the beach and dune system will 

exchange sediment with the offshore during seasonal variations in wave energy, and the form 

will continue to be present, although with episodic changes in dimension (Fig. 3). Under 

conditions of long-term positive sediment budget, the shoreline will migrate seaward and the 

topography will be composed of a series of stranded foredune ridges, each abandoned ridge 

representing a former shoreline position. Under a negative sediment budget, the dune-beach 

system will be displaced landward as sand is eroded and transported downdrift, causing the 

barrier island to narrow. Under a persistent negative sediment budget, the foredune may be lost 

to the profile and the beach may terminate against an eroding bluff, or some infrastructure, or the 

site may be a location of overwash and transfer of sediment from the ocean side to the bay side 

of the barrier. This is a condition that occurs toward the end of the life of part of a barrier island. 

It signals the time of redistribution of much of the remaining sand constituting that part of the 

barrier and the displacement of the barrier system as well as the displacement of the beach-dune 

components. Under extreme negative sediment budgets, the beach and portions of the barrier 

island will be lost if there is no human intervention. Importantly, the issue of sediment supply to 

beach systems and sediment budget will take on additional meaning as sea level continues to 

rise. Stability of the shoreline position and continuity of the habitat characteristics will require 

an increasing amount of sediment to maintain an equilibrium sediment budget. 
11

Human Manipulation

There are few portions of the Gateway shoreline that are in a natural state (Nordstrom, et al., 

1975; Smith, et al., 1985; Wolff, 1989; Psuty, 2008). Most of the coastal topography has been 

altered by the presence of engineering structures (groins, jetties, and seawalls) that are changing 

the rates and quantities of alongshore transport as well as the locations of sediment accumulation

and/or loss, summarized in the National Shoreline Study (USACOE, 1971). Further, dredging 

of navigation channels at inlets and entrances to harbors has moved great quantities of sediment 

and has affected the local sediment supply and budget. And, there have been several instances of 

beach nourishment that have created local accumulations, displacing the shorelines from tens to a 

hundred meters. Some episodes of the beach nourishment have been practiced within GNRA, 

whereas some have been in an updrift location that have subsequently migrated into the Park. 

Together, the human imprint dominates large portions of the GNRA shoreline and influences the 

evolution of topographical development.

Figure 7. Natural beach-dune configuration with adequate sediment budget, incorporating a foredune, an 

upper berm reached during storm conditions, and a lower surface that is affected by the normal tidal 

variations and incident waves. May 22, 2007

13

Landform Responses

The two major landform components of GNRA are the coastal barrier spits that compose Sandy 

Hook on the NJ coast and Riis Park – Breezy Point on the NY coast (Fig. 1). They are both 

products of the alongshore transport of sediment that have extended the two barrier features 

toward Lower New York Bay. Each of the coastal barriers retains a series of accretionary dune 

ridges that represent stages in the downdrift extension of the landform. Some of the dunal ridge 

forms are natural, whereas others are the product of human influences. In other parts of Gateway, 

Plumb Beach is formed on a remnant of the easterly terminus of the Coney Island barrier. Great 

Kills is located on a remnant of a barrier spit that formerly extended southwesterly along the 

ocean-facing margin of Staten Island. Each of the components has a suite of beach and foredune 

associations produced by local natural and cultural conditions.

Sandy Hook

The Sandy Hook Unit occupies the distal end of the Sandy Hook barrier spit that extends 

northward (downdrift) for 18 km from its origin at the coastal headland in Monmouth Beach. In 

the past, the barrier spit evolved by accumulating sediment at its northern portion and 

episodically building to the north-northwest. Several old shoreline positions are preserved as 

stranded foredune lines in the topography (Fig. 8). However, there is a very limited natural 

source of sediment to support the basal portion of the barrier spit, and the historical record 

(Moss, 1990) recounts periods of inlet formation opposite the Navesink and Shrewsbury 

drainage basins. During the historical period of 1733-1900, Sandy Hook has at times been an 

island detached from any part of the mainland, it has been connected to the mainland at the 

Highlands, and it has been connected at Long Branch, as now (Moss, 1990). Human alterations 

of Sandy Hook have interacted with the natural processes to harden the shoreline, to displace 

sites of localized erosion with emplaced sediment, and to focus erosional effects caused by 

structures (Nordstrom, et al., 1977; Allen, 1981; Psuty and Namikas, 1991). 

The former inlet breaches in the basal portion of Sandy Hook probably allowed a net sediment 

transport from the drainage systems into the coastal alongshore flows for some temporal span. 

However, a quest for coastal stability led to the construction of a 12 km long seawall during the 

period of 1900-1926, with numerous groins, that extended from the contact of the barrier spit 

with the headland, at the southern margin of Monmouth Beach, to a position currently within the 

Park (Fig. 8). The seawall and its impacts are now prime determinants for coastal features along 

most of the Park’s ocean shoreline at Sandy Hook. 

Caldwell (1966) estimated the volume of sand transported along the Sandy Hook ocean shoreline 

at about 382,000 m3/yr (500,000 yds3/yr) on the basis of the incident wave energy (magnitude 

and direction). The material is derived entirely from local sources (McMaster, 1954; Minard, 

1969). Allen (1981) described Sandy Hook as composed of three segments related to sediment

budget and sediment transport. He indicated that the southern portion (Segment 1), nearly northsouth in orientation, is marked by erosion because there is no adequate source of sand to buffer

the continuous loss, creating a negative sediment budget. That erosional portion continues until 

about halfway into the Park, where there is a change in orientation of the shoreline toward the
14

Figure 8. Coastal topography and engineering structures on the Sandy Hook Unit. The natural dunebeach system is divided into the active units and those which have been stranded inland as the spit has 

evolved.
15

north-northwest. Allen suggests that this mid portion (Segment 2) of Sandy Hook is a zone of

sediment transport with little net gain or loss, a balanced sediment budget because of lower wave 

energy and the input of eroded sediment from the south. After about 2.5 km, the orientation 

changes again, almost due northwest, resulting in additional lowering of the incident wave 

energy. This portion of Sandy Hook (Segment 3) shows evidence of sediment accumulation, a 

positive sediment budget, and a northerly extension of the Hook.

A major change in sediment availability and shoreline change historically occurred beyond the

northerly limit of the seawall. As is common in locations downdrift from a shoreline composed 

of hard structures, accelerated erosion developed beyond the limit of the seawall. Sherman, et al. 

(1977) referred to this location as the Critical Zone and determined that the erosion downdrift of 

the seawall began after 1950 and accelerated through 1976. Despite several attempts to stabilize 

the shoreline (Nakashima, et al., 1983), Psuty and Namikas (1991) measured a loss rate that 

peaked at 176,000 m3/yr (ca. 230,200 yds3/yr), including periods of beach nourishment.

Whereas the incident energy arriving at Sandy Hook has probably not changed during the past 

several decades, the shoreline displacement downdrift of the end of the seawall has been altered 

by the several episodes of beach nourishment in the Park,and, more importantly, by the beach 

nourishment projects updrift of the Park. Major inputs of sediment seaward of the seawall (Fig. 

9) have contributed to the local sediment budget and have displaced the shoreline position

seaward while contributing great quantities of material to downdrift transport. Approximately 

9,815,000 m3 (12,838,000 yds3) have been placed updrift of the park since 1985 (Psuty and 

Ofiara, 2002; Corps web site) The Park has placed 4,822,000 m3(ca. 6,300,000 yds3) of 

sediment in the vicinity of the Critical Zone over the span of 1975-2002 (Psuty and Ofiara, 

2002). The result of the massive nourishment projects updrift of the park and within the Critical 

Zone is a relatively low rate of net sediment loss in the location immediately downdrift of the 

end of the seawall in recent years, on the order of 20,000-40,000 m3/yr (ca. 26,000-52,000 

yds3/yr) (Psuty and Pace, 2009). 201,000 m3(263,000 yds3) of sediment was pumped into the 

Critical zone in late 2002. Most of that remains onsite (Psuty, et al., 2009). Meanwhile, the 

sediment transportation zone (Segment 2) in the middle portion of Sandy Hook is recording a 

modest gain, 30,000 m3/yr (ca. 39,000 yds3), and the northern portion (Segment 3) is building 

due north under a positive sediment budget. A large shoreline projection is both widening and 

elevating the northernmost portion of Sandy Hook (Fig. 10). Sediment is also transported 

beyond the northern tip of the Hook into the adjacent navigation channel, from where it has been 

dredged and emplaced at the Critical Zone on several occasions (Zammit and Slezak, 1987). 

Elements of the natural beach-dune geomorphology occur at several locations on the oceanside 

of Sandy Hook. Natural refers to the products of the ambient wave and currents mobilizing 

sediments to build parts of the beach-dune topography described earlier, distanced from the 

artificial structures and not created by human action. At Sandy Hook, there is a natural beachdune topography that begins near the northern margin of the Critical Zone and continues to the 

northerly point of the Hook (Fig. 8 and 10). There are a number of stranded foredune ridges that

exist in the topography. They represent stages in the accretional history of Sandy Hook (Fig. 8 

and 10). There are several parallel foredune ridges in Segment 3 that represent episodes of

northerly accretion, but they are truncated both to the east and the west, representative of a 

narrowing of the distal end of Sandy Hook. The dune-beach system seaward of the seawall and

at the Critical Zone is largely an engineered feature and is not part of the current sand-exchange
16

Figure 9. The artificially wide beach following beach nourishment at the Park entrance. 
17

Figure 10. Coastal topography of Sandy Hook derived from first-return LiDAR data. Elevation 

measurements were collected in 2005 using the NASA Experimental Advanced Airborne Research 

LiDAR (EAARL); part of a collaborative effort among the USGS, NASA, and NPS. The surface 

characteristics of the three segments display the recent evolutionary development of the Hook 

culminating in the multitude of accretionary ridges in Segment 3
18

topography described in Figure 3.

The dominant engineering structure external to the Park as well as within the Park is the massive 

seawall at its southern margin. The seawall was constructed in stages from 1898 through 1921 

(Sherman, et al., 1977). It has a general elevation of 5.1 m (NAVD88) and a width of 3.7 m. 

There are five groins on the seaward face of the seawall in the park. They do not presently alter 

the alongshore transport of sand at the beach. They are low rock and timber groins that are 

exposed usually only at low tide after a storm. With the exception of the rock groin immediately 

updrift from the northern end of the seawall, none of the existing groins associated with the 

seawall create a downdrift offset in the shoreline (Fig. 11).

There is a lengthy timber groin seaward of Battery Gunnison that is completely enveloped with 

sand. It was last seen in the 1980s. There are two rock groins near North Beach that are 

occasionally visible. There is a downdrift offset of the shoreline associated with these latter 

groins. They are low and permeable. They seem to be a factor in the shoreline response, but not 

the sole cause of the offset.

As with other coastal shorelines in GNRA, Sandy Hook contains a mix of natural and humancreated features. The seawall at the southern margin of the Park is the primary factor for other 

elements of the coastal topography. It supports the connection with the mainland and it 

maintains the continuity of the shoreline. Episodes of beach nourishment along its seaward 

margin supply material to maintain the ocean shoreline beyond the downdrift terminus of the 

structure. At present, a small negative sediment budget at the end of the seawall creates a slow 

rate of inland shoreline displacement. Most of the remainder of the ocean shoreline is slowly 

eroding (Segment 1), stable (Segment 2), or accreting (Segment 3).

Staten Island

The three components of the Park shoreline on Staten Island (Fig. 1) share a similar natural 

history. They are situated at a site where Pleistocene glacial deposits are being re-worked by 

waves and currents operating at the modern sea level. However, very little of the natural 

topography remains. It has been modified by large amounts of beach nourishment, dredged 

sediment to create the existing Great Kills park, and a myriad of shore structures. Okulewicz and 

DiGuardia (1984) describe a persistent NE-SW alongshore transport direction that is eroding the 

available sediments and creating a depositional spit at Crooke’s Point. They report that the 

ocean-facing Staten Island shoreline has been displaced inland an average of 38 m from 1836 to 

1961. The rate of displacement has slowed with the application of beach nourishment and the 

construction of a multitude of groins. 

Great Kills

Great Kills Park (Fig. 12) was constructed by huge excavations of sediment to create the boat 

basin of Great Kills Harbor and to build the surrounding upland (in 1935-1948, and in 1955). In 

part, the artificial upland re-established the connection from the mainland to Crooke’s Point. 

However, the alongshore transport of sediment to the southwest was now interrupted by the

construction of groins updrift of the Park location and the newly-created upland was a site of 

negative sediment budget and erosion. In addition to the retention of sediment updrift by the

variety of engineering structures, a portion of the eastern coastal upland and its associated
19

.Figure 11. Inland offset of shoreline downdrift of terminus of seawall, the Critical Zone, September 11, 

2008. 
20

wetland (formerly inland of the barrier spit leading to Crooke’s Point) now formed a projecting 

headland near Oakwood Beach and functioned as a further obstruction to alongshore processes. 

That is, wave diffraction altered the pattern of wave energy and accelerated the loss of sediment 

immediately downdrift of the headland (Smith, et al., 1985). In addition, Okulewicz and 

DiGuardia (1984) report that the rate of erosion at Great Kills more than doubled following the 

completion of the outfall pipe at the Oakwood sewage treatment pipe in 1975. The pipe serves 

as a very long groin and effectively stops any sediment from reaching Great Kills.

Beach nourishment was applied several times in the early 1970s, as well as in the period 1974-

1982, to try to preserve the bathhouse (Niedoroda, et al., 1975; Smith et al., 1985; Nordstrom, 

1987). Eventually, the sediment emplaced on the beach was eroded and the bathhouse was 

removed.

The Great Kills area is divided into four segments (modified after Smith, et al., 1985): 1) the

riprap structure and wetlands at Oakwood Beach; 2) the projecting headland; 3) the cliffed coast 

downdrift of the headland; and 4) the stable or accreting shoreline at the distal portion of the 

barrier. The Oakwood Beach wetlands (Segment 1) were originally inland of a sandy barrier 

spit. Following complete erosion of the spit, the remaining peaty wetlands were eroded and now 

occupy a niche downdrift and inland of the structural combination of the sewage treatment plant 

outfall and a low riprap seawall. The topography consists of a narrow band of sand transgressing 

a peaty layer. It is not a foredune-beach system because it lacks the full range of features and it 

is not exchanging sediment as in Figure 3. Segment 2 consists of a peat layer bounded inland by 

a thick deposit of fill. The fill is scarped and has a bluff that reaches 3-4 m high in places. The 

combined fill and peat are less easily eroded and now project seaward of the general trend of the 

Great Kills shoreline (Fig.13). Toward the southwestern margin and beyond the peat outcrop,

Segment 3 exhibits a cliffed coast that extends for about 1000 m (3280 ft) alongshore and is 

primarily retreating into fill material. A narrow beach face, about 10 m (33 ft) wide at mean 

water level, extends from the cliff to the water. The cliff is highest at the northeast portion, 

nearly 3 m (10 ft), and decreases in elevation to less than a meter to the southwest. The accreting 

Segment 4 has a low foredune, about 1.0-1.5 m (3-5 ft) high, and a beach width of 30 m (98 ft). 

The jetty at Crooke’s Point (built in 1958) establishes the southwestern extent of the barrier spit. 

It is meant to assist in maintenance of the navigation channel, 3 m (10 ft) deep and 45 m (150 ft) 

wide, immediately southwest of the jetty. At present, the updrift side of the jetty is completely

alluviated and sediment is being transported around the end of the jetty to build a narrow beach 

on the downdrift side, to move into the navigation channel, and to drift alongshore toward the 

entrance to the Great Kills boat basin. 

A key element in the Great Kills shoreline evolution is the erosional trend in Segment 3 (Fig. 

14). Smith, et al. (1985) calculated that the rate of erosion in the site of the former bathhouse 

reached 5 m/yr (16 ft/yr) because of the absence of an incoming sediment supply and the 

diffraction of wave energy around the peat outcrop. They describe the situation as a classic logspiral erosional beach extending inland and expanding its erosional scarp downdrift. Subsequent 

evaluations of the site of maximum erosion rates produced similar displacements, around 5 m/yr 

(16 ft/yr) through 2006 (Mellander, pers. commun., 2007). In the absence of an incoming 

sediment supply, the negative sediment budget at this site will continue to cause removal of 

material from this location, displace the shoreline inland, and supply eroded sediment to the 

downdrift accreting shoreline.
21

Figure 13. Comparison of topography from 1891 topographic map and location of existing park shoreline

on 2002 aerial photograph at Great Kills (Mellander, 2007).

Figure 12. Great Kills Park, Staten Island Unit, with mix of structures and topographical features.
22

Miller Field

The shoreline at Miller Field extends between two groins for a distance of 630 m (2067 ft), of 

which 500 m (1640 ft) is within Gateway (Fig. 15). This shoreline is completely artificial and is 

totally manipulated by the emplacement of fill and the transport restrictions imposed by the two 

groins (Fig. 15). The sand supply to support this beach and its topography is derived from the fill 

placed within the groin compartment and updrift of the northern groin (USACOE, 1965b, 1995). 

The beach form has a gently-sloping beach seaward of a constructed dike in this setting (Fig. 16).

Fort Wadsworth

The beach on the seaward-facing side of Ft. Wadsworth is a product of fill placed in the mid 

1950s (USACOE, 1965b, 1995). With the exception of the northern 75 m, which is lined by 

assorted riprap bounded by some sort of offshore breakwater, the beach form is a gently-sloping 

sand surface positioned against a sand dike (Figs. 17 and 18). There is no new sand being 

transported into this site. It is exposed to waves entering the bay between Sandy Hook and 

Breezy Point and thus sand mobilization will continue to remove some of the emplaced material 

and cause slow erosion. It was estimated that prior to a variety of forms of sand emplacement, 

the rate of erosion was on the order of 0.8 m (2.7 ft)/yr (USACOE, 1965b). However, that was a 

calculation applied to the time prior to the construction of groins and manipulation of the 

sediment supply. 

Breezy Point

Breezy Point is the westerly extension of the Rockaway barrier island (Fig. 1). Historically, the 

barrier island was slowly eroding and being displaced inland as it was extending westward. The 

natural evolution of the western point was altered by the construction of a large jetty adjacent to 

the Rockaway Inlet navigation channel in 1933. Since that time, the migration of the western end 

of Rockaway barrier has ceased, to be replaced by accumulations updrift of the jetty.

This component of Gateway NRA includes Jacob Riis Park, Fort Tilden, the Breezy Point 

Cooperative, and the western terminus of the barrier, Breezy Point (Fig. 19). There are some

elements of natural coastal topography in this portion of GNRA, but most reflect the impacts of

human intervention of either the sediment supply or manipulation of the topography. Groin

construction on the Rockaway barrier was primarily initiated in the period 1922-1927 

(USACOE, 1965a) and was accompanied by more than 3,8 million m3(5 million yrd3) of 

sediment placed on the beach (Kassner and Black, 1984). Eight stone groins and a stone 

bulkhead were constructed at Fort Tilden in 1943 (USACOE, 1965a).

Most of the Rockaway barrier is fronted by beach groins that are attempting to slow the 

alongshore transport of sediment to the west. There are 48 groins in the Jacob Riis Park – Fort 

Tilden shoreline. The groins in Jacob Riis Park are low stone and concrete structures that allow 

for sediment bypass and do not create major offsets in the shoreline or the beach form. 

However, eleven of the groins constructed at Fort Tilden are higher stone groins and they have a 

larger impact on the beach form and shoreline. They produce offsets in the beach from east to 

west and the foredune feature is often scarped at the inner margin of the groins. The beach 

narrows and the foredune is more impacted from east to west along the Fort Tilden shoreline.
23

Figure 14. Severe erosion downdrift of projecting headland. Pilings are at site of demolished bath house.

March 31, 2009.

Figure 15. Miller Field, Staten Island Unit, with coastal features and structures.
24

Figure 16. Beach seaward of constructed sand dike at Miller Field, March 31, 2009.

Figure 17. Fort Wadsworth, Staten Island Unit, coastal topography and structures.
25

Figure 18. Beach-dune profile seaward of constructed sand dike, Fort Wadsworth. Glacial deposits are 

immediately inland of veneer of fill at this site. May 5, 2008.
26

The Rockaway barrier is at the far end of a sediment pathway that transport sediment along the 

south shore of Long Island, at a rate of about 344,000 m3/yr (450,000 yds3/yr) (Hess and Harris, 

1987). Numerous inlets in the barrier chain are sites of interruption of the sediment pathway and 

a decreasing sediment supply to the west is accompanied by greater segmentation of the barrier 

island chain and greater dynamics of shoreline mobility (Taney, 1961). It is likely that impacts 

of erosion would be greater were it not for sediment transfers conducted at the inlets bordering 

some of the barrier islands. Sediment is supplied to the eastern end of the Rockaway barrier by 

routine dredging of Little Rockaway Inlet, approximately 153,000 m3(200,000 yds3) every two 

years (USACOE records) and deposition of the sediment downdrift to nourish the beaches in the 

Rockaway communities. In addition, starting in 1975 and continuing to 2004, 13,000,000 m3

(17,000,000 yds3) of sediment have been dredged from the offshore to supply sand to the 

Rockaway beaches (Yasso and Hartman, 1976; Nersesian, 1977; NY District website). Kana 

(1999) reports that over 19 million m3(25 million yds3) have been placed on the Rockaway 

beaches since 1920. 

However, not all of that sand has reached western Rockaway. A long and high groin at the 

eastern end of Jacob Riis Park, enlarged in 1982, currently intercepts the alongshore transport of 

this nourishment and has the effect of widening the beach in the updrift community while 

producing a negative offset in the shoreline in the park. One outcome of this deficit sediment 

supply immediately downdrift is a highly mobile beach profile that occasionally narrows to the

point that the water is nearly at the base of the park’s infrastructure, preventing the development 

of a foredune in the beach profile. Some measure of coastal stability is reached in the Fort 

Tilden area where the foredune feature has some continuity in form and survives the seasonal 

variation in beach width. Foredune topography continues throughout Fort Tilden, even though 

there is a riprap and wooden bulkhead along this entire length (Fig. 20). The foredune is 

interrupted seaward of the Breezy Point Cooperative, but exists as the primary dune and stranded 

foredunes west of the Cooperative (Figs. 19 and 21).

Construction of the 2550 m (8,400 ft) jetty at Breezy Point in 1933 changed the condition of 

sediment transport at this location. The jetty terminated western elongation of the barrier island 

and reduced alongshore transport to support maintenance of the navigation channel and 

accumulation at its updrift margin. A huge zone of accumulation occurred that displaced the 

shoreline seaward in the form of accretionary ridges (foredune features) that extended for a 

distance of 4.5 km (2.8 miles). At present, there may be a slightly-negative sediment budget in 

the eastern portion of this part of the park that will cause the zone of accumulation to retreat a bit 

and the junction of accumulation with the former shoreline will be erosional. As the negative 

budget continues and the deficit increases, the contact of the accumulation will shift to the west, 

exacerbating the erosional offset at this contact.

The far western margin of the sediment accumulation has a series of natural foredune ridges as 

the shoreline was accreting under the impetus of the local positive sediment budget.The 

accumulation has reached its maximum. The area updrift of the jetty is full and sand is being 

transported around the jetty. Some of the sand accumulates as an attenuated beach deposit on the 

downdrift and inland side. Most of the sediment transported beyond the jetty is presently 

accumulating in the Rockaway Inlet navigation channel, necessitating routine dredging to 

maintain channel dimensions. The ocean shoreline at Breezy Point should not change position 
27

much because it is constrained by the end of the jetty. However, the foredune in this western area 

could continue to increase in height and breadth because it is at the site of sediment transfer from 

the beach to an inland position. If the beach position is constant, the site of this eolian sediment 

transport and accumulation willalsobe relativelyconstant and will spur localizedforedune growth. 

Plumb Beach 

Plumb Beach is a remnant of the eastern end of the Coney Island barrier island and its associated 

tidal inlet delta. This location was isolated from the general barrier evolution by the westerly 

extension of Rockaway barrier island during the past several centuries (Taney, 1961) that 

shielded it from direct interaction with ocean waves (Fig. 22). Initially separated from the 

developed portions of Coney Island by 1902, the remnant coastal feature was effectively isolated 

from any alongshore sediment supply by the later dredging of the navigation channel into 

Sheepshead Bay . As a result of the absence of sediment input caused by the navigation channel, 

the remnant barrier migrated inland as a narrow beach/dune topographic form transgressing the 

wetland and shoal to its interior. Creation of the Belt Parkway (late 1930s) resulted in a large 

amounts of fill placed on the shoal inland of Plumb Beach and the establishment of a re-formed 

shoreline at the seaward margin of the fill. Because there was no natural source of sand coming 

to this area, net erosion displaced the shoreline inland toward the Belt Parkway. Although the 

record is incomplete, there is aerial photo evidence of several episodes of beach nourishment and 

riprap placement in the central portion of Plumb Beach. Severe erosion in 1984-85 resulted in 

loss of the existing pathway and its subsequent reconstruction atop a variety of construction 

debris. In 1992, a major beach nourishment project was conducted by placing 192,000 yds3of 

sand dredged from the Rockaway navigation channel onto this site (Bohlen, 1990; USACOE and 

CEP, 1994; Psuty, 2008). 

The existing coastal topography at Plumb Beach derives from the combination of emplacement 

of fill and the subsequent erosion and transport of the fill in this location at the eastern terminus 

of the Coney Island barrier island. The central area of Plumb Beach is an erosional zone that 

has a small escarpment (bluff) eroding back into the fill (Fig. 22). Minimal transport of the 

eroded sediment to the west has created narrow beach and low dune topography. The greater 

transport is to the east and it has created a spit-like beach-dune topography that is extending

easterly as sediment is entrained by the nearshore currents (Fig. 22). Because the incident wave 

energy is primarily arriving via the Rockaway Inlet, the locus of major erosion, about 1,900 m3 

(2,500 yrd3) annually (USACOE and CEP, 1994) and the direction of alongshore transport will 

not vary much. The central area will be the zone of loss of sediment and the major transport 

direction will be to the east. The erosion zone will expand both to the east and to the west. The 

eroded sediment will add to the distal end of the eastward extending spit and will both broaden 

the small foredune ridge and shift it inland over the adjacent wetland.

The easterly extending spit has elements of beach-dune topography that are natural products of a 

positive sediment budget. There is an equilibrium beach width, height, and slope that are related 

to the availability of sediment transported into the location. The foredune feature is highest and 

broadest east of the comfort station. It has a relatively constant height and width for about 350 m 

(1,148 ft) (pre-1992), then a much lower and narrower foredune for the next 150 m (492 ft) 

(1992-2002), and a very low foredune for the distal 50 m (164 ft). The post-1992 foredune is 

slowly shifting inland and encroaching on the wetland habitat that is occupying the
28

Figure 19. Ocean coast extends from the jettied Rockaway Inlet updrift to the eastern margin of Riis 

Park. The offset at the western portion of Fort Tilden follows the trend of the shoreline before 

construction of the Breezy Point jetty in 1933.

Figure 20. Portions of the wooden bulkhead and riprap wall exposed at base of foredune in Ft. Tilden. 

March 31, 2009.
29

Figure 21. Coastal topography of Breezy Point spit, derived from first-return measurements collected in 

2005 using the NASA Experimental Advanced Airborne Research LiDAR (EAARL); part of a collaborative 

effort among the USGS, NASA, and NPS. This data set provides metrics of the topographical elements of 

this site.
30

backmarsh/shoal location of the ancestral Plumb Beach barrier island (Figs. 23 and 24).

In addition to the great volumes of fill emplaced in the Plumb Beach area, there are a few other 

indications of human modifications that are affecting the coastal topography. The western 

margin consists of a bulkhead structure that functions as a groin and there is a slight seaward

displacement of the shoreline adjacent to the structure (built in early 1950s). In 1980-1983, an 

offshore breakwater of old tires was constructed to intercept the incident waves and reduce the 

energy reaching the beach (Nordstrom, 1987; USACOE and CPE, 1994) (Fig. 22). Remnants of 

the breakwater are exposed at the low water position during spring tides. There is little indication 

of geomorphological impact of this feature at present. In the same time as the breakwater, tires 

were used to construct five groins to the west of the comfort station (Fig. 22). No remnants of 

the groins are seen today. A further impact to the geomorphological evolution is the presence of 

sizeable rip-rap material emerging at the eroding margin in central Plumb Beach (Figs. 22 and 

25) (related to the response following the March 1984 storm, repairs to bike path, and 

construction of a loose rubble revetment, USACOE and CPE, 1994). This coarse material will 

function as a bulkhead and will slow the inland displacement of the shoreline, but will extend the 

erosional zone to the east and to the west. 
31

Figure 22. Topography and structures at Plumb Beach.

Figure 23. Small foredune developing at eastern margin of Plumb Beach, migrating inland over wetland 

and tidal channel. April 10, 2008.
32

Figure 24. Coastal topography of Plumb Beach, derived from first-return measurements collected in 2005 

using the NASA Experimental Advanced Airborne Research LiDAR (EAARL); part of a collaborative effort 

among the USGS, NASA, and NPS. This data set provides metrics of the topographical elements of this

site.
33

Figure 25. Riprap exposed at eroding sector, central Plumb Beach, March 31, 2009

35

Sediment Management

The ocean shoreline conditions in most of GNRA are driven by a cultural manipulation of the 

sediment supply and the resulting spatial variation in sediment budget along a barrier spit 

topographical system. Most of the park’s ocean shoreline is affected by conditions updrift of the 

Park’s boundary and the effects of structures at or near the boundary. In nearly every case, there 

is a negative impact to the sediment budget and a consequent erosional situation that is 

mobilizing sediment near the boundary and displacing the shoreline toward existing 

infrastructure within the Park. Further, in many instances, there is an additional downdrift effect 

of the local erosion that is causing accumulation and impacts on habitat and navigation channels. 

The combination of impacts of erosion at one site followed by impacts of accumulation at a 

downdrift site pleads for sediment management so as to reduce the impacts at both locations. 

Sediment management is not easy. It involves some sort of reduction of mobilization at the site 

of erosion and/or manipulation of the sites of accumulation. Furthermore, global climate change 

and increasing sea level rise present an additional challenge by changing and promoting an 

increase in the effects of storms upon the shoreline. Adaptation to the changing 

geomorphological controls and conditions must be taken into consideration in any sediment 

management plan, in order to guarantee a long-term solution in dealing with the changing coast. 

The Park’s history has shown that quick solutions often fail to incorporate the temporal and 

spatial aspects of the sediment-morphology system, aiming only to fix the sediment deficit at 

very local scales. These are not solutions for a long-term sediment management of the Parks’ 

shorelines. 

In a system-wide approach, with a potential adaptation to the changing conditions, sediment 

management may involve a physical transfer of sediment from the zone of accumulation to the 

zone of erosion, a recycling of the material in transport. Sandy Hook is the first of the Gateway 

units to embark on such a program of sediment recycling that transports sediment from the zone 

of accumulation to the zone of erosion via a slurry pipeline. This is an effective approach to 

sizeable quantities of sediment transfers. Plumb Beach and Great Kills have much lower 

quantities of sediment being transported and may not need the infrastructure of a pipeline. Riis 

Park could be the beneficiary of sediment recycling. However, it could also be assisted by 

improved alongshore sediment mobility at its eastern boundary. 
36

Areas for Future Inquiry

o The acquisition of shoreline position data and topographical analysis are essential

ingredients to the understanding of the vectors of change and the impacts of natural and 

cultural modifications to the coast. The implementation of the coastal monitoring effort 

undertaken through the NPS Inventory and Monitoring Program provides a consistent 

and coherent data set to track and to investigate the dimensions of these changes and their 

evolution under issues of sediment availability and sea-level rise. The one-dimensional, 

two-dimensional, and three-dimensional monitoring of beaches and dunes will be 

tracking the geotemporal vectors and will track the variety of responses to the constraints 

operating in the coastal system. These data are fundamental and will serve as a guide to 

future management decisions. 

o There are several CODAR HF radar units gathering wave and current data in Gateway 

NRA (http://marine.rutgers.edu/cool/codar.html, and http://hudson.dl.stevenstech.edu/maritimeforecast/). There is the potential to incorporate the spatial 

characteristics of these data sets and apply them to vectors of shoreline change. This type 

of information is unavailable through other means and the data are being collected now.

o There is a need for models that can describe the shoreline evolution with different 

combinations of natural processes and human manipulation. The presence and/or absence 

of structures and the sediment transfers by dredging and emplacement have short-term 

and long-term impacts. A modeling effort could help to weigh and evaluate options in 

sediment management and modification of structures.
37

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