National Assessment Of Shoreline Change: Part 2

Historical Shoreline Changes And Associated Coastal 

Land Loss Along The U.S. Southeast Atlantic Coast

Open-File Report 2005-1401

U.S. Department of the Interior

U.S. Geological Survey

By Robert A. Morton and Tara L. Miller
National Assessment Of Shoreline Change: Part 2

Historical Shoreline Changes And Associated Coastal 

Land Loss Along The U.S. Southeast Atlantic Coast

By Robert A. Morton 1 and Tara L. Miller 2

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2005-1401

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Any use of 

trade names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Morton, R. A., and Miller, T. L., 2005, National assessment of shoreline change: Part 2: Historical shoreline changes and 

associated coastal land loss along the U.S. Southeast Atlantic Coast: U.S. Geological Survey Open-file Report 2005-1401.

1

 U.S. Geological Survey

Center for Coastal and Watershed Studies

600 4th St. S.

 St. Petersburg, FL 33701

2 IMSG, Inc.

 NOAA Coastal Services Center

 2234 South Hobson Avenue

 Charleston, SC 29405
ii

Contents

EXECUTIVE SUMMARY .................................................................................................................1

INTRODUCTION .............................................................................................................................1

U.S. Geological Survey National Assessment of Shoreline Change ..............................1

Disclaimer ................................................................................................................................2

Acknowledgments ..................................................................................................................2

THE ROLE OF STATE AND FEDERAL GOVERNMENTS .............................................................3

PRIOR NATIONAL AND SOUTHEAST ATLANTIC SHORELINE ASSESSMENTS ..................3

METHODS OF ANALYZING SHORELINE CHANGE ...................................................................3

Compilation of Historical Shorelines ...................................................................................3

Delineation of a Modern (lidar-derived) Shoreline ...........................................................4

Geographic Information System (GIS) Procedures ..........................................................5

Calculation and Presentation of Rates of Change ............................................................7

Shoreline Definitions and Beach Alterations that Influence Rates of Change ............8

Reliability of the Results ........................................................................................................9

GEOMORPHOLOGY OF THE SOUTHEAST ATLANTIC REGION .............................................13

Southeast Atlantic Mainland Shores ................................................................................13

Estuaries and Lagoons .........................................................................................................13

Barrier Islands and Capes ...................................................................................................15

Tidal Inlets ..............................................................................................................................17

Delta Plains ............................................................................................................................19

GEOLOGIC HISTORY AND SETTING .........................................................................................19

Coastal Processes ................................................................................................................20

Sand Sources ........................................................................................................................22

GENERAL CHARACTERISTICS OF THE SOUTHEAST ATLANTIC SHORES BY STATE .......23

HISTORY OF INFRASTRUCTURE DEVELOPMENT ..................................................................25

SHORELINE CHANGE AND COASTAL LAND LOSS ................................................................26

East Florida .............................................................................................................................26

Georgia ...................................................................................................................................27

South Carolina .......................................................................................................................28

North Carolina .......................................................................................................................28

HUMAN RESPONSES TO COASTAL EROSION AND LAND LOSS ........................................28

DISCUSSION AND FURTHER CONSIDERATIONS ..................................................................31

Summary of Shoreline Changes .........................................................................................31

Planned Updates and Related Research ..........................................................................32

Influence of Human Activities ............................................................................................32

REFERENCES ...............................................................................................................................33
iii

Figures

Figure 1A. Index map of the Southeast Atlantic region showing locations in Florida and Georgia. ..................6

Figure 1B. Index map of the Southeast Atlantic region showing locations in South Carolina and North 

Carolina. ..........................................................................................................................................................7

Figure 2. Example of a lidar profile from September 26, 1997 at Kitty Hawk, North Carolina, for (A) the 

entire cross-shore region and (B) an expanded view of the foreshore region. ..................................9

Figure 3. Examples of common conditions where transects are eliminated in the absence of four 

shoreline intersections. ..............................................................................................................................11

Figure 4. Common coastal landforms of the Southeast Atlantic region. .............................................................14

Figure 5. Conceptual diagram showing possible origins of barrier islands. .......................................................15

Figure 6. Sea-level curve during the past 140,000 years .......................................................................................16

Figure 7. Geomorphological characteristics of high- and low-profile barrier islands.. ....................................17

Figure 8. Former active sand dunes on Shackleford Banks, North Carolina ......................................................18

Figure 9. Low, narrow barrier islands, such as those around Cape Romain, South Carolina, are 

overwashed frequently during storms. ...................................................................................................19

Figure 10. Long linear beach ridges and swales .......................................................................................................20

Figure 11. Tracks of some of the most deadly Atlantic and Gulf hurricanes in the 20th century.. ....................21

Figure 12. Erosion of the Atlantic shore can destroy roads and eliminate the beach.. ......................................22

Figure 13. Erosion and property damage near Floralton Beach, Florida caused by Hurricanes Francis and 

Jeanne in 2004. ............................................................................................................................................23

Figure 14. Long-term trends in average annual sea level in the Southeast Atlantic Ocean.. ............................24

Figure 15. Jetty construction at Charleston Harbor, South Carolina caused chronic beach erosion on 

adjacent Morris Island ...............................................................................................................................25

Figure 16. Outcrops of muddy marsh sediments on the lower beach are evidence of long-term erosion. ....26

Figure 17. Dead and fallen trees in the surf zone are indicators of long-term beach erosion. .........................27

Figure 18. Multiple structures including a seawall and riprap revetment on Anatasia Island, Florida ..........30

Figure 19. Many beaches have been nourished to mitigate against long-term erosion ....................................30

Figure 20. Lateral relocation of a beach house in North Carolina ..........................................................................31
iv

Tables

Table 1. Prior reports of quantitative regional analyses of long-term historical shoreline movement that 

used shorelines derived from T-sheets and/or aerial photographs. ......................................................4

Table 2. Providers and original sources of historical shoreline data for each 

Southeast Atlantic Coast state. ....................................................................................................................5

Table 3. Dates of compiled shorelines for selected periods. ..................................................................................8

Table 4. List of tide-gauge measurements used to calculate mean high-water elevation ..............................10

Table 5. Absolute horizontal and vertical differences between high water and mean high water shorelines. .12

Table 6. Maximum estimated measurement errors for Southeast Atlantic shorelines. ...................................12

Table 7a. Long-term shoreline change trends, 1800s to post-1997 ........................................................................13

Table 7b. Short-term shoreline change trends, 1960s to post-1997... ....................................................................13

Table 8. Technical responses to erosion and land loss in the Southeast Atlantic region. ..............................29
1

EXECUTIVE SUMMARY

Beach erosion is a chronic problem along most openocean shores of the United States. As coastal populations 

continue to grow and community infrastructures are threatened 

by erosion, there is increased demand for accurate information 

regarding past and present trends and rates of shoreline movement. There is also a need for a comprehensive analysis of 

shoreline movement that is consistent from one coastal region 

to another. To meet these national needs, the U.S. Geological 

Survey is conducting an analysis of historical shoreline changes along open-ocean sandy shores of the conterminous United 

States and parts of Hawaii and Alaska. One purpose of this 

work is to develop standard repeatable methods for mapping 

and analyzing shoreline movement so that periodic updates 

regarding coastal erosion and land loss can be made nationally 

that are systematic and internally consistent. 

This report on states comprising the Southeast Atlantic 

Coast (east Florida, Georgia, South Carolina, North Carolina) represents the second in a series that already includes 

the Gulf of Mexico and will eventually include the Northeast 

Atlantic Coast, Pacific Coast, and parts of Hawaii and Alaska. 

The report summarizes the methods of analysis, interprets 

the results, provides explanations regarding the historical and 

present trends and rates of change, and describes how different 

coastal communities are responding to coastal erosion. Shoreline change evaluations are based on comparing three historical 

shorelines with a recent shoreline derived from lidar (Light 

Detection and Ranging) topographic surveys. The historical 

shorelines generally represent the following periods: 1800s, 

1920s-1930s, and 1970s, whereas the lidar shoreline is 1998-

2002. Long-term rates of change are calculated using four 

shorelines (1800s to lidar shoreline), whereas short-term rates 

of change are calculated for the most recent period (1970s to 

lidar shoreline). The historical rates of change presented in this 

report represent past conditions and therefore are not intended 

for predicting future shoreline positions or rates of change.

Rates of erosion for the Southeast Atlantic region were 

generally highest in South Carolina along barrier islands and 

headland shores associated with the Santee delta. Erosion was 

also rapid along some barrier islands in North Carolina. Highest rates of erosion in Florida were generally localized around 

tidal inlets. The most stable Southeast Atlantic beaches were 

along the east coast of Florida where low wave energy and 

frequent beach nourishment minimized erosion. Some beach 

segments in Florida accreted as a result of net longshore drift 

convergence around Cape Canaveral and around tidal inlets 

that were stabilized by jetties. 

Seawalls, riprap revetments, and groins were constructed 

in all the Southeast Atlantic states as initial community 

responses to long-term beach erosion. Although some states, 

such as Florida, still permit shoreline stabilization structures, 

beach nourishment has become the preferred method of mitigating long-term erosion. Beach nourishment is common in all 

of the Southeast Atlantic states except Georgia.

INTRODUCTION

U.S. Geological Survey National Assessment of 

Shoreline Change

Sandy ocean beaches of the United States represent some 

of the most popular tourist and recreational destinations, and 

they also constitute some of the most valuable real estate in the 

country. These ephemeral interfaces between water and land 

are the sites of intense residential and commercial development 

even though they are frequently subjected to natural hazards 

including flooding, storm impacts, coastal erosion, and tsunami 

inundation. Because population centers continue to shift toward 

the coast where valuable coastal property is vulnerable to erosion, the U.S. Geological Survey (USGS) is conducting a National Assessment of Coastal Change. One aspect of this effort, 

the National Assessment of Shoreline Change, uses shoreline 

position as a proxy for coastal change because shoreline position is one of the most commonly monitored indicators of environmental change (Morton, 1996), and it is easily understood 

by those who are interested in historical movement of beaches.

A principal purpose of the USGS shoreline change 

research is to develop a repeatable surveying methodology so 

that shorelines for the continental U.S., and portions of Hawaii 

and Alaska can be periodically and systematically updated in 

an internally consistent manner. In addition, new methods 

for determining datum-based shoreline positions and assessing coastal change will provide the opportunity to achieve 

more comprehensive assessments of error in the future. USGS 

primary objectives of this project are: (1) to develop and implement improved methods of assessing and monitoring shoreline 

movement, (2) to obtain a better understanding of the processes 

controlling shoreline movement, and (3) to enter into strategic 

partnerships to facilitate data dissemination. 

Achieving these ongoing long-term objectives requires research that (1) examines the original sources of shoreline data 

[maps, air photos, global positioning system (GPS), lidar], (2) 

evaluates the utility of different shoreline proxies (geomorphic 

feature, water mark, tidal datum, elevation), including the errors associated with each method, (3) investigates the bias and 

potential errors associated with integrating different shoreline 

proxies from different sources, (4) develops standard uniform 

methods of shoreline-change analysis, (5) determines the effects of human activities on shoreline movement and rates of 

change, and (6) investigates mathematical methods for calculating historical rates of change and forecasting future rates of 

change.
2

This report summarizes historical changes in the U.S. 

Southeast Atlantic shoreline, both accretion and erosion, but 

emphasizes the erosion hazard because it impacts natural 

resources and the economy. Shoreline erosion is also presented 

in the context of coastal land loss (http://pubs.usgs.gov/

of/2003/of03-337/), which is a much broader issue than beach 

erosion because it also includes bluff retreat and erosion and 

submergence of wetlands around interior bays and estuaries. 

The brief accounts of coastal land loss for each state provide a 

more comprehensive view of coastal processes and key references that can be used to learn more about coastal change in a 

broader context.

Disclaimer

Results of the National Assessment of Shoreline Change 

are organized by coastal regions. This report for the Southeast 

Atlantic region is the second in a series of reports that include 

text summarizing methods, results, and implications of the 

results in addition to maps, via Internet Map Server (IMS), 

illustrating rates of shoreline change. Rates of shoreline change 

are being published for the purpose of regional characterization. The shoreline-change results and products prepared by the 

USGS are not intended for comprehensive, detailed, site-specific analysis of shoreline movement, nor are they intended to 

replace any official sources of shoreline change information 

identified by local or state government agencies or other federal 

entities that are used for regulatory purposes. Rates of shoreline change presented herein may differ from other published 

rates, but differences do not necessarily indicate that either 

set of rates is inaccurate. Some discrepancies are expected, 

considering the many possible historic shorelines and ways of 

determining rates of change, and the inherent uncertainty in 

calculating these rates. Rates of shoreline change presented in 

this report represent shoreline movement under past conditions. 

The results are not intended for predicting future shoreline 

positions or rates of shoreline change. For official rates of 

shoreline change within each state, contact the following agencies: Florida Department of Environmental Protection Bureau 

of Beaches and Coastal Systems, Georgia Department of 

Natural Resources Coastal Resources Division, South Carolina 

Department of Health and Environmental Control, Office of 

Ocean and Coastal Resource Management, and North Carolina 

Department of Environment and Natural Resources Division of 

Coastal Management.

This publication was prepared by an agency of the United 

States Government. Neither the United States Government nor 

any agency thereof, nor any of their employees, makes any 

warranty, expressed or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information apparatus, product, or process disclosed in the report, 

or represents that its use would not infringe privately owned 

rights. Reference to any specific commercial product, process, 

or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government 

or any agency thereof. Any views and opinions of authors 

expressed herein do not necessarily state or reflect those of the 

United States Government or any agency thereof.

Acknowledgments

This report was made possible by the hard work and 

generous cooperation of many individuals. We owe a debt of 

gratitude to Emmett Foster (Florida), Clark Alexander (Georgia), Susan Langley (Georgia), Dave Bush (Georgia), and 

Scott Harris (South Carolina) for providing electronic historical shorelines and accompanying metadata for their respective 

states. Compilation of historical shorelines in Georgia and 

South Carolina was funded by the USGS. We also thank Mike 

Rink (NOAA), Paul Frascione (Information Manufacturing 

Corporation), and Ben Oakley (Information Manufacturing 

Corporation) for providing scanned images of T-sheets or 

geo-referenced T-sheets, David Doyle (NOAA) for providing 

datum corrections so that T-sheets could be geo-referenced 

and digitized by the USGS, and Matt Stutz (Duke University) 

for providing information about beach nourishment projects. 

An enthusiastic and untiring USGS team was responsible for 

developing the methods and computer codes for calculating 

operational mean high-water elevations and extracting the lidar 

shorelines. The lidar research and development team included 

Abby Sallenger, Jeff List, Karen Morgan, Kristy Guy, Eric 

Nelson, Hillary Stockdon, and Kathy Weber. Rob Thieler 

worked closely with TPMC Environmental Services/Perot Systems Government Services to develop and improve the Digital 

Shoreline Analysis System (DSAS) code for shoreline-change 

measurement. Lindsey Kraatz, Heather Kaminsky, Jonathan 

Welker, and Brandon Owen provided tremendous assistance by 

geo-referencing and digitizing maps and preparing metadata. 

Betsy Boynton prepared many of the colorful illustrations, 

and Valerie Paskevich created the IMS. Critical reviews that 

greatly improved the technical content and clarity of the report 

were provided by John Haines, Cheryl Hapke, Jeff List, Bruce 

Richmond, Peter Ruggiero, Abby Sallenger, and Rob Thieler 

of the USGS; Spencer Rogers of North Carolina Sea Grant; 

Jim O’Connell of Woods Hole Oceanographic Institution Sea 

Grant; Steve Jones and Bob Mink of the Geological Survey 

of Alabama; Rebecca Beavers of the National Park Service; 

and Chris Parrish, Maryellen Sault, and Jason Woolard of the 

National Oceanographic and Atmospheric Administration 

(NOAA). 
3

THE ROLE OF STATE AND FEDERAL 

GOVERNMENTS

One reason for conducting this National Assessment of 

Shoreline Change is that there is no widely accepted standardized method of analyzing shoreline changes. Each state has its 

own data needs and coastal-zone management responsibilities 

(e.g., construction set-back lines, dune protection zones), and 

therefore each state uses a different technique and standard to 

compile shorelines and to calculate rates of shoreline movement. Consequently, calculated rates of shoreline change are 

inconsistent from state to state and cannot be compared directly. These inconsistencies were clearly demonstrated by the 

Federal Emergency Management Agency (FEMA) sponsored 

erosion studies (Crowell and Leatherman, 1999) that were used 

as a basis for evaluating erosion hazards (The Heinz Center, 

2000). The USGS National Assessment of Shoreline Change 

represents the first time that shorelines from original data 

sources have been compiled and rates of shoreline change have 

been calculated on a national scale using internally consistent 

methods. The results of this analysis allow direct comparison 

of rates of change from one coastal segment to another and 

form the basis for future comparison of shoreline position.

Several federal agencies [USGS, FEMA, NOAA, U.S. 

Army Corps of Engineers (USACE)] have regulatory or 

administrative responsibilities pertaining to shorelines. Yet 

these responsibilities are quite different, requiring different approaches and offering substantial opportunities for cooperation. 

For example, the USACE is authorized and funded by Congress to report on the economic and environmental implications of shoreline change and the costs of erosion mitigation. 

Their National Shoreline Management Study (Stauble and 

Brumbaugh, 2003) is being conducted using existing shoreline 

data. The USGS will share data and information, such as the 

lidar-derived shoreline and rates of change, in support of their 

effort. NOAA has the mandate to establish the official shoreline boundary for the nation using tidal data. Their emphasis is 

on safe navigation and using the shoreline to generate nautical 

charts. NOAA also has a developing program (V datum) that 

will greatly assist other agencies in establishing alternative 

shorelines for a variety of purposes where the official shoreline 

is inappropriate. Congress authorized and funded FEMA to 

report on the economic impact of erosion hazards on coastal 

communities and on claims to the National Flood Insurance 

Fund. To accomplish this, FEMA contracted state agencies 

and academic researchers to conduct a pilot study of erosion hazards that included shoreline-change data for limited 

geographic areas. The USGS is responsible for conducting research pertaining to coastal-change hazards including shoreline 

change, understanding the processes that cause coastal change, 

and developing models to predict future change. The USGS is 

the only government agency that has a dedicated program to 

monitor coastal change into the future using consistent methods 

nationwide. Such a program is critically important to assess 

national issues, such as the coastal impacts of sea-level rise.

PRIOR NATIONAL AND SOUTHEAST 

ATLANTIC SHORELINE ASSESSMENTS

The USACE (1971) conducted the first national assessment of coastal erosion that included the Southeast Atlantic 

region. That study identified areas of critical and non-critical 

erosion on the basis of economic development and potential 

for property loss, but rates of shoreline movement were not 

evaluated. Dolan and others (1985) conducted a comprehensive 

analysis of shoreline changes for the U.S. Their analysis was 

based on compilation of rates of shoreline change provided 

by other contributors and derived from their own studies of 

the middle Atlantic region. Rates of change were presented 

on maps, and the long-term trends of erosion and accretion 

were summarized in an accompanying text. There have been 

numerous local studies of shoreline movement in each of the 

Southeast Atlantic states. Rather than attempting to summarize 

all of these studies, Table 1 recognizes several statewide or 

sub-regional studies and provides appropriate references. 

Since the work of Dolan and others (1985), methods of 

obtaining, analyzing, displaying, and storing shoreline data 

have improved substantially, and coastal change has continued. 

Furthermore, coastal scientists have not agreed on standard 

methods for analyzing and reporting shoreline changes, nor 

have they identified rigorous mathematical tests that are widely 

accepted for quantifying the change and associated errors. 

Consequently, there are critical needs for (1) a nationwide 

compilation of reliable shoreline data including the most recent 

shoreline position, and (2) a standardization of methods for obtaining and comparing shoreline positions and mathematically 

analyzing the trends.

METHODS OF ANALYZING SHORELINE 

CHANGE

Compilation of Historical Shorelines

Coastal scientists in universities and government agencies have been quantifying rates of shoreline movement and 

studying coastal change for decades. Before GPS and lidar 

technologies were developed, the most commonly used sources 

of historical shoreline position were NOAA Topographic 

Sheets (T-sheets, see Shalowitz, 1964) and aerial photographs. 

Ideally, extraction of shoreline position from these data sources 

involves geo-referencing and removing distortions from maps 

or aerial photographs, followed by digitizing shoreline posi-
4

tion. Depending on coastal location, data source, and scientific 

preference, different proxies for shoreline position are used to 

document coastal change, including the high-water line [for 

discussion of the high-water line (HWL) see Shalowitz, 1964], 

wet-dry line, vegetation line, dune toe or crest, toe of the beach, 

cliff base or top, and the line of mean high water (MHWL). 

In addition to deriving a modern shoreline from lidar data, 

the USGS National Assessment of Shoreline Change Project 

incorporates shoreline positions from pre-existing historical 

shoreline databases. Numerous organizations and individuals 

have provided the USGS with digital shoreline data (Table 2). 

To maintain consistency at a national scale, shorelines from 

four periods (mid- to late-1800s, 1920s-1930s, 1970s, and 

post-1998) were selected for analysis regardless of the number 

of shorelines available from existing data sets. Any remaining 

data gaps were filled using scans of historical T-sheets provided by the NOAA Vectorization Project.

For this report, the Southeast Atlantic region encompasses 

east Florida (north of Key Biscayne), Georgia, South Carolina, 

and North Carolina. Geographic locations or features referred 

to in the text are shown on Figure 1.

Shorelines were compiled for each state following the 

guidelines established for the four selected periods (mid- to 

late-1800s, 1920s-1940s, 1960s-1980s, and post-1997) as 

closely as possible. Table 3 lists the final range of years of the 

shorelines compiled for each period by state. A few notable 

exceptions include a second-period shoreline for North Carolina covering years up to 1946 and a third-period shoreline that 

covers years up to1988; a third-period shoreline for Florida beginning in 1967 and ending in 1980; and a complete third-period shoreline covering the 1960s for South Carolina. In North 

Carolina, from Cape Lookout to the Virginia border, available 

T-sheet and aerial-photo surveys most closely matching the 

second-time period were completed in the 1940s. T-sheets most 

closely matching the third-time period for the same geographic 

region were completed in the 1980s. In Florida, the third-period shoreline incorporates two segments in Brevard County, 

north of Cape Canaveral, dated 1967 and 1969 and a segment 

in Nassau County dated 1980. In South Carolina, only a partial 

series of T-sheets representing time-period three were available 

for the 1970s, so a complete series from the early 1960s made a 

better alternative. 

Delineation of a Modern (lidar-derived) 

Shoreline

The most recent shoreline used in this National Assessment (post-1997) was derived from lidar (Light Detection 

and Ranging) data. The USGS, in collaboration with NASA, 

has been using the NASA Airborne Topographic Mapper 

(ATM) to map coastal areas since 1997 (Krabill and others, 

2000; Sallenger and others, 2003). The ATM surveys ground 

elevation using an elliptically rotating blue-green laser. GPS 

(global positioning system) positions and inertial navigation 

systems are used to correct for aircraft pitch, roll, and heading, 

providing ground elevations with accuracies of about ±15 cm 

(Sallenger and others, 2003). The lidar surveys used to extract 

shorelines for this report were conducted between 1997 and 

2000 (Table 3). 

To compare with historical shorelines, an operational 

MHW shoreline was extracted from the lidar surveys using 

a method developed by Stockdon and others (2002) (Fig. 2). 

Shorelines were extracted from cross-shore profiles, which 

consist of bands of lidar data 2-4 m wide in the alongshore 

direction and spaced every 20 m along the coast. A leastsquares linear regression line is passed through the cluster of 

data that encompasses the operational MHW datum (Weber 

and others, 2005) and is limited to the seaward-sloping beach 

foreshore. The regression equation is then used to derive the 

horizontal intersection of the operational MHW datum with the 

profile, giving the shoreline position for that profile. RepeatTable 1. Prior reports of quantitative regional analyses of long-term historical shoreline movement that used 

shorelines derived from T-sheets and/or aerial photographs.
5

ing this procedure at successive profiles 20 m apart generates a 

continuous shoreline. 

To determine the operational MHW elevation, the Southeast Atlantic region was divided into nine subregions (Weber 

and others, 2005). For each subregion, the operational MHW 

elevation represents an average of MHW elevations from 

individual open-ocean or near open-ocean tide gauges. A list 

of tide gauges and MHW elevations used in each subregion is 

presented in Table 4. The lidar-extracted MHW shoreline is 

not the same as a MHW shoreline surveyed by a licensed land 

surveyor. This is because the operational MHW elevation used 

for the lidar shoreline is an average of the MHW elevations at 

several tide gauges. Furthermore, the lidar-extracted shoreline 

is intended only as a reference feature for measuring shoreline 

change. It is not intended to establish legal boundaries.

Geographic Information System (GIS) 

Procedures

Digital shorelines for each selected period were compiled 

as ESRI ArcView shapefiles and a quality assessment was 

performed. Shoreline gaps for each period were identified 

and NOAA T-sheet indexes were used to determine T-sheet 

availability for those areas. T-sheets were then requested from 

NOAA and received as scanned TIF images or as geo-referenced images.

T-sheets were geo-referenced using Erdas Imagine geographic imaging software by placing at least six well-spaced 

ground-control points (GCPs) on selected T-sheet graticules in 

geographic coordinates. Some T-sheets produced before 1930 

required additional coordinate transformation information from 

NOAA to convert from the United States Standard Datum 

(USSD) to the North American Datum of 1927 (NAD27). The 

datum transformation was applied to T-sheet graticule coordinates prior to georeferencing. Total Root Mean Square (RMS) 

error for the georeferencing process was maintained below 1 

pixel, which is approximately 4 m at a scale of 1:20,000 and 

approximately 1.5 m at a scale of 1:10,000. Typically, the 

resulting RMS was much lower than one pixel. The geo-referenced T-sheets were displayed in ArcView and shorelines were 

digitized. Completed shoreline vectors were then converted to 

the Universal Transverse Mercator (UTM) projection using the 

North American Datum of 1983 (NAD83).

Shorelines from all sources were merged to produce a 

single shoreline for each of the four time periods by state. 

Final shorelines were coded with six attribute fields (ID, Type, 

Date, Description, Source, and Accuracy) to calculate shoreline-change rates using the Digital Shoreline Analysis System 

(DSAS). The attributes include the original survey year in the 

Date field and the source of the data in the Source field. 

Table 2. Providers and original sources of historical shoreline data for each Southeast Atlantic Coast state.
6

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Figure 1A. Index map of the Southeast Atlantic region showing locations in Florida and Georgia.
7

Calculation and Presentation of Rates of Change

Rates of long-term shoreline change were generated with 

the Digital Shoreline Analysis System (DSAS) version 2.0 

(Thieler and others, 2005), an ArcView extension. The extension is designed to lead a user efficiently through the major 

steps of shoreline change analysis. This extension to ArcView 

contains three main components that define a baseline, generate orthogonal transects at a user-defined separation along the 

coast, and calculate rates of change (linear regression, endpoint 

rate, average of rates, average of end points, jackknife). The 

extension utilizes Avenue code to develop transects and rates 

and uses the Avenue programming environment to automate 

and customize the user interface.

Baselines were constructed seaward of, and parallel to, 

the general trend of the four shorelines. Using DSAS, transects 

were spaced 50 m apart. Transects were manually eliminated 

to prevent calculation of rates in areas where less than four 

shorelines were intersected. Fewer than four shorelines can 

result from one or more of the following conditions (Fig. 3): 1) 

an inlet eliminated one or more of the shorelines, 2) shoreline 

segments were missing (data gaps), 3) a barrier island migrated 

laterally (no overlap of shorelines and/or misrepresentation of 

rates), and 4) a shoreline disappeared over time. 

Long-term rates of shoreline change were calculated at 

each transect using linear regression applied to all four shoreline positions from the earliest (1800s) to the most recent 

(derived from lidar). Linear regression was selected because 

it has been shown to be the most statistically robust quantitative method when a limited number of shorelines are available 

(Crowell and others, 1997). It is also the most commonly 

applied statistical technique for expressing shoreline movement and estimating rates of change (Crowell and Leatherman, 

1999). Short-term rates of shoreline change were calculated 

using the endpoint method comparing the 1970s and most 

recent (lidar-derived) shoreline positions. Long-term rates and 

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Figure 1B. Index map of the Southeast Atlantic region showing locations in South Carolina and North Carolina.
8

short-term rates of shoreline change, as defined here, are used 

throughout the report. Both long-term and short-term rates of 

shoreline change calculated for each transect (50- m alongshore 

spacing) were color coded according to class interval with 

green colors indicating accretion and red colors indicating erosion. The shoreline-change rates and individual shoreline-data 

layers were compiled into an ArcIMS, or Arc Internet Map 

Server, viewable at http://coastalmap.marine.usgs.gov/.

Shoreline Definitions and Beach Alterations that 

Influence Rates of Change

Shoreline Definitions

Inclusion of a lidar-derived shoreline represents a new 

approach to the investigation of shoreline change. The three 

pre-lidar historical shorelines come from topographic maps 

and aerial photographs that use the HWL as the shoreline 

proxy. For more than 150 years, the HWL has served as the 

authoritative shoreline because it could be visually identified in 

the field. With advanced technologies such as GPS and lidar, 

it is possible to define the shoreline on the basis of an elevation or a tidal datum, such as MHW. Changing the shoreline 

definition from a physical feature that is uncontrolled in terms 

of an elevation datum to a shoreline defined by an elevation 

has important implications with regard to inferred changes in 

shoreline position and calculated rates of change. 

Morton and others (2004) compiled published and unpublished data to evaluate the horizontal and vertical differences 

in HWL determined from beach profiles, aerial photographs, 

or GPS surveys, and the MHWL derived from beach profiles, 

GPS surveys, or lidar surveys (Table 5). The HWL and MHWL 

positions were established at the same time, or within a few 

weeks of one another, at multiple sites around the U.S. where 

the beach and wave characteristics are diverse. Comparing 

these HWL and MHWL positions assumes that the observed 

offsets are entirely artifacts of shoreline definition and are 

not related to actual changes in the beach profile between the 

survey dates. This is a relatively safe assumption, considering 

the short intervals between surveys or the knowledge that a 

particular shoreline segment is relatively stable.

Table 5 shows that average absolute horizontal and vertical offsets between the HWL and MHWL range from a few 

meters to more than 50 m, and vertical offsets can be as much 

as 2 m. Most of the horizontal offsets are less than 20 m, and 

most of the vertical offsets are less than 1 m. Offsets are greatest on relatively flat beaches where high waves produce high 

wave runup (southwest Washington). Conversely, offsets are 

least where beaches are relatively steep and wave runup is low 

(west coast of Florida). Because breaking waves run up on the 

beach, the MHWL is most commonly seaward of the HWL 

(Morton and Speed, 1998). For the data analyzed by Morton 

and others (2004), the MHWL was seaward of the HWL at 

more than 90% of the transects (Table 5). Because a MHWL 

shoreline is used for the latest period, this nearly systematic 

horizontal offset between the HWL and the MHWL could 

cause shoreline positions and calculated rates of change to 

imply slower erosion, a change from erosion to accretion, or 

faster accretion depending on actual changes at a given site. 

Human Activities

Attempts to stabilize the shore can also greatly influence 

the rates of shoreline change. Activities such as beach nourishment or emplacement of shoreline-stabilization structures tend 

to alter coastal processes, sediment transport, and shoreline 

position. For example, beach nourishment artificially causes 

rapid, temporary shoreline accretion. Depending on the frequency of beach nourishment, the placement of large volumes 

of sand on the beach will bias the rates of observed shoreline 

change toward accretion or stability, even though the natural 

beach, in the absence of nourishment, may be eroding.

Valverde and others (1999) prepared a summary of identifiable beach-nourishment projects in the Southeast Atlantic region before 1996. These records were used to identify shoreline 

segments that had been influenced by beach nourishment. Additional information regarding beach nourishment was provided by Ralph Clark of the Florida Department of Environmental 

Protection. Only projects that pre-date the lidar shoreline were 

included. There is no distinction made between large-volume, 

continuous projects and small-volume, finite projects. Differentiating between natural rates of erosion and the influences of 

beach nourishment is difficult because experiments have not 

Table 3. Dates of compiled shorelines for selected periods.
9

been conducted to address this issue specifically. In addition, 

available data may be inadequate because there are not enough 

shoreline positions immediately before, after, and between 

nourishment projects. Human responses to coastal erosion in 

each state, including beach nourishment and emplacement of 

structures, are discussed in more detail in a later section.

Reliability of the Results

Documented trends and calculated rates of shoreline 

change are only as reliable as: (1) measurement errors that 

determine the accuracy of each shoreline position, (2) sampling 

errors that account for the variability of shoreline position, 

and (3) statistical errors (variability) associated with compiling and comparing shoreline positions. Anders and Byrnes 

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Figure 2. Example of a lidar profile from September 26, 1997 at Kitty Hawk, North Carolina, for (A) the entire 

cross-shore region and (B) an expanded view of the foreshore region. (A) Laser returns off of the water’s 

surface are seen as the noisy signal seaward of x = 350 m. Bold symbols indicate data points within ± 0.5 

m of the operational MHW datum. (B) The asterisk marks the cross-shore position of the shoreline on 

the foreshore. The horizontal error bar represents the 95% confidence interval about the estimate. From 

Stockdon and others (2002).
10

(1991), Crowell and others (1991), Thieler and Danforth 

(1994), Moore (2000), and Daniels and Huxford (2001), 

provided general estimates of the typical measurement errors 

associated with mapping methods and materials for historical 

shorelines, registry of shoreline position relative to geographic 

coordinates, and shoreline digitizing. The largest errors were 

positioning errors of ±10 m, which were attributed to scales 

and inaccuracies in the original surveys (T-sheets and aerial 

photographs). However, the influence of large shoreline 

position errors on long-term rates of change can be reduced 

because the period of analysis is so long (>100 yrs). Stockdon 

and others (2002) provided estimates of GPS positioning errors 

(±1 m) and regression errors (±1.5 m) associated with shorelines derived from lidar data.

Estimates of the maximum measurement errors for this 

study are provided in Table 6 to show how each error contributes to uncertainty in the shoreline position and in the rates 

of change. A total shoreline position error (Esp)(Equation 

1) incorporates all of the measurement errors by taking the 

square root of the sum of the squares of: georeferencing error 

(Er), digitizing error (Ed), T-sheet survey error (Et), shoreline 

proxy offset (Eo), and lidar position error (El). Georeferencing 

error represents the elected maximum acceptable RMS error 

for T-sheets at a scale of 1:20,000 in this study. We assume 

data from outside sources conform to similar standards. The 

georeferencing error is applied to the historical shorelines only. 

Digitizing error reflects the maximum digitizing error specified 

in past studies (Anders and Byrnes, 1991; Crowell and others, 1991; Moore, 2000). The digitizing error is applied to the 

historical shorelines only. The maximum T-sheet survey error 

for time periods 1 and 2 (1800s and 1920s-1930s), determined 

by Shalowitz (1964), incorporates all of the errors associated 

with the mapping process, including distance to rodded points, 

plane-table position, and identification of the HWL. Because 

more recent T-sheets, including time-period three (1970s), are 

derived from aerial photographs, the T-sheet survey error is 

Table 4. List of tide-gauge measurements used to calculate mean high-water elevation 

(Weber and others, 2005).

Site Name

MHW above NAVD88

(m)

Average of MHW

(m)

Miami Beach, FL 0.03

Haulover Pier, FL 0.06

North Miami Beach, FL 0.04

Lauderdale-By-The-Sea, FL 0.11

Hillsboro Inlet, FL 0.07

Lake Worth Pier, FL 0.09

Fort Pierce, FL 0.00

Vero Beach, FL 0.13

0.07

Daytona Beach Shores, FL 0.28 0.28

Saint Augustine Beach, FL 0.45 0.45

Saint Augustine Beach, FL 0.45

Jacksonville Beach, FL 0.58 0.52

Little Talbot Island, FL 0.66

Saint Simons Island, GA 0.71 0.68

Braddock Point, SC 0.81

Port Royal Plantation, SC 0.75

Edisto Beach, SC 0.69

0.75

Isle of Palms Pier, SC 0.53

Pawleys Island Pier, SC 0.50

Garden City Pier, SC 0.46

Springmaid Fishing Pier, SC 0.55

Yaupon Beach, NC 0.49

0.51

Wilmington Beach, NC 0.36

Atlantic Beach, NC 0.37 0.36

Cape Hatteras Fishing Pier, NC 0.24

Duck, NC 0.27

Sandbridge Beach, VA 0.31

Virginia Beach, VA – 2 0.21

Virginia Beach, VA – 1 0.29

0.26
11

substantially less (Daniels and Huxford, 2001). The shorelineproxy offset reflects the maximum horizontal offset between 

high-water and mean high-water shorelines in the Southeast 

Atlantic region (see Table 5). The offset error pertains only 

to the lidar-derived shoreline. Lidar position error reflects the 

maximum error associated with the derivation of a lidar shoreline (Stockdon and others, 2002). The lidar position error is 

applied only to the lidar-derived shoreline. Thus, total shoreline-position error is expressed by:

A separate Esp can be calculated for each period. 

Sampling errors relating to the local short-term variability of true shoreline positions (Morton, 1991; Douglas and 

Crowell, 2000) are less well known. Temporally dense data 

are required to evaluate short-term shoreline variability resulting from seasonal cycles and from rapid storm erosion and 

subsequent recovery. Moreover, most datasets include some 

apparent shoreline movement caused by changes in water level 

(HWL) and not changes in sediment volume (Morton, 1991). 

Lack of reliable high-frequency data regarding short-term variability of true shoreline position at most coastal sites limits the 

ability to quantify and incorporate the associated uncertainty 

into the overall shoreline position uncertainty. An exception is 

the 20-year record of beach profiles surveyed by the USACOE 

at Duck, N.C. Using 460 shoreline positions from the Duck 

profile data, Barton and others (2003) showed that the envelope 

(range) of shoreline positions even around a relatively stable 

shoreline was about ±20 m. 

Linear regression is the most commonly applied statistical 

technique for expressing shoreline movement and estimating 

rates of change (Crowell and Leatherman, 1999). Linear regression assumes linear behavior, which technically is incorrect 

(Morton, 1991; Barton and others, 2003), but is adequate for a 

Figure 3. Examples of common conditions where transects are eliminated in the absence of four shoreline intersections.

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12

first approximation. Because linear regression fails to recognize 

the potential for temporal differences in trend (trend reversals) and accelerations or decelerations (Morton, 1991; 1996), 

average trends and rates of shoreline change in this study were 

calculated for long-term (entire period) and short-term (most 

recent) time scales. Long-term rates of shoreline change were 

determined at each transect by taking the slope of the regression line applied to all four shoreline positions. The resulting 

rate is reported in units of m/yr (Table 7). Uncertainties for the 

long-term rates (± values in Table 7) are also reported in units 

of m/yr. The reported uncertainties represent a 90% confidence 

interval for the slope of the regression line. This means with 

90% statistical confidence that the true rate of shoreline change 

falls within the range defined by the reported value plus or 

minus the error value. The variability around the trend line 

reflects both measurement and sampling errors. 

Field observations and prior studies of shoreline movement within each state in the Southeast Atlantic region (Table 

1) suggest that the trends and relative rates of change presented 

in this study are reasonably accurate. Reliability of the mapped 

results increases as both the persistence of the trend and rates 

of change increase. Stated another way, confidence in the analytical results is greatest where the rates of shoreline erosion 

or accretion are high, the trend has persisted for decades, and 

Table 5. Absolute horizontal and vertical differences between high-water and mean high-water shorelines (Morton and others, 2004).

Table 6. Maximum estimated measurement errors for Southeast Atlantic shorelines.
13

the trend is consistent for long stretches of coast. On the other 

hand, confidence in the absolute results decreases where the 

shoreline is relatively stable and the rates of change are low. 

This is because minor differences in historical or lidar shoreline positions can alter substantially the regression line and 

the calculated results. Data confidence also decreases in areas 

where frequent trend reversals occur.

Advanced technology such as GPS and lidar can better constrain shoreline positions, reduce the methodological 

errors, and improve the accuracy (reduce the error) for future 

shoreline analyses. Establishing a datum-based shoreline (lidar 

derived MHWL) as the standard for comparison provides the 

ability to perform an error analysis that is both quantitative 

and meaningful, in terms of its application. In the future, each 

digital MHWL shoreline could be presented with an accompanying error bar that would define the alongshore envelope of 

confidence. Subsequent shorelines and associated confidence 

envelopes would provide a more precise basis for determining the statistical significance of observed shoreline change. 

Unfortunately, the use of lidar or any other shoreline mapping 

technology will still require distinguishing between short-term 

variability in shoreline position and the long-term trend of 

shoreline change.

GEOMORPHOLOGY OF THE SOUTHEAST 

ATLANTIC REGION

The Southeast Atlantic region is a low-lying area that 

consists of a variety of coastal features including mainland 

shores, estuaries and lagoons, barrier islands and capes, tidal 

inlets, and delta plains (Fig. 4). The physical characteristics and 

geologic framework of each of these features partly determine 

the trends and rates of shoreline movement and related coastal 

changes of the region. 

Southeast Atlantic Mainland Shores

The Southeast Atlantic coast consists mainly of barrier 

islands, but there are some segments where the ocean meets 

the mainland shore without an intervening estuary or lagoon. 

In Florida, extensive stretches of sandy mainland shore are 

exposed to ocean waves north of Miami to Delray Beach, from 

Juno Beach to Jupiter Inlet, from north of Ormond by the Sea 

to south of Marineland, and from the St. Johns River to Ponte 

Vedra Beach. There are no ocean-fronting mainland shores 

in Georgia, but in South Carolina, the Grand Strand including Myrtle Beach is a sandy mainland shore that extends from 

North Inlet to Little River Inlet. Sandy mainland shores occupy 

much of the southern North Carolina coast between Little River 

Inlet and Oak Island. Only the Atlantic Intracoastal Waterway 

separates the ocean shore from the mainland along much of this 

segment. 

Estuaries and Lagoons

Most large coastal estuaries or sounds bordering the 

Southeast Atlantic coast are drowned river valleys that have 

remained unfilled because the rivers emptying into the estuaries are transporting very little sediment. Charleston Harbor, 

South Carolina and Albemarle Sound, North Carolina are good 

examples of estuaries. The estuaries generally are oriented perpendicular to the Atlantic shoreline, whereas lagoons are parallel to the shoreline. Some lagoons are named properly, such as 

Indian River Lagoon, Florida, whereas some are named sounds 

such as Pamlico Sound, and Currituck Sound, North Carolina. 

The moderately wide coastal lagoons, which formed when the 

uplands between the river valleys were flooded by rising sea 

level, separate the barrier islands from the mainland. Narrow 

coastal lagoons, like many of those in Florida, are formed by 

rivers that flow parallel to the shore. Some former lagoons are 
14

filled with extensive marshes, such as those along the Georgia 

coast.

Estuarine and lagoon shores account for the longest 

stretches of eroding shoreline in the Southeast Atlantic region. 

They are also the most complex in terms of land loss because 

they have different orientations and relief, and they cut across 

sediments with different elevations and resistance to erosion. 

Estuarine and lagoon shores can be composed of sand, shell, 

or mud, and they can form low beaches, tall bluffs, or marshes. 

Analyses of shoreline changes in estuaries and lagoons are not 

included because the focus of this report is on the Southeast 

Atlantic open-ocean shoreline.

Figure 4. Common coastal landforms of the Southeast Atlantic region.

River

Bayhead Delta Mainland

Shore

Peninsula

Tidal Inlet

Estuary

(Sound)

River

Delta plain

Lagoon

Barrier

Island

Tidal Inlet

Waves

Longshore

Currents
15

Barrier Islands and Capes

Origin and Evolution of Barriers and Capes

The origins and related morphologies of barrier islands 

can influence shoreline movement because the thicknesses 

and volumes of sand stored in the barriers are related to the 

processes that formed them. Barrier islands commonly form 

the outer fringes of low-lying coastal plains throughout the 

world. As their name implies, they are surrounded by water and 

are separated from the adjacent mainland by lagoons, bays, or 

marshes and from neighboring islands by tidal inlets. Barrier islands are long and narrow mounds of sand deposited by 

waves and wind over millennia. In general, they are produced 

by long-term submergence of the low-gradient coast. Three 

independent mechanisms (Fig. 5) have been proposed for the 

origins of barrier islands: (1) dune drowning (McGee, 1890), 

(2) spit elongation (Gilbert, 1885), and (3) shoal emergence 

(De Beaumont, 1845). Each mechanism explains the origin of 

some barriers (Hoyt, 1967), but no single cause explains the 

origins of all barriers (Schwartz, 1971). 

Barrier islands can form by dune drowning (Fig. 5A) 

when a relative rise in sea level partly inundates a mainland 

ridge of coastal dunes. The rising water encompasses the 

sand dunes along the beach and eventually floods the seaward 

sloping coastal plain between the dunes and upland, forming a 

lagoon.

Spit elongation (Fig. 5B) refers to lateral barrier extension along the prevailing trend of the beach. Sand transported 

along the coast by longshore currents is deposited on the 

flanks of headlands or at the downdrift ends of existing barrier 

islands. Spit elongation is a widely observed process whereby 

barriers are originally constructed across embayments, forming lagoons, or previously formed barriers are enlarged in a 

downdrift direction. Recurved beach ridges are diagnostic field 

evidence of spit accretion. This type of barrier formation generB. Spit Elongation C. Shoal Emergence

Time 1 Time 

2 Time 

3

A. Dune Drowning

Dune

Ridge

Sea Level

Dune

Ridge

Sea Level

Dune

Ridge

Sea Level

Sea Level

Sea Level

Sea Level

Headland

Headland

Headland

Embayment

Embayment

Lagoon

Ocean

Ocean

Ocean

Figure 5. Conceptual diagram showing possible origins of barrier islands.
16

ally occurs under stable sea-level conditions and/or a surplus of 

sand supply.

Shoal emergence (Fig. 5C) involves the upward growth of 

a submerged bar where sand is supplied by erosion and redistribution of sediment on the sea floor. The vertical accumulation 

of sand eventually causes the bar to rise above the ocean level 

so that the emergent bar forms a barrier island. Shoal emergence is aided by a slight lowering of relative sea level, such 

as after a storm, and it also requires a local surplus of sand to 

maintain the barrier. 

Many barrier islands in the Southeast Atlantic region, such 

as Amelia Island, Florida, Ossabaw Island and Wassaw Island, 

Georgia, Isle of Palms and Kiawah Island, South Carolina, and 

Bogue Banks, North Carolina, originally migrated across the 

continental shelf and then began to grow seaward when the 

rise in sea level slowed about 5,000 years ago (Fig. 6). Some 

barriers have grown laterally as a result of spit elongation (St. 

Catherines Island, Georgia), and other barriers formed around 

an island core of older barrier deposits left over from a previous time when sea level was at about the same level as today 

(Amelia Island, Florida, Jekyll Island and Cumberland Island, 

Georgia). Still other barriers, such as St. Simons Island and 

Tybee Island, Georgia, and South Island, South Carolina, have 

formed in conjunction with delta progradation at the mouths of 

the Altamaha, Savannah, and Santee-Pee Dee Rivers, respectively (Brown, 1977; Hayes, 1994).

There are five prominent cuspate forelands or capes 

along the Southeast Atlantic coast (Hoyt and Henry, 1971). 

From south to north they are Cape Canaveral, Florida, Cape 

Romain, South Carolina, and Cape Fear, Cape Lookout, and 

Cape Hatteras, North Carolina. Common characteristics of 

the capes are a general triangular shape, seaward protrusion 

beyond the general shoreline trend, abrupt changes in shoreline 

orientation, and multiple divergent beach ridges indicating that 

they have been sites of long-term sand deposition. The North 

Carolina capes also are oriented such that the updrift (northern or eastern) limb is exposed to strong winter waves and is 

eroding, whereas the downdrift (southern or western) limb is 

more sheltered from storm waves and is accreting (Moslow and 

Heron, 1994). A broad field of shoals extending offshore from 

each cape also indicates that the shoals have been zones of 

long-term accumulation of sand transported along the beaches. 

Hoyt and Henry (1971) reviewed the proposed origins of 

capes (large-scale oceanographic circulation, convergence of 

reversing longshore currents, wave refraction, structural uplift) 

and concluded that capes of the Southeast Atlantic region are 

probably associated with former rivers and developed as a 

result of ancestral delta deposits on the continental shelf. Later, 

Blackwelder and others (1982) demonstrated that antecedent 

topography on the shelf formed by outcrops of indurated strata 

largely controlled the positions of Cape Fear and Cape Lookout, North Carolina. It is possible that the offshore geologic 

framework also anchors other cape locations, and their growth 

and morphological changes are a result of seasonal reversals in 

longshore currents (Hayes, 1994).

Today, the highest elevations and largest sand dunes along 

the Southeast Atlantic coast are present on the sand-rich progradational (seaward-building) barrier islands and capes such 

Figure 6. Sea-level curve during the past 140,000 years that depicts the general magnitude and timing of sealevel changes in the Atlantic Ocean. Modified from Chappell and others (1996).

20

0

-20

-40

-60

-80

-100

-120

-140

0 20,000 40,000 60,000 80,000 100,000 120,000 140,000

years before present

sea level (m)
17

as Cape Canaveral, Florida, Little St. Simons Island, Georgia, 

Kiawah Island, South Carolina, and Currituck Banks, North 

Carolina. Much of the coastal sand that was washed ashore as 

sea level reached its present position is stored in these highprofile barriers (Fig. 7), and they typically have lower erosion 

rates because of the abundant sand. However, at some coastal 

locations, the volume of sand stored in the dunes may contribute to beach erosion (Fig. 8). Migrating and landward retreating barriers, such as Hutchinson Island, Florida, Edingsville 

Beach, South Carolina, and Core Banks, North Carolina, typically have higher erosion rates because they are located away 

from major sources of sand.

Morphologies of Southeast Atlantic Barrier 

Islands

Barrier islands make up more than two-thirds of the 

Southeast Atlantic shore. Each of the barriers can be classified 

as either high-profile or low-profile (Fig. 7) depending on the 

elevations and morphology of the island. The height and continuity of these elevations determine the ability of the barriers to 

withstand storm-surge flooding and overwash. The origins and 

profiles of the barriers also partly determine the stability of the 

shoreline.

Low-profile barriers, such as Hutchinson Island, Florida, 

Morris Island and islands around Cape Romain, South Carolina 

(Fig. 9), and Core-Portsmouth Banks and northern Hatteras 

Island, North Carolina, are typically narrow and characterized 

by discontinuous or narrow frontal dunes that are inundated 

by extreme storm surges. This makes the barrier vulnerable to 

overwash during storms. Overwash can create channels and 

fans that transfer sand from the ocean onto the barrier or into 

the adjacent lagoon. Barrier upbuilding, another common process of barrier evolution, is a response to a rise in relative sea 

level, and the transfer of sand from the ocean to the lagoon is 

a mechanism by which the barrier migrates landward and still 

retains its general shape and sand volume. Island migration is 

enhanced if there is a deficit in the sand supply or if there is a 

rapid rise in relative sea level. However, if the rate of sea-level 

rise is too great, then the barrier island may be drowned and 

left as a submerged sand shoal on the continental shelf.

High-profile barriers, such as Amelia Island, Florida, 

Wassaw Island, and Little St. Simons Island, Georgia (Fig. 10), 

Capers Island, Bull Island, and Kiawah Island, South Carolina, 

and minor segments of the barrier islands of North Carolina 

near Kitty Hawk are the result of abundant sand supply for 

thousands of years. These barriers are typically wide and have 

continuous, well-vegetated dunes. The high elevations effectively block storm surges and prevent island overwash, even 

during the most severe storms. In addition, enough sand is 

stored in the dunes that they are able to withstand prolonged 

erosion without being breached, which would allow flooding of 

the barrier core. However, flooding of high-profile barriers can 

occur from the lagoon side or from the ocean through artificial 

breaks in the dune ridge, such as beach-access roads or areas 

where dunes have been destroyed by coastal construction.

Tidal Inlets

Tidal inlets are the primary channels separating the barrier 

islands (Fig. 4). They also allow the exchange of water and 

migration of marine organisms between the Atlantic Ocean and 

adjacent estuaries and lagoons. In Georgia and southern South 

Carolina, more water flows out of the tidal inlets than flows in 

during a tidal cycle. This asymmetry, referred to as ebb-dominated flow, is a result of abundant freshwater inflow supplied 

by rivers in the adjacent estuaries. The ebb-flow asymmetry 

also contributes to the formation of large ebb shoals that store 

vast quantities of sand on the seaward margins of the inlets 

(Hayes, 1994). Periodic cycles of sand storage and release from 

the ebb-delta shoals throughout the Southeast Atlantic coast 

have had profound influences on the patterns of shoreline erosion and deposition adjacent to the inlets. Figure 7. Geomorphological characteristics of high- and lowprofile barrier islands. Modified from White and others (1978).

High-Profile Barrier Island

Low-Profile Barrier Island

OceanFore beachBack beachHummocky vegetated

fore -island dunes

Foredune ridgeIntervening swaleForedune ridgeVegetated barrier flatMarshLagoon

OceanFore beach

Back beach

Hummocky 

 discontinuous dunes

Overwash fansLagoon

A

B
18

The strength and relative proportion of tidal and wave 

energy greatly influences the morphology of barrier islands and 

lagoons, and the number and spacing of tidal inlets (Nummedal 

and others, 1977; Hayes, 1994). For example, in Florida and 

northern North Carolina, where tidal range is relatively low and 

subordinate to wave energy, wave-dominated barrier islands 

and adjacent lagoons are long and narrow, and tidal inlets are 

few, small, and widely spaced. In contrast, where tidal range 

is high, as in Georgia and southern South Carolina, tide-dominated barrier islands are short and wide, and tidal inlets are 

numerous and closely spaced.

Shorelines near unstabilized inlets are commonly sites of 

high variability and rapid erosion due to channel and shoal migration and high current velocities. Long-term rates of change 

and their associated uncertainties at sites near inlets can be 

useful in conveying the variable nature of the shoreline and the 

derived risks from a coastal-hazards perspective. For this study, 

some of this variability may be minimized in the rates and 

uncertainties around inlets because of the decision to maintain 

data consistency by deleting transects in cases where less than 

four shorelines were present.

Large inlets are used for navigation into and out of the 

coastal bays and adjacent ports. These navigable inlets have 

been modified for maintenance of deep-draft channels, and 

many of the channels are lined by long rock jetties. Where 

they are unmodified, sand banks and beaches line the inlets. 

Several man-made inlets through Southeast Atlantic barrier 

islands have altered water-circulation patterns, longshore currents, and littoral drift and have locally caused or contributed 

to both beach erosion and accretion (Dean and O’Brian, 1987). 

Some of the artificial inlets in Florida include Government Cut 

opened in 1905 near Miami and Bakers Haulover Cut opened 

in 1925 also near Miami, and South Lake Worth Inlet opened 

in 1927. In North Carolina, New Drum Inlet on Core Banks 

was opened in 1972.

Long, narrow microtidal barrier-island segments that have 

low relief (maximum dune elevations of less than 2 m) and that 

are far from existing tidal inlets are susceptible to breaching 

and new inlet formation during extreme storms (Morton, 2002). 

Inlet formation may occur when fast-moving hurricanes tracking near the coast produce storm surges that exceed the dune 

heights. When there is insufficient time for lagoon water levels 

to respond to elevated open-ocean water levels, a hydraulic 

head can be created, driving flows landward across the narrow 

barrier and incising channels. The North Carolina coast has 

been the site of numerous historical inlet openings or reactivaFigure 8. Former active sand dunes on Shackleford Banks, North Carolina, that partly buried a maritime 

forest, may contribute to erosion by removing sand from the beach. Dunes are activated when the stabilizing 

vegetation is destroyed either as a result of natural causes (droughts, grass fires) or as a result of human 

activities (off-road vehicles, overgrazing, construction).

Maritime forest

Former active dunes
19

tion of closed inlets (Fisher, 1962; Cleary and Hosier, 1979) 

and is particularly vulnerable to this extreme-storm response.

Some tidal inlets opened during storms may remain open 

for long periods. For example, in North Carolina, a hurricane 

in 1933 opened Barden Inlet at Cape Lookout. The 1962 Ash 

Wednesday storm opened an inlet at Buxton, and Hurricane 

Isabel (2003) opened two inlets near Hatteras. These latter 

inlets were quickly closed by the North Carolina Department 

of Transportation. A northeaster in 1986 cut through Folly 

Island, South Carolina, and Hurricane Hugo in 1989 cut a new 

inlet through Pawleys Island, the barrier just north of North 

Inlet. Barrier breaching commonly reoccurs where narrow spits 

or peninsulas attach to headlands. Breaching is also common where substantial downdrift inlet migration has over time 

produced a low barrier segment and a long ebb channel that is 

hydrodynamically inefficient.

Delta Plains

The Altamaha River in Georgia, the Savannah River at the 

Georgia/South Carolina border, and the Santee-Pee Dee River 

in South Carolina are the only fluvial systems of the Southeast 

Atlantic region that have built deltas into the Atlantic Ocean. 

The relatively small drainage areas, low topographic relief, and 

low sediment yields of rivers in Florida prevent delta construction along its Atlantic coast. In addition, most rivers draining 

the east coast of Florida are located landward of and parallel to 

the barriers forming narrow “lagoons” that separate the barriers 

from the mainland. The major rivers in North Carolina empty 

into estuaries rather than into the Atlantic Ocean (Meade, 

1982).

Ocean shores of the Altamaha delta have both eroded 

and accreted in historical time (Griffin and Henry, 1984). The 

shores of Wolf Island eroded, whereas Little St. Simon Island 

mostly accreted. Long-term historical shoreline changes of the 

Savannah delta have been mixed (Griffin and Henry, 1984). 

Wassaw Island rotated counter-clockwise, eroding on the north 

end and accreting on the southern end. Little Tybee Island and 

Tybee Island exhibited segments of both erosion and accretion.

Despite being the largest delta on the east coast of the 

United States and having sufficient sediment supply for delta 

construction in the past, some shores of the Santee-Pee Dee 

delta have eroded, whereas others have accreted. Artificial 

reductions in sediment supply related to dam construction and 

river diversion are largely responsible for rapid shoreline erosion along the Santee-Pee Dee delta (Hayes and others, 1994).

GEOLOGIC HISTORY AND SETTING

River deltas, barrier islands, and marshes built the broad 

coastal plain bordering the Southeast Atlantic coast during two 

periods when sea level was relatively high. The highest coastal 

plain elevations were formed about 130,000 years ago during 

a late Pleistocene interglacial period when sea level was about 

6 to 8 m higher than today (Fig. 6). The lower coastal-plain 

elevations associated with modern marshes and barrier islands 

formed when sea level reached its present position about 5,000 

years ago. Between these periods, the shape and origin of the 

present Southeast Atlantic coast was greatly influenced by 

changes in sea level due to expansion and melting of continental glaciers. The present-day shape of the Southeast Atlantic 

coast, and the origin of many of the distinctive coastal features 

found today, reflects these fluctuations in sea level that alternately exposed and submerged the coastal plain. 

About 18,000 years ago, at the end of the last glacial epoch, sea level was about 130 m lower than today (Fig. 6). This 

lower sea level caused coastal plain rivers to cut deep valleys 

across the continental shelf. As the glaciers melted and sea 

level rose to its current position, these valleys were drowned 

Figure 9. Low, narrow barrier islands, such as those around 

Cape Romain, South Carolina, are overwashed frequently 

during storms. 
20

and most were only partly filled with sediment. The unfilled 

remnants of former river valleys that rim the Southeast Atlantic 

coast are the major estuaries, such as Charleston Harbor, and 

Albemarle Sound.

Post-glacial climatic changes had dramatic effects on the 

amount of water and sediment transported by the coastal-plain 

rivers draining into the Atlantic Ocean. As rainfall decreased, 

so did stream flow and sediment load, which caused some 

river deltas to retreat. While the deltas were retreating, some 

adjacent beaches and barrier islands that had been migrating 

landward began to build seaward as a result of locally abundant 

sand supply. The sand that built the accreting shores was supplied by erosion of mainland shores and reworking of Pleistocene barrier-island and deltaic sediments on the continental 

shelf that were submerged by the rising sea. Numerous beach 

ridges that mark successive former positions of the Atlantic 

shoreline (Fig. 10) are evidence of the abundant supply of older 

sand. 

Riggs and others (1995) described shoreface settings along 

the North Carolina coast and explained how semi-indurated 

and indurated strata underlying the perched beaches and barrier 

islands influenced the: (1) nearshore physical processes, (2) 

production of beach sediment from the submerged outcrops, 

(3) shape of the shoreface, and (4) long-term movement of the 

shoreline. Similar conclusions regarding geologic framework 

and shoreline movement were reported for South Carolina by 

Gayes and others (2003). The shoreface classifications and 

associated shoreline conditions reported by Riggs and others 

(1995) could be applied to other segments of the Southeast 

Atlantic region where sand supply is limited and older strata 

are either exposed at or are near the sea floor.

Coastal Processes

The Southeast Atlantic coast is a storm-dominated region 

that is constantly changing as a result of active coastal processes that are directly linked to meteorological events. Winddriven waves and tidal currents are the most important geological agents controlling sediment transport and evolution of the 

Southeast Atlantic shores. Wind directions and intensities vary 

seasonally with southerly winds prevailing most of the year. 

During the winter months, wind-circulation patterns and low 

barometric pressures preceding the passage of cold fronts cause 

strong onshore winds and high waves that typically erode the 

beach. After each frontal system passes the coast, wind direction shifts and strong northerly winds can generate waves that 

erode estuarine and backbarrier shores at many locations. 

Tidal range of the Southeast Atlantic coast is influenced 

by the configuration of the shore and continental shelf (Redfield, 1958). The semi-diurnal tidal wave is amplified by the 

Georgia embayment, known as the Georgia Bight, and the tidal 

range changes systematically alongshore (Nummedal and others, 1977) such that it is highest (maximum ≈ 3 m) within the 

Georgia Bight, but decreases both to the north and to the south. 

Tidal range generally is lowest (maximum < 1 m) in Florida. 

Wave heights and associated wave energy also vary along the 

Southeastern Atlantic coast increasing northward from Florida 

to North Carolina (Nummedal and others, 1977). The combination of tidal and wave forces also varies; North Carolina has 

moderately high wave energy and moderate tidal energy, South 

Carolina has moderate wave energy and moderate tidal energy, 

Georgia has high tidal energy and moderately low wave energy, and Florida exhibits both moderately low tidal energy and 

wave energy.

Average wave heights in the Southeast Atlantic Ocean 

range from 0.8 to 1.5 m in Georgia and North Carolina, respectively (Nummedal and others, 1977). The largest waves and 

highest sustained wind speeds accompany major hurricanes. 

They also are responsible for the most property damage and 

Figure 10. Long linear beach ridges and swales that 

characterize some Southeast Atlantic barrier islands, such 

as Little St. Simons Island, Georgia, mark the former positions 

of the Atlantic shoreline. These features record shoreline 

accretion at time scales of hundreds to thousands of years.
21

loss of lives. Hurricanes tracking along the Southeast Atlantic 

coast normally follow a northward or westward path (Fig. 11). 

The preferred paths of the storms determine the likelihood that 

a storm will make landfall at a particular site. Using historical 

sites of hurricane landfall, the National Hurricane Center has 

shown that the areas at greatest risk are southeastern Florida, 

South Carolina, and North Carolina (Simpson and Lawrence, 

1971). Georgia has the lowest risk because of the position of 

its embayed shoreline relative to the tracks of most Atlantic 

hurricanes.

Before crossing the Southeast Atlantic coast, the counterclockwise circulation of hurricane wind drives nearshore 

currents and large volumes of beach and shoreface sand 

alongshore. High tides, large waves, and strong currents that 

accompany the storms can leave semi-permanent marks on the 

barrier islands and beaches. For example, in 2003, Hurricane 

Figure 11. Tracks of some of the most deadly and destructive Atlantic and Gulf hurricanes in the 20th 

century. Data are from the National Hurricane Center.

1938

1900

1928 Camille

(1969) Betsy

(1965) 1919

Carla

(1961) Hugo

(1989)
22

Isabel eroded the dunes along Hatteras Island, North Carolina, 

and cut several channels through the coastal highway. Shortly 

after the storm, the North Carolina Department of Transportation created an artificial dune ridge by bulldozing sand from 

the overwash terrace and pumping up sand from offshore to 

fill in the breaches. A similar but smaller artificial ridge was 

constructed from beach sand to protect the coastal road from 

erosion on Topsail Island, North Carolina (Fig. 12). In Florida, 

even relatively weak storms have destroyed piers, seawalls, 

dune walkovers, swimming pools, roads, houses, motels, and 

other buildings because structures were poorly sited and the 

beach did not recover from storm erosion before the next 

storm arrived (Clark, 1986). In 2004, two hurricanes only a 

few weeks apart (Francis and Jeanne) struck the east coast 

of Florida (Florida Department of Environmental Protection, 

2004), causing more erosion and property damage than either 

storm would have on its own (Fig. 13). 

Tide-gauge records along the Southeast Atlantic coast 

since the turn of the century all show the same general variations in sea level (Fig. 14). Annual variations are controlled by 

meteorological and oceanographic factors (Hicks, 1968). The 

tide-record trends show that some areas, such as Key West, 

are relatively stable because the underlying hard limestone 

substrates are stable. Other tide records, such as at Charleston, 

show a slightly higher relative rise in sea level of about 3.3 

mm/yr during the 20th century (Lyles and others, 1988). This 

rate of rise is about twice as fast as the global rise in sea level, 

which recently has averaged about 1.8 mm/yr (Gornitz and 

Lebedeff, 1987). 

The difference between recorded rates of submergence 

along the Southeast Atlantic coast and the global rate of sealevel rise is caused mostly by subsidence. Releveling surveys 

show that the subsidence is related to regional tilting of the 

coastal plain; areas near and seaward of the shoreline are sinking while inland areas are being uplifted (Holdahl and Morrison, 1974). Within the regional trend are areas where subsidence rates are relatively high, such as near Savannah, where 

accelerated sinking is attributed to groundwater withdrawal 

(Davis, 1987). 

Sand Sources

Eroding beaches and sand shoals on the adjacent inner 

continental shelf are the primary sources of sand for maintaining the Southeast Atlantic barriers and beaches. Southeast 

Atlantic rivers generally do not contribute significantly to the 

present sand budget of the beaches because most of the rivers 

empty into estuaries and deposit their sediment loads far inland 

from the Atlantic shoreline. A few moderately large Piedmont-draining rivers, such as the Altamaha and Savannah in 

Figure 12. Erosion of the Atlantic shore can destroy roads and eliminate the beach. This example at Topsail 

Island, North Carolina, shows the effects of long-term erosion and efforts to protect the highway.
23

Georgia and the Santee-Pee Dee in South Carolina, added sand 

directly to the littoral system before they were modified by dam 

construction or river diversion that greatly reduced their sand 

supply to the coast (Hayes, 1994).

Sand supply was further disrupted by other human activities such as dredging channels and constructing jetties. The 

jetties and navigation channels at inlets disrupt the longshore 

currents and compartmentalize the coast, preventing sediment 

exchange from one coastal segment to another. Before the littoral drift system was altered, sand was naturally transported 

around tidal inlets and shared between neighboring coastal segments. Now there are many coastal compartments isolated by 

long impermeable jetties or deep navigation channels like those 

maintained at the entrance to ¬Charleston Harbor. The history 

of Morris Island, South Carolina, is a good example of how 

jetty construction has influenced shoreline movement. Before 

jetties were constructed in 1896, Morris Island was a beachridge barrier wider than Folly Island, but the jetties blocked the 

alongshore supply of sand to Morris Island and it began eroding rapidly and pivoting as it migrated landward (Lennon and 

others, 1996). The lighthouse that once was on land now stands 

surrounded by water more than 600 m offshore (Fig. 15).

GENERAL CHARACTERISTICS OF THE 

SOUTHEAST ATLANTIC SHORES BY 

STATE

The east coast of Florida consists largely of long, narrow, 

sandy barrier islands that are backed by diverse wetlands. Mangroves occupy the backbarrier settings from Miami Beach to 

Vero Beach, whereas backbarrier salt marshes are present north 

of Vero Beach. Florida east coast barriers tend to be long and 

narrow because they are wave dominated and the sand supply 

is low. An exception is Amelia Island in north Florida, which 

resembles the wide, tide-dominated barrier islands of Georgia. 

The Florida barriers are separated by only a few natural tidal 

inlets, which are widely spaced and small because the tidal 

range is low and freshwater inflow is minor. Mainland beaches 

are prominent in Flagler County and Broward County. A feature unusual for the Florida coast is Cape Canaveral, a cuspate 

foreland that consists of multiple beach ridges separated by 

narrow, shallow lagoons. Florida rivers flowing to the Atlantic 

Ocean have small drainage areas and they do not transport the 

large volumes of sand necessary for building or maintaining 

beaches or the large volumes of water capable of creating large 

estuaries. Outcrops of beachrock and other indurated strata, 

which are common in the nearshore zone south of Cape Canaveral, are evidence of the low sand supply. These hard outcrops 

can slow the rates of shoreline erosion locally.

Short, wide barrier islands that are backed by extensive 

salt marshes and separated by large tidal inlets characterize the 

Georgia coast. Some of the barriers continue to receive sand 

and are accreting, whereas others are experiencing long-term 

erosion (Fig. 16). The morphologies of the barriers and inlets, 

which are similar to those of northern Florida (Amelia Island) 

and southern South Carolina (Hilton Head), are a result of 

the relatively high tidal range within the Georgia Bight. Even 

though the barriers do not adjoin lagoons, they are referred 

Figure 13. Erosion and property damage near Floralton Beach, 

Florida caused by Hurricanes Francis and Jeanne in 2004. 

8/12/97

post-Frances; 9/08/04

post-Jeanne; 9/29/04
24

to as Sea Islands because they are surrounded by water at 

high tide when the marshes are flooded (Hayes, 1994). Other 

prominent features of the Georgia coast are the funnel-shaped 

river mouths that also are characteristic of coastal areas with 

a relatively high tidal range. Many of the Georgia barriers are 

inaccessible except by boat and therefore are largely undeveloped (Clayton and others, 1992). 

The South Carolina coast has a variety of landforms that 

are products of variable sediment supply and coastal processes. The southern half of the coast, which has the highest 

tidal range, consists of both wide and stable barrier islands 

and narrow migrating barrier islands. Moderately large tidal 

inlets separate the islands. In contrast, the northern half of the 

South Carolina coast consists of narrow barriers and salt-marsh 

shores of the Cape Romain/Santee delta (Fig. 9), or sandy 

beaches and dunes of the mainland shore along the Grand 

Strand. No rivers cross the mainland shore of the Grand Strand, 

and only a few tidal inlets interrupt its long sandy beaches. 

Exposures of dead trees on the beaches of some South Carolina 

barriers, such as Pritchards Island (Fig. 17), are clear evidence 

of long-term shoreline erosion.

The coast of North Carolina is also morphologically diverse. A mainland shore extends from Little River Inlet, at the 

border with South Carolina, to Cape Fear. The most prominent 

features on the North Carolina coast are the sandy capes (Cape 

Fear, Cape Lookout, and Cape Hatteras) where the shoreline 

orientation changes dramatically (Fig. 1). Much of the shore 

between the capes consists of long, narrow barrier islands separated by small tidal inlets. The barriers are progressively more 

clearly defined and separated farther from the mainland shore 

between Cape Fear and Cape Lookout. North of Cape Lookout, 

broad lagoons (sounds) separate the barriers from the mainland.

Figure14. Long-term trends in average annual sea level at selected tide gauges in the Southeast Atlantic Ocean. Data are from the 

National Ocean Service.

1898 1903 1908 1913 1918 1923 1928 1933 1938 1943 1948 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003

Year

Wilmington, NC 

2.1mm/yr

Charleston, SC 

3.3 mm/yr

Ft. Pulaski, GA 

3.0 mm/yr

Fernandina, FL 

2.0 mm/yr

Mayport, FL 

2.4 mm/yr

Miami, FL 

2.3 mm/yr

Key West, FL 

2.2 mm/yr

0

100

200

Sea Level

Change (mm)
25

HISTORY OF INFRASTRUCTURE 

DEVELOPMENT

Since their early occupation by European settlers, the 

Southeast Atlantic barriers and mainland shores have served as 

safe harbors that promoted early economic development related 

to shipping and other maritime activities. Barrier islands strategically located at the mouths of major estuaries were the sites 

of quarantine stations, supply docks, military installations, and 

trading posts. 

The oldest city in the U.S., which was established by the 

Spanish in 1565, is St. Augustine, located on the east coast of 

Florida at the mouths of the Matanzas and Tolomato Rivers. 

The most advanced technological site is at Cape Canaveral, 

which is the launch and landing site for the space shuttle and 

other NASA space exploration activities. In general, development of the east Florida coast was gradual but increased beginning in the mid-1800s. What is now Miami Beach was a narrow strip of sand covered with mangroves before it was cleared 

and filled for construction beginning in the mid-1800s (Pilkey 

and others, 1984). High-density development accelerated during the post-World War II building boom, and many of the 

building practices were not suitable for coastal construction. 

Hurricanes exposed many of these construction deficiencies 

shortly after development began, but some of the consequences 

are still being experienced. For example, beach houses built in 

the 1950s south of Miami did not present a problem until 1992 

when Hurricane Andrew destroyed many of them. 

The histories of settlement and eventual recreational 

development of the beaches and barriers of Georgia, South 

Carolina, and North Carolina are similar. They all were initially sites of sparse occupation in the 1500s by the Spanish 

or French, but later fell under the control of the English, who 

established small colonies. Before the Civil War, some barrier 

islands in Georgia and the Carolinas were the sites of vast 

plantations for crops such as cotton, tobacco, and rice. Development after the Civil War for tourism and recreation was 

slowed by the lack of access. The construction of bridges and 

roads by military operations in the 1940s facilitated the rapid 

post-World War II development of some of the barrier islands 

(Pilkey and others, 1998).

The Southeast Atlantic barriers have always had a strong 

military presence beginning with early construction of forts. In 

fact, fortifications and training facilities represent the earliest 

occupation of some Southeast Atlantic barrier islands. Fort 

construction began as early as 1672 (St. Augustine, Florida) 

and continued through the mid-1800s. Later, other military facilities were constructed on barrier islands as training sites used 

during World War II (Pilkey and others, 1984). 

Some of the oldest landmarks, like lighthouses and forts, 

are especially vulnerable to erosion because these aids to 

navigation and military defense were strategically located on 

the tips of barrier islands or on points of land that provided 

unobstructed visibility. These structures also provide a basis 

for determining long-term shoreline change. For example, the 

Cape Hatteras lighthouse, built more than 450 m landward of 

the shore in 1870, had to be relocated because of long-term 

beach erosion (Pilkey and others, 1998). The lighthouse at the 

entrance to Charleston Harbor also stands as a testament to the 

vulnerability of coastal structures. This structure was built on 

Morris Island, but the island migrated westward more than 600 

m, leaving the lighthouse exposed to wave attack (Fig. 15). The 

lighthouse is now surrounded by water and protected by a rock 

revetment that prevents it from being completely undermined 

and destroyed (Lennon and others, 1996). 

Most developed beaches of the Southeast Atlantic region 

front private property. The longest publicly owned beaches 

belong to federal agencies including the National Park Service, 

which is responsible for managing the Canaveral National 

Seashore in Florida, Cumberland Island National Seashore in 

Figure 15. Jetty construction at Charleston Harbor, South 

Carolina caused chronic beach erosion on adjacent Morris 

Island that left the lighthouse isolated far offshore in the 

Atlantic Ocean. 
26

Georgia, and the Cape Hatteras and Cape Lookout National 

Seashores in North Carolina. In addition to these federal holdings, the Southeast Atlantic states have many wildlife refuges 

and state and local parks that account for a significant percentage of the non-private ocean-front property. 

SHORELINE CHANGE AND COASTAL 

LAND LOSS

In this section, shoreline changes are presented with an 

emphasis on shoreline erosion, because it is an important 

natural coastal hazard along many Southeast Atlantic beaches. 

Table 7 summarizes both long-term and short-term rates of 

shoreline change as averages of all the changes, including 

both erosion and accretion, and as averages of only the erosion 

values and only the accretion values. Distinguishing between 

erosion and accretion provides more quantitative detail to the 

results.

The summary discussion includes references to shoreline 

erosion and to the broader issue of coastal land loss in order to 

provide a more complete perspective of coastal change. In the 

Southeast Atlantic states, coastal land loss is occurring primarily because of episodic high wave energy, natural changes in 

the coastal system, and as a consequence of human activities. 

Additional information about coastal land loss is available in a 

USGS Open-File Report at http://pubs.usgs.gov/of/2003/of03-

337/.

East Florida

Land losses on the east coast of Florida are primarily 

associated with erosion of sandy beaches and barrier islands, 

especially around inlets (Clark, 1990) where swift tidal currents 

easily remove the loose sand that forms the ends of the barriers. 

Land loss along the lagoon shores generally is minor because 

these water bodies are narrow or are already protected by erosion control structures such as bulkheads. Wakes generated by 

Figure 16. Outcrops of muddy marsh sediments on the lower beach are evidence of long-term erosion. This example is from Wolf 

Island, Georgia.
27

boats in the lagoons, such as along the Intracoastal Waterway, 

can contribute to local bank erosion in some areas. 

Compared to historical shoreline changes in the other 

Southeast Atlantic states, the average long-term change rate of 

0.2 ± 0.6 m/yr for east Florida (Table 7a) was low, primarily 

because tidal and wave energy were low and beach nourishment projects were common where erosion persisted. Even 

though long-term erosion rates were generally low (average is 

-0.5 m/yr), at least 39% of the Atlantic shoreline experienced 

long-term erosion. The highest long-term rates of erosion were 

observed at the southern end of Amelia Island on the margin 

of Nassau Sound, and relatively high rates of erosion persisted 

along the northern end of Jupiter Island at Jupiter Inlet. Longterm and short-term trends and rates of shoreline change were 

similar, such as around Cape Canaveral, where there was apparently little or no alteration of the sediment supply. Slow but 

chronic erosion along the east coast of Florida eventually results in narrowing of the state’s valuable recreational beaches, 

and many highly developed beaches have no dunes to protect 

buildings from large storm waves and flooding. Consequently, 

beach nourishment is commonly used to mitigate the effects 

of long-term erosion. Short-term shoreline stability or accretion increased where beach nourishment was common, such as 

along Miami Beach and Jacksonville Beach.

The Florida Department of Environmental Protection 

Bureau of Beaches and Coastal Systems reports that much of 

the east coast of Florida is undergoing critical erosion. Their 

definition of critical erosion is based on the vulnerability of 

resources to erosion rather than on the rate of erosion; therefore, even low rates of erosion would be critical in most areas 

of economic development. 

Georgia

In Georgia, coastal land loss is caused primarily by erosion of the Atlantic Ocean beaches. Open lagoons are not 

present landward of the barrier islands and estuaries are small, 

so erosion of backbarrier shores and interior marshes is not a 

significant component of coastal land loss in Georgia as it is 

in other states. Other mechanisms that cause land loss, such as 

coastal submergence, appear to be minor in Georgia (Fig. 14). 

Analysis of long-term historical shoreline change indicates 

that 65% of the Georgia shore was stable or accreting, with an 

overall average shoreline change rate of 1.0 ± 2.7 m/yr (Table 

7a). The eroding portion of coast had an average erosion rate 

of -1.5 m/yr. Highest long-term erosion rates (-9.4 ± 4.0 m/yr) 

occurred along Wolf Island (Fig. 16). The spatial patterns of 

historical shoreline changes in Georgia were highly variable, 

with eroding and accreting segments located adjacent to one 

another. Despite the high lateral variability, both long-term 

and short-term shoreline changes were similar for the same 

Figure 17. Dead and fallen trees and beach houses in the surf zone are indicators of long-term beach 

erosion. This example is from Pritchards Island, South Carolina.
28

beach segments. Short-term rates of change were higher than 

long-term rates, and erosion increased slightly from 35% for 

the long-term period to 40% for the short-term period. Erosion persisted along segments of Tybee, St. Catherines, Wolf, 

north St. Simons, north Jekyll, and central Cumberland Islands. 

Many beach segments reported by Griffin and Henry (1984) to 

be experiencing long-term erosion continued to erode, except 

for the areas influenced by beach nourishment.

South Carolina

Some of the highest rates of shoreline retreat and land 

loss in the Southeast Atlantic region are found in coastal South 

Carolina. Land losses are concentrated primarily along eroding 

beaches of the Atlantic Ocean; however, some land loss occurs 

around backbarrier marshes, along tidal creeks and mud flats, 

and other shores of the estuaries, but rates of erosion have not 

been determined (Lennon and others, 1996). 

The alongshore patterns of shoreline changes along the 

Atlantic Ocean in South Carolina were highly variable, and 

eroding and accreting beach segments were located close to 

one another. On some barriers, such as Edisto and Hunting 

Islands, beach erosion was severe on the northeastern end, 

whereas beaches were stable or accreting on the southwestern 

end. This spatial pattern indicates alongshore transfer of sand 

by southwesterly-directed ocean currents. Despite the high 

lateral variability, both long-term and short-term shoreline 

changes were similar for the same beach segments. The overall 

long-term trend of shoreline change was erosion for 51% of 

the shore, with a long-term average erosion rate of -0.5 ± 

3.0 m/yr. The highest long-term rate of erosion (-13.0 ± 18.8 

m/yr) was at the northeastern end of Hunting Island. Longterm erosion persisted on segments of Fripp, Hunting, Edisto, 

Morris, Bull, and Cape Islands. For the short-term period, the 

percent of eroding shoreline decreased to 39%, probably due to 

beach-nourishment projects, such as along Hilton Head Island, 

Hunting Island, and the Grand Strand. Although the percent 

of eroding shoreline decreased in the short-term, the average 

short-term rate of change increased slightly to -0.6 m/yr. This 

indicates that the average rates of erosion increased enough 

along eroding segments (-2.8 in the long-term to -4.1 m/yr in 

the short-term) to offset the rates of change along stable or accreting segments. 

North Carolina

The longest continuous segments of beach erosion and 

land loss in the Southeast Atlantic region occurred in North 

Carolina. This includes land losses associated with erosion of 

the Atlantic Ocean beaches as well as erosion along estuarine 

shorelines including coastal marshes and fringe habitats. The 

high coastal land losses in North Carolina are caused by high 

wave energy associated with frequent storms and the relative rise in sea level (Riggs and Ames, 2003). The long wave 

fetches associated with the broad estuaries also contribute to 

land losses around their margins.

The average long-term rate of change for the North Carolina Atlantic shoreline was erosion at -0.7 ± 1.3 m/yr (Table 7a). 

About 70% of the shoreline experienced long-term erosion at 

average rates of -1.4 m/yr. Maximum rates of erosion occurred 

on the margins of Ocracoke and Hatteras Inlets. Long-term 

erosion persisted on Smith, Masonboro, Topsail, Ocracoke, 

south Hatteras, and central Hatteras Islands. The short-term 

trends show a decrease in the length of eroding coast to about 

60%, but for the retreating segments, average rates of erosion 

increased to -1.8 m/yr (Table 7). The short-term decrease in 

length of eroding coast was likely a result of extensive beach 

nourishment projects.

HUMAN RESPONSES TO COASTAL 

EROSION AND LAND LOSS

Each Southeast Atlantic state uses a different combination 

of technical and regulatory responses to combat beach erosion and to mitigate land loss. The technical responses include 

hard structures, beach nourishment, sand bypassing at inlets, 

and retreat (Table 8). Many developed interior shores exhibit 

a patchwork of relatively low-cost structures such as wooden 

and metal bulkheads, concrete seawalls, revetments, and small 

groins. Common interior shoreline structures are rubble revetments composed of various materials including large rocks, 

broken masses of concrete, and wooden bulkheads. These 

low-cost structures typically become ineffective in less than 

20 years because the structures deteriorate and are unable to 

withstand the repeated forces of storm waves. 

Bulkheads, seawalls, and revetments are used to protect portions of some of the Southeast Atlantic open-ocean 

shores. Pilkey and others (1998) estimated that only 6% of the 

North Carolina shore was armored, whereas 27% of the South 

Carolina coast and 45% of the east coast of Florida had been 

armored. Engineering structures have little effect on beach 

stability where sand supply is plentiful, but on eroding beaches 

they can accelerate beach loss by reducing beach width and 

preventing the growth of dunes.

The following statements illustrate the types of community responses to shoreline erosion in the Southeast Atlantic region. They provide typical examples rather than a comprehensive review of shoreline protection projects within each state. 

The examples also reveal some of the unintended consequences 

of shoreline development and subsequent modification.

Hard structures such as seawalls, rock revetments, bulkheads, and groins are common along the east coast of Florida 

(Fig. 18) where high-density development began more than 80 

years ago. Coastal projects that disrupted the alongshore supply 
29

of sediment began in the late 1800s, and structural responses 

to beach erosion began as early as the 1920s (Pilkey and others, 1984). Many of the structures were destroyed by storms 

or failed over time and were subsequently rebuilt, only to be 

destroyed again. The artificial inlet at St. Lucie is an example 

of unexpected environmental costs resulting from construction of a hard structure (Pilkey and others, 1984). The inlet 

was opened in 1892, but it shoaled frequently so a jetty was 

constructed in 1930 to prevent sand from entering the channel. 

The jetty contributed to beach erosion, so seawalls, revetments, 

and groins subsequently were constructed to mitigate the erosion. These structures did not prevent erosion and as a result, 

several beach nourishment projects were undetaken to restore 

the beach on Jupiter Island (Valverde and others, 1999).

 In Georgia, seawalls and rock revetments armor more 

than half of the shore of the developed barrier islands (Tybee, 

Sea, St. Simon, and Jekyll) (Clayton and others, 1992). The 

beach in some areas is wide enough that these structures are 

not directly interfering with beach processes. Along some 

portions of Tybee Island, the beach continues to erode despite 

several attempts to stabilize it with groins, a seawall, and large 

blocks of riprap. 

South Carolina prohibits construction of new engineering 

structures, such as seawalls and revetments, but some beaches 

such as on Hilton Head Island, Folly Beach, and Myrtle Beach 

had already been armored extensively before the no-structure 

legislation was passed. North Carolina also has a strict policy 

prohibiting the placement of hard structures on beaches, and 

little of the shoreline is permanently stabilized. However, 

North Carolina has permitted the use of sand bags in the backbeach for emergency protection. Unfortunately, extensive use 

of sand bags has had the same negative effect on the beaches as 

hard structures (Pilkey and others, 1998)

Beach nourishment (Fig. 19) is a popular alternative to 

structural erosion control along the Southeast Atlantic coast. 

Pilkey and Clayton (1990) and Valverde and others (1999) 

compiled beach-nourishment data that included the Southeast 

Atlantic region through 1996. They reported that Florida spent 

the most money in the region to nourish beaches and had the 

greatest number of projects, whereas Georgia had the fewest 

nourished beaches. In Florida, nourishment has been used to 

counteract long-term erosion of many beaches. Those receiving nourishment multiple times include Fernandina Beach, 

Amelia Island, Jacksonville Beach, Miami Beach, Jupiter 

Island, Lake Worth Inlet, Palm Beach, and Delray Beach. Only 

Tybee Island and Sea Island have been nourished repeatedly 

in Georgia. Beaches receiving the most nourishment in South 

Carolina are Hilton Head Island, Hunting Island, Folly Beach, 

Pawleys Island, and Myrtle Beach. Sand has been trucked and 

hydraulically emplaced to nourish beaches and to reconstruct 

dunes multiple times at several sites in North Carolina including Holden Beach, Wrightsville Beach, and Carolina Beach. 

All of these projects typically have provided only temporary 

relief from the long-term erosion. 

One of the most successful beach-nourishment projects on 

the Southeast Atlantic coast has been at Miami Beach (Wiegel, 

1992). The beach fill has lasted an average of 15 to 20 years 

because wave energy is low, the rate of relative sea-level rise 

is low (Fig. 14), and no major storms have impacted the area 

recently. Even though beach nourishment is a favored method 

of controlling beach erosion, it can lead to some unfavorable 

results, such as steep scarps and shelly or rocky beach material. 

A specific example of undesirable consequences of beach nourishment is the ¬Miami Beach project that derived its fill from 

offshore dredging near reefs. The beach-fill material contained 

a substantial amount of rocks (pieces of coral up to 30 cm in 

diameter) that were concentrated in the surf zone and on the 

surface of the beach by wave reworking. The rocks in the surf 

zone posed a hazard for recreation and had to be removed at 

substantial additional expense (Wiegel, 1992). 

Sand bypassing is another engineering response to beach 

erosion at inlets where jetties have been constructed to help 

maintain the inlet for boat traffic. At Lake Worth Inlet, Florida, 

a small fixed bypassing plant was constructed to transfer sand 

from the updrift side to the downdrift side of the inlet. Although this bypassing operation may reduce erosion near the 

inlet, it is unable to transfer the sand as efficiently as the natural 

unimpeded waves and currents. Therefore, sand bypassing may 

Table 8. Technical responses to erosion and land loss in the 

Southeast Atlantic region.
30

not entirely compensate for the erosion caused by the channel 

dredging and jetty construction.

Submerged berms (Table 8) are another non-structural 

response to beach erosion near tidal inlets. They are constructed of sediment dredged from navigation channels and are 

promoted as a solution to two problems, disposal of dredged 

material and mitigation of beach erosion. The dredged material 

is deposited under water in a low mound parallel to the beach 

and in relatively shallow water. The berm acts as a submerged 

breakwater, causing large waves to break offshore, thus reducing storm beach erosion. If the berm is oriented properly and 

built in shallow water, the waves may transfer some of the 

sand onshore and add to the forebeach. Along the Southeast 

Atlantic coast, the Army Corps of Engineers has constructed a 

submerged berm to reduce erosion and storm damage at New 

River Inlet, North Carolina (Schwartz and Musialowski, 1977). 

Submerged berms are not as efficient in controlling erosion 

as beach nourishment, but they are also less costly than direct 

placement of the dredged material on the beach.

Relocation of buildings (Fig. 20) is not a common 

response to beach erosion and attendant coastal land loss in 

the Southeast Atlantic region. Nevertheless, there are several 

examples of relocation, including the famous Cape Hatteras 

lighthouse, which was moved inland more than 800 km in 

1999. In some Southeast Atlantic states, involuntary retreat 

from the eroding shoreline has been the result of both physical 

and legal forces. The resulting landward relocation of houses 

and highways is designed to maintain a coastal presence while 

recognizing the inevitability of future coastal erosion. 

Figure 18. Multiple structures including a seawall and riprap revetment on Anatasia Island, Florida, protect 

the upland property from wave attack but do not prevent erosion and loss of the beach. 

Figure 19. Many beaches along the east coast of 

Florida, such as this one at Patrick Air Force Base, 

have been nourished to mitigate against long-term 

erosion. Photo provided by the Minerals Management 

Service.
31

DISCUSSION AND FURTHER 

CONSIDERATIONS

Summary of Shoreline Changes

According to measurements by the National Ocean 

Service, states bordering the Southeast Atlantic region have 

1870 km of open-ocean coastline (Shalowitz, 1964). In this 

report, rates of shoreline change are provided for 1543 km of 

shore, which represent the extent of the lidar-derived shoreline. 

Shoreline-change analyses were not conducted for approximately 17% of the Southeast Atlantic shore where a lidarderived shoreline was unavailable, such as Bulls Bay, South 

Carolina, or where all four shorelines were not present (Fig. 3).

Of the Southeast Atlantic shoreline where rates of change 

were quantified, at least 700 km (45%) eroded with average 

long-term erosion rates as high as -13.0 ± 8.8 m/yr. Short-term 

rates of change were slightly lower with about 609 km (39%) 

of the evaluated shore eroding in spite of beach nourishment 

and other attempts to stabilize the shore. 

Rates of erosion for the Southeast Atlantic region were 

generally highest in South Carolina along the northeastern 

end of barrier islands and also along headland shores associated with the Santee delta. Erosion was also rapid along some 

barrier islands and headlands in North Carolina. Much of the 

Georgia Atlantic shore is undeveloped and some natural-beach 

segments experienced long-term erosion, whereas others experienced long-term accretion. Rates of shoreline change were 

relatively low along the east coast of Florida where low wave 

energy and frequent beach nourishment minimized erosion. 

The highest rates of beach erosion in Florida were generally 

localized around tidal inlets. Some beach segments in Florida 

accreted as a result of net longshore drift convergence (Cape 

Canaveral), and around tidal inlets that were stabilized by jetties.

Comparing long-term and short-term summary values for 

each state (Table 7a and 7b) shows a systematic decrease in 

the length (percent) of eroding shore except in Georgia. The 

decrease in eroding shore and complementary increase in accreting shore may partly be related to the systematic seaward 

offset in the lidar shoreline and partly to the frequency of beach 

nourishment. Beach nourishment was common in all the states 

except Georgia.

The trends and rates of shoreline change presented in this 

report represent past beach conditions that may not apply to 

Figure 20. Lateral relocation of a beach house in North Carolina is an example of retreat from the eroding 

shore. Photo source is unknown.
32

present conditions. Major storms that occur after the date of the 

most recent (lidar) shoreline initiate cycles of beach recession 

and recovery. Those erosional events commonly alter shoreline 

positions and rates of shoreline change. An example would 

be the erosional effects of Hurricanes Francis and Jeanne in 

2004 that impacted the same area of the east coast of Florida 

within weeks of one another. How those back-to-back events 

will affect long-term shoreline position and rates of change is 

uncertain.

Planned Updates and Related Research

The USGS plans to revise and report on rates of shoreline change for the Southeast Atlantic region every 5 to 10 

years. The revision interval will depend on the need for 

updated information and technological advances that will 

allow relatively rapid shoreline position acquisition, processing, and dissemination. Future revisions will also incorporate 

the results of ongoing shoreline research. For example, we 

plan to evaluate the advantages and disadvantages of using the 

MHWL to determine if another datum-based shoreline would 

be more suitable for historical analysis. We will also explore 

other approaches to reduce shoreline-positioning uncertainty 

(spatial errors) and shoreline-sampling uncertainty (temporal 

variability). GPS technology has so greatly reduced positioning errors that they are no longer a significant component of 

the uncertainty analysis like they were in the past. GPS and 

lidar also eliminate the need for digitization and introduction 

of their associated positioning errors. Switching from the HWL 

to the operational MHWL will reduce some of the apparent 

short-term sampling variability that limits the reliability of the 

results. A datum-based shoreline that is higher on the beach 

profile than the operational MHWL might further reduce some 

of the short-term sampling variability by taking advantage of 

the more stable portion of the beach profile. The dynamics of 

sandy beaches ensure that short-term shoreline fluctuations will 

not be eliminated entirely from future shoreline positions, but 

data being collected in various coastal regions as part of the 

USGS regional studies will provide quantitative assessments of 

seasonal and interannual changes in shoreline position. These 

assessments will provide a means to determine if the observed 

shoreline change is within the expected range of movement 

and allow us to constrain the shoreline position uncertainties 

further.

Another ongoing topic of research involves non-linear 

analysis of shoreline movement. It has been shown that timeaveraged linear methods of estimating future rates of shoreline 

movement (the existing paradigm) may not be appropriate for 

future predictions of shoreline position because coastal dynamics are non-linear. However, time series analyses based on 

non-linear theories require numerous shoreline positions (high 

sampling frequency) that generally are unavailable for most 

coastal areas.

Influence of Human Activities

As coastal communities expand along the shores of the 

Southeast Atlantic region, potential conflicts may arise between 

preservation of privately owned upland property and conservation of the publicly owned beach. Past responses indicate that 

these conflicts most likely will be resolved through a combination of beach-nourishment projects and shoreline-protection 

structures. Both of these engineering responses to erosion alter 

the natural beach processes and eventually lead to shoreline 

positions that are not related to the natural unaltered rates of 

beach erosion. 

Adding sand to eroding beaches is the most common 

method used to mitigate storm damage and to maintain a 

recreational beach. Beach nourishment alters the rates of retreat 

by causing rapid artificial accretion of the shoreline. In those 

areas where nourishment is frequent, the trends of shoreline 

change will be biased toward accretion or stability, even 

though the beach is still eroding. Because many beaches are 

already altered by shoreline-protection projects and many more 

will be altered in the future, the methods of analyzing shoreline 

movement will need to take shoreline stabilization activities 

into account so that the documented trends and derived rates of 

change can be expressed in their proper context.

Distinguishing between natural rates of shoreline movement and those influenced directly by human activities is 

crucial when historical rates of change are used for planning 

and to project future shoreline positions. Improved methods of 

analyzing shoreline movement will be needed to document the 

natural rates of shoreline change.
33

REFERENCES 

Anders, F. J., Reed, D. W., and Meisburger, E. P., 1990, Shoreline 

movements Report 2, Tybee Island, Georgia to Cape Fear, 

North Carolina, 1851-1983: U.S. Army Corps of Engineers, 

Coastal Engineering Research Center, Technical Report 

CERC 83-1, 147 pp.

Anders, F. J., and Byrnes, M. R., 1991, Accuracy of shoreline 

change rates as determined from maps and aerial 

photographs: Shore and Beach, v. 59, p. 17-26.

Barton, C. C., Dismukes, J. S., and Morton, R. A., 2003, 

Complexity analysis of the change in shoreline position at 

Duck, NC: Proceedings Coastal Sediments ‘03, 7p.

Blackwelder, B. W., MacIntyre, I. G., and Pilkey, O. H., 1982, 

Geology of continental shelf, Onslow Bay, North Carolina, 

as revealed by submarine outcrops: American Association 

of Petroleum Geologists Bulletin, v. 66, p. 44-56.

Brown, P. J., 1977, Variation in south Carolina coastal 

morphology, in Nummedal, D., ed., Beaches and barriers of 

the central South Carolina coast: Field Trip Guidebook for 

Coastal Sediments ’77 meeting, Charleston S.C., p. 11-24.

Chappell, J., Omura, A., Esat, T., McCulloch, M., Padolfi, J., Ota, 

Y., and Pillans, B., 1996, Reconciliation of late Quaternary 

sea levels derived from coral terraces at Huon Peninsula 

with deep sea oxygen isotope records: Earth and Planetary 

Science Letters, v. 141, p. 227-236.

Clark, R., 1986, The impact of Hurricane Elena and tropical 

storm Juan on coastal construction in Florida: Florida 

Department of Natural Resources, Division of Beaches and 

Shores, Report 85-3, 140p.

Clark, R., 1990, Coastal land loss in Florida: Transactions Gulf 

Coast Association of Geological Societies, v. 40, p. 117.

Clark, R., 1992, Beach conditions in Florida: Florida Department 

of Natural Resources, Division of Beaches and Shores, 

Technical Memorandum 89-1, 200p.

Clayton, T. D., Taylor, L. A. Jr., Cleary, W. J., Hosier, P. E., Graber, 

P. H. F., Neal, W. J., and Pilkey, O. H. Sr., 1992, Living with 

the Georgia shore: Duke University Press, Durham, N.C., 

188p.

Cleary, W. J., and Hosier, P. E., 1979, Geomorphology, washover 

history, and inlet zonation; Cape Lookout, North Carolina 

to Bird Island, North Carolina, in Leatherman, S. P., ed., 

Barrier Islands from the Gulf of St. Lawrence to the Gulf of 

Mexico: Academic Press, New York, 237-271.

Crowell, M., and Leatherman, S. P., eds., 1999, Coastal erosion 

mapping and management: Journal of Coastal Research, 

Special Issue 28, 196p.

Crowell, M., Douglas, B. C., and Leatherman, S. P., 1997, On 

forecasting future U.S. shoreline positions: A test of 

algorithms: Journal of Coastal Research, v. 13, p. 1245-

1255.

Crowell, M., Leatherman, S. P., and Buckley, M. K., 1991, 

Historical shoreline change; Error analysis and mapping 

accuracy: Journal of Coastal Research, v. 7, p. 839-852.

Daniels, R. C., and Huxford, R. H., 2001, An error assessment of 

vector data derived from scanned National Ocean Service 

topographic sheets: Journal of Coastal Research, v. 17, p. 

611-619.

Davis, G. H., 1987, Land subsidence and sea level rise on the 

Atlantic coastal plain of the United States: Environmental 

Geology Water Science, v. 10, p. 67-80.

Dean, R. G., and O’Brian, M. P., 1987, Florida’s east coast inlets: 

Shoreline effects and recommended action: Coastal and 

Oceanographic Engineering Department, University of 

Florida, Rept. 87/017, 100p.

Dean, R. G., Cheng, J., and Malakar, S. B., 1998, Characteristics 

of the shoreline change along the sandy beaches of the 

state of Florida: An atlas: Florida Sea Grant Report UFL/

COEL-98/015, variable pagination.

De Beaumont, L. E., 1845, Lecons de geologie practique: 

Septieme lecon, Bertrand Paris, p. 221-252.

Dolan, R., Anders, F., and Kimball, S., 1985, Coastal erosion and 

accretion, in National Atlas of the United Sates of America: 

U.S. Geological Survey, Reston, Va.

Douglas, B. C., and Crowell, M., 2000, Long-term shoreline 

position prediction and error propagation: Journal of 

Coastal Research, v. 16, p. 145-152.

Everts, C. H., Battley, J. P., Jr., and Gibson, P. N., 1983, Shoreline 

movements Report 1, Cape Henry, Virginia to Cape 

Hatteras, North Carolina, 1849-1980: U. S. Army Corps of 

Engineers, Coastal Engineering Research Center, Technical 

Report CERC-83-1, 111p.

Fisher, J. J., 1962, Geomorphic expression of former inlets along 

the Outer Banks of North Carolina: unpub. MS thesis, 

University of North Carolina, Chapel Hill, 120p.

Florida Department of Environmental Protection, 2004, 

Hurricane Francis and Hurricane Jeanne: Bureau of 

Beaches and Coastal Systems, Tallahassee, FL., 88p.

Gayes, P. T., Schwab, W. C, Driscoll, N. W., Morton, R. A., 

Baldwin, W. E., Denny, J. J., Wright, E. E., Harris, M. S., 

Katuna, M. P., and Putney, T. R., 2003, Sediment dispersal 

pathways and conceptual sediment budget for a sediment 

starved embayment: Long Bay, SC: Proceedings Coastal 

Sediments ’03, 14p.

Gilbert, G. K., 1885, The topographic features of lake shores: 

U.S. Geological Survey 5th Annual Report, p. 69-123.

Gornitz, V., and Lebedeff, S., 1987, Global sea level changes 

during the last century, in Nummedal, D., Pilkey, O. H., and 

Howard, J. D., eds., Sea-level Fluctuation and Coastal 

Evolution: Society of Economic Paleontologists and 

Mineralogists, Special Publication 41, p. 3-16.
34

Griffin, M. M., and Henry, V. J., 1984, Historical changes in the 

mean high water shoreline of Georgia: Georgia Geologic 

Survey Bulletin 98, 96p.

Hayes, M. O., 1994, The Georgia Bight barrier system, in Davis, 

R. A., ed., Geology of Holocene Barrier Islands: SpringerVerlag, Berlin, p. 233-304.

Hayes, M.O., Sexton, W.J., Colquhoun, D.J., Eckard, T.L., 1994, 

Evolution of the Santee/Pee Dee Delta complex, South 

Carolina, USA, in Kay, R., ed., Deltas of the World: Am. Soc. 

Civil Eng., New York, p. 54-64.

Hicks, S. D., 1968, Long-period variations in secular sea level 

trends; Shore and Beach, v. 36, p. 32-36.

Holdahl, S. R., and Morrison, N. L., 1974, Regional investigations 

of vertical crustal movements in the U.S using precise 

relevelings and mareograph data: Tectonophysics, v. 23, p. 

373-390.

Hoyt, J. H., 1967, Barrier island formation: Geological Society of 

America Bulletin, v. 78. p. 1125-1135.

Hoyt, J. H., and Henry, V. J., 1971, Origin of capes and shoals 

along the southeastern coast of the United States: 

Geological Society of America Bulletin, v. 82, 59-66.

Krabill, W., Wright, C., Swift, R., Frederick, E., Manizade, S., 

Yungel, J., Martin, C., Sonntag, J., Duffy, M., Hulslander, W., 

and Brock, J., 2000, Airborne laser mapping of Assateague 

National Seashore Beach. Photogrammetric Engineering & 

Remote Sensing, v. 66, p. 65-71.

Langley, S. K., Alexander, C. R., Bush, D. M., and Jackson, C. W., 

2003, Modernizing shoreline change analysis in Georgia 

using topographic survey sheets in a GIS environment: 

Journal of Coastal Research Special Issue 38, p. 168-177.

Lyles, S. D., Hickman L. E., Jr., Debaugh, H. A., Jr., 1988, Sealevel variations for the United States 1855-1986: U.S. 

Department of Commerce, NOAA-NOS, Rockville Md., 

182p.

Lennon, G., Neal, W. J., Bush, D. M., Pilkey, O. H., Stutz, M., 

and Bullock, J., 1996, Living with the South Carolina shore: 

Duke University Press, Durham, N.C., and 241p.

McGee, W. D., 1890, Encroachments of the sea: The Forum, v. 9, 

p. 437-449.

Meade, R. H., 1982, Sources, sinks, and storage of river 

sediment in the Atlantic drainage of the United States: 

Journal of Geology, v. 90, p. 235-252. 

Moore, L. J., 2000, Shoreline mapping techniques: Journal of 

Coastal Research, v. 16, p. 111-124

Morton, R. A., 1991, Accurate shoreline mapping: past, present, 

and future: American Society of Civil Engineers, Coastal 

Sediments ‘91, v. 1, p. 997-1010.

Morton, R. A., 1996, Geoindicators of coastal wetlands 

and shorelines, in Berger, A. R., and Iams, W. J., eds., 

Geoindicators: Assessing rapid environmental changes in 

earth systems: A.A. Balkema, Rotterdam, p. 207-230.

Morton, R. A., 2002, Factors controlling storm impacts on 

coastal barriers and beaches – A preliminary basis for 

real-time forecasting: Journal of Coastal Research, v. 18, p. 

486-501.

Morton, R. A., and Speed, F. M., 1998, Evaluation of shorelines 

and legal boundaries controlled by water levels on sandy 

beaches: Journal of Coastal Research, v. 14, p. 1373-1384.

Morton, R. A., Miller, T. L., and Moore, L. J., 2004, National 

assessment of shoreline change: Part 1: Historical 

shoreline changes and associated coastal land loss along 

the U.S. Gulf of Mexico: U.S. Geological Survey Open-File 

Report 2004-1043 (http://pubs.usgs.gov/of/2004/1043/).

Moslow, T. F., and Heron, S. D., 1994, The Outer Banks of North 

Carolina, in Davis, R. A., ed., Geology of Holocene Barrier 

Islands: Springer-Verlag, Berlin, p. 47-74.

North Carolina Division of Coastal Management, 2004, Longterm average annual shoreline change study and setback 

factors updated through 1998: N.C. Department of 

Environment, and Natural Resources, Raleigh, http://dcm2.

enr.state.nc.us/Maps/ER_1998/SB_Factor.htm.

Nummedal, D., Oertel, G. F., Hubbard, D. K., and Hine, A. C., 1977, 

Tidal inlet variability - Cape Hatteras to Cape Canaveral: 

American Society of Civil Engineers, Coastal Sediments 

’77, p. 543-562.

Pajak, M. J., and Leatherman, S. P., 2002, The high water line as 

shoreline indicator: Journal of Coastal Research, v. 18, p. 

329-337.

Pilkey, O. H., and Clayton, T. D., 1990, Summary of beach 

replenishment experience on U.S. East coast barrier 

islands: Journal of Coastal Research, v. 5, p. 147-159.

Pilkey, O. H., Jr., Sharma, D. C., Wanless, H. R., Doyle, L. J., 

Pilkey, O. H., Sr., Neal, W. J., and Gruver, B. L., 1984, 

Living with the East Florida shore: Duke University Press, 

Durham, N.C., 222p.

Pilkey, O. H., Jr., Neal, W. J., Riggs, S. R., Webb, C. A., Bush, 

D. M., Pilkey, D. F., Bullock, J, and Cowan, B. A., 1998, 

The North Carolina shore and its barrier islands: Duke 

University Press, Durham, N.C., 318p.

Redfield, A. C., 1958, The influence of the continental shelf on 

the tides of the Atlantic coast of the United States: Journal 

of Marine Research, v. 17, p. 432-448.

Riggs, S. R., Cleary, W. J., and Snyder, S. W., 1995, Influence 

of inherited geologic framework on barrier shoreface 

morphology and dynamics: Marine Geology, v. 126, p. 213-

234.
35

Riggs, S. R., and Ames, D. V., 2003, Drowning the North Carolina 

coast: sea-level rise and estuarine shoreline erosion: 

Report prepared for the North Carolina Department of 

Environment and Natural Resources Division of Coastal 

Management, Raleigh.

Ruggiero, P., Kaminsky, G. M., and Gelfenbaum, G., 2003, Linking 

proxy-based and datum-based shorelines on a high-energy 

coastline: Implications for shoreline change analyses: 

Journal of Coastal Research Special Issue 38, p. 57-82.

Sallenger, A. H., Krabill, W., Swift, R., Brock, J., List, J., Hansen, 

M., Holman, R. A., Manizade, S., Sontag, J., Meredith, A., 

Morgan, K., Yunkel, J. K., Frederick, E. and Stockdon, H., 

2003, Evaluation of airborne scanning lidar for coastal 

change applications: Journal of Coastal Research, v.19, p. 

125-133.

Schwartz, M. L., 1971, The multiple causality of barrier islands: 

Journal of Geology, v. 79, p. 91-94.

Schwartz, R. K., and Musialowski, F. R., 1977, Nearshore 

disposal: Onshore sediment transport: American Society of 

Civil Engineers, Coastal Sediments ’77, p. 85-101.

Shalowitz, A. L., 1964, Shore and sea boundaries. Publication 

10-1, U.S. Department of Commerce, Washington, DC, 749p.

Simpson, R. H., and Lawrence, M. B., 1971, Atlantic hurricane 

frequencies along the U.S. coastline: National Oceanic 

and Atmospheric Administration, NOAA Technical 

Memorandum NWS SR-581, 15p.

Stauble, D. K., and Brumbaugh, R. W., 2003, An assessment of 

the nation’s shorelines, USA: Shore and Beach, v. 71, p. 

11-18.

Stockdon, H. F., Sallenger, A. H., List, J. H., and Holman, R. 

A., 2002, Estimation of shoreline position and change 

from airborne topographic lidar data: Journal of Coastal 

Research, v. 18, p. 502-513.

The Heinz Center, 2000, Evaluation of erosion hazards: The H. 

John Heinz III Center for Science, Economics and the 

Environment, Washington, D.C., 203p.

Thieler, E. R., and Danforth, W. W., 1994, Historical shoreline 

mapping (1). Improving techniques and reducing 

positioning errors: Journal of Coastal Research, v. 10, p. 

549-563.

Thieler, E.R., Himmelstoss, E.A., Zichichi, J.L., and Miller, T.L., 

2005, Digital Shoreline Analysis System (DSAS) version 3.0; 

An ArcGIS extension for calculating shoreline change: U.S. 

Geological Survey Open-File Report 2005-1304. 

U.S. Army Corps of Engineers, 1971, National shoreline study: 

Washington, D.C.

Valverde, H. R., Trembanis, A. C., and Pilkey, O. H., 1999, 

Summary of beach nourishment episodes on the U.S. East 

Coast barrier island: Journal of Coastal Research, v. 15, p. 

1100-1118.

Weber, K. M., List, J. H., and Morgan, K. L. M., 2005, An 

operational mean high water datum for determination 

of shoreline position from topographic lidar data: U.S. 

Geological Survey Open-File report 2005-1027.

White, W. A., Morton, R. A., Kerr, R. S., Kuenzi, W. D., and 

Brogden, W. B., 1978, Land and water resources, historical 

changes, and dune criticality, Mustang and North Padre 

Islands, Texas: The University of Texas at Austin, Bureau of 

Economic Geology Report of Investigations No. 92, 46 p.

Wiegel, R.L., 1992. Dade County, Florida, beach nourishment 

and hurricane surge protection project: Shore and Beach, 

v. 60, p. 2-26.