7 

Prepared in cooperation with the Massachusetts Office of Coastal Zone Management

Massachusetts Shoreline Change Mapping and Analysis 

Project, 2013 Update

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2012–1189
THIS PAGE INTENTIONALLY LEFT BLANK
Prepared in cooperation with the Massachusetts Office of Coastal Zone Management

Massachusetts Shoreline Change Mapping and Analysis 

Project, 2013 Update

By E. Robert Thieler, Theresa L. Smith, Julia M. Knisel, and Daniel W. Sampson

Open-File Report 2012–1189

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013

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contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items 

must be secured from the copyright owner.

Suggested citation:

Thieler, E.R., Smith, T.L., Knisel, J.M., and Sampson, D.W., 2013, Massachusetts Shoreline Change Mapping and 

Analysis Project, 2013 Update: U.S. Geological Survey Open-File Report 2012–1189, 42 p., 

http://pubs.usgs.gov/of/2012/1189/.
Acknowledgements

This assessment of historical shoreline change in Massachusetts was undertaken through an 

agreement between the U.S. Geological Survey (USGS) and the Massachusetts Office of Coastal Zone 

Management (CZM) with funding from the National Oceanic and Atmospheric Administration. 

Massachusetts Geographic Information System (MassGIS) personnel provided orthoimagery and 

metadata.

We thank several people from the USGS Coastal and Marine Geology Program for their support in 

completing this project. Emily Himmelstoss assisted with estimating uncertainties and writing metadata, 

helping to calculate rates of shoreline change, and providing technical support. Amy Farris generated the 

2007 lidar shoreline data. Jeff List provided technical advice and computed regionally averaged rates and 

confidence intervals. Meredith Kratzmann suggested improvements for the figures.

We thank Cheryl Hapke and Erika Lentz for their technical reviews of this report.

iii
Contents

Acknowledgements........................................................................................................................................................ iii

Abstract ........................................................................................................................................................................ 1

Introduction.................................................................................................................................................................... 1

Methods......................................................................................................................................................................... 2

Compilation of Shoreline Positions ............................................................................................................................ 2

Estimation of Shoreline Position Uncertainty ............................................................................................................. 3

Proxy-Datum Bias Correction Between High Water and Mean High Water Shorelines ............................................. 5

Calculation of Rates of Shoreline Change ................................................................................................................. 5

Long-Term Rates ................................................................................................................................................... 5

Short-Term Rates................................................................................................................................................... 6

Historical Shoreline Change Analysis and Interpretation ............................................................................................... 6

North Shore................................................................................................................................................................ 7

Boston........................................................................................................................................................................ 7

South Shore............................................................................................................................................................... 8

Cape Cod Bay............................................................................................................................................................ 9

Outer Cape Cod......................................................................................................................................................... 9

South Cape Cod ........................................................................................................................................................ 9

Buzzards Bay............................................................................................................................................................10

Elizabeth Islands.......................................................................................................................................................10

Martha’s Vineyard .....................................................................................................................................................11

Nantucket..................................................................................................................................................................11

Effect of Shorelines From the 1970s and 1994 on Rates of Shoreline Change ........................................................12

Comparison of Rates of Shoreline Change With Previous Studies...........................................................................13

Examples of Different Types of Shoreline Behavior..................................................................................................14

Summary ......................................................................................................................................................................14

References Cited..........................................................................................................................................................16

Appendix 1.Historical Shorelines ..................................................................................................................................42

Figures

1. Index map of the Massachusetts coastline, showing place names mentioned on maps and in text................19

2. Map showing the spatial extent of new shoreline data produced for this study ...............................................20

3. Map showing areas identified as having poor-quality orthophotography from 2009 due principally to image 

distortions and poor contrast ...........................................................................................................................21

4. Diagram showing the relation between the measurement baseline, the transects from the Digital Shoreline 

Analysis System database, shoreline measurement points, and shoreline positional uncertainty...................22

5. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the North Shore region ......................................................................................................23

6. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the Boston region...............................................................................................................24

7. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the South Shore region......................................................................................................25

8. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the Cape Cod Bay region ..................................................................................................26

9. Map and graphs showing long-term linear regression and short-term rates of end-point shoreline change in 

Massachusetts for the Outer Cape Cod region................................................................................................27

iv
10. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the South Cape Cod region ...............................................................................................28

11. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the Buzzards Bay region....................................................................................................29

12. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the Elizabeth Islands region...............................................................................................30

13. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the Martha’s Vineyard region.............................................................................................31

14. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline change in 

Massachusetts for the Nantucket region..........................................................................................................32

15. Map showing the spatial extent of historical shoreline data for the coast of Massachusetts compared with the 

data used in the 2010 national assessment of shoreline change ....................................................................33

16. Orthophotograph and historical shorelines showing a unidirectional long-term trend of shoreline change at 

transect 769 on the southern coast of Nantucket, Massachusetts...................................................................34

17. Orthophotograph and historical shorelines showing a unidirectional long-term trend of shoreline change at 

transect 899 on a barrier spit near Osterville, Massachusetts .........................................................................35

18. Orthophotograph and historical shorelines showing a fluctuating history of shoreline change at transect 899 

on a sandy beach in Brewster, Massachusetts................................................................................................36

19. Orthophotograph and historical shorelines showing a landward constraint on shoreline movement due to a 

seawall at transect 1745 in Marshfield, Massachusetts...................................................................................37

20. Orthophotograph and historical shorelines showing significant artificial seaward shoreline movement due to 

human activities at transect 33 at Carson Beach, Massachusetts...................................................................38

Tables

1. Lengths of shoreline indicators alongshore used to delineate new shorelines in Massachusetts....................39

2. Measurements of uncertainty for the regions used to calculate rates of shoreline change in Massachusetts .39

3. Maximum statistically significant rates of shoreline change in Massachusetts ................................................40

4. Long-term linear regression rates of shoreline change in Massachusetts .......................................................40

5. Long-term linear regression rates of shoreline change in Massachusetts calculated by this study and by 

Hapke and others (2010).................................................................................................................................41

v 
Conversion Factors, Datums, and Abbreviations

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

kilometer (km) 0.5400 mile, nautical (nmi) 

meter (m) 1.094 yard (yd) 

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.

Abbreviations

CZM Coastal Zone Management

DSAS Digital Shoreline Analysis System

HWL high water line

LTW long-term weighted

MassGIS Massachusetts Geographic Information System

MHW mean high water

NOAA National Oceanic and Atmospheric Administration

RMS root mean square

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey

WLR weighted linear regression

vi
Massachusetts Shoreline Change Mapping and Analysis 

Project, 2013 Update

By E. Robert Thieler, Theresa L. Smith, Julia M. Knisel, and Daniel W. Sampson

Abstract

Information on rates and trends of shoreline change can be used to improve the understanding of 

the underlying causes and potential effects of coastal erosion on coastal populations and infrastructure

and can support informed coastal management decisions. In this report, we summarize the changes in 

the historical positions of the shoreline of the Massachusetts coast for the 165 years from 1844 through

2009. The study area includes the Massachusetts coastal region from Salisbury to Westport, including 

Cape Cod, as well as Martha’s Vineyard, Nantucket, and the Elizabeth Islands. New statewide shoreline 

data were developed for approximately 1,804 kilometers (1,121 miles) of shoreline using color aerial 

orthoimagery from 2008 and 2009 and topographic lidar from 2007.

The shoreline data were integrated with existing historical shoreline data from the U.S. 

Geological Survey (USGS) and Massachusetts Office of Coastal Zone Management (CZM) to compute 

long- (about 150 years) and short-term (about 30 years) rates of shoreline change. A linear regression 

method was used to calculate long- and short-term rates of shoreline change at 26,510 transects along 

the Massachusetts coast. In locations where shoreline data were insufficient to use the linear regression 

method, short-term rates were calculated using an end-point method.

Long-term rates of shoreline change are calculated with (LTw) and without (LTwo) shorelines 

from the 1970s and 1994 to examine the effect of removing these data on measured rates of change. 

Regionally averaged rates are used to assess the general characteristics of the two-rate computations, 

and we find that (1) the rates of change for both LTw and LTwo are essentially the same; (2) including 

more data slightly reduces the uncertainty of the rate, which is expected as the number of shorelines 

increases; and (3) the data for the shorelines from the 1970s and 1994 are not outliers with respect to the 

long-term trend. These findings are true for regional averages, but may not hold at specific transects.

Introduction

The Commonwealth of Massachusetts coastal zone has a broad base of natural and economic 

resources in which tourism, shipping, and commercial fishing industries constitute an important part of 

the economy of the Commonwealth. Coastal areas are dynamic in nature: changes such as shoreline 

erosion and accretion occur over many time scales. The coastal zone is also the site of high-density 

residential and commercial development. As coastal population growth continues, natural hazards such 

as shoreline erosion, flooding, and storm effects can have an increasing influence on coastal 

communities and economies. For these reasons, shoreline change analysis has become a common 

objective of coastal management programs (Morton, 1991; Thieler and Danforth, 1994; Moore, 2000).

In 1989, the Massachusetts Office of Coastal Zone Management (CZM) initiated the Shoreline 

Change Project to identify erosion-prone areas of the coast. Historical shoreline positions along the 

1
coast of Massachusetts (fig. 1) were delineated from paper maps and aerial photographs from the mid1800s to 1978 and compiled into a GIS compatible format (Benoit, 1989). The project was updated 

when new data became available and improved statistical techniques for calculating rates of shoreline 

change were developed. In 1996, a digitally computed statistical analysis of shoreline change was 

completed by Applied Geographics, Inc. (O’Connell, 1997; Van Dusen, 1997) using a modified version 

of the U.S. Geological Survey (USGS) Digital Shoreline Analysis System version 1.0 (DSAS; Danforth 

and Thieler, 1992). In 2001, a shoreline for 1994 digitized from 1-meter (m)-resolution 

orthophotographs was added to the CZM historical shoreline database, and long-term linear regression 

(for data from 1844 through 1994) and short-term end-point (for data from the 1970s through 1994) 

rates of shoreline change were calculated for the Commonwealth (Thieler and others, 2001). In 2006, 

the CZM contracted with Applied Coastal Research and Engineering, Inc. (Applied Coastal) to delineate 

a 2001 shoreline from 0.5-m resolution orthophotographs and calculate rates of shoreline change for the 

South Shore region from Hull to the Cape Cod Canal. Shorelines from these previous studies are 

available from the Massachusetts Ocean Resource Information System (MORIS; 

http://www.mass.gov/czm/mapping/index.htm).

For this report, historical shorelines from the mid-1800s to 2001 were compiled from previous 

CZM studies as well as recent USGS work (Himmelstoss and others, 2010) along predominantly openwater-facing sections of the Massachusetts coast (appendix 1). New shorelines (fig. 2) of about 

1,804 km (1,121 miles) were delineated for Massachusetts using color orthoimagery for 2008 and 2009 

from the USGS and extracted from topographic lidar data for 2007 obtained from the U.S. Army Corps 

of Engineers (USACE). The new shorelines were integrated with existing CZM and USGS historical 

shoreline data, and DSAS version 4.0 was used in Environmental Systems and Research Institute, Inc. 

(Esri) ArcGIS version 9.3 to calculate long- and short-term rates of shoreline change. The total number 

of historical shorelines used to estimate rates of change along the coast generally ranges from four to 

seven, with a minimum of two and a maximum of eight.

This report provides updated delineations of shorelines and rates of shoreline change for the 

coastal shoreline of Massachusetts. In this report, we (1) summarize the methods used to compile 

historical shorelines, delineate the 2007, 2008, and 2009 shorelines, evaluate errors and uncertainty 

associated with each data source, and calculate rates of shoreline change; (2) provide an overview of the 

results for each region to facilitate the interpretation and use of the shoreline change data; and (3) 

compare regionally averaged rates of shoreline change in this report to a dataset with a reduced number 

of shorelines and to a recent compilation (Himmelstoss and others, 2010) of rates of shoreline change 

for some of the Massachusetts sandy ocean shoreline.

Methods

In this section, we describe the methods used to compile and delineate the shorelines used in this 

report, quantify their positional uncertainty, correct for biases between shorelines that delineate different 

shoreline proxies, and estimate rates of shoreline change.

Compilation of Shoreline Positions

Data from before 2007.—Shorelines for the mid-1800s to 1994 are derived primarily from 

National Oceanic and Atmospheric Administration (NOAA) topographic map sheets (T-sheets) and 

aerial photographs that were obtained from the CZM (Thieler and others, 2001) and the USGS 

(Himmelstoss and others, 2010). The shorelines cover the Massachusetts coastal region from Salisbury 

to Westport, including Cape Cod, the Elizabeth Islands, Martha’s Vineyard, and Nantucket. Data for a

2
lidar-derived shoreline in 2000 covering most of the ocean-facing coastline of Massachusetts was also 

obtained from the USGS (Himmelstoss and others, 2010). In addition, the CZM provided a shoreline 

digitized by Applied Coastal from 50-centimeter (cm)-resolution color orthophotographs collected 

during aerial photography missions in April 2001that cover sections of the coast from Nantasket Beach 

to the Cape Cod Canal (the South Shore study region; Applied Coastal Research and Engineering, Inc., 

2006). The total number of historical shorelines used to estimate rates of change at any given location 

along the Massachusetts coast generally ranges from four to seven.

Lidar from 2007.—An operational mean high water (MHW) shoreline was derived from lidar 

surveys collected by the USACE in 2007 following methods in Stockdon and others (2002). This 

approach converts the lidar orthometric datum to a MHW datum using data compiled by Weber and 

others (2005). This methodology is also used in other USGS shoreline change assessments nationwide 

(http://coastal.er.usgs.gov/shoreline-change/), including Hapke and others (2011) and Himmelstoss and 

others (2010), which cover Massachusetts. A positional uncertainty associated with each shoreline point 

was computed following Stockdon and others (2002) and is described in the Estimation of Shoreline 

Position Uncertainty section.

Orthophotographs from 2008 and 2009.—Vector shorelines representing the local high water 

line (HWL) were digitized from 15- and 30-cm resolution, four-band (natural red, green, and blue and 

infrared) color orthophotographs using the sketch tool in Esri ArcEditor/ArcMap version 9.3. The 

shorelines were digitized at a scale of 1:300 for the 15-cm and 1:500 for the 30-cm orthophotographs. 

These scales were found to reasonably balance image pixel size representation on a computer monitor 

and the ability of the interpreter to identify the shoreline indicator (for example, high water mark or 

tonal change across rocky or sandy coast).

The HWL shoreline is recognized as the landward limit of wave runup at the time of local high 

tide. The HWL was delineated using the following indicators as proxies for the high water line, after 

Thieler and others (2001) and Boak and Turner (2005): (1) the previous high tide line seaward of the 

storm debris wrack line, as indicated by the tonal changes between wet and dry beach material (that is, 

sand, gravel, cobble), a seaweed or debris line, or a combination of both; (2) the high-tide wrack line, 

created when the high tide deposits seaweed and debris on the upper beach; (3) the vegetation change 

between Spartina patens (saltmeadow cordgrass) in the high marsh zone and Spartina alterniflora

(smooth cordgrass or saltmarsh cordgrass) in the low marsh zone (Bertness, 1991) or the outer limits of 

emergent marsh vegetation (when vegetation types were not discernible); (4) the algal line on rocky 

outcrops, indicated by the tonal change between wet surfaces that host algae and dry surfaces with no 

algae; (5) the maximum wave runup limit at or near high tide indicated by the interface between the land 

and water ; and (6) the interface between vertical seawalls and bulkheads and open water. The lengths of 

the coast line characterized by the different shoreline indicators are listed in table 1.

Estimation of Shoreline Position Uncertainty

The numerous potential errors involved in the process of calculating rates of shoreline change 

make it necessary to provide a best estimate of the total positional uncertainty associated with each 

shoreline position. Uncertainties for HWL shorelines include errors introduced by data sources and 

errors introduced by measurement methods (Anders and Byrnes, 1991; Crowell and others, 1991; 

Thieler and Danforth, 1994; Moore, 2000; Ruggiero and others, 2003). The following components 

(uncertainty terms) were considered when estimating the positional uncertainty for HWL shorelines: 

(1) georeferencing uncertainty; (2) digitizing uncertainty; (3) T-sheet survey uncertainty; (4) aerial

photograph collection and rectification uncertainty; and (5) the uncertainty of the HWL at the time of 

survey (Crowell and others, 1991). For each HWL shoreline position, the HWL position uncertainty is 

3
found as the square root of the sum of the squares (Taylor, 1997) of the relevant uncertainty terms, 

based on an assumption that each term is random and independent of the others (Hapke and others, 

2011). The average values for each uncertainty term and the total average positional uncertainty were 

estimated for each shoreline type (table 2) using methods described in Hapke and others (2011) and in 

the metadata for previously published Massachusetts shorelines (Himmelstoss and others, 2010).

One component of the total average uncertainty is the uncertainty of the HWL at the time of 

survey, which is an estimate of the uncertainty in the position of the shoreline resulting from the slope 

of the beach and water level variations due to waves and tides (Ruggiero and List, 2009). Where one or 

more lidar surveys are available, the lidar data provide a site-specific estimate of the beach slope. Sitespecific wave and tidal information are derived from wave information studies (U.S. Army Corps of 

Engineers, 2010) and NOAA tidal datum information (Weber and others, 2005), respectively. The 

uncertainty in these parameters is used to compute the HWL uncertainty following methods described 

by Ruggiero and List (2009).

The site-specific HWL uncertainty values are combined with the positional uncertainty for the 

historic shorelines to compute a total HWL positional uncertainty at each transect following the method 

described in Himmelstoss (2009, appendix 2). For sections of coast where lidar-derived beach slope data 

are not available, the average HWL uncertainty ( ±4.3 m; table 2) is combined with the historic 

shoreline uncertainty. This average value is determined by averaging the HWL uncertainty for regions 

where a lidar-derived beach slope is available. The values listed in table 2 are used only when sitespecific estimates of the uncertainty in the HWL position are unknown.

Orthophotographs.—The positional uncertainty estimates for shorelines derived from the 15-cm 

orthophotographs from 2008 and the 30-cm orthophotographs from 2008 and 2009 were calculated from 

the following components: (1) digitizing error (1.0 m; Hapke and others, 2011), (2) root-mean-square 

(RMS) error of orthorectification obtained from the source orthophotography ( ±0.25 m for the 15-cm 

orthophotographs, and ±2.12 m for the 30-cm orthophotographs), and (3) the average HWL uncertainty 

( ±4.3 m) for the Commonwealth described above. The total positional uncertainty was estimated by 

combining the three uncertainty components using the square root of the sum of the squares. The 

statewide average positional uncertainty values are ±4.4 m for the 15-cm shoreline data from 2008 and

±4.9 m for the 30-cm shoreline data from 2008 and 2009 (table 2).

Some areas in the orthophotograph dataset from 2009 contained poor-quality imagery (fig. 3), 

which manifested principally as image distortions and poor contrast. This resulted in the inability to 

confidently identify the shoreline position. Shorelines digitized in areas with poor-quality imagery were 

assigned an aerial photograph uncertainty of ±4.23 m to account for these issues, based on comparisons 

with other sources of orthophotography.

Lidar.—Determination of positional uncertainty for each lidar-derived MHW (2000 and 2007) 

shoreline position follows established methods described by Stockdon and others (2002) and Ruggiero 

and List (2009). The lidar-derived MHW shoreline position uncertainty includes the following

components: (1) the 95-percent confidence interval (CI) associated with the regression estimate in the 

determination of the shoreline position for each cross-shore profile of lidar point cloud data (Stockdon 

and others, 2002); (2) the uncertainty of the raw lidar data position in which the vertical uncertainty 

determined by Sallenger and others (2003) is converted to horizontal shoreline position uncertainty 

using the beach slope as determined by linear regression; and (3) the uncertainty due to extrapolation, 

which is the difference between an observed position and a position predicted on a projected regression 

line (Stockdon and others, 2002). The lidar position uncertainty is calculated using the square root of the 

sum of the squares. This total uncertainty varies on a profile-by-profile basis with a statewide average of

±1.27 m (table 2).

4
Proxy-Datum Bias Correction Between High Water and Mean High Water Shorelines

Shorelines derived from NOAA T-sheets, aerial photographs, and high-resolution 

orthophotographs use the HWL as the shoreline proxy. Lidar-derived shorelines, however, are not based 

on visual criteria but rather on the cross-shore position of an elevation contour extracted from 

topographic data and are defined on the basis of an elevation or a tidal datum, such as MHW (Smith and 

Zarillo, 1990; List and Farris, 1999; Stockdon and others, 2002; Leatherman and others, 2003; 

Robertson and others, 2004; Ruggiero and others, 2005; Moore and others, 2006). Several studies have 

determined that the proxy-datum bias between HWL and MHW shorelines is a unidirectional offset (or 

bias) with the HWL position located landward of the MHW position (Ruggiero and others, 1996, 2001, 

2003; Morton and others, 2004; Moore and others, 2006; Stockdon and others, 2006; Ruggiero and List, 

2009). When this bias is left uncorrected, the proxy-datum offset causes calculated rates of change to 

show rates of erosion or accretion not indicative of actual shoreline movement or to show trend 

reversals (for example, from erosion to accretion) that did not actually occur (Ruggiero and List, 2009).

Therefore, changing the shoreline definition from a proxy-based physical feature (HWL) to a datumbased shoreline (MHW) is important when inferring changes in shoreline position and calculating rates 

of change to minimize bias (Ruggiero and List, 2009).

The rates of shoreline change presented in this report apply a proxy-datum bias correction to the 

data using functionality in the DSAS software tool used to calculate shoreline rates of change 

(Himmelstoss, 2009, appendix 2). DSAS incorporates a proxy-datum bias value to reconcile the 

horizontal offsets between the MHW and HWL shoreline proxies described above. The specific 

methodology used to determine the proxy-datum bias is detailed in Ruggiero and List (2009).

Calculation of Rates of Shoreline Change

Rates of Long- (about 150 years) and short-term (about 30 years) shoreline change for this study 

were calculated using DSAS version 4.0, an ArcGIS tool developed by the USGS (Thieler and others, 

2009). The tool is a freely available application for ArcGIS. The DSAS uses a measurement baseline 

method (Leatherman and Clow, 1983) to calculate rate-of-change statistics for a time series of shoreline 

positions (fig. 4).

The reference baseline serves as the starting point for measurement transects generated by the 

DSAS software. A new reference baseline was digitized in ArcMap at a scale of 1:10,000. Baselines 

were placed either onshore (adjacent to the most landward shoreline) or offshore (adjacent to the most 

seaward shoreline) and positioned to generally parallel the combined orientation of all shorelines. This 

ensures that measurement transects are perpendicular to the trend of overall shoreline movement 

through time. Transects were cast at 50-m spacing along the coast.

The transects were visually inspected to check that every transect established an intersection 

point with each shoreline. These measurement points were then used to perform the rate of change 

calculations. Transects were removed or moved if they intersected coastal engineering structures such as 

groins and jetties, extended if they did not intersect one of the shorelines, or repositioned if they were 

not perpendicular to the general trend of the shoreline data. Transects were modified using standard 

editing tools in ArcMap by moving or deleting the transects individually or by adjusting the position of 

the baseline and recasting the transects.

Long-Term Rates

Long-term rates of shoreline change were determined by fitting a least squares regression line to 

all shoreline positions from the earliest (mid-1800s) to the most recent (2007, 2008, or 2009). The rate 

5
of change is the slope of the regression line. Negative values indicate erosion, and positive values

indicate accretion. The calculation of linear regression rates requires a minimum of shoreline data from 

3 years at each transect. Long-term rates of shoreline change calculated with many shoreline positions 

can increase confidence in the data by reducing potential errors associated with the source data, and 

fluctuating short-term changes (Dolan and others, 1991). For regions that included a lidar shoreline, the 

proxy-datum bias correction was applied to correct for horizontal offsets between the MHW and HWL 

proxies.

The linear regression method for determining rates of shoreline change assumes a linear trend of 

change between the earliest and most recent shoreline dates. However, in locations where rates of 

shoreline change have not remained constant through time, a linear trend does not exist. For example, a 

shoreline may exhibit accretion during the first 100 years, but in later years, the shoreline may shift to 

an erosional trend. In these cases, it is expected that the resulting linear fit to the data is poorer, and the 

uncertainty of the rate of shoreline change is higher.

Short-Term Rates

Short-term rates of shoreline change were calculated using the linear regression method for the 

time interval beginning between 1970 and 1982 and ending between 2000 and 2008 or 2009. These two 

time periods define an approximately 30-year span that includes multiple shorelines. Shoreline change 

that occurs over a short time span can be characterized by cyclic or episodic nonlinear behavior, such as 

storm-induced shoreline retreat. High short-term variability increases the uncertainty of the rate of 

shoreline change relative to the linear trend assumed in linear regression calculations. This increases the 

potential for rates of shoreline change that are statistically insignificant. In many locations, the shortterm trend is calculated with only three to four shorelines. Because uncertainty generally decreases with 

an increasing number of shoreline data points, the small number of shorelines in the short-term 

calculation can result in higher uncertainty. To supplement gaps in the short-term data, end-point rates 

were calculated at each transect that did not intersect the minimum number of three shorelines required 

to calculate a linear regression rate. Due to the limited availability of data from 1970 to 1982, short-term 

rates of shoreline change for the Boston and Elizabeth Islands regions were calculated using the endpoint method (except Peddocks Island in the Boston region). With a few exceptions, end-point rates for 

all regions were calculated using the 1994 to 2008 or 2009 timespan, or about 14 to 15 years. For 

regions where a lidar shoreline was used in the rate calculation, the proxy-datum bias correction was 

applied to correct for horizontal offsets between the MHW and HWL proxies.

End-point rates are reported in locations where there are insufficient data to use the linear 

regression method. The end-point rate is calculated by dividing the distance between shorelines by the 

time elapsed between the oldest and the most recent shoreline. End-point rates represent the net change 

between the two shorelines divided by the elapsed time period. Unlike the linear regression method, 

end-point rates do not have an associated expression (such as a confidence interval) of how scattered the 

shoreline positions are relative to an assumed linear trend.

Historical Shoreline Change Analysis and Interpretation

Shorelines are continuously moving in response to winds, waves, tides, sediment supply, 

changes in relative sea level, and human activities. Shoreline changes are not constant through time and 

frequently switch from negative (erosion) to positive (accretion) and vice versa. Cyclic and noncyclic 

processes change the position of the shoreline over a variety of timescales, from the daily and seasonal 

effects of winds and waves, to changes in sea level over a century to thousands of years. The shoreline 

6
"rate of change" statistic thus reflects a cumulative summary of the processes that altered the shoreline 

for the time period analyzed.

This section summarizes the results of shoreline change analysis of the Massachusetts coastline. 

Shoreline rates of change are summarized for Massachusetts by dividing the coast into 10 geographic 

regions (fig. 1). The regions are North Shore, Boston, South Shore, Cape Cod Bay, Outer Cape Cod, 

South Cape Cod, Buzzards Bay, Elizabeth Islands, Martha’s Vineyard, and Nantucket. These regions 

differ slightly from the administrative regions defined by CZM regional offices 

(http://www.mass.gov/czm/regions.htm). The maximum erosion and accretion rates presented in this 

report (table 3) are the highest rates that are statistically significant for each region, as determined by 

selecting the highest rate within each region that had a value greater than the uncertainty defined by the 

90-percent confidence interval.

North Shore

The North Shore region extends from Salisbury at the New Hampshire border to the western side 

of Deer Island in Boston Harbor (fig. 5). The northern part of the region, from Salisbury to Cape Ann, is 

dominated by sandy barrier islands, including Salisbury Beach and Plum Island. Following the coastal 

development classification system of Hapke and others (2011), the coastline in this region ranges from 

moderately to highly developed. Coastal engineering structures include groins and jetties at the mouth 

of the Merrimack River in Newburyport. The southern part of the region is dominated by rocky 

coastline with small pocket beaches between headlands and by urbanized coastline in the more densely 

populated areas such as Beverly, Gloucester, Lynn, and Winthrop. Beaches in these population centers 

are frequently armored with seawalls, riprap revetments, groins, and breakwaters. Beaches throughout 

the region, such as those on Plum Island, Revere Beach, and Winthrop Beach, have a history of beach 

nourishment (Western Carolina University, 2012).

Long-term rates of shoreline change (fig. 5) for the North Shore were calculated for 3,932

transects along approximately 224 km (139 miles) of shoreline. The most dynamic section of the region 

is the system of barrier islands and beaches from Salisbury to Cape Ann that includes Salisbury Beach, 

Plum Island, and Castle Neck. The maximum long-term erosion rate (-1.7 ±0.7 m/yr) occurred on the 

western side of Plum Island, facing the Parker River (table 3). The average long-term rate of shoreline 

change for Plum Island from the Merrimack River to Sandy Point was -0.09 ±0.6 m/yr, which is not a 

statistically significant trend and reflects the mobility of this beach system. The long-term maximum 

accretion rate of 2.7 ±2.1 m/yr occurred at Sandy Point (Plum Island), at the end of a spit that extends 

into the mouth of the Parker River.

Short-term linear regression rates of change for the North Shore region were calculated for 2,505

transects along 223 km (139 miles) of shoreline. Because of a lack of historical data on shorelines in this 

area since the 1970s, not all transects intersected the minimum of three shorelines required to compute 

linear regression statistics. To supplement gaps in the short-term data, end-point rates were calculated 

for 1,427 transects for 1994 to 2008 (fig. 5). The maximum short-term linear regression erosion rate

(-16.3 ±12.8 m/yr) occurred at Sandy Point, near the location of the long-term maximum erosion rate. 

The highest short-term accretion rate (5.0 ±3.9 m/yr) was measured on Plum Island at the entrance to 

the Merrimack River, northwest of the jetty. The average short-term rate for Plum Island from the 

Merrimack River to Sandy Point was -0.93 ±3.1 m/yr, which also is not statistically significant.

Boston

The Boston region extends from Carson Beach in South Boston to the Weymouth River, and 

includes the Boston Harbor Islands (fig. 6). The mainland coastline in this region is moderately to 

7
densely developed (Hapke and others, 2011), with tourist and commercial infrastructure. Seawalls and 

revetments frequently occur along the mainland beaches. Consistent with previous studies on shoreline 

change in Massachusetts (Benoit, 1989; O’Connell, 1997; Thieler and others, 2001), areas of heavily 

developed coastline in the city of Boston were not included in rates of shoreline change calculations, 

principally because there has been no shoreline movement in areas dominated by permanent, fixed 

structures. Geomorphology in this region includes rocky outcrops interspersed with pocket beaches and 

sandy ocean-facing beaches that are nourished with dredged material (Western Carolina University, 

2012), mud flats, and poorly developed salt marshes. The Boston Harbor Islands are dominated by a 

partially submerged drumlin field deposited during the late Pleistocene glaciation of this area. A few of 

the outer islands are underlain by bedrock.

Long-term rates of shoreline change (fig. 6) for Boston are based on 1,295 transects covering 

approximately 112 km (70 miles) of coastline. The highest rate of erosion -1.5 ±0.09 m/yr, was found at 

Lovells Island in Boston Harbor downdrift of a groin field and a breakwater running parallel to the 

shoreline. The maximum accretion rate was 2.6 ±0.8 m/yr measured at Columbia Point, east of Carson 

Beach where some of the harbor was filled in for development.

Short-term rates were measured at 1,160 transects along approximately 112 km (70 miles) of 

shoreline. Due to a lack of historical shorelines, the end-point statistic was used to calculate rates for 

1994 to 2008. Linear regression rates were calculated only for Peddocks Island (fig. 6). The maximum 

erosion end-point rate of -7.7 m/yr was measured in mud flats southwest of Nickerson Beach. The 

maximum end-point accretion rate, located west of Nickerson Beach in Quincy, was 4.7 m/yr.

South Shore

The South Shore region extends from the Weymouth River to Scusset Beach on the western side 

of the Cape Cod Canal (fig. 7). The geomorphology of the region’s coast varies, with headland beaches 

consisting of consolidated till fronted by boulders, tall glacial coastal banks with narrow linear beaches, 

rocky outcrops interspersed with pocket beaches, and long barrier spits that extend across bays or 

estuaries. Because most of the coastline faces the east, the South Shore is exposed to the storm winds 

from the north and northeast, and particularly extratropical storms (nor’easters) that occur during the fall 

and winter months. The South Shore region is moderately to heavily developed (Hapke and others, 

2011); coastal engineering structures are relatively common and include jetties and breakwaters at 

harbor entrances, scattered groin fields, and long stretches of rip rap and seawalls.

Long-term rates of shoreline change for the South Shore were calculated for 3,479 transects 

along approximately 198 km (123 miles) of shoreline. The maximum erosion rate (-3.0 ±0.5 m/yr) was 

measured along a highly dynamic spit at New Inlet at the mouth of Herring River (table 3). The highest 

accretion rate for the long-term (2.8 ±0.3 m/yr) was measured on the northern side of the Cape Cod 

Canal at Scusset Beach, where a 3,000-ft jetty was constructed in the early 1900s. Rate of change 

calculations in this area include a shoreline delineated in 1861, predating construction of the canal.

Short-term linear regression rates of change for the South Shore region were calculated for 2,665

transects along 198 km (123 miles) of shoreline. Because of a lack of historical shorelines in this area, 

not all transects intersected the minimum of three shorelines required to compute linear regression 

statistics. To supplement gaps in the short-term data, end-point rates were calculated for 820 transects 

for 1994 to 2008 (fig. 7). The short-term maximum linear regression erosion rate was -5.5 ±2.8 m/yr, 

measured on the eastern side of Plymouth Beach, facing Cape Cod Bay. The highest short-term linear 

regression accretion rate for the region was 5.6 ±1.7 m/yr, at the end of the Plymouth barrier at 

Plymouth Beach.

8
Cape Cod Bay

The Cape Cod Bay region extends from the Cape Cod Canal in Sandwich to Long Point in 

Provincetown (fig. 8). The geomorphology of the Cape Cod Bay region includes barrier spits fronting 

large estuaries, sandy headland beaches, and tall coastal banks composed principally of stratified glacial 

deposits. The region ranges from sparsely to moderately developed (Hapke and others, 2011). Coastal 

engineering structures such as seawalls, bulkheads, revetments, jetties and groin fields are abundant, 

particularly along the eastern portion of the region’s coastline.

Long-term rates of shoreline change for Cape Cod Bay are based on 2,303 transects along 

approximately 129 km (80 miles) of coastline. The maximum erosion rate -3.0 ±1.2 m/yr, was measured 

near the entrance to Herring River, along a narrow barrier connecting the Wellfleet mainland to Great 

Island. The highest accretion rate (3.5 ±2.1 m/yr) was measured at Chapin Memorial Beach in Dennis.

Short-term linear regression rates of change for the Cape Cod Bay region were calculated for 

1,655 transects along 129 km (80 miles). Because of the limited number of historical shorelines in this 

area, not all transects intersected the minimum of three shorelines required to compute short-term linear 

regression statistics. To supplement gaps in the short-term data, end-point rates were calculated for 654 

transects for 1971 to 2009 (fig. 8). The maximum linear regression erosion rate of -4.2 ±3.3 m/yr was at 

Chapin Memorial Beach in Dennis. The maximum linear regression accretion rate of 11.5 ±11.2 m/yr 

was located at the end of Sandy Neck, a long barrier spit in Barnstable.

Outer Cape Cod

The Outer Cape Cod region extends from Long Point in Provincetown to Monomoy Island and 

contains mostly east-facing Atlantic Ocean shoreline (fig. 9). Outer Cape Cod is sparsely developed 

(Hapke and others, 2011), and most of the region lies within the boundaries of the Cape Cod National 

Seashore. There are no coastal engineering structures on the ocean-facing coastline. The geomorphology 

of the northern end of the region from Provincetown to High Head is a series of welded spits capped by

a large, stable dune field. South of High Head, tall, glacially derived coastal banks are fronted by narrow 

sandy beaches. The southern end of the Outer Cape region is made up principally of barrier islands and 

spits.

Long-term rates of shoreline change were measured at 2,294 transects along approximately 

187 km (116 miles) of coastline. Long-term rates of shoreline change are more uniform in the north and 

more variable in the barrier system in the south (fig. 9). The highest long-term erosion and accretion 

rates were measured in the southern portion of the region, along the dynamic barrier system that extends 

from Nauset Beach to Monomoy Island. The highest erosion rate was -7.0±4.2 m/yr on Monomoy 

Island and the highest accretion rate, 10.0 ±9.2 m/yr was measured on the backshore of Monomoy 

Island (facing west in Nantucket Sound). In the north, high accretion rates up to 2.3 ±0.9 m/yr are found 

near Race Point Light.

The short-term linear regression rates of change for the Outer Cape Cod region (2,073 transects)

are highly variable, especially along the southern barrier system. The highest short-term erosion rate of -

17 ±10 m/yr was located at Monomoy Island near Hammonds Bend. The highest accretion rate 

(42.6 ±41.8 m/yr) was also measured at Monomoy Island, along the back shore facing Nantucket Sound.

South Cape Cod

The South Cape Cod region extends along the southern coast of Cape Cod in Nantucket Sound 

and Vineyard Sound from Stage Harbor Light in Chatham to Nobska Point in Woods Hole (fig. 10). The 

region is moderately to highly developed (Hapke and others, 2011). Jetties, bulkheads, seawalls, 

9
revetments, and extensive groin fields are present throughout much of the region. The geomorphology 

of this region is predominantly sandy headland beaches and small barrier systems fronting lagoons or 

ponds and well developed wetlands.

Long-term rates of shoreline change were measured at 1,558 transects along approximately 

91 km (57 miles) of coastline. The highest erosion rate (-4.3 ±3.3 m/yr) was measured at Cockle Cove 

Beach in Chatham, east of the entrance to Mill Creek. The beach at this location is backed by seawalls 

and is adjacent to a jetty system that impedes the transport of sediment to the beach. The maximum 

long-term accretion rate is 3.3 ±2.1 m/yr at Davis Beach on the updrift side of a jetty located at the 

mouth of Bass River.

Short-term linear regression rates of shoreline change were calculated for 1,459 transects along 

91 km (57 miles) of coastline. The highest erosion rate of -2.6 ±2.5 m/yr was recorded at Cockle Cove 

Beach, approximately 300 m east of the location of the maximum long-term erosion rate. The highest 

accretion rate of 2.3 ±1.4 m/yr was measured at Sampsons Island near the end of a westward-accreting 

spit at the entrance to Cotuit Bay.

Long-term and short-term rates of shoreline change in the Cape Cod South region show erosion 

and accretion trends that appear to be influenced by shoreline stabilization structures such as jetties and 

groin fields. Relatively small beach nourishment projects are also common on the southern shore of 

Cape Cod and may have also affected the rates of shoreline change.

Buzzards Bay

The Buzzards Bay region extends from Nobska Point in Woods Hole to Westport at the 

Massachusetts-Rhode Island border (fig. 11). The geomorphology of this region is variable, with narrow 

beaches often backed by low coastal banks or headlands, salt marshes, and barrier spits. Much of the 

coastline lies within low-energy bays and coves. The coastline is moderately to highly developed 

(Hapke and others, 2011), and coastal engineering structures such as groins, breakwaters, seawalls and 

revetments are abundant. Heavily populated areas such as New Bedford contain stretches of commercial 

and industrial coastline lined with bulkheads, wharves, and similar structures. Heavily developed areas 

in the New Bedford region were not included in the shoreline change analysis reported here.

Long-term rates of shoreline change in the Buzzards Bay region were computed at 5,026

transects along 298 km (185 miles) of coastline. The maximum long-term erosion rate for the region

(-1.0 ±0.5 m/yr) was measured near an inlet at the southwestern end of Mattapoisett Neck. The highest 

accretion rate of 2.1 ±1.5 m/yr was measured at a narrow sandy beach connecting Great Neck and Stony 

Point Dike in Wareham.

Short-term linear regression rates were calculated for 4,564 transects. The highest erosion rate 

was -1.7 ±1.7 m/yr, at Demarest Lloyd State Park near the mouth of the Slocum River in South 

Dartmouth. The maximum accretion rate of 2.3 ±0.3 m/yr was measured along a northward-accreting 

spit west of Taylor Point.

Elizabeth Islands

The Elizabeth Islands region consists of a chain of small islands extending southwestward from 

the southwestern coast of Cape Cod and faces Buzzards Bay to the north and Vineyard Sound to the 

south (fig. 12). The islands are sparsely developed (Hapke and others, 2011), and with the exception of 

Cuttyhunk Island, the coastline has few coastal engineering structures. Cuttyhunk Island has a small 

village and is a popular tourist destination. The geomorphology of the islands is predominantly glacial 

coastal banks and narrow beaches scattered with coarse, often boulder-sized material. There are a few 

10
small barrier spits connecting islands and extending across the entrance to small lagoons, most of which 

are located on Cuttyhunk Island.

Long-term rates of shoreline change for the Elizabeth Islands were computed for 1,785 transects 

covering 114 km (71 miles). The highest long-term erosion rate (-1.2 ±0.7 m/yr) is located on the shore 

of a small lagoon in Nonamesset Island. The highest long-term accretion rate is 1.1 ±0.4 m/yr, on the 

updrift side of the Cuttyhunk Harbor jetty.

Short-term rates of shoreline change for the Elizabeth Islands were measured for 1,783 transects 

along 114 km (71 miles) of shoreline using the end-point method between 1994 and 2009 due to the 

lack of historical shorelines from the 1970s in the region. The maximum short-term erosion rate 

(-3.8 m/yr) was at Nonamesset Island, and the maximum short-term accretion rate (1.7 m/yr) was 

measured at Cuttyhunk Island (table 3).

Martha’s Vineyard

The Martha’s Vineyard region consists of Martha’s Vineyard Island and Nomans Land (fig. 13). 

The coastal geomorphology of the region includes barrier and headland beaches as well as tall coastal 

banks composed of mostly stratified glacial deposits. The open coastline of Martha’s Vineyard is 

sparsely to moderately developed (Hapke and others, 2011). The more populated areas such as 

Edgartown are on the Nantucket and Vineyard Sounds side of the island in the north. There are a few 

small, isolated coastal engineering structures (principally groins and seawalls) in this area. The southern 

coast of Martha’s Vineyard faces the Atlantic Ocean and is subject to highly variable rates of shoreline 

change due to exposure to the open ocean.

Long-term rates of shoreline change were calculated for 2,579 transects along 169 km 

(105 miles) of shoreline. The maximum erosion rate (-5.0 ±3.1 m/yr) was measured near the inlet at 

Norton Point, a narrow ocean-facing barrier fronting Katama Bay (fig. 13). This high erosion rate and 

associated confidence interval is partly attributed to the reformation of the Katama Bay Inlet in the mid2000s and northward migration of the barrier at the ends of the spit. For the long-term, the Atlantic

Ocean-facing side of Martha’s Vineyard, including Norton Point and Lucy Vincent Beach, is highly 

erosional; the average rate of change measured from Wasque Point to Squibnocket Point is 

-1.7 ±0.4 m/yr. The maximum accretion rate was 1.9 ±1.3 m/yr, located near Edgartown Light in

Edgartown Harbor.

Short-term rates of shoreline change for Martha’s Vineyard were measured using linear 

regression at 1,878 transects over 132 km (82 miles) of shoreline. Due to a lack of historical shorelines 

for the last 30 years, end-point rates for 1994 to 2009 were calculated at 143 transects to supplement the 

gaps in the linear regression data (fig. 13). The maximum short-term linear regression erosion rate, 

located at Norton Point, was -5.7 ±2.4 m/yr, near Wasque Point. The average short-term rate of change 

for the southern shore of Martha’s Vineyard (from Wasque Point to Gay Head) was -1 ±2.6 m/yr, which 

is not statistically significant and reflects high short-term variability in the shoreline position here. The 

maximum short-term linear regression accretion rate of 3.7 ±3.7 m/yr was located at East Beach north of 

Wasque Point.

Nantucket

The Nantucket region includes Nantucket, Tuckernuck, and Muskeget Islands and lies partially 

within Nantucket Sound and the Atlantic Ocean (fig. 14). Similar to Martha’s Vineyard, the 

geomorphology of the region consists of barrier and headland beaches, as well as tall coastal banks 

made up of mostly stratified glacial deposits. A long, thin sandy barrier connects Great Point to the main 

portion of Nantucket Island. The Nantucket region is moderately developed (Hapke and others, 2011) 

11
with the greatest concentration of coastal development along the Siasconset Beach and harbor areas. 

There are limited coastal engineering structures on the open-ocean coastline of Nantucket Island; 

however, there are seawalls, bulkheads, riprap, and groins on the developed side of Nantucket Harbor,

including an extensive jetty system at the mouth of the harbor. Tuckernuck and Muskeget Islands on the 

Atlantic Ocean side both have dynamic barrier spits that are continuously changing orientation.

Long-term rates of shoreline change for the Nantucket region are variable, showing erosion on 

the Atlantic Ocean-facing southern shore but also high accretion rates, often located at the end of barrier 

spits. Long-term change rates were calculated at 2,227 transects covering 147 km (91 miles). The 

maximum erosion rate (-7.2 ±1.3 m/yr) was located on a barrier spit at Muskeget Island. High erosion 

rates occurred also on Tuckernuck Island and the southern shore. The long-term average erosion rate for 

the southern shore from Tom Nevers Beach to Madaket was -2.1 ±0.5 m/yr. The highest long-term 

accretion rate of 4.3 ±3.7 m/yr occurred on the eastern (Nantucket Sound) side of Muskeget Island.

Short-term shoreline linear regression change rates for the Nantucket region were calculated at 

1,983 transects along 119 km (74 miles). Due to a lack of historical shorelines for the past 30 years, endpoint rates for 1994 to 2009 period were calculated for 248 transects to supplement the gaps in the linear 

regression data (fig. 14). The maximum short-term linear regression erosion rate -12.4 ±1.5 m/yr, was 

measured at Tuckernuck Island. Tom Nevers Beach also had high short-term erosion rates up to 

-4.9 ±1.5 m/yr. For the short-term, the average rate of change for the Nantucket southern shore was 

-1.2 ±2.6 m/yr, which is not a statistically significant trend and reflects the mobility of this beach 

system. The short-term maximum linear regression accretion rate of 5.5 ±4.6 m/yr was located at the 

end of a spit on Esther Island at the entrance to Madaket Harbor.

Effect of Shorelines From the 1970s and 1994 on Long-term Rates of Shoreline Change

Here we present the results of an experiment that compares the effect of removing certain data 

from the analysis of long-term rates of shoreline change. Specifically, we computed long-term rates of 

change that omitted the shorelines from the 1970s and 1994, which have larger positional uncertainties 

due to source photography, registration errors, potential influence of storm events, and poor image 

contrast.

For this analysis, rates of shoreline change and the associated rate uncertainties were computed 

at individual transects in each of the 10 regions with the full dataset and with the reduced dataset that 

omits the shorelines from the 1970s and 1994. We then generated regionally averaged rates of change

(table 4) for the full (LTw) and the reduced (LTwo) datasets to assess whether any significant changes 

in rates or uncertainties occurred.

The uncertainty associated with a regionally averaged rate of shoreline change is found from the 

estimated confidence intervals (CI) associated with the reported change rate at individual transects. The 

simple arithmetic mean of all CI values is rejected (Hapke and others, 2011) because it assumes no 

spatial independence of CI values and therefore no cancellation of uncertainty due to random variability 

between transects. Also, an average-rate CI based on the quadrature addition of CIs (square root of the 

sum of the squares) is rejected because it assumes complete independence of all CI values (that is, no 

serial correlation between CI values at adjacent transects).

An alternative approach in which the CI associated with regionally averaged rates of shoreline 

change ( Esc *), described as a “uncertainty reduced for independent n”, is found as:

*

*

sc

sc

E E

n = (1)

12
where

Esc is the arithmetic mean CI, and

n* is the number of CI data points reduced for their serial (spatial) correlation.

Uncertainty values (table 4) found using equation 1 are generally much smaller than an arithmetic mean 

CI but larger than a quadrature-averaged CI.

The regionally averaged rates are a convenient way to assess the general characteristics of the 

LTw and LTwo rates of change in each region. Three principal observations for the regionally averaged 

rates used here are (1) the rates of change for both LTw and LTwo are essentially the same; (2) 

including more data slightly reduces the uncertainty of the rate; and (3) the shorelines from the 1970s 

and 1994 are not outliers with respect to the long-term trend. These observations are true for the 

regional averages, but may not hold at specific transects.

The regional average long-term change rates for LTw and LTwo are essentially the same for 8 of 

the 10 regions (table 4). The Boston LTw rate is significant, but the LTwo rate is not. For Outer Cape 

Cod, the LTw erosion rate is about 75 percent lower than the LTwo rate, but both the LTw and LTwo 

rates of change are not significantly different from 0. Including more shoreline data points in this dataset 

reduces the uncertainty of the regionally averaged rates of shoreline change, which is expected as the 

number of shorelines increases. This is true for all 10 regions in this report.

This comparison suggests that, for the dataset used here, the shorelines from the 1970s and 1994 

are not outliers with respect to the long-term regionally averaged trend. That is, neither the rates nor the 

uncertainties change substantially when the shorelines from the 1970s and 1994 are included.

The data compared here represent regional averages, which allow a general assessment of 

whether the shorelines from the 1970s and 1994 influence calculated rates of long-term shoreline 

change, which they do not do at the regional scale. At individual transects, however, that may not be the 

case due to a number of factors such as the sources of uncertainty described in this section.

Comparison of Rates of Shoreline Change With Previous Work

A recent coastal change assessment for the mid-Atlantic and New England (Hapke and others, 

2011) used nearly identical shoreline data to the data presented here. The results presented here, 

however, include more extensive spatial coverage along the coast and a more recently delineated (2007, 

2008, or 2009) shoreline. The addition of this shoreline might be expected to decrease the uncertainty in 

the rate of change estimates.

To compare the long-term rates of shoreline change reported in Hapke and others (2011) and 

those reported here, we used the long-term rate of change data for the measurement transects from 

Hapke and others (2011) that were spatially closest (adjacent) to the transects used in this report. The 

Hapke and others (2011) data cover a much smaller spatial extent than this study (fig. 15) and include 

principally sandy beaches. The Hapke and others (2011) data are present in portions of 7 of the 10 

geographic regions used in this report. Table 5 lists a comparison of the regionally averaged rates of 

change and rate uncertainties for these regions. The method for computing the regional averages is the 

same as that described above for the LTw and LTwo rate of change comparison.

There is not a significant difference between the rates found by Hapke and others (2011) and this 

study (table 5). Interpretations of this finding are that, for regionally averaged rates of change on sandy 

beaches, adding a shoreline from 2007 through 2009 in the area in the study of Hapke and others (2011) 

did not result in significant improvement in estimates of the rate of change or its uncertainty, and the 

newer, additional shoreline added in this study is consistent with the linear trend of the rates (that is, the 

13
new shoreline is not an outlier) estimated by Hapke and others (2011). These observations, however, 

may not hold for individual transects.

It is reasonable to expect an improvement (reduction) in rate of change uncertainty by adding a 

new shoreline. As shown in table 5, however, that is not the case in this study. One explanation is that 

the shoreline from 2007 through 2009, in fact, is a sufficient outlier relative to a linear trend that it 

offsets a reduction in rate uncertainty that would be expected by increasing the number of shorelines 

used in the regression. Another explanation is that for the assumption of linear shoreline behavior, 

increasing the degrees of freedom (that is, adding more shoreline positions) decreases the rate of change 

uncertainty, but for more than seven to eight shorelines, this decrease is small. It is likely that the 

addition of the shoreline from 2007 through 2009 in this study demonstrates this effect.

Examples of Different Types of Shoreline Behavior

The data presented in this report illustrate a number of different kinds of historical shoreline 

behavior, including (1) unidirectional shoreline change, (2) fluctuating shoreline position, (3) 

constrained shoreline position, and (4) anthropogenic shoreline relocation.

Several locations along the Massachusetts coast exhibit unidirectional long-term shoreline 

movement (that is, continuous erosion or accretion). This behavior can occur in both open-ocean 

settings as well as sounds and bays. For example, figure 16 depicts a section of the Nantucket southern

shore and the location of a representative transect where the rate of shoreline change was measured. The 

historical shorelines show continuous erosion between 1846 and 2009. The long-term rate of shoreline 

change for the transect is -3.5 ±0.3 m/yr. Figure 17 shows a similar history of shoreline change for a 

barrier beach near Osterville, where the long-term rate of change is -0.8 ±0.2 m/yr.

Fluctuating shoreline positions are illustrated by a sandy beach in Brewster (fig. 18). The beach 

is highly mobile, likely reflecting the influence of the adjacent creek inlets on beach erosion and 

accretion. The long-term rate of change is 0.0 ±3.4 m/yr, which indicates high variability in shoreline 

position with no significant trend.

A constrained shoreline position is characterized by locations where the shoreline indicator (for 

example, HWL on a sandy beach) is limited in its ability to move. This can occur when an eroding 

sandy shoreline moves landward until it encounters a rock outcrop or anthropogenic shoreline structure 

such as a seawall or revetment. At that point, the position of the shoreline is constrained. An example is 

illustrated in figure 19, where the shoreline in Marshfield exhibits historical landward movement, but 

during the past several decades has been essentially fixed by a seawall constructed in 1965. Here, the 

short-term rate of change that postdates the construction of the seawall is -0.2 ±0.6 m/yr. This rate is not 

statistically significant and indicates little net shoreline movement.

Carson Beach in Boston is an example of anthropogenic shoreline relocation. Figure 20 shows 

the position of the shoreline in 1893, which was moved seaward approximately 250 m by artificially 

filling this embayment some time before 1938. The shoreline position has been relatively stable since 

1938.

Summary

Shoreline change analysis of the Massachusetts coast was conducted using historical shoreline 

positions spanning 164 years from 1845 to 2009. The Commonwealth was divided into 10 regions for 

the purposes of this study. Long- and short-term linear regression rates of shoreline change were 

calculated for a total of 26,510 transects covering 1,804 kilometers (1,121 miles) of shoreline. End-point

rates were calculated in locations where there were insufficient data to use the linear regression method.

14
The highest statistically significant long-term rates of change (erosion and accretion) were observed on 

Nantucket, Outer Cape Cod, and Martha’s Vineyard (table 3). The highest long-term erosion rate 

(-7.2 ±1.3 m/yr) was observed on Muskeget Island in the Nantucket region. The highest long-term 

accretion rate (10 ±2.3 m/yr) was observed on the backshore of Monomoy Island (Outer Cape Cod), in 

Nantucket Sound. The highest statistically significant short-term rates of change (erosion and accretion) 

occurred on the North Shore, Outer Cape Cod and Nantucket. The highest short-term erosion rate 

(-16.3 ±12.8 m/yr) was observed on the North Shore at Sandy Point. The maximum accretion rate for 

the Commonwealth (42.6 ±41.8 m/yr) was observed on Monomoy Island on the Atlantic Ocean side of 

the barrier.

Long-term rates computed with all the shoreline position data available (1800s through 2009) 

and a reduced dataset (excluding data from the 1970s and 1994) were regionally averaged using 

methods described in Hapke and others (2011). The two datasets were compared to determine whether 

the 1970s and 1994 shorelines (derived from source material with larger positional uncertainties) 

influenced calculated rates of long-term change (table 4). The regionally averaged rates provided a 

convenient way to assess the general characteristics of rates of shoreline change computed for both 

datasets in each region. Results include the following observations: (1) the rates of change for both 

datasets are essentially the same; (2) including more data slightly reduces the uncertainty of the rate of 

shoreline change; and (3) the data on the shorelines from the 1970s and 1994 are not outliers with 

respect to the long-term regionally averaged trend. Neither the rates nor the uncertainties change 

significantly when the shorelines from the 1970s and 1994 are included. This observation may not hold 

true at individual transects due to a number of environmental and technical considerations.

A comparison of long-term rates of shoreline change on predominantly sandy, open-ocean 

facing beaches from this study and Hapke and others (2011) was conducted by regionally averaging 

long-term data selected from spatially adjacent transects (table 5). Results indicate no significant 

difference between the rates found by Hapke and others (2011) and those reported here. For regionally 

averaged rates of change on sandy beaches, we find that adding a shoreline from 2007 through 2009 to 

the study area in the study by Hapke and others (2011) did not result in significant improvement in 

estimates of the rate of change or its uncertainty and the newer, additional shoreline added in this study 

is consistent with the linear trend of the rates estimated by Hapke and others (2011). Possible 

explanations as to why the addition of a new shoreline did not reduce long-term rate of change 

uncertainty are that the shoreline from 2007 through 2009 is a sufficient outlier relative to a linear trend 

that it offsets a reduction in rate uncertainty that would be expected by increasing the number of 

shorelines used in the regression or that, for the assumption of linear shoreline behavior, increasing the 

degrees of freedom (that is, adding more shoreline positions) decreases the rate of change uncertainty, 

but for more than seven to eight shorelines this decrease is small.

It is important to understand trends in shoreline behavior due to the influences of natural forces 

or anthropogenic effects and how those trends are reflected in shoreline change data. Shoreline trends 

identified in this study include (1) unidirectional long term shoreline movement, characterized by 

continuous erosion or accretion, which can occur in both high-energy open ocean settings or low-energy 

settings (sounds and bays); (2) fluctuating shoreline positions, which are highly mobile shorelines that 

have undergone both erosion and accretion on a long-term basis; (3) constrained shorelines in which 

movement of the shoreline indicator (for example, high-water line) is limited by natural or 

anthropogenic features; and (4) anthropogenic shoreline relocation such as the infilling of embayments 

for development purposes.

Short-term shoreline change can be characterized by fluctuating (for example, cyclic or episodic) 

nonlinear behavior. High short-term variability increases the rate uncertainty relative to the linear trend 

15
assumed in linear regression calculations, which in turn increases the potential for rates of shoreline 

change that are statistically insignificant. Short-term linear regression rates calculated with fewer 

shorelines can also result in higher uncertainty. Highly variable rates of shoreline change that are 

statistically insignificant or show negligible net change over the short term do not necessarily indicate a 

low potential hazard at that location. For example, shoreline response to storms can result in significant 

and rapid erosion followed by post-storm recovery or accretion over a relatively short time span (in 

some cases, days or weeks; List and Farris, 1999). The magnitude of the variability in shoreline position 

can pose a hazard due to these fluctuations.

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18
19

Figure 1. Index map of the Massachusetts coastline, showing place names mentioned on maps and in text.

Dashed lines indicate boundaries between regions.
20

Figure 2. Map showing the spatial extent of new shoreline data produced for this study. HWL, high water line; 

MHW, mean high water.
21

Figure 3. Map showing areas (indicated by polygons) identified as having poor-quality orthophotography from 

2009 due principally to image distortions and poor contrast. 
Figure 4. Diagram showing the relation between the measurement baseline, the transects generated by the 

Digital Shoreline Analysis System (DSAS) software, shoreline measurement points, and shoreline positional 

uncertainty. From Thieler and others (2009).

22
Figure 5. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the North Shore region. End-point shoreline change rates were calculated for 1994 to 

2008. Numbers on the map indicate distance alongshore in the graphs. 

23
Figure 6. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the Boston region. End-point shoreline change rates were calculated for 1994 to 

2008. Numbers on the map indicate distance alongshore in the graphs.

24
Figure 7. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the South Shore region. Short-term shoreline rates were calculate for 1994 to 2008, 

except where otherwise noted on the graph. Numbers on the map indicate distance alongshore in the graphs.

25
Figure 8. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the Cape Cod Bay region. End-point shoreline change rates were calculated for 1994 

to 2008. Numbers on the map indicate distance alongshore in the graphs.

26
Figure 9. Map and graphs showing long-term linear regression and short-term rates of end-point shoreline 

change in Massachusetts for the Outer Cape Cod region. End-point shoreline change rates were calculated for 

1994 to 2008. Numbers on the map indicate distance alongshore in the graphs.

27
Figure 10. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the South Cape Cod region. End-point shoreline change rates were calculated for 

1994 to 2008. Numbers on the map indicate distance alongshore in the graphs.

28
Figure 11. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the Buzzards Bay region. End-point shoreline change rates were calculated for 1994 

to 2008. Numbers on the map indicate distance alongshore in the graphs.

29
Figure 12. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the Elizabeth Islands region. End-point shoreline change rates were calculated for 

1994 to 2008. Numbers on the map indicate distance alongshore in the graphs.

30
Figure 13. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the Martha’s Vineyard region. End-point shoreline change rates were calculated for 

1994 to 2008, except where noted on the graph. Numbers on the map indicate distance alongshore in the graphs.

31
Figure 14. Map and graphs showing long-term linear regression and short-term end-point rates of shoreline 

change in Massachusetts for the Nantucket region. End-point shoreline change rates were calculated for 1994 to 

2008. Numbers on the map indicate distance alongshore in the graphs.

32
Figure 15. Map showing the spatial extent of historical shoreline data in Massachusetts compared with the data 

used in the 2010 national assessment of shoreline change (Hapke and others, 2011). NEMA, New England and 

Mid-Atlantic.

33
Figure 16. Orthophotograph and historical shorelines showing a unidirectional long-term trend of shoreline 

change at transect 769 (yellow line) on the southern coast of Nantucket, Massachusetts. (Image source: Esri World 

Imagery.) 

34
Figure 17. Orthophotograph and historical shorelines showing a unidirectional long-term trend of shoreline 

change at transect 899 (yellow line) on a barrier spit near Osterville, Massachusetts. (Image source: Esri World 

Imagery.) 

35
Figure 18. Orthophotograph and historical shorelines showing a fluctuating history of shoreline change at transect 

899 (yellow line) on a sandy beach in Brewster, Massachusetts. (Image source: Esri World Imagery.) 

36
Figure 19. Orthophotograph and historical shorelines showing a landward constraint on shoreline movement due 

to a seawall at transect 1745 (yellow line) in Marshfield, Massachusetts. (Image source: Esri World Imagery.) 

37
Figure 20. Orthophotograph and historical shorelines showing significant artificial seaward shoreline movement 

due to human activities at transect 33 (yellow line) at Carson Beach, Massachusetts. (Image source: Esri World 

Imagery.) 

38
Table 1. Lengths of shoreline indicators alongshore used to delineate new shorelines in Massachusetts. [km, kilometers; —, not applicable]

Region High water 

line,

1 in km

Operational mean 

high water line,

2 in 

km

Marsh high 

water line, in 

km

Anthropogenic

features,

3 in km

North Shore 170 — 25 77

Greater Boston 45 — 9 29

South Shore 137 — 38 36

Cape Cod Bay 138 — 50 14

Outer Cape Cod 49 85 30 2

Cape Cod South 99 — 4 28

Buzzards Bay 231 — 65 61

Elizabeth Islands 92 — 1 1

Martha’s Vineyard 134 — 6 8

Nantucket 131 — 7 2

Total 1,226 85 85 85

1

Includes previous high-tide line, high-tide wrack line, tonal changes between wet and dry beach material, and algal line on 

rocky outcrops.

2

Derived from lidar data.

3

Includes the interface between manmade features (such as vertical seawalls, bulkheads, groins) and open water.

Table 2. Measurements of uncertainty for the regions used to calculate rates of shoreline change in 

Massachusetts. [—, not applicable]

Measurement uncertainty, in meters

T-sheets Aerial 

photographs, 

1970s to 1994

Orthophotographs

Lidar, 

2000–7

50 

cm, 

200

1

15 cm, 

2008

30 cm

1800s

to 

1950s

1960s

to 

1980s

2008–9 Distorted, 

2009

Georeferencing (Ug) 4 4 — — — — — —

Digitizing (Ud) 1 1 1 1 1 1 1 —

T-sheet survey (Ut) 10 3 — — — — — —

Air Photo (Ua) — — 5 3 0.25 2.12 4.23 —

Uncertainty of the high water line 

(Upd) 4.3 4.3 4.3 4.3 4.3 4.3 4.3 —

Lidar total position uncertainty (Up) — — — — — — — 1.27

Total shoreline position 

uncertainty (Up) 11.6 6.7 6.7 5.3 4.4 4.9 6.1 1.27

39
Table 3. Maximum statistically significant rates of shoreline change in Massachusetts.

[max., maximum; m/yr, meters per year; ±, plus or minus]

Region Long-term rate Short-term rate

Rate, in m/yr Location Rate, in m/yr Location

Maximum erosion

North Shore -1.7 ±0.7 Plum Island -16.3 ±12.8 Sandy Point

Boston -1.5 ±0.1 Lovells Island1 -7.7 Nickerson Beach

South Shore -3.0 ±0.5 New Inlet -5.5 ±2.8 Plymouth Beach

Cape Cod Bay -3.0 ±1.2 Entrance to Herring River -4.2 ±3.3 Chapin Memorial 

Beach

Outer Cape Cod -7.0 ±4.2 Monomoy Island -17.0 ±10.0 Monomoy Island

South Cape Cod -4.3 ±3.3 Chatham -2.6 ±2.5 Chatham

Buzzards Bay -1.0 ±0.5 Mattapoisett Neck -1.7 ±1.7 Demarest Lloyd Beach

Elizabeth Islands -1.2 ±0.7 Nonamesset Island1 -3.8 Nonamesset Island

Martha’s Vineyard -5.0 ±3.1 Norton Point -5.7 ±2.4 Norton Point

Nantucket -7.2 ±1.3 Muskeget Island -12.4 ±1.5 Tuckernuck Island

Maximum accretion

North Shore 2.7 ±2.1 Sandy Point 5 ±3.9 Plum Island

Boston 2.6 ±0.8 Columbia Point1 4.7 Quincy

South Shore 2.8 ±0.3 Scusset Beach 5.6 ±1.7 Plymouth Beach

Cape Cod Bay 3.5 ±2.1 Chapin Memorial Beach 11.5 ±11.2 Sandy Neck

Outer Cape Cod 10.0 ±9.2 Monomoy Island, 

backshore

42.6 ±41.8 Monomoy Island

South Cape Cod 3.3 ±2.1 Davis Beach 2.3 ±1.4 Sampsons Island

Buzzards Bay 2.1 ±1.5 Great Neck 2.3 ±0.3 Taylor Point

Elizabeth Islands 1.1 ±0.4 Cuttyhunk1 1.7 Cuttyhunk

Martha’s Vineyard 1.9 ±1.3 Edgartown Light 3.7 ±3.7 East Beach

Nantucket 4.3 ±3.7 Muskeget Island 5.5 ±4.6 Esther Island

1

End-point rate.

Table 4. Long-term linear regression rates of shoreline change in Massachusetts. [LTw, includes shorelines from 1970 to 1979 and 1994; LTwo, excludes shorelines from 1970 to 1979 and 1994; m/yr, 

meters per year; ±, plus or minus]

Region Long-term regional averages (m/yr) Maximum erosion rates (m/yr)

LTw LTwo LTw LTwo

North Shore -0.01 ±0.05 -0.01 ±0.05 -1.3 ±1.2 -1.2 ±0.4

Boston 0.03 ±0.03 0.03 ±0.11 -1.5 ±0.1 -1.5 ±1.0

South Shore -0.08 ±0.01 -0.08 ±0.02 -2.6 ±1.0 -2.8 ±1.2

Cape Cod Bay -0.22 ±0.05 -0.21 ±0.08 -3.4 ±1.5 -3.4 ±0.4

Outer Cape Cod -0.04 ±0.35 -0.17 ±0.39 -7.0 ±4.2 -5.8 ±3.9

South Cape Cod -0.14 ±0.05 -0.13 ±0.09 -4.2 ±1.7 -4.1 ±2.4

Buzzards Bay -0.06 ±0.02 -0.06 ±0.03 1.0 ±0.5 -1.0 ±0.2

Elizabeth Islands -0.07 ±0.01 -0.06 ±0.02 -1.01 ±0.7 -0.6 ±0.4

Martha’s Vineyard -0.53 ±0.05 -0.57 ±0.08 -3.6 ±0.1 -3.3 ±0.7

Nantucket -0.66 ±0.07 -0.67 ±0.11 -6.8 ±1.5 -6.9 ±3.4

40
Table 5. Long-term linear regression rates of shoreline change in Massachusetts calculated by this study and 

by Hapke and others (2011). [m/yr, meters per year; ±, plus or minus]

Region

Long-term regional 

averages, this report 

(m/yr)

Long-term regional 

averages for Hapke and 

others (2011) (m/yr)

North Shore -0.06 ±0.06 -0.06 ±0.05

South Shore -0.10 ±0.02 -0.11 ±0.04

Cape Cod Bay -0.01 ±0.11 -0.07 ±0.11

Outer Cape Cod -0.34 ±0.46 -0.35 ±0.48

Buzzards Bay -0.15 ±0.03 -0.15 ±0.03

Martha’s Vineyard -1.29 ±0.12 -1.31 ±0.13

Nantucket -1.57 ±0.13 -1.53 ±0.13

41
Appendix 1. Historical Shorelines

Table 1–1. Sources of historical data on shorelines.

[cm, centimeters; CZM, Massachusetts Office of Coastal Zone Management; m, meters; MassDOT, Massachusetts 

Department of Transportation; MassGIS, Massachusetts Office of Geographic Information; T-sheets, National Oceanic and 

Atmospheric Administration topographic map sheets; USGS, U.S. Geological Survey]

Years Data source Positional uncertainty, in meters Contributor

1845–1955 T-sheet 11.6 USGS, CZM

1960–1969 T-sheet 6.7 USGS, CZM

1970–1979, 1982 Aerial photography 6.7 CZM

1994 1-m digital orthophotography 6.7 CZM

2000, 2007 Lidar 1.27 USGS

2001 50-cm digital orthophotography 5.3 MassGIS, 

MassDOT

2008 15-cm digital orthophotography 4.4 USGS

2009 30-cm digital orthophotography 4.9 USGS

42
Prepared by the Pembroke Publishing Service Center.

For more information concerning this report, contact:

Director

U.S. Geological Survey

Woods Hole Coastal and Marine Science Center

384 Woods Hole Road

Quissett Campus

Woods Hole, MA 02543-1598

WHSC_science_director@usgs.gov

508-548-8700 or 508-457-2200

or visit our Web site at:

http://woodshole.er.usgs.gov/
Thieler and others—Massachusetts Shoreline Change Mapping and Analysis Project, 2013 Update—Open-File Report 2012–1189