Analysis of Shoreline Change in Connecticut · 7/19/2014 · Change in Connecticut 100+ Years of Erosion and Accretion: Methodology and Summary Results A cooperative effort between

By: Kevin O’Brien (DEEP), Joel Stocker (UCONN-CLEAR), Juliana Barrett (CT Sea Grant) and Bruce Hyde (UCONN-CLEAR)

Analysis of Shoreline Change in Connecticut

100+ Years of Erosion and Accretion: Methodology and Summary Results

A cooperative effort between the Connecticut Department of Energy & Environmental Protection (DEEP), the Connecticut Sea Grant (CT Sea Grant) and the University of Connecticut Center for Land Use

Education and Research (UCONN-CLEAR)

7/19/2014

July 2014 Page 2 of 29

Contents Figures: .......................................................................................................................................................... 3

Tables: ........................................................................................................................................................... 3

Project Goal:.................................................................................................................................................. 4

Disclaimers & Caveats: .................................................................................................................................. 4

Summary: ...................................................................................................................................................... 4

Long-term rates (ca. 1880s - 2006) ........................................................................................................... 5

Short-term rates (1983 – 2006) ................................................................................................................ 5

Data Compilation: ......................................................................................................................................... 6

General Shoreline Archive ........................................................................................................................ 8

Uncertainty Estimates ............................................................................................................................... 9

Shoreline Change Analysis Data .............................................................................................................. 10

Data Review/Assessment ............................................................................................................................ 10

Data Processing: .......................................................................................................................................... 13

Overview ................................................................................................................................................. 13

Baseline Development ............................................................................................................................ 14

Transect & Statistical Generation ........................................................................................................... 16

Statistical Review and Processing: .............................................................................................................. 21

Short-Term Data (1983 – 2006) .............................................................................................................. 21

Long-Term Data (ca. 1880 – 2006) .......................................................................................................... 23

Works Cited ................................................................................................................................................. 27

Appendices: ................................................................................................................................................. 29


Figures: Figure 1: Coastal USGS Quads by Year .......................................................................................................... 8

Figure 2: Sample shoreline data ................................................................................................................... 9

Figure 3: Examples of suitable (top) and unsuitable (bottom) shoreline vectors. ..................................... 12

Figure 4: Connecticut Shoreline Districts .................................................................................................... 18

Figure 5: Final Data Structure output ......................................................................................................... 19

Figure 6: Example of baselines, shoreline vectors, and analysis transects ................................................. 20

Figure 7: Example of shoreline transects clipped to the shoreline change envelope ................................ 20

Tables: Table 1: Uncertainty Terms ......................................................................................................................... 10

Table 2: Table of Short-term (1983 – 2006) statistics summary ................................................................. 23

Table 3: Table of Long-term (ca 1880 – 2006) statistics summary ............................................................. 26


Project Goal: To conduct a Geographic Information System (GIS) time series analysis using maps of the Connecticut

shoreline from several different time periods between 1880 and 2006 (100+ years) so as to provide a

high-level, quantifiable data set describing CT shoreline trends from both a statewide, regional, and a

localized perspective.

Disclaimers & Caveats: Shoreline change data presented here may differ from those found in other sources; any differences do

not necessarily indicate other data sources are inaccurate.

When considering other sources of shoreline change, discrepancies are to be expected considering the

many possible ways of determining shoreline positions and rates of change, and the inherent

uncertainty in calculating these rates.

The results from this analysis represent shoreline movement under past conditions and are not intended

for use in predicting future shoreline positions or future rates of shoreline change.

The materials presented can be reasonably used to:

identify areas that have historically exhibited erosion or accretion trends;

identify areas that have shown a “trend reversal” from the long term to the short term (either

changing from erosion to accretion or vice-versa);

generally assess the speed or magnitude of change; or

support or direct research investigations or planning purposes .

The materials presented should not be used to:

solely differentiate/explain the cause of change;

state with absolute certainty the magnitude or speed of change at a given location;

predict future rates and/or amount of change; or

develop engineering or design plans.*

* Without a review of the underlying data

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

relative sea level, and human activities. As a result, shoreline changes are generally not constant

through time and frequently switch from erosion (landward migration) to accretion (waterward

migration) and vice versa. Cyclic and non-cyclic 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

spanning decades, or more. The shoreline "rate of change" statistics offered here reflect a cumulative

summary of the processes that altered the shoreline for the time period analyzed, and cannot be

attributed to any one (or more) drivers.


Long-term rates (ca. 1880s - 2006) Long-term rates of shoreline change were determined using two methods. One approach fitted a least

squares regression line to all shoreline positions from the earliest (ca. 1880s) to the most recent (2006).

The rate of change is given by the slope of the regression line to the data. The calculation of linear

regression rates uses all shoreline data at a given location, but requires a minimum of three shorelines.

The rates calculated with many shoreline positions can increase confidence by reducing potential errors

associated with the source data, and fluctuating short-term changes. (Dolan, Fenster, & Holme, 1991)

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

among the shoreline dates. However, in locations where shoreline change rates have not remained

constant through time, a linear trend would not exist. For example, a shoreline may exhibit accretion

over the first 100 years, but in later years, the shoreline may shift to an erosion trend. In these cases, it

is expected that using a linear model provides a poor fit to the data, and as a result the uncertainty

associated with these shoreline change rates is higher than those in which the trend is more linear.

A second approach calculated end-point rates representing 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, nor do they use any more than two shorelines. However, they can

be used where the required number of shorelines will not support the linear regression approach and

thus can provide a potentially more robust suite of data.

In both cases, negative rate values indicate erosion (movement of the shoreline away from a predefined

baseline) and positive rate values indicate accretion (movement of the shoreline towards the baseline.)

The baseline, described in more detail in the Data Processing section of this document, is simply a

reference datum from which to measure change.

Short-term rates (1983 – 2006) Typically, shoreline change occurring over a short time span can be characterized by cyclic or episodic

non-linear behavior, such as storm-induced shoreline erosion. High short-term variability increases the

shoreline change rate uncertainty and the potential for rates of shoreline change that are statistically

insignificant. In many locations, the short-term trend is calculated with only 3 shorelines. As noted

above, uncertainty generally decreases with an increasing number of shoreline data points; thus the

small number of shorelines in the short-term calculation can result in higher uncertainty.

Since the short-term timeframe considers comparatively less data than the long-term, the rate

calculation only used an end point rate. 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.


As with the long-term rates, negative rate values indicate erosion (movement of the shoreline away

from the established baseline) and positive rate values indicate accretion (movement of the shoreline

towards the established baseline.)

Data Compilation: Vector based shoreline data was derived from the following sources:

1880s:

1) Connecticut Historic Shoreline 1880s* Vector layer derived from assorted scanned National

Oceanic and Atmospheric Administration (NOAA) Topographic Survey sheets ( T-sheet) images

(ca. 1880s ) provided to DEEP by NGS (http://tinyurl.com/l3obnfn) All shorelines (with the

exception of the New Haven harbor area) were hand digitized from T-sheets georeferenced for

this effort as part of a DEEP / UCONN collaboration

2) EC4B04-LIS* NOAA Shoreline Data Explorer (http://www.ngs.noaa.gov/NSDE/) Used to fill in

gaps of shoreline from missing T-Sheet scans for New Haven Harbor area

1900s:

1) CT1900A; CT1900B; CT1908A; CT1909A NOAA Shoreline Data Explorer

(http://www.ngs.noaa.gov/NSDE/) Vector data created by NOAA

1910s:

1) CT1915A NOAA Shoreline Data Explorer (http://www.ngs.noaa.gov/NSDE/) Vector data created

by NOAA

1930s:

1) CT132ELA; CT132FMA NOAA Shoreline Data Explorer (http://www.ngs.noaa.gov/NSDE/) Vector

data created by NOAA

1940s:

1) PH3148A; PH3148AZ; PH3148F; PH31B NOAA Shoreline Data Explorer


1950s:

1) Connecticut Hydrography Line (1953)**; Connecticut Hydrography Line (1958)**; U.S.

Geological Survey (USGS) Quadrangle Based Digital Line Graph (DLG) Hydrography Line Data

provided by DEEP (http://tinyurl.com/lk5emx6) Coastal arcs extracted from statewide layer

based on best available date of USGS quad compilation.

2) PH142A; PH142B NOAA Shoreline Data Explorer (http://www.ngs.noaa.gov/NSDE/) Vector data

created by NOAA

1960s:

1) Connecticut Hydrography Line (1960)**; Connecticut Hydrography Line (1961)**; Connecticut

Hydrography Line (1964)**; Connecticut Hydrography Line (1967)**; Connecticut Hydrography

http://tinyurl.com/l3obnfn

http://www.ngs.noaa.gov/NSDE/





http://tinyurl.com/lk5emx6



Line (1968)**; USGS Quadrangle Based DLG Hydrography Line Data provided by DEEP

(http://tinyurl.com/lk5emx6) Coastal arcs extracted from statewide layer based on best

available date of USGS quad compilation.

2) PH6002; PH6007; PH6815 NOAA Shoreline Data Explorer (http://www.ngs.noaa.gov/NSDE/)

Vector data created by NOAA

1970s:

1) Connecticut Hydrography Line (1970)**; USGS Quad Based DLG Hydrography Line Data

provided by DEEP (http://tinyurl.com/lk5emx6) Coastal arcs extracted from statewide layer

based on best available date of USGS quad compilation.

1980s:

1) Connecticut Hydrography Line (1983)**; Connecticut Hydrography Line (1984)**; USGS Quad

DLG Hydrography Line Data provided by DEEP (http://tinyurl.com/lk5emx6) Coastal arcs

extracted from statewide layer based on best available date of USGS quad compilation.

2) CM8312; CM8315 NOAA Shoreline Data Explorer (http://www.ngs.noaa.gov/NSDE/) Vector data

created by NOAA

1990s:

1) NOAA Environmental Sensitivity Index (ESI) data - CT* NOAA ESI Inventory

(http://response.restoration.noaa.gov/esi) Vector data created by NOAA

2000s:

1) CT0401A**; CT0401B**; CT0410C**; CT0410D**; CT0410E** NOAA Shoreline Data Explorer


* indicates the set itself provides coast-wide coverage.

** indicates a set, that when combined with others, provides coast-wide coverage.

It is important to note that the variety of data sources used employed different methodologies for

deriving a shoreline. Moreover, the representation of what the shoreline is relative to the actual mark

on the ground also varied and can be classified into two characterizations:

1) Office of Coast Survey/NOAA T-Sheets (Topographic Survey Sheets – “T-Sheets”):

Mean High Water (MHW): By definition, this is the average of the two daily high water lines for areas in

a diurnal tidal cycle. On T-sheets from the Atlantic coast it is interpreted by trained topographers using

the physical appearance of the beach, usually a line from the preceding high water limit. (Shalowitz,

1962)

2) USGS 1:24K Topographic Quad Sheets:

Wet/Dry Line: These are best described as the “wet/dry line” or the intersection of land and water as

interpreted from the source material - typically aerial photos. Depending on the tide stage when the

photography was taken, the wet/dry line and MHW may not be exactly the same.






http://response.restoration.noaa.gov/esi



Discussions with USGS-Woods Hole validate the rationale to use shorelines taken from disparate sources

and timeframes, with the increase in available data outweighing the drawbacks of using data derived

from different methodologies or referencing different shorelines. (Thieler & Himmestoss, DEEP/UCONN

meeting with USGS - Woods Hole, 2013) Successful integrations of such data were used in studies in

California, with the caveat being to responsibly address issues of errors in uncertainty. This is addressed

in a following section. (Hapke, Reid, Richmond, Ruggiero, & List, 2006)

General Shoreline Archive All source material was first converted (when necessary) into a common coordinate system (CT State

Plane (ft) NAD83.) The source material was then organized by grouping unique feature classes by

decade. For NOAA shoreline data this designation was predicated on the stated survey date provided

with the data attribution. For USGS data, the statewide line data was classified by a USGS Quadrangle

Index cross referenced against source material dates from scans of the original Topographic map scans

(Figure 1.) Next, the unique feature classes from each decade were imported in into a standardized data

schema based on a combination of NOAA shoreline attributes as well as attributes required by the

software package used to support the change analysis. Where needed, attribute values were

transferred or reclassified based on comparable native values. The standardized layers were then

merged into a data layer for each decade. The decadal layers were then merged into a statewide master

coverage (Figure 2.) All variants – original source material, decadal-based merges, and the entire

statewide datalayer - were stored within an Environmental Systems Research Institute (ESRI)

Geodatabase format to serve as a master archive of data suitable for supporting a variety of possible

uses.

Figure 1: Coastal USGS Quads by Year


Figure 2: Sample shoreline data

Uncertainty Estimates The numerous potential errors involved in deriving shoreline data make it necessary to provide a best

estimate of the total positional uncertainty associated with each shoreline position. Uncertainties for

shorelines include errors introduced by data sources as well as errors introduced by measurement

methods and are well documented: (Anders & Byrnes, 1991) (Crowell, Leatherman, & Buckley, 1991)

(Thieler & Danforth, 1994); (Moore, 2000) (Ruggiero, Kaminsky, & Gelfenbaum, 2003). The following five

components are considered when estimating the positional uncertainty for shorelines:

1) georeferencing uncertainty;

2) digitizing uncertainty;

3) T-sheet survey uncertainty;

4) air photo collection and rectification uncertainty; and

5) the uncertainty of the high water line at the time of survey (Crowell, Leatherman, & Buckley,

1991)

For each shoreline, the position uncertainty is defined as the square root of the sum of squares (Taylor,

1997) of the relevant uncertainty terms, based on an assumption that each term is random and

independent of the others (Hapke, Himmelstoss, Kratzmann, List, & Thieler, 2010). The average values

for each uncertainty term and the total average positional uncertainty were estimated for each


shoreline type (Table 1) using methods described in (Hapke, Himmelstoss, Kratzmann, List, & Thieler,

2010).

* USGS DLG Topo uncertainty value based on review of CT data, above citations, and personal communication with USGS

WHOI staff. Uncertainty value used is an average of upper and lower error bounds (15m and 30m)

** NOAA CT ESI source photo uncertainty taken from CT 1990 DOQQ positional accuracy assessments; assumes the same

values for ESI overflights

Shoreline Change Analysis Data A separate version of the master archive was extracted to specifically support the shoreline change

analysis described here. This dataset differs from the master archive in the following ways:

Vectors only correspond to lines classified as “Shoreline” based on representative values from the

standard attribute schema field describing the classification of the linework (i.e., this layer omits

lines classified as upland marsh boundaries, transportation features, hazard areas, etc. that were

included in some of the original source material).

The coordinate system was converted to UTM Zone 18 (meters) to conform to the requirements of

the software analysis package used.

Data Review/Assessment The review of shoreline change analysis data began by creating a buffer around the shorelines using the

appropriate error estimates. This provided a window of reasonable position to compare the shoreline

to other sources of coastal information and assess whether or not to include it.

Visual inspection of buffered lines:

1. For shorelines 1990 – present, it was possible to compare the shorelines to the actual

orthophoto imagery used to derive them (or to orthophotos taken within a year of the linework

at a comparable level of detail) to confirm if the linework was suitable. “Suitable” areas were

typically defined by:

Measurement Errors (m) Tsheets UDGS DLG Topo NOAA CT ESI Air Photos

1880s-1950s

1960s-1980s

1950s-1960s

1970s-1980s

1990s DOQQ /

ESI Flights 1995

CTDEP 1970-2000s

Georeferencing 4 4 4 4 0 4 0

Digitizing 1 1 1 1 1 1 1

Tsheet survey 10 3 0 0 0 0 0

Air Photos 0 0 0 0 10** 3 3

USGS DLG Topo 0 0 22.5* 22.* 0 0 0

Shoreline location 4.5 4.5 4.5 4.5 4.5 4.5 4.5

Square root of Sum of Squares (m) 11.72 6.80 23.31 23.31 11.01 6.80 5.50

Square root of Sum of Squares (ft) 38.43 22.31 76.47 76.47 36.12 22.31 18.04

Table 1: Uncertainty Terms

Table 1: Uncertainty Terms


The error-bounded shoreline capturing what could best be determined as the “MHW

vicinity” – i.e., an area that captures the land-water interface as well as a portion

landward. In this way, we can be reasonably confident that the error-bounded

shoreline is close to MH or a high-water mark and at least above low-water. This metric

is typically applied to areas of open coastline such as beaches or marshes that do not

have a well-defined point of reference such as jetties, groins, rocky outcrops, seawalls,

rocky headlands, etc.

For areas of the coast that do have well-defined points of reference such as jetties,

groins, rocky outcrops, seawalls, rocky headlands, etc., the error-bounded shoreline

needed to overlap or reasonably define the shape, extent, or orientation of these

features.

Areas deemed “unsuitable” for this analysis generally corresponded to conditions such as:

Misinterpretations of the vicinity of MHW shoreline (e.g., exposed tidal flats or other

areas of obvious low water rather than a more appropriate area in the vicinity of the

beach/water interface );

Unknown/unexplainable digitizing errors such that the shorelines do not follow typical

interpretations used to define similar areas within the data.

Any unsuitable areas were coded as such during the review and removed from the final version

used in the analysis.


Figure 3: Examples of suitable (top) and unsuitable (bottom) shoreline vectors.

In the top image of Figure 3, the blue shoreline generally follows the photo trend but more

importantly, the buffered area is also largely consistent. Below both the shoreline and the

buffered area do not provide a good visual match along the southern section of the land form.

2. For shorelines pre-dating 1990, it was not possible to replicate the same methodology described

above. Whereas the 1990-present shorelines were directly digitized from available (or

comparable) orthophotos, the shorelines pre-dating 1990 were digitized from scans of hardcopy

maps – T-sheets and USGS Topographic Quadrangle maps. These scanned maps required an

intermediary step to georeference them (referencing the image coordinates of the scan to real-

world coordinate locations,) which introduced an additional source of error. So while it was

possible in many cases to access the scanned maps and assess whether the shoreline was

interpreted and/or traced correctly, this alone was not sufficient to assess whether the

georeferencing process accurately located the maps to correspond to a reasonable location on

the ground. In order to assess the validity of the georeferencing, the error-bounded lines were

displayed over ca. 2010 orthophotography and examined along areas of the coast with well-

defined common points of reference such as jetties, groins, rocky outcrops, seawalls, rocky

headlands, etc., that were assumed to be constant over time. Fortunately the Connecticut

coastline has a well distributed set of these features enabling a coast-wide approach. The error-

bounded shoreline needed to overlap or reasonably define the shape, extent, or orientation of

these features in order to be considered suitable. In many cases, historic shorelines exhibited

an offset from these “constants” such that the overall configuration of the shoreline was

adequately represented, but the spatial location was shifted too far east, west, north or south -

indicating positional accuracy exceeded the error bounds. In these cases, the discrepant

shorelines were coded as unsuitable during the review and removed from the final version used

in the analysis. It should be noted that while this approach was employed coast-wide, it was


necessarily limited in scope to areas that provided the means to assess the data; it is therefore

possible that some shorelines included in the analysis may exceed their stated positional error

boundary estimates. However, there was no conclusive way to identify or quantify these within

the constraints of this study’s time and funding, so taking a conservative approach in the

analysis aspect of this effort was employed.

Data Processing:

Overview Data processing used USGS Digital Shoreline Analysis System (DSAS) version 4.3 software extension for

ESRI ArcGIS. (Thieler, Himmelstoss, Zichichi, & Ergul, 2009) DSAS generates geospatial data and

statistical calculations for shoreline time-series data by analyzing the proximity and distribution of

shorelines from an established baseline (starting point) at user-defined intervals (transects.) DSAS

provides great flexibility in establishing parameters; consultations with USGS – Woods Hole staff (Thieler

& Himmestoss, DEEP/UCONN meeting with USGS - Woods Hole, 2013) provided the following best-

practices guidelines:

Locating baselines:

o Baselines should be oriented as close to shore as possible to minimize issues with multiple

transect crossings and drawn to force transects to be as orthogonal to shoreline trends as

possible. There is no “golden rule” and there will always be some interpretive work here. If

the above two criteria are held to, there’s very little difference in the resulting analyses –

i.e., similar baselines will produce essentially similar results.

o It is generally easier to create baselines for large stretches of shore and then edit/remove

transects from analysis rather than a series of shorter baselines that ignore certain areas.

Transect intervals:

o A typical interval of 50m will produce suitable data. This is what was used in Massachusetts,

could be more or less as needed.

Statistical derivations;

o Do not use WLR (weighted linear regression) calculations. Application of weighting

parameters in the coding is not done well enough to provide defensible results.

o Do not use EPR (end point rate) Confidence Interval values –values do not provide realistic

meaning.

o Ordinary least squares is the preferred statistic for anything >= 3 shorelines. Use EPR when

you only have two shorelines.

Other points of consideration

o Using as many shorelines as possible, even if they do not match the datum exactly, is more

useful in the data analysis. Adjusting the uncertainty values can help mitigate datum related

inconsistencies. Shorelines from USGS topographic maps have been mixed in with NOAA

shorelines in California – reports exist with the uncertainties used for those studies that we

have adopted/modified. (Hapke, Reid, Richmond, Ruggiero, & List, 2006)


o Any photo derived shoreline can safely be assumed to use a wet/dry line which can be

considered comparable to MHW. Care should be taken to account for additional

uncertainty if there is any specific notation of only using a low-water line interface. Adjust

uncertainty as needed.

o Better to adjust uncertainty values than edit lines that do not “match” known shoreline

features like rocks, outcrops, etc. If data have systemic errors, then consider omitting all or

parts. General rule is to keep what can reasonably be kept, and adjust uncertainty.

o Using LIDAR derived shorelines is typically only useful in areas of consistently sloping sandy

beaches. For Connecticut, using LIDAR to fill in gaps of coverage in the eastern part of the

state is not likely a good use of time/effort as results may not be optimal. Better to acquire

USGS Topographic shorelines or NOAA ESI data as noted above.

o May want to consider looking at shorelines of similar type (i.e., sandy beach or marsh) to

examine comparing apples to apples.

o Calculating an “average” rate for a given aggregation of shoreline (i.e., a town, a county,

etc.) is doable, but this will likely be using shorelines of varying geologic characteristics. So

for example, any area of geologic stability over time will drive values down from areas of

actual erosion.

In general the outcome was to develop data for use in addressing two fundamental questions: “How

much has the shoreline changed?” (How far has it moved?) and “How fast has the shoreline

changed?” (At what rate is it moving?)

Baseline Development A baseline is used in the DSAS model as a starting point to create transects which then cross through the

individual shoreline vectors and provide measures of change over time. All baseline segments were

created at a distance offshore of the furthest seaward shoreline vector for all of the available years yet

oriented close enough to ensure that transects are reasonably perpendicular to the primary direction of

change. Segments of the baseline contain attributes to identify sections for individual analysis and

codes to provide a directional sequence for the model (west to east).

The baseline was created and edited within an ESRI file geodatabase (gdb) as a line feature. The file

geodatabase format maintains curve topology and provides additional functionality to easily create and

modify the line feature during the development and maintain a record of editing history. Once

completed this file geodatabase feature was exported to an ESRI personal geodatabase (mdb) for

compatibility with the DSAS modeling program.

An ESRI ArcGIS project was built for editing the baseline using additional feature layers for visible

reference in the background. The primary background layers were the available shoreline vectors for

each year, aerial imagery, and political boundaries helpful for identifying the attributes and positions of

the existing shorelines. To improve computer performance all shoreline vectors were cropped (clipped)

to a study zone created using a data layer that extends the town boundaries off shore far enough to

include all islands associated with a political boundary. The 24 coastal towns were selected and the


feature was modified to extend beyond the western and eastern most towns. The baseline and final

analysis were contained within this clipped “zone”.

Before creating the baseline the shorelines were reviewed for what would eventually be included in the

final analysis. The 2006 vector layer was more detailed than prior years and included islands and rock

features not identified in earlier layers. These islands were removed from the analysis, as if they were

not removed the output would have provided false rates of change where transects crossed these

features. For larger island features not included in the time analysis, the baseline was drawn to fall

between the island and the furthest seaward shoreline, essentially removing the island from the results.

These offshore islands may affect the dynamics of the neighboring shoreline and provide a reason for

change or stability yet do not contribute directly to the calculations of change. The baseline was also

adjusted to avoid islands visible in the aerial imagery yet not identified in any of the vector datasets.

The Connecticut shoreline is very complex, it is not a simple linear feature where a baseline can easily

remain perpendicular to all of the shoreline features. Curved arcs were used to best align around

peninsulas and within embayments where straight-line baseline segments would not work. The DSAS

software does interpolate a curve for quick changes in baseline direction, however, pre-setting the arcs

allows for more control of the output transects, improving the odds the result transects would intersect

the shoreline features properly. Testing with intermediate runs of the DSAS software, then adjusting

the curves, improved the results.

Baseline Attributes: The attribute information within the baseline was coded to match political town

boundaries based on the starting point of a given line segment moving from West to East. The

shoreline towns were numbered west to east, starting in Greenwich with the number 1 and ending in

Stonington as 24. These codes were entered as attributes and each segment within a town was

numbered from 1 to the final segment count for that town (group sub-order). The segments were

broken at significant changes in the land features and shoreline directions. If a segment extended into

the next town the segment was broken, ensuring the attribute code changed at the boundary.

Important baseline attributes:

ID (LONG) – Primary unique identifier for DSAS. 100 plus Town order concatenated with 100 plus

group sub order. Adding 100 maintains a six digit format. Sample: Greenwich (Town 1) Segment #

3 = 101103

DSASGROUP (LONG) – Group value for optional use in DSAS. Value is the town number as identified

by DEEP.

CastDir (SHORT) – Value tells DSAS if the baseline segment is offshore (0) or inland (1) of the

shoreline vectors. In this study all values were set to 0.

townOrder (SHORT) – Towns labeled as 1 to 24 from West to East. Value used in ID.

grpSubOrder (LONG) – Values 1 to the last segment for a given town (west to east). Value used in

ID.

Additional attributes were used during the build of the dataset to help maintain edit history, include

town information, and provide suggested transect lengths for individual sections.


The draft baseline was converted to a personal geodatabase and reviewed for consistency and accuracy.

A few segments were subsequently adjusted to extend selected features and better align sections to

maximize perpendicular transects.

Transect & Statistical Generation For both long-term data (i.e., shorelines from ca. 1880 to 2006) and short-term data (i.e., shorelines

from 1983 to 2006) the following process steps were implemented within DSAS:

1. Transects were generated with 50m spacing.

2. Transect geometry reviewed; where necessary baselines were adjusted to correctly orient

transects; transects regenerated with modified baselines.

3. Initial Statistics (using a Confidence Interval of 1.5 standard deviations) and intersect points

based on revised transects were created. Confidence Interval was chosen to provide a balance

of quantity of data and quality of data. Higher Confidence Interval values provide quality data at

(generally) the expense of quantity and/or distribution of data; Lower Confidence Intervals will

generally produce more data but of lower quality.

4. Reviewed revised transects and coded certain classes for removal:

a. Transects that were too skewed (i.e., they did not sufficiently intersect the general trend

of the shorelines in a more or less perpendicular fashion;

b. Multiple transects hitting at or near the same location (e.g., around a point of land, or

where one baseline ends and the next adjacent one begins.)

5. Reviewed intersection table and removed erroneous points (typically when transects were long

enough to pick up inland shoreline arcs with distinctly different dates or in areas behind where

parts of shorelines were removed due to accuracy issues.) This effectively sets a corrected

inventory of shoreline intersections.

6. Clipped revised transects based on the corrected intersect points to produce a set showing only

the envelope of change (limiting the transect length to just the area between the closest and

furthest shorelines from the baseline)

7. Used the clipped transects to generate revised (final) statistics; joined statistics table to clipped

transects to create a final analysis data set via the [ObjectId] field. Statistical output included:

a. Net Shoreline Movement (NSM): The net shoreline movement reports a distance, not a

rate. The NSM is associated with the dates of only two shorelines. It reports the distance

between the oldest and youngest shorelines for each transect. This represents the total

distance between the oldest and youngest shorelines.

b. End Point Rate (EPR): The end point rate is calculated by dividing the distance of

shoreline movement by the time elapsed between the oldest and the most recent

shoreline. The major advantages of the EPR are the ease of computation and minimal

requirement of only two shoreline dates. The major disadvantage is that in cases where

more data are available, the additional information is ignored.

c. Confidence of End Point Rate (ECI): Generated, but ignored for this study per USGS-

Woods Hole.


d. Shoreline Change Envelope (SCE): The shoreline change envelope reports a distance, not

a rate. The SCE is the distance between the shoreline farthest from and closest to the

baseline at each transect. This represents the total change in shoreline movement for all

available shoreline positions and is not related to their dates.

e. Linear Regression Rate (LRR): A linear regression rate-of-change statistic can be

determined by fitting a least-squares regression line to all shoreline points for a

particular transect. The regression line is placed so that the sum of the squared residuals

(determined by squaring the offset distance of each data point from the regression line

and adding the squared residuals together) is minimized. The linear regression rate is

the slope of the line. The method of linear regression includes these features: (1) All the

data are used, regardless of changes in trend or accuracy, (2) The method is purely

computational, (3) The calculation is based on accepted statistical concepts, and (4) The

method is easy to employ (Dolan, Fenster, & Holme, 1991). However, the linear

regression method is susceptible to outlier effects and also tends to underestimate the

rate of change relative to other statistics, such as EPR (Dolan, Fenster, & Holme, 1991)

(Genz, Fletcher, Dunn, Frazer, & Rooney, 2007).

f. The R-squared statistic, or coefficient of determination, is the percentage of variance in

the data that is explained by a regression. It is a dimensionless index that ranges from

1.0 to 0.0 and measures how successfully the best-fit line accounts for variation in the

data. In other words, it reflects the linear relationship between shoreline points along a

given DSAS transect.

g. Standard Error of the Estimate: The standard error of the estimate measures the

accuracy of the predicted values of y by comparing them to known values from the

shoreline point data.

h. LRR 86.6% Confidence Interval: The standard error of the slope with confidence interval

(LCI for ordinary linear regression) describes the uncertainty of the reported rate. The

LRR rates are determined by a best-fit regression line through the sample data. The

slope of this line is the reported rate of change (in meters/year). The confidence interval

(LCI) is calculated by multiplying the standard error (also called the standard deviation)

of the slope by the two-tailed test statistic at the user-specified confidence percentage

(Zar, 1999). The specific confidence interval was chosen to provide a balance between

quantity of data and quality of data.

8. Identified transects as:

a. Not statistically valid (e.g., where the LRR Confidence interval exceeded the LRR value),

b. Part of heavily industrialized harbors (Bridgeport, New Haven, Thames River) or areas of

significant fill (largely localized in the western 6 coastal communities) based on a review

of ca. 2010 aerial photographs and shoreline vectors.

c. Suitable for analysis – effectively those that were not coded as ‘a’ or ‘b’ above.

NOTE: all transects were used to assess net shoreline movement to track and display the

magnitude of shoreline change over time. The transects coded as described in 8a and 8b


above were omitted from any rate-based assessments as we felt the changes derived from

the obvious areas of heavy industrialization and fill would skew the overall results.

9. Added shoreline districts outlined in a 1979 CTDEP shoreline assessment to ID similar sections of

shoreline for organization and comparative purposes. (Connecticut Coastal Area Management

Program, 1979) (Figure 4) From west to east the following districts are defined as:

a. Rock and Drift/Much Artificial Fill

b. Glacial Drift and Beaches

c. Glacial Drift and Rock

d. Rock and Marshes

e. Glacial Drift and Beaches

f. Glacial Drift and Rock

g. Rock and Marshes

Figure 4: Connecticut Shoreline Districts

10. To account for a desire to address regional averaging of rates and uncertainties in the shoreline

change data (e.g., by geologic categorization or by town/political boundaries) we needed to

address how uncertainty values of each individual shoreline change value is used in the mean.

(Hapke, Himmelstoss, Kratzmann, List, & Thieler, 2010) In shorelines generally dominated by

long stretches of uniform orientation and geomorphology, it is possible to make use of

automated processes such as spatially lagged autocorrelation tools in commercial off the shelf

software packages. Given that the nature of the Connecticut shoreline does not match with


these conditions, discussions with USGS – Woods Hole (List, 2013) led to a manual best-

professional judgment routine within ArcGIS to identify self-similar stretches of shoreline

(typically defined by unique littoral cells such as pocket beaches and smaller stretches of beach

or marsh-dominated shorelines.) The identification of these “reduced transect” estimators was

used when determining regional uncertainty averages.

The resulting data show in Figures 5 – 7 were subsequently generated:

Figure 5: Final Data Structure output


Figure 6: Example of baselines, shoreline vectors, and analysis transects

Figure 7: Example of shoreline transects clipped to the shoreline change envelope


Statistical Review and Processing: Resulting data for both long and short-term rates were exported from ArcGIS into an MS Excel

spreadsheet for processing and analysis. Data were exported on the basis of shoreline districts as

defined above and organized using a combination of town identification codes and transect Ids to

provide an organized progression of transect data along the Connecticut coastline from west to east.

This enabled the generation of overall statistics for shoreline districts and the coastal communities

contained within.

Short-Term Data (1983 – 2006) For Short-term data (1983 – 2006), the following metrics were summarized on a per-town and district-

wide basis. In the vicinity of the Connecticut River we identify sections as fronting Long Island Sound

and the Connecticut River proper for towns on the western and eastern shores (Old Saybrook and Old

Lyme, respectively.) Here we only include the EPR, as the density of shoreline data is limited by the

temporal range and only small poorly distributed sections of the coast had the necessary number of

shorelines required to compute LRR-based statistics.

Net Shoreline Movement (how much has the shoreline moved): The Net Shoreline Movement

calculations included data from all transects in order to portray the overall characteristics of

change across the state and regions.

o Minimum

o Maximum

o Average

End Point Rate (how fast has the shoreline moved): The End Point Rate calculations excluded

data from transects corresponding to those coded as heavily urbanized or the likely result of

obvious fill in order to mitigate skewing the overall characteristics of rates of change across the

state and regions.

With respect the End Point Rate calculations, the following pros and cons are worth noting:

End Point Rate Pros:

A simple calculation that’s easily understandable;

Can be used essentially anywhere there are data (only need 2 shorelines.)

Easily applied to both Long Term and Short Term analyses

End Point Rate Cons:

Ignores other shorelines so the rate can be idealized;

Assumes a linear fit; not always the case

Can be highly influenced by the quality of either (or both) of the shorelines;

Provides no measure of confidence in the rate.

The Short-term data results are summarized below (Table 2). In cases where a community is split across

a shoreline district, we provide results for each component as well as a total:


Town NSM Min

NSM Max

NSM Ave

EPR Ave

Greenwich -23.88 45.43 1.21 0.06

Stamford -29.28 50.57 -1.91 -0.10

Darien -18.19 52.7 0.29 0.01

Norwalk - A -16.36 36.25 1.89 0.09

Zone A -29.28 52.7 0.60 0.03

Norwalk - A & B -24.08 36.25 1.33 0.06

Norwalk - B -24.08 19 -0.03 0.00

Westport -52.13 20.16 -3.90 -0.18

Fairfield -31.37 20.28 -5.12 -0.24

Bridgeport -30.51 92.65 -3.33 -0.23

Stratford -47.43 50.05 -5.56 -0.26

Milford - B -82.67 289.45 17.24 0.81

Zone B -82.67 289.45 -1.14 -0.06

Milford - B & C -82.67 289.45 8.09 0.38

Milford - C -64.07 37.08 -0.07 0.00

West Haven -73.53 140.46 -6.21 -0.24

New Haven - C -17.55 28.76 -4.55 N/A

Zone C -73.53 140.46 -3.54 -0.13

New Haven - C & D -18.05 28.76 0.03 0.02

New Haven - D -18.05 27.48 2.48 0.02

East Haven -7.78 32.33 1.15 0.05

Branford -26.52 21.45 0.82 0.04

Guilford - D -21.21 55.29 4.96 0.23

Zone D -26.52 55.29 2.45 0.10

Guilford - D & E -21.21 55.29 5.05 0.24

Guilford - E -16.99 36.16 5.71 0.35

Madison -40.11 11.88 -3.64 -0.17

Clinton -

133.55 29.91 -3.33 -0.15

Westbrook -12.12 19.51 2.14 0.10

Old Saybrook - LIS -19.89 23.8 -2.60 -0.12

Old Saybrook - CT River -20.51 25.83 6.18 0.28

Old Saybrook - All -20.51 25.83 0.75 0.03

Old Lyme - CT River - E -34.51 31.75 -9.81 -0.47

Old Lyme - LIS - E -

152.22 30.57 -14.05 -1.92

Old Lyme - E -

152.22 31.75 -12.28 -1.31

Zone E - 36.16 -3.04 -0.28


Town NSM Min

NSM Max

NSM Ave

EPR Ave

152.22

Old Lyme - E & F -

152.22 33.12 -9.41 -1.02

Old Lyme - F -12.51 33.12 1.35 0.08

East Lyme -36.44 32.53 -11.64 -0.50

Waterford -

120.77 19.63 -11.61 -0.56

New London -35.28 22.99 -6.23 -0.60

Groton - F -46.3 38.41 -3.34 -0.29

Zone F -

120.77 38.41 -7.04 -0.42

Groton - F & G -46.3 38.41 -3.33 -0.25

Groton - G -35.45 20.97 -3.32 -0.15

Stonington -71.72 34.02 -3.75 -0.17

Zone G -71.72 34.02 -3.68 -0.17 Table 2: Table of Short-term (1983 – 2006) statistics summary

Additional Short-Term products include the following (and are contained in Appendices)

Average Short-Term NSM Chart (by Town and District)

Long-Term Data (ca. 1880 – 2006) For Long-term data (ca. 1880 – 2006), the following metrics were summarized on a per-town and

district-wide basis. As there was a greater density of data due to the longer time horizon, there are

more data products. In the vicinity of the Connecticut River we identify sections as fronting Long Island

Sound and the Connecticut River proper for towns on the western and eastern shores (Old Saybrook and

Old Lyme, respectively.) As the long-term data generally have sufficient density across the entire coast,

we are able to compute both EPR and LRR-based statistics.

Net Shoreline Movement: The Net Shoreline Movement calculations included data from all

transects in order to portray the overall characteristics of change across the state and regions.

o Minimum

o Maximum

o Average

Linear Regression Rate: The Linear Regression Rate calculations excluded data from transects

corresponding to those coded as heavily urbanized or the likely result of obvious fill in order to

mitigate skewing the overall characteristics of rates of change across the state and regions.

o Minimum

o Maximum

o Average

Ave. Uncertainty (via reduced transect estimates)


End Point Rate: The End Point Rate calculations excluded data from transects corresponding to

those coded as heavily urbanized or the likely result of obvious fill in order to mitigate skewing

the overall characteristics of rates of change across the state and regions.

o Minimum

o Maximum

o Average

With respect to the rate of change calculations, the pros and cons are regarding the use of the End

Point rate are the same as those noted above in the Short-Term data section. Below are pro and con

points that are relevant for Linear Regression rates that are applied to the long-Term data:

Linear Regression Rate Pros:

Relatively easy to implement;

Uses all shoreline data;

Provides a rate and an estimate of confidence in it;

Allows user to specify level of confidence (in this case, 86.5% or 1.5 Standard Deviations)

Linear Regression Rate Cons:

Assumes a linear fit; not always the case

Requires at least 3 data points (ideally more)

Can return “inconclusive” results (e.g., where the measure of uncertainty is greater than the

rate) – requires user to interpret results

There may be areas where no output can be used.

The Long-term data results are summarized below (Table 3). In cases where a community is split across

a shoreline district, we provide results for each component as well as a total:

Town NSM Min

NSM Max

NSM Ave

EPR Ave LRR Ave

LRR CI Regional

Ave. Uncertainty

LRR CI Ave

Lower Bound

LRR CI Ave

Upper Bound

Greenwich -91.45 340.77 15.04 0.04 0.05 0.01 0.03 0.06

Stamford -64.3 416.78 17.34 0.05 0.06 0.03 0.03 0.08

Darien -112.49 196.13 6.24 0.02 0.04 0.01 0.02 0.05

Norwalk - A -49.63 436.05 19.15 0.05 0.05 0.02 0.03 0.07

Zone A -112.49 436.05 14.44 0.04 0.05 0.01 0.04 0.06

Norwalk - A & B -254.59 436.05 23.04 0.06 0.07 0.02 0.05 0.09

Norwalk - B -254.59 383.92 32.61 0.07 0.12 0.04 0.08 0.17

Westport -120.68 139.13 4.88 0.04 0.10 0.03 0.07 0.13

Fairfield -30.69 104.86 8.87 0.07 0.12 0.04 0.08 0.16

Bridgeport -51.62 343.97 42.82 0.22 0.28 0.05 0.23 0.33

Stratford -102.56 162.42 -12.52 -0.10 -0.06454 0.06452 -0.13 0.00

Milford - B -117.6 369.83 18.62 0.16 0.14 0.08 0.06 0.23


Town NSM Min

NSM Max

NSM Ave

EPR Ave LRR Ave

LRR CI Regional

Ave. Uncertainty

LRR CI Ave

Lower Bound

LRR CI Ave

Upper Bound

Zone B -254.59 383.92 16.04 0.07 0.12 0.02 0.10 0.13

Milford - B & C -117.6 369.83 16.63 0.06 0.06 0.03 0.03 0.09

Milford - C -95.07 42.95 -4.39 -0.04 -0.01 0.03 N/A N/A

West Haven -72.09 110.77 7.49 0.03 0.16 0.09 0.06 0.25

New Haven - C 11.96 791.13 430.63 0.03 N/A N/A N/A N/A

Zone C -95.07 791.13 64.98 0.00 0.08 0.04 0.04 0.12

New Haven - C & D -36.75 791.13 166.23 0.10 0.16 0.05 0.11 0.20

New Haven - D -36.75 353.85 43.59 0.10 0.16 0.06 0.10 0.21

East Haven -82.21 84.58 5.06 0.05 0.08 0.05 0.03 0.12

Branford -80.29 78.48 1.08 0.01 0.018 0.017 0.00 0.03

Guilford - D -203.67 111.53 -2.47 -0.02 -0.03 0.02 -0.06 -0.01

Zone D -203.67 353.85 6.97 0.01 0.02 0.01 0.01 0.03

Guilford - D & E -203.67 111.53 -8.02 -0.07 -0.08 0.02 -0.11 -0.06

Guilford - E -133.41 13.79 -43.43 -0.35 -0.39 0.13 -0.51 -0.26

Madison -204.63 63.34 -8.78 -0.07 -0.05 0.03 -0.08 -0.03

Clinton -183.71 45.96 -16.73 -0.14 -0.13 0.03 -0.16 -0.11

Westbrook -39.68 80.88 2.47 0.02 0.019 0.023 N/A N/A

Old Saybrook - LIS -67.15 212.89 -4.28 -0.03 -0.018 0.023 N/A N/A

Old Saybrook - CT River -26.34 258.34 11.95 0.10 0.09 0.07 0.02 0.15

Old Saybrook - All -67.15 258.34 1.86 0.01 0.022 0.024 N/A N/A

Old Lyme - CT River - E -77.74 65.36 -9.66 -0.08 -0.06 0.08 N/A N/A

Old Lyme - LIS - E -313.99 55.2 -43.26 -0.36 -0.31 0.09 -0.40 -0.21

Old Lyme - E -313.99 65.36 -30.03 -0.25 -0.21 0.07 -0.28 -0.14

Zone E -313.99 258.34 -11.46 -0.09 -0.08 0.02 -0.10 -0.07

Old Lyme - E & F -313.99 65.36 -25.27 -0.21 -0.18 0.05 -0.23 -0.13

Old Lyme - F -27.73 22.31 -6.90 -0.06 -0.064 0.058 -0.12 -0.01

East Lyme -97.03 70.77 -1.39 -0.01 0.03 0.04 N/A N/A

Waterford -129.06 87.26 -4.92 -0.08 -0.04 0.05 N/A N/A

New London -30.02 316.52 19.05 0.02 0.059 0.064 N/A N/A


Town NSM Min

NSM Max

NSM Ave

EPR Ave LRR Ave

LRR CI Regional

Ave. Uncertainty

LRR CI Ave

Lower Bound

LRR CI Ave

Upper Bound

Groton - F -74.01 249.38 10.74 -0.02 0.02 0.03 N/A N/A

Zone F -129.06 316.52 5.96 -0.03 0.00 0.02 N/A N/A

Groton - F & G -74.01 249.38 8.56 -0.01 0.03 0.02 0.00 0.05

Groton - G -37.59 52.34 2.06 0.02 0.04 0.03 0.01 0.08

Stonington -152.39 58.96 -5.89 -0.05 -0.02 0.01 -0.04 -0.01

Zone G -152.39 58.96 -4.53 -0.04 -0.01 0.012 N/A N/A Table 3: Table of Long-term (ca 1880 – 2006) statistics summary

Additional Long-Term products include the following (and are contained in Appendices)

Long-Term EPR &LRR and Short-Term EPR Averages Chart (by Town and District)

Average Long-Term NSM Chart (by Town and District)

District A:

o Long-term NSM Chart

o Long-term EPR Chart

District B:

o Long-Term NSM Chart


o Long-term LRR Chart

District C:




District D:




District E:




District F:



District G:





Works Cited Anders, F. J., & Byrnes, M. R. (1991). Accuracy of shoreline change rates as determined from maps and

aerial photographs. Shore and Beach , 59, 17-26.

Connecticut Coastal Area Management Program. (1979). Shoreline Erosion Analysis and Recommended

Planning Process. Hartford: State of Connecticut, Department of Environmental Protection.

Crowell, M., Leatherman, S. P., & Buckley, M. K. (1991). Historical shoreline change; Error analysis and

mapping accuracy. Journal of Coastal Research , 7, 839-852.

Dolan, R., Fenster, M. S., & Holme, S. J. (1991). Temporal analysis of shoreline recession and accretion.

Journal of Coastal research , 7, 723-744.

Genz, A. S., Fletcher, C. H., Dunn, R. A., Frazer, L. N., & Rooney, J. J. (2007). The predictive accuracy of

shoreline change rate methods and alongshore beach variation on Maui, Hawaii. Journal of Coastal

Research , 23, 87-105.

Hapke, C. J., Himmelstoss, E. A., Kratzmann, M. G., List, J. H., & Thieler, E. R. (2010). National Assessment

of Shoreline ChangeL Historical Change along the New England and Mid-Atlantic Coasts. U.S. Geological

Survey.

Hapke, C. J., Reid, D., Richmond, B. M., Ruggiero, P., & List, J. (2006). National Assessment of Shoreline

Change Part 3: Historical Shoreline Change and Associated Coastal Land Loss Along Sandy Shorelines of

the California Coast. U.S. Geological Survey.

List, J. (2013 йил 21-November). Phone Conversation with USHS WHOI - Averaging Uncertainty. (K.

O'Brien, Interviewer)

Moore, L. (2000). Shoreline mapping techniques. Jounal of Coastal Research , 16, 111-124.

Ruggiero, P., Kaminsky, G. M., & 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 , 57-82.

Shalowitz, L. A. (1962). Shore and Sea Boundaries - with Special Reference to the Intepretation and Uses

of Coast and Geodectic Data (Vol. 2). Washington, DC: United States Goverenment Printing Office.

Taylor, J. R. (1997). An Introduction to Error Analysis: The Study of Uncertainties in Physical

Measurement. Sausalito, CA: University Science Books.

Thieler, E. R., & Danforth, W. W. (1994). Historical shoreline mapping (1). Improving techniques and

reducing positioning errors. Journal of Coastal Reseach , 10, 549-563.

Thieler, E. R., & Himmestoss, E. A. (2013 йил 5-April). DEEP/UCONN meeting with USGS - Woods Hole.

(K. O'Brien, & J. Stocker, Interviewers)


Thieler, E. R., Himmelstoss, E. A., Zichichi, J. L., & Ergul, A. (2009). Digital Shoreline Analysis System

(DSAS) version 4.0— An ArcGIS extension for calculating shoreline change. U.S. Geological Survey.

Zar, J. H. (1999). Biostatistical Analysis (4th ed ed.). Upper Saddle River, NJ: Prentice Hall.

Appendices:

1) Long-Term EPR, Long Term LRR, and Short-Term EPR Averages Chart (by Town and District)

2) Average Long-Term NSM Chart (by Town and District)

3) Average Short-Term NSM Chart (by Town and District)

4) District A:

a. Long-term NSM Chart

b. Long-term EPR Chart

5) District B:

a. Long-Term NSM Chart


c. Long-term LRR Chart

6) District C:




7) District D:




8) District E:




9) District F:



10) District G:




-2.00

-1.80

-1.60

-1.40

-1.20

-1.00

-0.80

-0.60

-0.40

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

Met

ers/

Year

Long Term (1880 - 2006) & Short Term (1983 - 2006) Shoreline Change Rate Comparison:

All Zones

Average Long Term Regression Rate w/ 86.6% Confidence Interval Average Long Term End Point Rate Average Short Term End Point Rate

Zone A: Rock, Drift, Artificial Fill Zone B: Glacial Drift & Beaches Zone C: Glaicial Drift & Rock

Zone E: Glacial Drift & Beaches

Zone D: Rock & Marshes

Zone F: Glacial Drift & Rock Zone G:

Rock & Marshes

A

B

C D E

F G

Analysis of Shoreline Change in Connecticut: 100 Years of Erosion & Accretion

A cooperative effort between the Connecticut Department of Energy & Environmental Protection, the University of Connecticut Center for Land Use Education and Research and the Connecticut Sea Grant. June, 2014

-100

-50

0

50

100

150

200

250

300

350

400

450

Met

ers

Long Term (1880 - 2006) Average Net Shoreline Movement: All Zones

Net Shoreline Movement

A

B

C D E

F G




Zone F: Glacial Drift & Rock

Zone G: Rock &

Marshes



-25

-20

-15

-10

-5

0

5

10

15

20

Met

ers

Net Shoreline Movement

A B

C D E F G

Short Term (1983 - 2006) Average Net Shoreline Movement: All Zones




Zone F: Glacial Drift & Rock Zone G:

Rock & Marshes



-200

-100

0

100

200

300

400

500

0001-57 0013-57 0025-57 0037-57 0049-57 0061-57 0073-57 0085-57 0097-57 0109-57 0121-57 0133-57 0146-57 0160-57 0175-57 0187-57 0199-57 0211-57 0224-57 0236-57 0248-57 0264-57 0277-57 0289-57 0303-57 0315-57 0327-57 0339-57 0352-57 0375-57 0391-57 0403-57 0417-57 0433-57 0447-57 0463-57 0475-57 0490-57 0504-57 0516-57 0528-57 0544-57 0556-57 0568-57 0580-57 0593-57 0605-57 0619-57 0634-57 0647-135 0659-135 0671-135 0686-135 0698-135 0710-135 0722-135 0736-135 0748-135 0760-135 0772-135 0784-135 0796-135 0808-135 0820-135 0832-135 0845-135 0858-135 0870-135 0882-35 0895-35 0911-35 0923-35 0936-35 0948-35 0960-35 0972-35 0987-35 1001-35 1014-35 1027-35 1040-35 1054-35 1067-35 1081-35 1093-35 1109-35 1123-35 1137-35 1150-35 1163-35 1175-103 1187-103 1199-103 1214-103 1228-103 1240-103 1252-103 1264-103 1276-103 1289-103 1301-103 1314-103 1326-103 1340-103 1352-103 1364-103 1376-103 1388-103 1401-103 1413-103

Net

Sho

relin

e M

ovem

ent (

met

ers)

Transect Order (west to east)

Long Term (1880 - 2006) Net Shoreline Movement: Zone A - Rock, Drift, & Artificial Fill

Net Shoreline Movement (Positive) Net Shoreline Movement (Negative)

Greenwich: + 15.04 m

Darien: + 6.24 m

Norwalk*: + 19.15 m

Minimum Net Shoreline Movement: - 112.49 m Maximum Net Shoreline Movement: + 436.05 m

Average Net Shoreline Movement: + 14.44 m

* Only includes portions of town in Zone A

Manressa Island

Cove Island Beach / Weed

Beach

Scott Cove Shippan

Point

West Beach / Cummings

Beach

Darien River

Stamford Harbor

Greenwich Cove

Cook Point

Cos Cob Harbor

Indian Harbor

Greenwich Harbor

Field Point

Byram Harbor

Byram Point

Dolphin Cove

Greenwich Point / Green wich Point Beach

Stamford: + 17.34 m

Contentment / Butlers Islands Roton / Noroton Point

Five Mile River

Long Neck Point

Wilson Cove

Norwalk River



-1.5

-1

-0.5

0

0.5

1

1.5

2

0001-57 0013-57 0025-57 0037-57 0049-57 0061-57 0073-57 0085-57 0097-57 0109-57 0121-57 0133-57 0146-57 0160-57 0175-57 0187-57 0199-57 0211-57 0224-57 0236-57 0248-57 0264-57 0277-57 0289-57 0303-57 0315-57 0327-57 0339-57 0352-57 0375-57 0391-57 0403-57 0417-57 0433-57 0447-57 0463-57 0475-57 0490-57 0504-57 0516-57 0528-57 0544-57 0556-57 0568-57 0580-57 0593-57 0605-57 0619-57 0634-57 0647-135 0659-135 0671-135 0686-135 0698-135 0710-135 0722-135 0736-135 0748-135 0760-135 0772-135 0784-135 0796-135 0808-135 0820-135 0832-135 0845-135 0858-135 0870-135 0882-35 0895-35 0911-35 0923-35 0936-35 0948-35 0960-35 0972-35 0987-35 1001-35 1014-35 1027-35 1040-35 1054-35 1067-35 1081-35 1093-35 1109-35 1123-35 1137-35 1150-35 1163-35 1175-103 1187-103 1199-103 1214-103 1228-103 1240-103 1252-103 1264-103 1276-103 1289-103 1301-103 1314-103 1326-103 1340-103 1352-103 1364-103 1376-103 1388-103 1401-103 1413-103

End

Poin

t Rat

e (m

eter

s/ye

ar)


Long Term (1880 - 2006) End Point Rates: Zone A - Rock, Drift, & Artificial Fill

End Point Rate (Positive) End Point Rate (Negative)

Greenwich: + 0.04 m/yr

Darien: + 0.02 m/yr

Norwalk*: + 0.05 m/yr

Minimum End Point Rate: - 1.26 m/yr Maximum End Point Rate: + 1.62 m/yr

Average End Point Rate: + 0.04 m/yr

* Only includes portions of town in Zone A

Manressa Island

Cove Island Beach / Weed

Beach

Scott Cove

Shippan Point

West Beach / Cummings Beach

Darien River

Stamford Harbor

Greenwich Cove

Cook Point

Cos Cob Harbor

Indian Harbor Greenwich

Harbor

Field Point

Byram Harbor

Byram Point

Dolphin Cove

Greenwich Point / Green wich Point

Beach

Stamford: + 0.05 m/yr

Contentment / Butlers Islands

Roton / Noroton

Point

Five Mile River

Long Neck Point

Wilson Cove

Norwalk River



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400

1421-103 1431-103 1441-103 1452-103 1463-103 1475-103 1485-103 1495-103 1505-103 1515-103 1525-158 1536-158 1546-158 1556-158 1569-158 1579-158 1589-158 1599-158 1609-158 1619-158 1629-158 1639-158 1649-158 1659-158 1670-158 1680-158 1690-158 1700-158 1710-158 1720-158 1730-158 1741-158 1751-158 1763-158 1773-158 1783-158 1793-158 1804-158 1814-158 1824-158 1834-51 1844-51 1855-51 1865-51 1877-51 1887-51 1898-51 1908-51 1918-51 1928-51 1938-51 1950-51 1960-51 1970-51 1980-15 1990-15 2000-15 2010-15 2021-15 2031-15 2041-15 2051-15 2062-15 2072-15 2082-15 2092-15 2102-15 2112-15 2122-15 2132-15 2145-15 2159-15 2169-15 2179-15 2189-15 2200-15 2210-15 2224-15 2235-15 2245-15 2255-15 2265-138 2275-138 2285-138 2295-138 2305-138 2315-138 2325-138 2335-138 2345-138 2355-138 2365-138 2386-138 2400-138 2410-138 2422-138 2432-138 2445-84 2457-84 2467-84 2477-84 2487-84 2497-84 2507-84 2517-84 2527-84 2537-84 2547-84 2557-84 2567-84 2577-84

Net

Sho

relin

e M

ovem

ent (

met

ers)


Long Term (1880 - 2006) Net Shoreline Movement: Zone B - Glacial Drift & Beaches


Norwalk*: + 32.61 m

Westport: + 4.88 m

Fairfield: + 8.87 m

Bridgeport: + 42.82 m

Milford*: + 18.62 m

Stratford: - 12.52 m


* Only includes portions of town in Zone B

Fort Trumbull Beach

Wildemere / Walnut Beaches

Silver Sands State Park

Milford Point / Cedar Beach

Short Beach

Long Beach

Pleasure Beach

Seaside Park Beach

Jennings Beach

Fairfield Beach

Pine Creek Point

Sasco Hill / Sasco

Beaches

Frost Point / Burial Hill Beach

Alvord / Shrewood Island

Beaches

Canfield Island / Seymour Point

Saugatuck River / Harbor

Fitch Point

Calf Pasture Point

Black Rock Harbor

Lordship Beach

Bridgeport Harbor Analysis of Shoreline Change in Connecticut: 100 Years of

Erosion & Accretion A cooperative effort between the Connecticut Department of Energy & Environmental Protection, the University of Connecticut Center for Land Use Education and Research and the Connecticut Sea Grant. June, 2014

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End

Poin

t Rat

e (m

eter

s/ye

ar)


Long Term (1880 - 2006) End Point Rates: Zone B - Glacial Drift & Beaches


Norwalk*: + 0.07 m/yr

Westport: + 0.04 m/yr

Fairfield: + 0.07 m/yr

Bridgeport: + 0.22 m/yr

Milford*: + 0.16 m/yr

Stratford: - 0.10 m/yr

Minimum End Point Rate: - 0.99 m/yr Maximum End Point Rate: +3.09 m/yr

Average End Point Rate: + 0.07 m/yr



Silver Sands State Park


Short Beach

Long Beach

Pleasure Beach

Seaside Park Beach

Penfield / Jennings Beach

Fairfield Beach

Pine Creek Point

Sasco Hill / Sasco

Beaches


Alvord / Shrewood Island

Beaches

Canfield Island / Seymour Point


Calf Pasture Point

Black Rock Harbor

Lordship Beach

Bridgeport Harbor

Fort Trumbull Beach



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1421-103 1431-103 1441-103 1452-103 1463-103 1475-103 1485-103 1495-103 1505-103 1515-103 1525-158 1536-158 1546-158 1556-158 1569-158 1579-158 1589-158 1599-158 1609-158 1619-158 1629-158 1639-158 1649-158 1659-158 1670-158 1680-158 1690-158 1700-158 1710-158 1720-158 1730-158 1741-158 1751-158 1763-158 1773-158 1783-158 1793-158 1804-158 1814-158 1824-158 1834-51 1844-51 1855-51 1865-51 1877-51 1887-51 1898-51 1908-51 1918-51 1928-51 1938-51 1950-51 1960-51 1970-51 1980-15 1990-15 2000-15 2010-15 2021-15 2031-15 2041-15 2051-15 2062-15 2072-15 2082-15 2092-15 2102-15 2112-15 2122-15 2132-15 2145-15 2159-15 2169-15 2179-15 2189-15 2200-15 2210-15 2224-15 2235-15 2245-15 2255-15 2265-138 2275-138 2285-138 2295-138 2305-138 2315-138 2325-138 2335-138 2345-138 2355-138 2365-138 2386-138 2400-138 2410-138 2422-138 2432-138 2445-84 2457-84 2467-84 2477-84 2487-84 2497-84 2507-84 2517-84 2527-84 2537-84 2547-84 2557-84 2567-84 2577-84

Line

ar R

egre

ssio

n Ra

tes

(met

ers/

year

)


Long Term (1880 - 2006) Valid Linear Regression Rates: Zone B - Glacial Drift & Beaches

Linear regression rate (Positive) Linear regression rate (Negative)


Norwalk*: + 0.12 m/yr (+/- 0.04 m)

Westport: + 0.10 m/yr (+/- 0.03 m)

Fairfield: + 0.12 m/yr (+/- 0.04 m)

Bridgeport: + 0.28 m/yr (+/- 0.05 m)

Milford*: + 0.14 m/yr (+/- 0.08 m)

Stratford: N/A

Fort Trumbull Beach


Silver Sands

State Park


Short Beach

Long Beach

Pleasure Beach

Seaside Park Beach

Jennings Beach

Fairfield Beach

Pine Creek Point

Sasco Hill / Sasco Beaches


Alvord / Sherwood Island

Beaches

Canfield Island


Calf Pasture Beach / Point

Bridgeport Harbor

Penfield / Jennings Beach

Minimum Linear Regression Rate: - 0.94 m/yr Maximum Linear Regression Rate: + 2.57 m/yr

Average Linear Regression Rate: + 0.12 m/yr

Average Uncertainty (at 86.6% Confidence Interval:) +/- 0.02 m/yr



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3005-93 N

et S

hore

line

Mov

emen

t (m

eter

s)


Long Term (1880 - 2006) Net Shoreline Movement: Zone C - Glacial Drift & Rock


Milford*: -4.39 m

New Haven*: + 430.63 m



* Only includes portions of town in Zone C

Sandy Point

West / Prospect Beaches

Bradley Point

East Beach

Woodmont

Anchor Beach Morningside Bayview / Point

Beaches

Burwells Beach

Gulf Beach

Rocky Beach

West Haven: + 7.49 m

City Point

Western New Haven Harbor



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3005-93 En

d Po

int R

ate

(met

ers/

year

)


Long Term (1880 - 2006) End Point Rates: Zone C - Glacial Drift & Rock


Milford:* - 0.04 m/yr

New Haven*,**: N/A


Average End Point Rate: 0.00 m/yr

* only includes portion of townin Zone C ** No transects present viable rate data

Sandy Point


Bradley Point

East Beach

Woodmont

Anchor Beach

Morningside Bayview / Point Beaches

Burwells Beach

Gulf Beach

Rocky Beach

West Haven: + 0.03 m/yr



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near

Reg

ress

ion

Rate

(met

ers/

year

)


Long Term (1880 - 2006) Valid Linear Regression Rates: Zone C - Glacial Drift & Rock

Linear Regression Rate (Positive) Linear Regression Rate (Negative)

Milford*: N/A

New Haven*,**: N/A

Minimum Linear RegressionRate: - 1.69 m/yr Maximum Linear Regression Rate: + 1.37 m/yr

Average Linear Regression Rate: + 0.08 m/yr (+/- 0.04 m)

Sandy Point


Bradley Point

East Beach

Woodmont

Anchor Beach

Morningside

Burwells Beach

Gulf Beach

Rocky Beach

West Haven: + 0.16 m/yr (+/- 0.09 m)

* only includes portion of townin Zone C ** No transects present viable rate data



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100

200

300

400

3009-93 3016-93 3023-93 3031-93 3038-93 3045-93 3053-93 3060-93 3071-93 3078-93 3085-93 3092-93 3099-93 3106-93 3113-93 3120-93 3127-93 3134-93 3142-44 3149-44 3157-44 3164-44 3171-44 3181-44 3188-44 3195-44 3202-44 3210-44 3217-44 3224-44 3231-44 3238-44 3247-14 3260-14 3267-14 3275-14 3282-14 3289-14 3297-14 3304-14 3315-14 3324-14 3332-14 3339-14 3347-14 3355-14 3363-14 3370-14 3379-14 3386-14 3393-14 3401-14 3408-14 3419-14 3430-14 3437-14 3444-14 3451-14 3458-14 3465-14 3472-14 3479-14 3486-14 3493-14 3500-14 3507-14 3514-14 3521-14 3530-14 3539-14 3547-14 3554-14 3561-14 3572-14 3583-14 3591-14 3598-14 3605-14 3613-60 3620-60 3627-60 3634-60 3641-60 3649-60 3658-60 3665-60 3672-60 3679-60 3686-60 3694-60 3702-60 3710-60 3717-60 3724-60 3731-60 3738-60 3745-60 3752-60 3762-60 3769-60 3777-60 3785-60 3792-60 3799-60 3806-60 3813-60 3820-60 3827-60 3834-60 3841-60 3849-60 3857-60 3868-60 3875-60 3883-60 3890-60

Net

Sho

relin

e M

ovem

ent (

met

ers)


Long Term (1880 - 2006) Net Shoreline Movement: Zone D - Rock & Marshes


New Haven*: + 43.59 m

Guilford*: - 2.47 m



* Only includes portions of town in Zone D

Horton Point

Limewood Beaches

Hotchkiss Grove Beach

Pleasant Point

Lighthouse Point

Farm River

Silver Sands Beach / East Haven Town Beach

East Shore Park / Nathan Hale Park

Forbes Bluff

Eastern New Haven Harbor

Lindsey Cove

East Haven: + 5.06 m

Joshua Cove

Tuttle's Point / Chaffinch Island

Branford: + 1.08 m

Lighthouse Point Beach / Morgan Point / West

Silver Sands Beach

Johnson Point

Indian Neck Point

Hoadley Neck

Flying Point

Island Bay

Sachem Head

Indian Cove



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End

Poin

t Rat

e (m

eter

s/ye

ar)


Long Term (1880 - 2006) End Point Rate: Zone D - Rock & Marshes


New Haven*: + 0.1 m/yr

Guilford*: - 0.02 m/yr


Average End Point Rate: 0.01 m/yr


Horton Point

Limewood Beaches

Hotchkiss Grove Beach

Pleasant Point

Lighthouse Point

Farm River

Silver Sands Beach / East Haven Town

Beach

East Shore Park / Nathan Hale

Park

Forbes Bluff

Lindsey Cove

East Haven: + 0.05 m/yr

Joshua Cove


Branford: + 0.01 m/yr

Lighthouse Point Beach / Morgan

Point / West Silver Sands Beach

Johnson Point

Indian Neck Point

Hoadley Neck

Flying Point

Island Bay

Sachem Head

Indian Cove


A cooperative efort between the Connecticut Department of Energy & Environmental Protection, the University of Connecticut Center for Land Use Education and Research and the Connecticut Sea Grant. June, 2014

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Line

ar R

egre

ssio

n Ra

te (m

eter

s/ye

ar)


Long Term (1880 - 2006) Valid Linear Regression Rates: Zone D - Rock & Marshes


New Haven*: + 0.16 m/yr (+/- 0.06 m)

Guilford*: - 0.03 m/yr (+/- 0.02 m)


Average Linear Regression Rate: + 0.02 m/yr (+/- 0.01 m)


Horton Point

Limewood Beaches

Juniper Point Farm River

Silver Sands Beach / East Haven Town Beach

Nathan Hale Park

Forbes Bluff

Lindsey Cove

East Haven: + 0.08 m/yr (+/- 0.05 m)

Joshua Cove


Branford: + 0.018 m/yr (+/- 0.017 m)

Lighthouse Point Beach / Morgan

Point / West Silver Sands Beach

Johnson Point

Indian Neck Point

Hoadley Neck

Flying Point

Island Bay

Joshua Point



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300

3893-60 3905-60 3915-60 3924-60 3935-60 3944-76 3953-76 3962-76 3972-76 3982-76 3991-76 4000-76 4010-76 4021-76 4030-76 4039-76 4048-76 4058-76 4067-76 4076-76 4086-76 4095-76 4104-76 4113-76 4122-76 4131-76 4140-76 4149-76 4158-76 4169-27 4178-27 4187-27 4196-27 4206-27 4215-27 4224-27 4233-27 4242-27 4252-27 4262-27 4271-27 4280-27 4289-27 4298-27 4307-154 4316-154 4325-154 4334-154 4343-154 4352-154 4361-154 4370-154 4379-154 4388-154 4397-154 4407-154 4417-154 4426-154 4438-106 4447-106 4457-106 4466-106 4475-106 4485-106 4494-106 4503-106 4512-106 4521-106 4530-106 4539-106 4548-106 4557-106 4566-106 4575-106 4584-106 4597-106 4606-106 4616-106 4625-106 4634-106 4643-106 4653-106 4664-106 4673-106 4682-106 4692-105 4701-105 4710-105 4719-105 4728-105 4737-105 4747-105 4760-105 4769-105 4778-105 4787-105 4796-105 4805-105 4814-105 4823-105 4833-105 4843-105 4852-105 4861-105 4870-105 4879-105 4888-105

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Long Term (1880 - 2006) Net Shoreline Movement: Zone E - Glacial Drift & Beaches


Guilford*: - 43.43 m

Madison: - 8.78 m

Clinton: - 16.73 m

Westbrook: + 2.47 m

Old Saybrook - LIS: - 4.28 m

Old Lyme - LIS*: - 43.26 m

Old Saybrook - CT River: + 11.95 m

Old Lyme - CT River: -9.66 m


Average Net Shoreline Movement: - 11.46 m

Old Saybrook - All: +1.86 m

Old Lyme - All*: - 30.03 m

* Only includes portions of town in Zone E

Meigs Point, Hammonasset Beach

Cedar Island

Clinton Beach

Grove Beach

Chapman Point

Harvey'sBeach

Fenwood / Fenwick

Lynde Point

South Cove

North Cove

Ragged Rock Creek

Great Island

Griwold Point to White Sands Beach

Chaffinch Island

Grass Island

Surf Club

Beach

Webster Point

Analysis of Shoreline Change in Connecticut: 100 Years of Erosion & Accretion A cooperative effort between the Connecticut Department of Energy & Environmental Protection, the University of Connecticut Center for Land Use Education and Research and the Connecticut Sea Grant. June, 2014

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3893-60 3905-60 3915-60 3924-60 3935-60 3944-76 3953-76 3962-76 3972-76 3982-76 3991-76 4000-76 4010-76 4021-76 4030-76 4039-76 4048-76 4058-76 4067-76 4076-76 4086-76 4095-76 4104-76 4113-76 4122-76 4131-76 4140-76 4149-76 4158-76 4169-27 4178-27 4187-27 4196-27 4206-27 4215-27 4224-27 4233-27 4242-27 4252-27 4262-27 4271-27 4280-27 4289-27 4298-27 4307-154 4316-154 4325-154 4334-154 4343-154 4352-154 4361-154 4370-154 4379-154 4388-154 4397-154 4407-154 4417-154 4426-154 4438-106 4447-106 4457-106 4466-106 4475-106 4485-106 4494-106 4503-106 4512-106 4521-106 4530-106 4539-106 4548-106 4557-106 4566-106 4575-106 4584-106 4597-106 4606-106 4616-106 4625-106 4634-106 4643-106 4653-106 4664-106 4673-106 4682-106 4692-105 4701-105 4710-105 4719-105 4728-105 4737-105 4747-105 4760-105 4769-105 4778-105 4787-105 4796-105 4805-105 4814-105 4823-105 4833-105 4843-105 4852-105 4861-105 4870-105 4879-105 4888-105

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Long Term (1880 - 2006) End Point Rates: Zone E - Glacial Drift & Beaches


Guilford*: - 0.35 m/yr

Madison: - 0.07 m/yr

Clinton: - 0.14 m/yr

Westbrook: + 0.02 m/yr

Old Saybrook - LIS: - 0.03 m/yr

Old Lyme - LIS*: - 0.36 m/yr

Old Saybrook - CT River: + 0.10 m/yr

Old Lyme - CT River: - 0.08 m/yr

Old Saybrook - All: + 0.01 m/yr

Old Lyme - All*: - 0.25 m/yr



Cedar Island

Clinton Beach

Grove Beach

Chapman Point

Harvey'sBeach

Fenwood / Fenwick

Lynde Point

South Cove

North Cove

Ragged Rock Creek Great

Island

Griwold Point to White

Sands Beach

Chaffinch Island

Grass Island

Surf Club

Beach

Webster Point


Average End Point Rate: -0.09 m/yr


-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

3893-60 3905-60 3915-60 3924-60 3935-60 3944-76 3953-76 3962-76 3972-76 3982-76 3991-76 4000-76 4010-76 4021-76 4030-76 4039-76 4048-76 4058-76 4067-76 4076-76 4086-76 4095-76 4104-76 4113-76 4122-76 4131-76 4140-76 4149-76 4158-76 4169-27 4178-27 4187-27 4196-27 4206-27 4215-27 4224-27 4233-27 4242-27 4252-27 4262-27 4271-27 4280-27 4289-27 4298-27 4307-154 4316-154 4325-154 4334-154 4343-154 4352-154 4361-154 4370-154 4379-154 4388-154 4397-154 4407-154 4417-154 4426-154 4438-106 4447-106 4457-106 4466-106 4475-106 4485-106 4494-106 4503-106 4512-106 4521-106 4530-106 4539-106 4548-106 4557-106 4566-106 4575-106 4584-106 4597-106 4606-106 4616-106 4625-106 4634-106 4643-106 4653-106 4664-106 4673-106 4682-106 4692-105 4701-105 4710-105 4719-105 4728-105 4737-105 4747-105 4760-105 4769-105 4778-105 4787-105 4796-105 4805-105 4814-105 4823-105 4833-105 4843-105 4852-105 4861-105 4870-105 4879-105 4888-105 Li

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Long Term (1880 - 2006) Valid Linear Regression Rates: Zone E - Glacial Drift & Beaches

Linear regression rate (Positive) Linear regression rate (Negative)

Guilford*: - 0.39 m/yr (+/- 0.11 m)

Madison: - 0.05 m/yr (+/- 0.03 m)

Clinton: - 0.13 m/yr (+/- 0.03 m)

Westbrook: N/A

Old Saybrook - LIS: N/A

Old Lyme - LIS*: - 0.31 m/yr (+/- 0.09 m)

Old Saybrook - CT River: 0.09 m/yr

(+/- 0.07 m)

Old Lyme - CT River: N/A

Old Saybrook - All: N/A

Old Lyme - All*: - 0.21 m/yr (+/- 0.07)



Cedar Island

Clinton Beach

Grove Beach

Chapman Point

Harvey'sBeach

Fenwood / Fenwick

Lynde Point

South Cove

North Cove

Ragged Rock Creek

Great Island

Griwold Point to White

Sands Beach Chaffinch Island

Grass Island Surf

Club Beach

Webster Point


Average Linear Regression Rate: - 0.08 m/yr

Average Uncertainty (at 86.6% Confidence Interval): +/- 0.02 m/yr


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-100

0

100

200

300

400

4893-105 4902-105 4911-105 4921-105 4930-105 4939-105 4948-45 4958-45 4968-45 4977-45 4987-45 4997-45 5006-45 5015-45 5024-45 5033-45 5042-45 5051-45 5060-45 5070-45 5079-45 5088-45 5097-45 5106-45 5115-45 5124-45 5133-45 5142-45 5151-152 5160-152 5169-152 5178-152 5188-152 5197-152 5207-152 5217-152 5226-152 5235-152 5251-152 5260-152 5269-152 5278-152 5287-152 5296-152 5305-152 5314-152 5323-152 5336-152 5346-152 5358-95 5367-95 5378-95 5387-95 5396-95 5405-95 5414-95 5423-95 5432-95 5441-95 5451-95 5461-95 5472-95 5482-95 5491-95 5502-95 5511-95 5520-95 5529-95 5538-95 5547-95 5556-95 5565-59 5574-59 5583-59 5592-59 5601-59 5610-59 5619-59 5628-59 5642-59 5655-59 5664-59 5673-59 5682-59 5692-59 5702-59 5712-59 5722-59 5731-59 5740-59 5749-59 5758-59 5767-59 5776-59 5786-59 5795-59 5804-59 5813-59 5822-59 5832-59 5841-59 5851-59 5860-59 5870-59 5879-59 5888-59 5897-59 5906-59

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Long Term (1880 - 2006) Net Shoreline Movement: Zone F - Glacial Drift & Rock


Old Lyme*: - 6.90 m

New London*: + 19.05 m



* Only includes portions of town in Zone F

Millstone Point

MItchell College

Ocean Beach

State Pier

Black Point / Black Point

Beaches

The Bar

Pattagannsett River

Hatchett Point

Rocky Neck Beach

Goshen Cove

East Lyme: - 1.39 m

Bushy Point Beach / Bluff Point Beach

Jordan Cove

Waterford: - 4.92 m

Pond Point

Millstone

Magonk Point

USCG Academy

Greens Harbor

Electric Boat

US Navy Sub Base

Avery Point

Groton*: + 10.74 m

Venetian Harbor

Mumford Cove

Groton Long Point


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-5

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-4

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-3

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-1

-0.5

0

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4893-105 4902-105 4911-105 4921-105 4930-105 4939-105 4948-45 4958-45 4968-45 4977-45 4987-45 4997-45 5006-45 5015-45 5024-45 5033-45 5042-45 5051-45 5060-45 5070-45 5079-45 5088-45 5097-45 5106-45 5115-45 5124-45 5133-45 5142-45 5151-152 5160-152 5169-152 5178-152 5188-152 5197-152 5207-152 5217-152 5226-152 5235-152 5251-152 5260-152 5269-152 5278-152 5287-152 5296-152 5305-152 5314-152 5323-152 5336-152 5346-152 5358-95 5367-95 5378-95 5387-95 5396-95 5405-95 5414-95 5423-95 5432-95 5441-95 5451-95 5461-95 5472-95 5482-95 5491-95 5502-95 5511-95 5520-95 5529-95 5538-95 5547-95 5556-95 5565-59 5574-59 5583-59 5592-59 5601-59 5610-59 5619-59 5628-59 5642-59 5655-59 5664-59 5673-59 5682-59 5692-59 5702-59 5712-59 5722-59 5731-59 5740-59 5749-59 5758-59 5767-59 5776-59 5786-59 5795-59 5804-59 5813-59 5822-59 5832-59 5841-59 5851-59 5860-59 5870-59 5879-59 5888-59 5897-59 5906-59

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Long Term (1880 - 2006) End Point Rate: Zone F - Glacial Drift & Rock


Old Lyme*: - 0.06 m/yr

New London*: + 0.02 m/yr


Average Net End Point Rate: - 0.03 m/yr

* Only includes portions of town in Zone F

Millstone Point

MItchell College

Ocean Beach

Black Point / Black Point

Beaches

The Bar

Pattagannsett River Hatchett

Point

Rocky Neck Beach

Goshen Cove

East Lyme: - 0.01 m/yr

Bushy Point Beach / Bluff Point Beach

Jordan Cove

Waterford: - 0.08 m/yr

Pond Point

Millstone

Magonk Point Avery Point

Groton*: - 0.02 m/yr

Venetian Harbor

Mumford Cove

Groton Long Point


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-50

50

150

5913-59 5919-59 5925-59 5931-59 5937-59 5943-59 5949-59 5955-59 5961-59 5967-59 5973-59 5981-59 5988-59 5997-59 6003-59 6009-59 6015-59 6021-59 6027-59 6033-137 6039-137 6047-137 6055-137 6061-137 6068-137 6075-137 6081-137 6087-137 6093-137 6101-137 6107-137 6113-137 6119-137 6125-137 6132-137 6138-137 6144-137 6150-137 6156-137 6162-137 6168-137 6176-137 6182-137 6188-137 6195-137 6201-137 6207-137 6213-137 6219-137 6226-137 6232-137 6238-137 6244-137 6251-137 6258-137 6265-137 6271-137 6278-137 6284-137 6290-137 6296-137 6303-137 6309-137 6315-137 6321-137 6329-137 6336-137 6342-137 6348-137 6354-137 6362-137 6370-137 6376-137 6382-137 6390-137 6396-137 6402-137 6408-137 6414-137 6420-137 6427-137 6433-137 6439-137 6446-137 6452-137 6458-137 6464-137 6470-137 6476-137 6482-137 6489-137 6495-137 6501-137 6507-137 6513-137 6519-137 6526-137 6535-137 6542-137 6548-137 6554-137 6560-137 6566-137 6572-137 6579-137 6585-137 6591-137 6597-137 6603-137 6610-137

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Long Term (1880 - 2006) Net Shoreline Movement: Zone G: Rock & Marshes


Groton*: + 2.06 m


Average Net Shoreline Movement: -4.53 m

* Only includes portions of town in Zone G

Latimer Point

Edwards Point

Lords Point

Six Penny Island

Noank Dock Morgan Point

Groton Long Point

West Cove

West Shore, Stonington

Harbor

Barn Island

Quaimbog Cove

Ram Point

East Shore,

Mason's Island

MasonPoint

Stonington Point

Wequetequock Cove

Stonington: - 5.89 m

Pawcatuck Point

Pawcatuck River

Palmer Cove



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-1

-0.5

0

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1

5913-59 5919-59 5925-59 5931-59 5937-59 5943-59 5949-59 5955-59 5961-59 5967-59 5973-59 5981-59 5988-59 5997-59 6003-59 6009-59 6015-59 6021-59 6027-59 6033-137 6039-137 6047-137 6055-137 6061-137 6068-137 6075-137 6081-137 6087-137 6093-137 6101-137 6107-137 6113-137 6119-137 6125-137 6132-137 6138-137 6144-137 6150-137 6156-137 6162-137 6168-137 6176-137 6182-137 6188-137 6195-137 6201-137 6207-137 6213-137 6219-137 6226-137 6232-137 6238-137 6244-137 6251-137 6258-137 6265-137 6271-137 6278-137 6284-137 6290-137 6296-137 6303-137 6309-137 6315-137 6321-137 6329-137 6336-137 6342-137 6348-137 6354-137 6362-137 6370-137 6376-137 6382-137 6390-137 6396-137 6402-137 6408-137 6414-137 6420-137 6427-137 6433-137 6439-137 6446-137 6452-137 6458-137 6464-137 6470-137 6476-137 6482-137 6489-137 6495-137 6501-137 6507-137 6513-137 6519-137 6526-137 6535-137 6542-137 6548-137 6554-137 6560-137 6566-137 6572-137 6579-137 6585-137 6591-137 6597-137 6603-137 6610-137

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Long Term (1880 - 2006) End Point Rate: Zone G: Rock & Marshes


Groton*: + 0.02 m/yr


Average End Point Rate: - 0.04 m/yr


Latimer Point

Edwards Point

Lords Point

Six Penny Island

Noank Dock Morgan

Point

Groton Long Point

West Cove


Harbor

Barn Island Quaimbog

Cove

Ram Point

East Shore,

Mason's Island

MasonPoint

Stonington Point

Wequetequock Cove

Stonington: - 0.05 m/yr

Pawcatuck Point

Pawcatuck River Palmer Cove



-1.5

-1

-0.5

0

0.5

1

5913-59 5919-59 5925-59 5931-59 5937-59 5943-59 5949-59 5955-59 5961-59 5967-59 5973-59 5981-59 5988-59 5997-59 6003-59 6009-59 6015-59 6021-59 6027-59 6033-137 6039-137 6047-137 6055-137 6061-137 6068-137 6075-137 6081-137 6087-137 6093-137 6101-137 6107-137 6113-137 6119-137 6125-137 6132-137 6138-137 6144-137 6150-137 6156-137 6162-137 6168-137 6176-137 6182-137 6188-137 6195-137 6201-137 6207-137 6213-137 6219-137 6226-137 6232-137 6238-137 6244-137 6251-137 6258-137 6265-137 6271-137 6278-137 6284-137 6290-137 6296-137 6303-137 6309-137 6315-137 6321-137 6329-137 6336-137 6342-137 6348-137 6354-137 6362-137 6370-137 6376-137 6382-137 6390-137 6396-137 6402-137 6408-137 6414-137 6420-137 6427-137 6433-137 6439-137 6446-137 6452-137 6458-137 6464-137 6470-137 6476-137 6482-137 6489-137 6495-137 6501-137 6507-137 6513-137 6519-137 6526-137 6535-137 6542-137 6548-137 6554-137 6560-137 6566-137 6572-137 6579-137 6585-137 6591-137 6597-137 6603-137 6610-137

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Long Term (1880 - 2006) Linear Regression Rate: Zone G: Rock & Marshes


Groton*: + 0.04 m/yr (+/- 0.03 m)


Average Linear Regression Rate: N/A


Latimer Point

Edwards Point

Lords Point

Six Penny Island

Noank Dock

Morgan Point

West Cove


Harbor

Barn Island

Quaimbog Cove

East Shore,

Mason's Island

MasonPoint

Stonington Point

Wequetequock Cove

Stonington: - 0.02 m/yr (+/- 0.01 m)

Pawcatuck River

Palmer Cove

Groton Long Point



Documents

Analysis of Shoreline Change in Connecticut · 7/19/2014 · Change in Connecticut 100+ Years of Erosion and Accretion: Methodology and Summary Results A cooperative effort between