Digital Shoreline Analysis System (DSAS) version 5.1.2 transects with long-term rate calculations for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River)

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Frequently anticipated questions:

What does this data set describe?

Title:
Digital Shoreline Analysis System (DSAS) version 5.1.2 transects with long-term rate calculations for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River)
Abstract:
This dataset consists of long-term (greater than 60 years) shoreline change rates for the west coast of Alaska between Cape Prince of Wales and the Kotlik River. Rate calculations were computed within a GIS using the Digital Shoreline Analysis System (DSAS) version 5.1.2, an ArcGIS extension developed by the U.S. Geological Survey. Long-term rates of shoreline change were calculated using a linear regression or end point rate-of-change based on available shoreline data between 1949 and 2015. A reference baseline was used as the originating point for the orthogonal transects cast by the DSAS software. The transects intersect each shoreline establishing measurement points, which are then used to calculate long-term rates.
Supplemental_Information:
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the Alaska Division of Geological & Geophysical Surveys or the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the dataset in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Gibbs, Ann E., Snyder, Alexander G., and Nieminski, Nora M., 20260102, Digital Shoreline Analysis System (DSAS) version 5.1.2 transects with long-term rate calculations for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River): data release 10.5066/P1RYHDR7, U.S. Geological Survey, Coastal and Marine Geology Program, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz.

    Online Links:

    This is part of the following larger work.

    Gibbs, Ann E., Snyder, Alexander G., and Nieminski, Nora M., 2026, National assessment of shoreline change: A GIS compilation of vector shorelines (1949 to 2015) and associated shoreline change data for the west coast of Alaska, Cape Prince of Wales to Kotlik River: data release 10.5066/P1RYHDR7, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    Other_Citation_Details:
    Suggested Citation: Gibbs, A.E., Snyder, A.G., Nieminski, N.M., 2026, National assessment of shoreline change: A GIS compilation of vector shorelines (1949 – 2015) and associated shoreline change data for the west coast of Alaska, Cape Prince of Wales to Kotlik River: U.S. Geological Survey data release, https://doi.org/10.5066/P1RYHDR7.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -168.0948
    East_Bounding_Coordinate: -160.4740
    North_Bounding_Coordinate: 65.5317
    South_Bounding_Coordinate: 62.9810
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1949
    Ending_Date: 2015
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data (polyline)
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • String (20085)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in Decimal seconds. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    Attribute Table
    Table containing attribute information associated with the dataset. (Source: Producer defined)
    FID
    Internal feature number (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry (Source: Esri)
    ValueDefinition
    Polyline ZMESRI polyline shapefile
    TransectID
    A permanent and unique identification number for each transect in the output rates table calculated by DSAS. (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:223
    Maximum:21868
    Units:Unitless
    BaselineID
    Values in this field correlate to the baseline attribute field “ID” and are assigned by DSAS to identify the baseline segment used to generate the measurement transect. (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:1
    Maximum:40
    Units:Unitless
    TransOrder
    Assigned by DSAS based on ordering of transects along the baseline or baselines. If the user manually adds transects to the file in an edit session, they will be added to the end of the transect attribute table and given a new TransectID (ObjectID). However, TransOrder will be updated to reflect the position of the new transect with respect to the other transects along the baseline. This field provides the user with a method to sort transect attribute data from the start of the baseline segment with an ID=1 and increment by one alongshore to the end of the final baseline segment. (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:223
    Maximum:22153
    Units:Unitless
    Azimuth
    Used to record the azimuth of the transect measured in degrees clockwise from north. (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:0
    Maximum:360
    Units:Degrees
    ShrCount
    The total number of shorelines intersected by the transect and used for change analysis. (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:2
    Maximum:3
    Units:Number of shorelines
    TCD
    Total cumulative distance in meters from start of baseline to transect location. (Source: U.S. Geological Survey)
    Range of values
    Minimum:11100.00
    Maximum:1162943.01
    Units:Meters
    SCE
    The shoreline change envelope (SCE) reports a distance, not a rate. The SCE is the distance between the most seaward and most landward shoreline at each transect. This represents the total change in shoreline movement for all available shoreline positions and is not related to their dates. (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:0
    Maximum:798.23
    Units:Meters
    NSM
    The net shoreline movement (NSM) reports the distance between the oldest and youngest shorelines for each transect. This represents the total distance between the oldest and youngest shorelines. If this distance is divided by the number of years elapsed between the two shoreline positions, the result is the End Point Rate (EPR). (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:-798.23
    Maximum:288.97
    Units:Meters
    EPR
    End-point rate (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:-12.45
    Maximum:4.72
    Units:meters per year
    EPRunc
    Uncertainty of the end point rate (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:0.08
    Maximum:0.38
    Units:meters per year
    LRR
    A linear regression rate-of-change statistic was calculated by fitting a least-squares regression line to all shoreline points for a particular transect. The best-fit 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 rate is reported in meters per year with positive values indicating accretion and negative values indicating erosion. A value of 9999 (no data) indicates that only 2 shorelines were available and a LRR rate could not be calculated. (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:-10.53
    Maximum:4.66
    Units:meters per year
    LR2
    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. The smaller the variability of the residual values around the regression line relative to the overall variability, the better the prediction (and closer the R-squared value is to 1.0). (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:0
    Maximum:1
    Units:Unitless
    LSE
    The predicted (or estimated) values of y (the distance from baseline in meters) are computed for each shoreline point by using the values of x (the shoreline date) and solving the equation for the best-fit regression line (y=mx+b). The standard error is also called the standard deviation. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:276.51
    Units:Meters
    LCI90
    The standard error of the slope with confidence interval describes the uncertainty of the reported rate. The LRR rates are determined by a best-fit regression line for the shoreline data at each transect. 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 90 percent confidence. This value is often reported in conjunction with the slope to describe the confidence of the reported rate. For example: LRR = 1.2 LCI90 = 0.7 could be reported as a rate of 1.2 (+/-) 0.7 meters/year. (Source: U.S. Geological Survey)
    Range of values
    Minimum:0
    Maximum:38.45
    Units:Meters per year
    WLR
    Weighted linear regression rate (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:-10.65
    Maximum:6.2
    Units:Meters per year
    WR2
    R-squared of weighted linear regression (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:0
    Maximum:1
    Units:Unitless
    WSE
    Standard error of weighted linear regression (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:0
    Maximum:49.21
    Units:Meters
    WCI90
    90 percent confidence interval of weighted linear regression (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:0
    Maximum:40.31
    Units:Meters per year
    BestRate
    The best shoreline change statistic for the transect. End-point rate (EPR) where RateType = EPR and linear regression rate (LRR) where RateType = LRR (Source: U.S. Geological Survey)
    Range of values
    Minimum:-12.45
    Maximum:4.72
    Units:meters per year
    BestUNCY
    Uncertainty of the BestRate. EPRunc where RateType=EPR, LCI90 where RateType=LRR (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.0
    Maximum:38.45
    Units:meters per year
    RateType
    User defined rate type (Source: U.S. Geological Survey)
    ValueDefinition
    EPRBestRate is end-point rate type where ShrCount = 2
    LRRBestRate is linear regression rate type used where ShrCount = 3
    SHAPE_Leng
    Length of transect in meter units, assuming data were properly projected in a meter-based coordinate system. This field is automatically generated and maintained when data are within a geodatabase. (Source: Himmelstoss and others (2018))
    Range of values
    Minimum:40.99
    Maximum:900
    Units:Meters
    Entity_and_Attribute_Overview:
    The entity and attribute information provided here describes the tabular data associated with the dataset. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the dataset.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information were generated by the individual and/or agency identified as the originator of the dataset. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Ann E. Gibbs
    • Alexander G. Snyder
    • Nora M. Nieminski
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

Coastal erosion is a persistent process along most open-ocean shores of the United States and affects both developed and natural coastlines. Along the coast of Alaska, coastal erosion is widespread and threatens communities, infrastructure, and coastal habitat. As the coast changes, there are many ways that change can affect coastal communities, habitats, and the physical characteristics of the coast including beach erosion, shoreline retreat, land loss, and damage to infrastructure. The U.S. Geological Survey (USGS) is responsible for conducting research on coastal change hazards, understanding the processes that cause coastal change, and developing models to forecast future change. To understand and adapt to shoreline change, accurate information regarding the past and present configurations of the shoreline is essential, and a comprehensive, nationally consistent analysis of shoreline movement is needed. To meet this national need, the USGS is conducting an analysis of historical shoreline changes along open-ocean coasts of the United States and parts of the Great Lakes. This dataset is one in a series of regionally focused reports on historical shoreline change. As more data are gathered, periodic updates are made, which provide information that can be used in multidisciplinary assessments of coastal change hazards.

How was the data set created?

  1. From what previous works were the data drawn?
    DSAS baselines (source 1 of 2)
    U.S. Geological Survey, 2025, Midshore baselines for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) generated to calculate shoreline change rates: U.S. Geological Survey, online.

    Online Links:

    Type_of_Source_Media: Digital Resources
    Source_Contribution:
    DSAS baselines used for calculation of shoreline change rates, available from this same data release..
    DSAS shoreline (source 2 of 2)
    U.S. Geological Survey, 2025, Shorelines from 1949 to 2015 for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) used in shoreline change analysis: U.S. Geological Survey, online.

    Online Links:

    Type_of_Source_Media: Digital Resources
    Source_Contribution:
    DSAS shoreline file used for calculation of shoreline change rates, available from this same data release.
  2. How were the data generated, processed, and modified?
    Date: 2024 (process 1 of 7)
    Transect features were generated using DSAS v5.1.2 in ArcMap v10.8.1. Parameters Used: Baseline Layer=NorthwestAK_baselines, Baseline ID Field=ID, baseline placement=midshore, Baseline Orientation=Land is to the LEFT, Search Distance From Baseline=variable, Transect Spacing=50 meters, Smoothing Distance=500 meters. For additional details on these parameters, please see the DSAS help file distributed with the DSAS software.
    Date: 2024 (process 2 of 7)
    Some transects were manually edited to ensure they intersected all shorelines and were as close to perpendicular as possible.
    Date: 2025 (process 3 of 7)
    Rate calculations performed using DSAS v5.1.2 in ArcMap v10.8.1 on selected shoreline features. Parameters Used: Shoreline Layer= NorthwestAK_Shorelines, Shoreline Date Field=DATE_, Shoreline Uncertainty Field=UNCY, Default Data Accuracy=0 meters, Intersection Parameters=Seaward Intersection, Statistics to Calculate = [Shoreline Change Envelope (SCE)], [Net Shoreline Movement (NSM)], [End-point Rate (EPR)], [Linear Regression Rate (LRR)], [Weighted Linear Regression Rate (WLR)],Confidence Interval=90 percent, producing rates and intersect points.
    Date: 2025 (process 4 of 7)
    The transect feature class was exported from a personal geodatabase to a shapefile in ArcCatalog v10.8.1 by performing a right-mouse click on the data layer > export > to shapefile (single).
    Date: 2025 (process 5 of 7)
    BestRate, BestUNCY, and RateType fields were added to the shapefile. BestRate was calculated as EPR where ShrCount=2 and LRR where ShrCount=3. BestUNCY was calculated as EPRUncy where ShrCount=2 and LCI90 where ShrCount=3.RateType was calculated as EPR where ShrCount=2 and LRR where ShrCount=3.
    Date: 2025 (process 6 of 7)
    The exported shoreline shapefile was reprojected in Esri's ArcGIS Pro v3.4.3 > Data Management Tools > Projections and Transformations > Project. Parameters: input projection = NAD 1983 UTM Zone 3N; output projection = geographic coordinates (WGS84); transformation = WGS_1984_(ITRF00)_To_NAD_1983.
    Date: 2025 (process 7 of 7)
    The exported and edited transect shapefile was projected in Esri's ArcGIS Pro v3.4.3 ) > Data Management Tools > Projections and Transformations > Feature > Project. Parameters: input projection – NAD 1983 UTM Zone 3N); output projection - geographic coordinates (WGS84); transformation = WGS_1984_(ITRF00)_To_NAD_1983.
  3. What similar or related data should the user be aware of?
    Himmelstoss, Emily A., Henderson, Rachel E., Kratzmann, Meredith G., and Farris, Amy S., 2021, Digital Shoreline Analysis System (version 5.1) User Guide.

    Online Links:

    Other_Citation_Details:
    Himmelstoss, E.A., Henderson, R.E., Kratzmann, M.G., and Farris, A.S., 2021, Digital Shoreline Analysis System (version 5.1) User Guide: U.S. Geological Survey Open-File Report 2021-1091.
    Himmelstoss, Emily A., Farris, Amy S., Henderson, Rachel E., Kratzmann, Meredith G., Ergul, Ayhan, Zhang, Ouya, Zichichi, Jessica L., and Thieler, E. Robert, 2018, Digital Shoreline Analysis System (version 5.1): U.S. Geological Survey Software.

    Online Links:

    Other_Citation_Details:
    Current software at time of use was 5.1. The second link directs to the DSAS project page.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The attributes of this dataset are based on the field requirements of the Digital Shoreline Analysis System and were automatically generated by the software during the generation of the transect layer or during the calculation of shoreline change rates performed by the software. ShoreType attributes were added after rate calculations. The data have been quality checked.
  2. How accurate are the geographic locations?
    The transect serves as a reference point along which measurements are calculated by the Digital Shoreline Analysis System (DSAS) software. It does not correspond to any real-world feature.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This dataset contains the transects automatically generated by the DSAS software application that were used to calculate shoreline change rates along sections of the west coast of Alaska, between Cape Prince of Wales and the Kotlik River, where shoreline position data were available. Additional transects may have been generated but did not intersect the shoreline dates specified.
  5. How consistent are the relationships among the observations, including topology?
    These data were generated using DSAS version 5.1.2. The transects automatically generated by the software were visually inspected along with the shoreline data prior to rate calculations. Sometimes transect positions were manually edited within a standard ArcMap edit session to adjust the position at which an individual transect intersected the shorelines to better represent an orthogonal position to the general trend of the coast over time.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints No access constraints
Use_Constraints USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. These data are marked with a Creative Common CC BY 4.0 License, and users must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. Please recognize and acknowledge the U.S. Geological Survey and the Alaska Division of Geological & Geophysical Surveys as the originators of the dataset and in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    CA

    888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? These data are available in shapefile format contained in a single zip file, which also includes CSDGM FGDC-compliant metadata.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS) and the Alaska Division of Geological & Geophysical Surveys (DGGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: Zip file contains shoreline change rates measured along shore perpendicular transects on the northwest coast of Alaska and associated metadata. in format Shapefile (version ArcGIS Pro v3.4.3) Esri polyline shapefile Size: 1.8
      Network links: https://doi.org/10.5066/P1RYHDR7
    • Cost to order the data: None.

  5. What hardware or software do I need in order to use the data set?
    These data are available in a polyline shapefile format. The user must have software to read and process the data components of a shapefile.

Who wrote the metadata?

Dates:
Last modified: 02-Jan-2026
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P1RYHDR7/NorthwestAK_LT_rates_metadata.faq.html>
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