Shorelines from 1949 to 2015 for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) used in shoreline change analysis

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Frequently anticipated questions:

What does this data set describe?

Title:
Shorelines from 1949 to 2015 for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) used in shoreline change analysis
Abstract:
This dataset includes historical shoreline positions that span up to 66 years, from 1949 to 2015, for the west coast of Alaska between Cape Prince of Wales and the Kotlik River. Shorelines were compiled from aerial orthophotographs (U.S. Geological Survey (USGS); State of Alaska Division of Natural Resources, Division of Geological and Geophysical Surveys). Historical shoreline positions serve as easily understood features that can be used to describe the movement of beaches through time. These data are used to calculate rates of shoreline change. Rates of long-term (greater than 60 years) and short-term (less than 40 years) shoreline change were generated in a GIS using the Digital Shoreline Analysis System (DSAS) version 5.1.2. DSAS uses a measurement baseline method to calculate rate-of-change statistics. Transects are cast from the reference baseline to intersect each shoreline, establishing measurement points used to calculate shoreline change 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, Shorelines from 1949 to 2015 for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) used in shoreline change analysis: 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 to 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: -168.0921
    East_Bounding_Coordinate: -160.7629
    North_Bounding_Coordinate: 65.6001
    South_Bounding_Coordinate: 63.0317
  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 (3760)
    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 84.
      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
    Index number unique to each record in the attribute table. (Source: Esri) Sequential unique whole numbers that are automatically generated
    Shape
    Feature geometry (Source: Esri)
    ValueDefinition
    Polyline ZMESRI polyline shapefile
    DATE_
    Date of survey (MM/DD/YYYY), as indicated on source material from which shoreline position was digitized. (Source: Producer defined)
    Range of values
    Minimum:09/01/1949
    Maximum:08/31/2015
    Units:MM/DD/YYYY
    Year_
    Year of survey (YYYY) as indicated on source material from which shoreline position was digitized. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1949
    Maximum:2015
    Units:Year
    UNCY
    Total shoreline position uncertainty, in meters. Actual shoreline position is within the range of this value. The uncertainty was determined as described in the Horizontal_Positional_Accuracy_Report above. (Source: U.S. Geological Survey)
    Range of values
    Minimum:2.13
    Maximum:8.93
    Units:Meters
    ShoreProxy
    Shoreline feature digitized (Source: U.S. Geological Survey)
    ValueDefinition
    LWIThe instantaneous land-water interface observed in the imagery
    VLThe seaward-most vegetation line observed in the imagery
    WDLThe wet-dry line observed in the imagery.
    ShoreType
    A shoreline type classification (Source: U.S. Geological Survey)
    ValueDefinition
    ArtificialCoastal type where the natural shoreline is altered by emplacement of infrastructure, rocks, rip-rap, revetments, seawalls, groins, jetties, or construction of inlets.
    BarrierCoastal type that includes barrier island, barrier spit, or barrier beach
    MainlandThe mainland coast that is not a barrier or predominantly rocky.
    Rocky mainlandCoastal type characterized by shear cliffs, bedrock, or beaches covered with large boulders.
    Rocky mainland with beachesCoastal type characterized as mostly rocky but with discontinuous sand, gravel, and boulder beaches.
    Agency
    Agency that provided shoreline feature and the data source used to digitize shoreline feature. (Source: U.S. Geological Survey)
    ValueDefinition
    State of Alaska Department of Natural Resources, Division of Geological and Geophysical SurveysAlaska State agency that published the data.
    United States Geological SurveyFederal agency that published the data.
    Source
    Type of source imagery (Source: U.S. Geological Survey)
    ValueDefinition
    OrthoimageryTrue-color RGB orthoimagery.
    Aerial photo single frames, black and white aerial photographyAerial single frame imagery obtained from U.S. Geological Survey’s Earth Explorer.
    Aerial photo single frames, color-infrared Alaska High-Altitude Aerial Photography (AHAP)Aerial single frame imagery obtained from U.S. Geological Survey’s Earth Explorer.
    Source_a
    Specific source ID of data used to digitize shoreline feature. (Source: U.S. Geological Survey) Source data IDs are assigned by the data providers
    SHAPE_Leng
    Length of shoreline segment in meters (Source: Esri)
    Range of values
    Minimum:0.048
    Maximum:10640.413
    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?
    1980s imagery (source 1 of 4)
    U.S. Geological Survey, and NASA AMES Research Center, 2023, Aerial photo single frames, color-infrared Alaska High-Altitude Aerial Photography.

    Online Links:

    Type_of_Source_Media: Digital Data (.tif)
    Source_Contribution:
    1980s imagery was used to delineate the instantaneous land-water interface shoreline.
    1950s imagery (source 2 of 4)
    U.S. Geological Survey, U.S. Air Force, and Navy, U.S., 2023, Aerial photo single frames, black and white Alaska aerial photography.

    Online Links:

    Type_of_Source_Media: Digital Data (.tif)
    Source_Contribution:
    1950s imagery was used to delineate the instantaneous land-water interface shoreline.
    2015 imagery (source 3 of 4)
    Overbeck, J.R., Hendricks, M.D, and Kinsman, N.E.M., 2016, Photogrammetric digital surface models and orthoimagery for 26 coastal communities of western Alaska: Alaska Division of Geological & Geophysical Surveys, online.

    Online Links:

    Type_of_Source_Media: Digital Data (.tif)
    Source_Contribution:
    Fodar imagery was used to delineate approximate land-water interface.
    NOAA tide predictions (source 4 of 4)
    NOAA Center for Operational Oceanographic Products and Services (NOAA CO-OPS), 2018, Predicted Tide Data from CO-OPS September 1, 1949 – August 31, 2015: NOAA Center for Operational Oceanographic Products and Services, online.

    Online Links:

    Type_of_Source_Media: Digital
    Source_Contribution:
    Predicted tide data were used to account for uncertainty in shoreline position.
  2. How were the data generated, processed, and modified?
    Date: 2021 (process 1 of 13)
    The orthorectified 2015 imagery was obtained from Alaska Division of Geological and Geophysical Surveys.
    Date: 2023 (process 2 of 13)
    Aerial photo single frames from the 1950s and 1980s were identified and downloaded from USGS Earth Explorer. The 1950s imagery is black and white and part of multiple mapping projects. The 1980s imagery is colored near infrared and part of the Alaska High Altitude Aerial Photography Project. Additional information about the specific source imagery is available on USGS Earth Explorer and can be found using the specific attribute ENTITY_ID, which is also identified as the attribute “Source_a” in this dataset.
    Date: 2023 (process 3 of 13)
    1950s and 1980s aerial photo single frames were used to generate a 3-dimensional model using structure from motion (SfM) methods in Agisoft Metashape v1.7, following the methods detailed by Over and others, 2021.
    Date: 2023 (process 4 of 13)
    Horizontal and vertical positions of ground control points (GCPs) were digitized from the 2015 imagery, using ArcGIS Pro v3.32. These consisted of features that were visible in the 1950s, 1980s, and 2015 imagery.
    Date: 2023 (process 5 of 13)
    Ground control points (GCPs) were added to the structure from motion (SfM) model using Agisoft Metashape v1.7 to georeference and further refine the accuracy of the SfM model, following the methods detailed in Over and others, 2021.
    Date: 2024 (process 6 of 13)
    Georeferenced, orthorectified imagery mosaics for the 1950s and 1980s were generated and exported as 1 meter resolution GeoTIFFs, using Agisoft Metashape v1.7, following the methods detailed by Over and others, 2021.
    Date: 2025 (process 7 of 13)
    Vector shorelines, including land water interface, wet dry line, and vegetation line, were identified in the georeferenced orthoimagery and digitized using ArcGIS Pro version 3.32 at a scale of 1:1,500 or less.
    Date: 2025 (process 8 of 13)
    The name of the source imagery used to determine the shoreline was added to the shoreline shapefile using a shapefile that contained the boundaries of the source imagery to split the polyline segments into distinct records.
    Date: 2025 (process 9 of 13)
    Shoreline uncertainty values were calculated in Matlab version 2024b using tide predictions from NOAA Tide Predictions (NOAA, 2025), then exported to a table and appended to the shapefile of shorelines using the 'Join' tool in ArcGIS Pro version 3.32. For more information see Horizontal_Positional_Accuracy_Report section above.
    Date: 2024 (process 10 of 13)
    The shoreline shapefile was imported into a personal geodatabase in ArcCatalog v10.8.1 by right-clicking on the geodatabase > Import for use with the Digital Shoreline Analysis System (DSAS) software to perform rate calculations.
    Date: 2025 (process 11 of 13)
    The shoreline feature class was used as the input within the Digital Shoreline Analysis System (DSAS) software to perform rate calculations.
    Date: 2025 (process 12 of 13)
    The shoreline 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 13 of 13)
    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.
  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.
    Over, Jin-Si, Ritchie, Andrew C., Kranenburg, Christine J., Brown, Jenna A., Buscombe, Daniel D., Noble, Tom, Sherwood, Christopher R., Warrick, Jonathan A., and Wernette, Phillipe A., 2021, Processing Coastal Imagery With Agisoft Metashape Professional Edition, Version 1.6—Structure From Motion Workflow Documentation.

    Online Links:

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

  1. How well have the observations been checked?
    The data provided here are a compilation of shorelines from multiple sources, spanning 66 years. The attributes in this table record positional and measurement uncertainties and datum offsets calculated during the process of extracting the shoreline from the orthoimagery data as described in the process steps. The attributes are based on the requirements of the Digital Shoreline Analysis System (DSAS) software and have gone through a series of quality assurance procedures.
  2. How accurate are the geographic locations?
    Horizontal positional accuracy for this dataset is composed of three contributing factors: georeferencing error, digitization error, and the water line position uncertainty. The georeferencing error was estimated by identifying the same features in imagery from each time period (1950s, 1980s, and 2015), measuring the horizontal distance between the same feature in different imagery datasets, then calculating the RMSE for each imagery processing region for the 1950s and 1980s datasets. These values ranged from 3.12 to 3.86 meters for 1950s and 2.42 to 3.89 meters for the 1980s. The georeferencing error for all 2015 imagery was reported by contractor (Fairbanks Fodar) to be 0.3 meters. The digitization error is the variability in the digitized location of the vector shoreline. The digitization error was determined to be 3 meters for the 1950s imagery, 3 meters for the 1980s imagery, and 2 meters for the 2015 imagery. The uncertainty of the position of the water line at the time of imagery capture was calculated by dividing the minimum and maximum water level deviations from mean high water, using the NOAA Tide Predictions based on the tidal stations at Unalakleet (9468333) and Nome (9468756), by the estimated shoreface slope (1:20). These three components were added in quadrature. The resulting horizontal positional accuracy ranged from 2.13 meters to 8.93 meters.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    This shoreline file is complete and contains all shoreline segments used to calculate shoreline change rates along sections of the specified Alaska coastal region where shoreline position data were available. These data adequately represented the shoreline position at the time of the survey. Remaining gaps in these data are a consequence of non-existing data or existing data that did not meet quality assurance standards.
  5. How consistent are the relationships among the observations, including topology?
    Adjacent shoreline segments do not overlap and are not necessarily continuous. Shorelines were quality checked for accuracy. Any slight offsets between adjacent segments due to georeferencing and digitizing error are taken into account in the uncertainty of the shoreline position, as reported in this metadata file.

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. These data are not to be used for navigation.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - Science Base
    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 containing a shapefile of digitized shoreline positions from 1949 to 2015 for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) and associated metadata. in format Vector Digital Dataset (Polyline) (version ArcGIS Pro v3.4.3) Esri polyline shapefile Size: 2.44
      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_shorelines_metadata.faq.html>
Generated by mp version 2.9.51 on Mon Jan 12 12:51:45 2026