Midshore baselines for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) generated to calculate shoreline change rates

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Frequently anticipated questions:

What does this data set describe?

Title:
Midshore baselines for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) generated to calculate shoreline change rates
Abstract:
This dataset includes reference baselines used by the Digital Shoreline Analysis System (DSAS) version 5.1.2 to calculate rate-of-change statistics for the exposed, open-ocean coast of western Alaska between Cape Prince of Wales to the Kotlik River for the time period 1949 to 2015. This baselines layer serves as the starting point for all transects cast by the DSAS application and can be used to establish 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, Midshore baselines for the northwest coast of Alaska (Cape Prince of Wales to Kotlik River) generated to calculate shoreline change rates: data release 10.5066/P1RYHDR7, 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.

    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: -168.1244
    East_Bounding_Coordinate: -160.7629
    North_Bounding_Coordinate: 65.6920
    South_Bounding_Coordinate: 63.0331
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2025
    Currentness_Reference:
    publication date
  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 (39)
    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 degrees. 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: U.S. Geological Survey)
    FID
    Index number unique to each record in the attribute table. (Source: Esri)
    ValueDefinition
    Polyline ZMESRI polyline shapefile
    Sequential unique whole numbers that are automatically generated.
    DSAS_ID
    Field required by the Digital Shoreline Analysis System (DSAS) software. DSAS uses this value to determine the ordering sequence of transects when the baselines feature contains multiple segments. Individual segments are numbered sequentially alongshore. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:40
    Units:Unitless
    SearchDist
    An optional field within the DSAS software that allows users to set a search distance in meters. DSAS will use this value to search for shorelines extending out from either side of the baseline. (Source: U.S. Geological Survey)
    Range of values
    Minimum:40
    Maximum:450
    Units:Meters
    Shape_Leng
    Length of feature in meter units (UTM zone 3N, NAD83) (Source: Esri)
    Range of values
    Minimum:395
    Maximum:212167
    Units:Meters
    Entity_and_Attribute_Overview:
    The entity and attribute information provided here describes the tabular data associated with the dataset. Please review the individual attribute descriptions for detailed information.
    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?
    U.S. Geological Survey
  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?
  2. How were the data generated, processed, and modified?
    Date: 2024 (process 1 of 5)
    Baselines were constructed midshore from the time series of shoreline positions using standard editing tools in Esri ArcMap v10.8.1. The baselines were positioned to conform to changes in the orientation of the historical shorelines also presented in this data release. This was done so that transects, which are generated by the Digital Shoreline Analysis System v. 5.1 from the baseline, would intersect perpendicular to the general trend of the shorelines.
    Date: 2024 (process 2 of 5)
    The baselines 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 3 of 5)
    The baselines feature class was used as the input within the Digital Shoreline Analysis System (DSAS) software to generate transects and perform rate calculations.
    Date: 2025 (process 4 of 5)
    The baselines 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 5)
    The data were projected 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.

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

  1. How well have the observations been checked?
    The attribute in this layer is based on the requirements for use within the Digital Shoreline Analysis System (DSAS) software (Himmelstoss and others, 2018, 2021). The data have been quality checked.
  2. How accurate are the geographic locations?
    The baseline serves as a reference point for transects cast 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?
    The baseline serves as a reference point for transects cast by the Digital Shoreline Analysis System (DSAS) software. It does not correspond to any real-world feature.
  4. Where are the gaps in the data? What is missing?
    This baselines file is complete and contains all baseline segments used to cast transects where shoreline data are present to calculate a rate of change.
  5. How consistent are the relationships among the observations, including topology?
    All polylines have a unique identification attribute (ID). This field is used by the Digital Shoreline Analysis System (DSAS) to designate the alongshore order of baselines if there are more than one. Adjacent baseline segments do not overlap and are not necessarily continuous.

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 and 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 - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (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 baselines 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 Format_Specification: Esri polyline shapefile) Size: 0.60047
      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_baselines_metadata.faq.html>
Generated by mp version 2.9.51 on Mon Jan 12 12:51:45 2026