Ann E. Gibbs Alexander G. Snyder Nora M. Nieminski 20260102 vector digital data (polyline) data release 10.5066/P1RYHDR7 U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz U.S. Geological Survey, Coastal and Marine Geology Program https://doi.org/10.5066/P1RYHDR7 Ann E. Gibbs Alexander G. Snyder Nora M. Nieminski 2026 data release 10.5066/P1RYHDR7 Pacific Coastal and Marine Science Center, Santa Cruz, CA U.S. Geological Survey 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. https://doi.org/10.5066/P1RYHDR7 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. 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. 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. 1949 2015 ground condition Complete None planned -168.0921 -160.7629 65.6001 63.0317 ISO 19115 Topic Category oceans environment geoscientificInformation Data Categories for Marine Planning Distributions Physical/Chemical Features USGS Thesaurus coastal processes geospatial datasets Marine Realms Information Bank (MRIB) keywords shoreline accretion shoreline erosion None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC Shoreline Shoreline change Digital Shoreline Analysis System DSAS USGS Metadata Identifier USGS:68bf176dd4be023bd943d04c Geographic Names Information System (GNIS) State of Alaska Bering Sea Norton Sound Brevig Mission Teller Nome Elim Golovin Shaktoolik Unalakleet Stebbins Saint Michael None United States of America Alaska No access 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. U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

2885 Mission Street

Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Emily A. Himmelstoss Rachel E. Henderson Meredith G. Kratzmann Amy S. Farris 2021 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. https://doi.org/10.3133/ofr20211091 https://www.usgs.gov/centers/whcmsc/science/digital-shoreline-analysis-system-dsas Emily A. Himmelstoss Amy S. Farris Rachel E. Henderson Meredith G. Kratzmann Ayhan Ergul Ouya Zhang Jessica L. Zichichi E. Robert Thieler 2018 Current software at time of use was 5.1. The second link directs to the DSAS project page. https://code.usgs.gov/cch/dsas/-/tree/v5.1?ref_type=tags https://www.usgs.gov/centers/whcmsc/science/digital-shoreline-analysis-system-dsas Jin-Si Over Andrew C. Ritchie Christine J. Kranenburg Jenna A. Brown Daniel D. Buscombe Tom Noble Christopher R. Sherwood Jonathan A. Warrick Phillipe A. Wernette 2021 https://pubs.usgs.gov/publication/ofr20211039 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. 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. 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. 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. U.S. Geological Survey NASA AMES Research Center 2023 Raster Digital Data Set https://doi.org/10.5066/F7610XKM Digital Data (.tif) 19800710 19850801 ground condition at time data were collected 1980s imagery 1980s imagery was used to delineate the instantaneous land-water interface shoreline. U.S. Geological Survey U.S. Air Force U.S. Navy 2023 Raster Digital Data Set https://doi.org/10.5066/F7610XKM Digital Data (.tif) 19490901 19520907 ground condition at time data were collected 1950s imagery 1950s imagery was used to delineate the instantaneous land-water interface shoreline. Overbeck, J.R. Hendricks, M.D Kinsman,N.E.M. 2016 Raster Digital Data Set online Alaska Division of Geological & Geophysical Surveys http://dggs.alaska.gov/pubs/id/29548 Digital Data (.tif) 2015 2015 ground condition at time data were collected. 2015 imagery Fodar imagery was used to delineate approximate land-water interface. NOAA Center for Operational Oceanographic Products and Services (NOAA CO-OPS) 2018 .json file online NOAA Center for Operational Oceanographic Products and Services https://api.tidesandcurrents.noaa.gov/api/prod/ Digital 19490901 20150831 ground condition at time data were collected. NOAA tide predictions Predicted tide data were used to account for uncertainty in shoreline position. The orthorectified 2015 imagery was obtained from Alaska Division of Geological and Geophysical Surveys. 2021 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. 2023 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. 2023 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. 2023 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. 2023 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. 2024 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. 2025 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. 2025 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. 2025 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. 2024 The shoreline feature class was used as the input within the Digital Shoreline Analysis System (DSAS) software to perform rate calculations. 2025 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). 2025 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. 2025 The metadata title was modified to move the location to the beginning of the title. This was done to meet new system requirements as ScienceBase is migrated to a new platform, and to keep datasets grouped by location on the new data release landing page. (20260327). 20260327 Manda Au U.S. Geological Survey Data Management Specialist Mailing

2885 Mission Street

Santa Cruz CA 95060 831-460-7575 mau@usgs.gov Vector String 3760 0.0000001 0.0000001 Decimal seconds D_WGS_1984 WGS 84 6378137.0 298.257223563 Attribute Table Table containing attribute information associated with the dataset. Producer defined FID Index number unique to each record in the attribute table. Esri Sequential unique whole numbers that are automatically generated Shape Feature geometry Esri Polyline ZM ESRI polyline shapefile Esri DATE_ Date of survey (MM/DD/YYYY), as indicated on source material from which shoreline position was digitized. Producer defined 09/01/1949 08/31/2015 MM/DD/YYYY Year_ Year of survey (YYYY) as indicated on source material from which shoreline position was digitized. U.S. Geological Survey 1949 2015 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. U.S. Geological Survey 2.13 8.93 Meters ShoreProxy Shoreline feature digitized U.S. Geological Survey LWI The instantaneous land-water interface observed in the imagery U.S. Geological Survey VL The seaward-most vegetation line observed in the imagery U.S. Geological Survey WDL The wet-dry line observed in the imagery. U.S. Geological Survey ShoreType A shoreline type classification U.S. Geological Survey Artificial Coastal type where the natural shoreline is altered by emplacement of infrastructure, rocks, rip-rap, revetments, seawalls, groins, jetties, or construction of inlets. U.S. Geological Survey Barrier Coastal type that includes barrier island, barrier spit, or barrier beach U.S. Geological Survey Mainland The mainland coast that is not a barrier or predominantly rocky. U.S. Geological Survey Rocky mainland Coastal type characterized by shear cliffs, bedrock, or beaches covered with large boulders. U.S. Geological Survey Rocky mainland with beaches Coastal type characterized as mostly rocky but with discontinuous sand, gravel, and boulder beaches. U.S. Geological Survey Agency Agency that provided shoreline feature and the data source used to digitize shoreline feature. U.S. Geological Survey State of Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys Alaska State agency that published the data. U.S. Geological Survey United States Geological Survey Federal agency that published the data. U.S. Geological Survey Source Type of source imagery U.S. Geological Survey Orthoimagery True-color RGB orthoimagery. U.S. Geological Survey Aerial photo single frames, black and white aerial photography Aerial single frame imagery obtained from U.S. Geological Survey’s Earth Explorer. U.S. Geological Survey 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. U.S. Geological Survey Source_a Specific source ID of data used to digitize shoreline feature. U.S. Geological Survey Source data IDs are assigned by the data providers SHAPE_Leng Length of shoreline segment in meters Esri 0.048 10640.413 meters 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. 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. U.S. Geological Survey - Science Base mailing and physical address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 CA 888-275-8747 sciencebase@usgs.gov These data are available in shapefile format contained in a single zip file, which also includes CSDGM FGDC-compliant metadata. 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. Vector Digital Dataset (Polyline) ArcGIS Pro v3.4.3 Esri polyline shapefile 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. Use WinZip or equivalent 2.44 https://doi.org/10.5066/P1RYHDR7 Data can be downloaded using the Network_Resource_Name link and selecting the specific Child Items title page. None. These data are available in a polyline shapefile format. The user must have software to read and process the data components of a shapefile. 20260327 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

2885 Mission Street

Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998