Alexander L. Nereson Ann E. Gibbs Li H. Erikson 20260313 raster digital data data release DOI: 10.5066/P13BXTXV Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/P13BXTXV Alexander L. Nereson Ann E. Gibbs Li H. Erikson 2025 raster digital data Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey Suggested citation: Nereson, A.L., Gibbs, A.E., and Erikson, L.H., 2025, Topobathymetric digital elevation models - coastal Alaska (ver. 2.0, March 2026): U.S. Geological Survey data release, https://doi.org/10.5066/P13BXTXV. https://doi.org/10.5066/P13BXTXV This dataset contains a 1-meter resolution, seamless topobathymetric digital elevation model (TBDEM) and associated spatial metadata for Wales, Alaska. The TBDEM contains best available (at the time of processing) multi-source topographic and bathymetric elevation data collected between the years 1950 and 2015. Processing was done by the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC) and results are provided as a Cloud Optimized GeoTIFF (COG). This product was created to help advance coastal storm response and recovery in Alaskan coastal communities in the wake of the September 2022 extratropical Typhoon Merbok disaster. It is being used by the USGS to support the development of dynamic flood models for more than 20 communities along the northwest coasts of Alaska. This product is intended for reuse by scientists, managers, and the general public. These data can be opened with most geographic information systems (GIS) software for data visualization and analysis purposes. Work was funded by Title VII of Division N in the Consolidated Appropriations Act, 2023 (Public Law 117-328) to support direct recovery and rebuilding decisions in the wake of declared disasters related to hurricanes and typhoons in 2022. For more information on these efforts, see https://www.usgs.gov/supplemental-appropriations-for-disaster-recovery-activities/typhoon-merbok-coastal-community. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the dataset in nonproprietary form, this metadata file may include some vendor-specific terminology. 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. 1950 2015 ground condition at the time source data were collected Complete None planned -168.20449 -167.99077 65.65229 65.58122 USGS Metadata Identifier USGS:2c6d131e-96d1-40af-bc6d-8c13802581b0 ISO 19115 Topic Category elevation Data Categories for Marine Planning Bathymetry and Elevation USGS Thesaurus topography bathymetry digital elevation models geospatial datasets Marine Realms Information Bank (MRIB) coast None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC Geographic Names Information System (GNIS) State of Alaska Nome Census Area City of Wales Bering Sea Bering Strait Cape Prince of Wales 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 CC0 1.0 Universal License. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes. PCMSC Science Data Coordinator U.S. Geological Survey, Pacific Coastal and Marine Science Center mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov wales_browse.png Quick view image of seamless topobathymetric digital elevation model for Wales, Alaska. PNG Global Mapper v26.0.2 and ArcGIS Pro 3.4.3 No formal attribute accuracy tests were conducted. Quality checks were performed on the elevation raster and spatial metadata files, including review of minimum/maximum elevation values, shoreline positions, gridding artifacts, and descriptive attributes. Data values fall within expected ranges. Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. The horizontal accuracy of the final seamless TBDEM was not assessed quantitatively. Please refer directly to the elevation data sources for measures of accuracy and uncertainty, when available. The authors calculated the mean bias error (MBE) and root mean square error (RMSE) of the final, seamless TBDEM relative to the check point subsets. The MBE (TBDEM minus all check points) is 0.033 m and the RMSE is 0.107 m. For other measures of vertical accuracy, please refer directly to the metadata for each input data source cited below. Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys 2016 raster digital data online Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys https://dggs.alaska.gov/pubs/id/29548 Digital and/or Hardcopy 2015 ground condition at time data were collected 2015 DGGS sfm Elevations in this data source were used with the other source data to interpolate a seamless topobathymetric digital elevation model. Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys 2015 tabular digital data online Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys https://dggs.alaska.gov/pubs/id/29348 Digital and/or Hardcopy 2012 ground condition at time data were collected 2012 DGGS sonar Elevations in this data source were used with the other source data to interpolate a seamless topobathymetric digital elevation model. Office of Coast Survey, National Ocean Service, NOAA, U.S. Department of Commerce 2011 raster digital data online NOAA National Centers for Environmental Information https://www.ngdc.noaa.gov/nos/H12001-H14000/H12228.html Digital and/or Hardcopy 2010 ground condition at time data were collected 2010 NOS multibeam Elevations in this data source were used with the other source data to interpolate a seamless topobathymetric digital elevation model. Office of Coast Survey, National Ocean Service, NOAA, U.S. Department of Commerce 1951 raster digital data online NOAA National Centers for Environmental Information https://www.ngdc.noaa.gov/nos/H06001-H08000/H07845.html Digital and/or Hardcopy 1950 ground condition at time data were collected 1950 NOS sonar (H07845) Elevations in this data source were used with the other source data to interpolate a seamless topobathymetric digital elevation model. Office of Coast Survey, National Ocean Service, NOAA, U.S. Department of Commerce 1951 raster digital data online NOAA National Centers for Environmental Information https://www.ngdc.noaa.gov/nos/H06001-H08000/H07849.html Digital and/or Hardcopy 1950 ground condition at time data were collected 1950 NOS sonar (H07849) Elevations in this data source were used with the other source data to interpolate a seamless topobathymetric digital elevation model. Alaska Department of Natural Resources 2025 online Alaska Department of Natural Resources https://dggs.alaska.gov/hazards/coastal/ak-tidal-datum-portal.html online database 2025 date data were accessed conversion constant Local conversion constants Alaska Department of Commerce, Community, and Economic Development (AK DCRA) 2024 online Alaska Department of Commerce, Community, and Economic Development https://dcra-cdo-dcced.opendata.arcgis.com/maps/7f5ca7eafcbb40dc88c06a8a5072b6e3/about online database 2024 date data were accessed Community Profile CAD Community profile feature layer used to identify culverts National Oceanic and Atmospheric Administration (NOAA) 2024 online National Oceanic and Atmospheric Administration (NOAA) https://alaskafisheries.noaa.gov/mapping/sz/ online database 2024 date data were accessed ShoreZone oblique aerial imagery used to identify culverts Define an area of interest (AOI) and gather published topographic and bathymetric elevation datasets with coverage in the AOI. 20251119 View and prioritize source elevation datasets based on date of acquisition, spatial distribution, accuracy, and point density. In general, more recent dates of acquisition, wider spatial distribution, higher accuracy, and higher point density result in a higher priority level. Source elevation datasets are listed in their order of priority in the Lineage section of this metadata file and in the associated spatial metadata, where the first source dataset is of the highest priority. 2015 DGGS sfm 2012 DGGS sonar 2010 NOS multibeam 1950 NOS sonar (H07845) 1950 NOS sonar (H07849) 20251119 Prepare each source elevation dataset, as applicable. In Global Mapper software: A) transform the source dataset from its native horizontal and vertical spatial reference systems to the appropriate NAD83 (2011) Universal Transverse Mercator (UTM) zone projection and to NAVD88 GEOID12B, respectively. Convert source elevations to NAVD88. The local constants used for this project are listed in the last process step of this metadata file, along with any additional transformations that may have been used bring source datasets into NAVD88 GEOID12B. B) Save the transformed dataset as a LAZ point file. C) Clip LAZ point file to AOI polygon. D) Classify and remove non-ground points from structure-from-motion (SfM)-derived digital surface models (DSMs) using lidar auto-classification. E) Spatially thin LAZ file to one-meter resolution, using the minimum value method. F) Clip the LAZ file to all higher-priority datasets using a buffer of 2x the average point density/resolution of the source dataset being prepared. G) Split the LAZ file into two subsets, one containing 95 percent of the points (active points) and the other containing the remaining 5 percent, or every 20th point (check points). The active points are later gridded in the elevation model along with associated interpolation guides to derive the final topographic surface, while the check points are used to compute the interpolation accuracy of the derived surface. conversion constant 20251119 Create interpolation guides. Interpolation guides are author-defined 3D points, lines, or polygons used to help derive the final topographic surface. Interpolation guides are used to A) smooth or accentuate breaks in slope along shared boundaries of source datasets, B) prevent topographic creep/shoreline migration from onshore regions into offshore regions, C) fill data gaps in source datasets with plausible heights when local knowledge, qualitative field observations, remotely sensed optical imagery, or other information sources are available, or D) otherwise facilitate the seamless integration of all source datasets. Details of interpolation guides used to create the final elevation surface for this release are listed in the last process step of this metadata file. 20251119 Interpolate a one-meter resolution seamless elevation surface from input source data and interpolation guides using the Create Elevation Grid tool (triangulation method). 20251119 Export grid as a Cloud Optimized GeoTIFF (COG) using Global Mapper, clipping the grid bounds to the project AOI and snapping the output raster cells to the appropriate UTM zone projection, using a bilinear resampling method. 20251119 Quantify interpolation error in MATLAB by calculating the mean bias error (MBE) and root mean square error (RMSE) of the final, seamless TBDEM relative to the check point subsets. MBE and RMSE are reported in the Vertical Positional Accuracy section of this metadata file. 20251119 Create spatial metadata for each source dataset by converting LAZ points to simplified bounding polygons and save in an Esri file geodatabase feature class, along with descriptive attributes about the source dataset. Spatial metadata files are further described in the Entity and Attribute Overview section of this metadata file. 20251119 Perform quality checks on the output elevation raster and spatial metadata files, including review of minimum/maximum elevation values, shoreline positions, gridding artifacts, and descriptive attributes. 20251119 Special considerations: A) Vertical datum conversion constants: i) 0 m NAVD88 is -0.81 m above Mean Lower Low Water (per Alaska Tidal Datum Portal). B) Additional vertical transformations: none. C) Interpolation guides: i) Foreshore contours: two foreshore contours were created in Global Mapper to prevent topographic creep of the shoreline into the offshore realm. ii) Lopp lagoon contours: several shore-parallel contours were created in Lopp Lagoon to fill data gaps using the buffer tool in Global Mapper. Maximum lagoon depth assumed to be 2 meers below MLLW, similar to maximum depths for nearby Shishmaref Inlet. iii) Inland water bodies: Source data gaps over inland water bodies (lakes, ponds, and streams) were digitized into 3D polygons in Global Mapper and assigned constant elevation values of approximately 1 meter below the edge elevation of the water body. iv) Culverts: Culverts were identified using the AK DCRA Community Profile CAD Planimetric Features layer (https://dcra-cdo-dcced.opendata.arcgis.com/maps/7f5ca7eafcbb40dc88c06a8a5072b6e3/about) and NOAA ShoreZone oblique aerial imagery (https://alaskafisheries.noaa.gov/mapping/sz/). Each culvert was digitized into a 3D polygon with a constant elevation value and used in the interpolation step above. conversion constant ShoreZone Community Profile CAD 20251121 Raster Grid Cell 7492 9512 1 Universal Transverse Mercator 2 0.9996 -171.0 0.0 500000.0 0.0 row and column 1.0 1.0 meters NAD83_National_Spatial_Reference_System_2011 GRS 1980 6378137.0 298.257222101004 North American Vertical Datum of 1988 0.001 meters Explicit elevation coordinate included with horizontal coordinates wales_tbdem_1m_1950_to_2015.tif Raster geospatial data file. Producer Defined Elevation orthometric height in meters NAVD88 (GEOID12B). Values of -9999 = no data. Producer Defined -9999 No Data Producer defined -34.121 293.771 meters 0.001 These metadata describe a Cloud Optimized GeoTIFF (COG) raster file whose floating point grid cell values represent orthometric heights (elevations) in meters NAVD88 GEOID12B. The file name for the elevation raster follows the format: "location_tbdem_1m_YYYY_to_YYYY.tif", where "location" is the geographic name of the place depicted in the data, "tbdem" indicates "topobathymetric digital elevation model", "1m" indicates 1-meter grid resolution, and "YYYY_to_YYYY" indicates the date range (in years) of all the source data. The source data are further described in a supplementary "spatial" metadata file that contains polygonal boundaries and descriptive attributes for each source. Polygons and attributes are saved as a feature class in an Esri file geodatabase with a file name that follows the naming convention described above, along with the following suffix: "_spatial_metadata.gdb". The file geodatabase has been compressed into a ZIP file of the same name. The following attribute fields are included in the polygon feature class: Name of dataset (Title), the organization major project or activity (Source_Project), source dataset organization (Source_Organization), date(s) acquired (Date_Acquired), publication date (Publication Date), source elevation type (Data_Type), source projection (Source_Projection), source horizontal resolution (Source_Horizontal_Resolution), source horizontal datum (Source_Horizontal_Datum), source vertical units (Source_Vertical_Units), source vertical datum (Source_Vertical_Datum), source geoid (Geoid), spatial extent of source (Coverage_Area), source URL (Source_Publication), perimeter of polygon feature in meters (Shape_Length), and area of polygon feature in square meters (Shape_Area). Descriptive attributes for interpolation guides are set to Null. See Process Steps above for more information on how and where guides were created. U.S. Geological Survey U.S. Geological Survey - CMGDS mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov These data are available in Cloud Optimized GeoTIFF (COG) raster file format accompanied by a spatial metadata geodatabase file and 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), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. GeoTIFF Global Mapper v26.0.2 and ArcGIS Pro 3.4.3 Cloud Optimized GeoTIFF (COG) raster file whose floating point grid cell values represent orthometric heights (elevations). No data value is -9999. No compression applied. 144.1 https://doi.org/10.5066/P13BXTXV Data and metadata can be downloaded using the Network_Resource_Name link and scrolling down to the Topobathymetric digital elevation model of Wales, Alaska, 1950 to 2015 section. None Most geospatial data software and their supporting operating systems (for example, QGIS, Global Mapper, Esri ArcGIS Pro, or similar). 20260313 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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