Paul Russel Colin Lyons Li H. Erikson Ann E. Gibbs 20250708 comma-delimited text data release DOI:10.5066/P13YIWKC Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/P13YIWKC Li H. Erikson Ann E. Gibbs Richard M. Buzard Daniel J. Nowacki Alexander G. Snyder Anita C. Engelstad Cordell Johnson Alexander L. Nereson Jin-Si R. Over Paul Russel Colin Lyons 2025 data release DOI:10.5066/P13YIWKC Pacific Coastal and Marine Science Center, Santa Cruz, CA U.S. Geological Survey Suggested Citation: Erikson L.H., Gibbs A.E., Buzard R.M., Nowacki D.J., Snyder A.G., Engelstad A.C., Johnson C., Nereson A.L., Over J.R., Russel, P., Lyons, C., 2025, In situ field data, Coastal Alaska, 2023 to 2025: U.S. Geological Survey data release, https://doi.org/10.5066/P13YIWKC https://doi.org/10.5066/P13YIWKC First finished floor elevation data, as well as ground survey points for critical infrastructure, for example bridges, fuel farms, and power generators, were collected in Elim, Golovin, Kotzebue, Mekoryuk, Saint George, Stebbins, and Tununak, Alaska. The elevation data were collected with real-time kinematic global navigation satellite system (RTK-GNSS) equipment. Data are available in CSV file format. Two files are available per community: one in a geographic coordinate system (this dataset) and the other in the Alaska State Plane coordinate system (in this same data release). Additionally, the supplemental survey reports are provided. 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 establish a baseline of current conditions and integrate them with forecasted coastal flood extents to inform proactive planning, strengthen community resilience, and support the development of targeted policies that mitigate the impacts of future storm events. This product is intended for reuse by scientists, managers, and the general public. 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. To comply with statue requirements (AS 34.65.020. Entry Upon Land for Survey Purposes), notice was given to each community on the timing of the surveys and nature of the work being conducted. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 20180710 20250129 Ground condition at time data were collected Complete None planned -169.67477 -162.24351 66.90424 56.56750 USGS Metadata Identifier USGS:5bab9b51-1d87-4d2c-a6d3-3223f32a506c ISO 19115 Topic Category geoscientificInformation Marine Realms Information Bank (MRIB) keywords beach shore Data Categories for Marine Planning Bathymetry and Elevation USGS Thesaurus coastal processes topography geospatial datasets None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC Typhoon Merbok Geographic Names Information System (GNIS) State of Alaska Elim Golovin Kotzebue Mekoryuk Saint George Stebbins Tununak 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. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. 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 FFE_DataCollection_locations.png Satellite image showing the locations where elevation data were collected. PNG Trimble Business Center, National Geodetic Survey Online Positioning User Service (https://geodesy.noaa.gov/OPUS/) No formal accuracy assessment was performed. All data fall within expected ranges. Dataset is considered complete for the information presented, as described in the abstract. The estimated horizontal accuracy of these points ranges from 0.011 meters to 0.094 meters. These values are derived by summing the manufacturer reported vertical uncertainty (0.008 meters) and the horizontal accuracy of the NGS OPUS-derived position of the GNSS base station operating on temporary benchmark at the 95 percent confidence level in quadrature. The mean estimated horizontal accuracy for all points is 0.036 meters. The estimated vertical accuracy of these points ranges from 0.353 meters to 0.364 meters. These values are derived by summing the manufacturer report vertical uncertainty (0.015 meters) and, where available, the vertical precision for each point (calculated at the 95 percent confidence level by the post-processing software, and reported as the Network accuracy at the 95 percent confidence level), and the vertical accuracy of the NGS OPUS-derived position of the GNSS base station operating on temporary at the 95 percent confidence level (0.352-0.360 meters, of which the geoid error (GEOID12B) accounts for 0.352 meters) in quadrature. The mean estimated vertical accuracy for all points is 0.356 meters. Survey teams from or contracted by the Alaska Native Tribal Health Consortium traveled to seven communities and surveyed first floor elevations (FFEs) of all critical buildings and base elevations for critical infrastructure that are within anticipated coastal erosion and flood zones. Surveyed infrastructure FFEs include the airport runway corners and center, schools, clinics, fuel tank farms, offices, washeterias, public buildings, homes, landfills, sewage lagoons, water treatment plants, power plants, cemeteries, fish processing plants, bridges, barge landings, public safety buildings, and other structures identified as critical by local government. To comply with statue requirements (AS 34.65.020. Entry Upon Land for Survey Purposes), notice was given to each community on the timing of the surveys and nature of the work being conducted. Surveys were conducted under the supervision of a licensed land surveyor using Trimble survey grade receivers. Elevation data were collected using a real-time-kinematic global navigation satellite system (RTK-GNSS) positioning techniques. Surveys were tied into existing control benchmarks, where available, as documented by the National Geodetic Survey (NGS) and the National Oceanographic and Atmospheric Administration (NOAA). The base station data were post-processed using the NGS online positioning user service (OPUS) tool. All data were post-processed and quality checked using Trimble Business Center software. Additional information is available in the supplementary survey reports provided (see FFE_supplemental_SurveyReports.zip). 20250211 Point Point 4520 0.00001 0.00001 Decimal degrees NAD83 GRS 1980 6378137.0 298.257222101 North American Vertical Datum of 1988 0.01 Meters Explicit elevation coordinate included with horizontal coordinates FFE_7AlaskaCommunities_GeographicCoordinates.zip Zip file contains first floor and ground survey measurements provided for seven communities (defined by CommunityName in file name) in a file with geographic coordinates (“GEO”). Producer defined ID Identifying point number Producer defined Unique numbers identifying location points within each community. IDs are not unique across communities. Latitude Latitude coordinate Producer defined 56.56750 66.90424 Decimal degrees 0.00001 Longitude Longitude coordinate Producer defined -169.67477 -162.24351 Decimal degrees 0.00001 Elev_ft Elevation relative to NAVD88 (GEOID12B) Producer defined 7.14 192.97 feet 0.01 Elev_m Elevation relative to NAVD88 (GEOID12B) Producer defined 2.18 58.82 Meters 0.01 Description Description of point Producer defined Descriptive text. FF stands for first floor and GS for ground survey. The first line of the csv file is a header line. U.S. Geological Survey U.S. Geological Survey - CMGDS mailing and physical

2885 Mission Street

Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Resource_Description: These data are available in csv format 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 on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. comma-delimited text 2025 zip file (FFE_7AlaskaCommunities_GeographicCoordinates.zip ) contains seven CSV files with location and elevation data WinZip 0.1 https://doi.org/10.5066/P13YIWKC Data and metadata can be downloaded using the Network_Resource_Name link then scrolling down to the Location-Elevation Data section. Portable Document Format 2025 zip file (FFE_supplemental_SurveyReports.zip) contains survey reports in Portable Document Format (PDF) WinZip 1 https://doi.org/10.5066/P13YIWKC The supplemental survey reports can be downloaded using the Network_Resource_Name link then scrolling down to the Supplemental Files section of this data release. None. The CSV data can be viewed with any text reading software. The PDF files can be viewed with Acrobat Reader or similar software. 20250708 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