Kees Nederhoff Li H. Erikson Anita C. Engelstad 20250923 text files data release DOI: 10.5066/P1EPN6SK Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/P1EPN6SK Li H. Erikson Anita C. Engelstad Kees Nederhoff Alexander L. Nereson Ann E. Gibbs Dee M. Williams Maya K. Hayden Nicole Herman-Mercer 2025 data release DOI: 10.5066/P1EPN6SK Alaska Climate Adaptation Science Center, Anchorage, AK U.S. Geological Survey Suggested Citation: Erikson, L.H., Engelstad, A.C., Nederhoff, K., Nereson, A.L., Gibbs, A.E., Williams, D.M., Hayden, M.K., and Herman-Mercer, N., 2025, CoSMoS-AK Modeled Flood and Erosion Hazards at Utqiagvik - Coastal Alaska: U.S. Geological Survey data release, https://doi.org/10.5066/P1EPN6SK. https://doi.org/10.5066/P1EPN6SK The data sets provided here consist of 2D XBeach model files and sample input files used for Coastal Storm Modeling System (CoSMoS) simulations of flood and erosion hazards in Utqiagvik, Alaska. The models produce outputs for a suite of hazard products (see products in this release), such as flood depths, flood extents, and erosion and sedimentation. In this release, example forcing files for conditions with a 100-year return period coastal storm and a sea level rise of 0.5 m are provided, in addition to all other files needed to run the model in surfbeat and nonhydrostatic modes. This product was created to fulfill the Bureau-wide vision of an integrated, predictive science capability to support Alaska Native communities in building resiliency from natural disasters, sovereignty and self-determination, and emergency response and planning capacity. Work was funded by US Geological Survey Climate Adaptation Science Center Project EN05ES9 (see Projects - Climate Adaptation Science Centers). For more information on coastal storm modeling, see https://www.usgs.gov/centers/pcmsc/science/coastal-storm-modeling-system-cosmos. 2025 publication year Complete None planned -156.875387 -156.510246 71.362726 71.247795 USGS Metadata Identifier USGS:e4c7fb20-0c5b-40ce-99f3-7287cd069360 Data Categories for Marine Planning Physical Habitats and Geomorphology Global Change Master Directory (GCMD) Hazards Planning Ocean Waves Beaches Erosion Storm Surge Extreme Weather Water Depth USGS Thesaurus Storms Wind Floods mathematical modeling earth sciences ISO 19115 Topic Category Oceans ClimatologyMeteorologyAtmosphere Marine Realms Information Bank (MRIB) keywords waves coastal erosion 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 Utqiagvik 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 of the dataset and in products derived from these data. These data are not intended to be used for navigation. 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 Resources supporting this work were provided by USGS Advanced Research Computing (Falgout and others, 2024). The datasets were created in a Windows 11 Operating system, using Matlab v2024. G.W. Brunner 2024 Brunner, G.W., 2024. HEC-RAS River Analysis System 2D User’s Manual. Version 6.7_Beta3. US Army Corps of Engineers. Hydrologic Engineering Center. https://www.hec.usace.army.mil/confluence/rasdocs/r2dum/latest/developing-a-terrain-model-and-geospatial-layers/creating-land-cover-mannings-n-values-and-impervious-layers https://www.hec.usace.army.mil/confluence/rasdocs/r2dum/latest/developing-a-terrain-model-and-geospatial-layers/creating-land-cover-mannings-n-values-and-impervious-layers Deltares 2025 Deltares, 2025, Beach online manual documentation, Available online: xbeach.readthedocs.io (accessed 01 February 2025) xbeach.readthedocs.io J.T. Falgout J. Gordon B. Williams M.J. Davis 2024 Falgout, J.T., Gordon J., Williams B., Davis M. J., USGS Advanced Research Computing, USGS Denali Supercomputer: U.S. Geological Survey, https://doi.org/10.5066/P9PSW367 https://doi.org/10.5066/P9PSW367 K.C. Horen A.C. Poisson Z.J. Siemsen J.M. Donohue K.L. Widmer J.D. Adams J.R. Overbeck 2022 Horen, K.C., Poisson, A.C., Siemsen, Z.J., Donohue, J.M., Widmer, K.L., Adams, J.D., and Overbeck, J.R., 2022, Storm impact survey data for selected Alaska coastal communities in response to Extra-Tropical Cyclone Merbok, September 2022: Alaska Division of Geological & Geophysical Surveys Raw Data File 2022-14, 8 p. https://doi.org/10.14509/30909 https://doi.org/10.14509/30909 National Climatic Data Center (NCDC) 2019 National Climatic Data Center (NCDC), 2019, Storm data, last accessed May 2019. http://www.ncdc.noaa.gov/IPS/sd/sd.html Office for Coastal Management (OCM) 2025 Office for Coastal Management, 2025: 2020-2023 CCAP Version 2 Impervious Cover, https://www.fisheries.noaa.gov/inport/item/70563 U.S. Geological Survey 2024 U.S. Geological Survey, 2025, Short-Term Network Data Portal, accessed on October 15, 2024, at http://water.usgs.gov/floods/FEV/ Model setup was validated against observation-based storm flood elevations (NCDC 2019; Horen and others 2022, USGS, 2024). However, accurate historic water level recordings and detailed observations of floodings are sparse and vary between communities. Data have undergone quality checks and fall within expected/reasonable ranges. Dataset is considered complete for the information presented. Data are concurrent with topobathymetric digital elevation model (TBDEM, see Nereson and others, 2025) locations. Model bathymetry and topography are accurate within the published topobathymetric data (DOI: doi.org/10.5066/P13BXTXV) and interpolation onto model grid Alexander L. Nereson Ann E. Gibbs Li H. Erikson 2025 GeoTIFF online U.S. Geological Survey https://doi.org/10.5066/P13BXTXV online database 2025 publication date TBDEM Topographic and bathymetry elevation data used in models Model grids (x.grd, y.grid), elevations (bed.dep, in meters above NAVD88) and other XBeach-specific setup files (params, disch_loc_file, disch_timeseries_file, jonswap, waterlevel_ini, ne_layer, bedfricfile, and stormtide) were developed for surfbeat (XB-SB) and non-hydrostatic (XB-NH)simulations. See Deltares manual (2025) for a description of model files and differences between the surfbeat and non-hydrostatic modes. The XB-SB and XB-NH models can be run independent of each other or sequentially to leverage the strengths of both XBeach modes for a comprehensive simulation of wave dynamics, particularly in the context of swash zone (active beach area) processes and wave runup. The SB mode is computationally efficient and well-suited for capturing long-wave (infragravity) variations and their interactions with the shoreline, including morphodynamic change (erosion and sedimentation). The NH mode provides a detailed, wave-resolved simulation that includes individual wave overtopping. Models are set up in the cartesian coordinate system (Universal Transverse Mercator (UTM) zone 4 N) and elevations are referenced to the North American Vertical Datum of 1988 (NAVD88). Bed level data files of both the XB-SB and XB-NH models were populated using nearest grid-point mean TBDEM elevations, except in regions of breakwaters, constructed berms, and elevated roads, which were manually digitized to ensure that maximum elevations were accurately represented. Bed friction was populated using established Manning n values related to land-use map data (OCM 2025; Brunner 2024) but capped at a friction value of 0.028. Model setup was calibrated and validated against observation-based flood extents and surveyed high-water marks (NCDC 2019; Horen and others 2022, USGS, 2024). TBDEM 20241101 Raster Pixel Universal Transverse Mercator 4 0.9996 -159.00000 0.00000 500000.0 0.00 row and column 0.55 0.8 Meters NAD83 GRS 1980 6378137.00 298.257222101 North American Vertical Datum of 1988 0.01 meters Implicit coordinate 2D_XBeach_ModelInput_SB_Utqiagvik.zip and 2D_XBeach_ModelInput_NH_Utqiagvik.zip One zip file for the surfbeat (SB) model and one for the non-hydrostatic (NH) model, each with sample time-series forcing data (stormtide.txt and jonswap.txt) and all necessary input files. Producer defined Model setup files include all files necessary to run XBeach model simulations first in surfbeat mode and then, after updating the change in bathymetry with the surfbeat output, in non-hydrostatic mode. To provide the user with an example, the boundary conditions (jonswap and stormtide files) are included here for a projected 100-year return period storm and a sea level rise of 0.50 mm. 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 as text files contained in two zip files accompanied by 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 on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. text 2025 Zip file (2D_XBeach_ModelInput_SB_Utqiagvik.zip) contains 11 model input files for the surfbeat model WinZip 14.0 https://doi.org/10.5066/P1EPN6SK Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. text 2025 Zip file (2D_XBeach_ModelInput_NH_Utqiagvik.zip) contains 11 model input files for the non-hydrostatic model WinZip 22.5 https://doi.org/10.5066/P1EPN6SK Data can be downloaded using the Network_Resource_Name link then scrolling down to the Simulation Data section. None. The text data can be viewed with any text reading software. 20250923 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