James B. Shope Curt D. Storlazzi 2019 netCDF files data release DOI:10.5066/P9U28JFO Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/P9U28JFO https://www.sciencebase.gov/catalog/item/5be5f849e4b0b3fc5cf8c9ab Schematic atoll models with varying theoretical morphologies were used to evaluate the relative control of individual morphological parameters on alongshore transport gradients. Here we present physics-based numerical SWAN model results of incident wave transformations for a range of atoll and island morphologies and sea-level rise scenarios. Model results are presented in NetCDF format, accompanied by a README text file that lists the parameters used in each model run. These data accompany the following publication: Shope, J.B., and Storlazzi, C.D., 2019, Assessing morphologic controls on atoll island alongshore sediment transport gradients due to future sea-level rise: Frontiers in Marine Science, doi:10.3389/fmars.2019.00245. Low-lying atoll islands are threatened by the effects of climate change, sea-level rise, and wave-driven flooding. Atolls differ widely in their morphologies and other physical characteristics; the wave and water level conditions along these coastlines vary in space and time. These factors make it difficult to project wave-driven alongshore sediment transport changes in accretion and/or deposition along atoll island shorelines under different forcing conditions, especially for future sea-level rise. We generated a number of ideal schematic atoll and atoll island topographies/bathymetries, then used a physics-based numerical wave model and empirical formulations of alongshore sediment transport to project how sea-level rise may alter alongshore sediment transport gradients along atoll island shorelines. The transport gradients were used to evaluate the relative risk of coastal change on atoll islands of differing morphologies due to sea-level rise. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 2019 publication date Complete None planned -180.00000000 180.00000000 90.00000000 -90.00000000 USGS Metadata Identifier USGS:5be5f849e4b0b3fc5cf8c9ab ISO 19115 Topic Category geoscientificInformation oceans Data Categories for Marine Planning water column features USGS Thesaurus hazards coastal processes Marine Realms Information Bank (MRIB) keywords coral reefs reef waves flooding coastal processes numerical modeling None water level U.S. Geological Survey USGS Coastal and Marine Geology Program CMGP Pacific Coastal and Marine Science Center PCMSC None 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 University of California at Santa Cruz and the U.S. Geological Survey as the originators 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

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov James B. Shope Curt D. Storlazzi 2018 Shope, J.B., and Storlazzi, C.D., 2019, Assessing morphologic controls on atoll island alongshore sediment transport gradients due to future sea-level rise: Frontiers in Marine Science, doi:10.3389/fmars.2019.00245. https://doi.org/10.3389/fmars.2019.00245 See Shope and Storlazzi (2019) for an in-depth discussion of accuracy. No formal logical accuracy tests were conducted. See Shope and Storlazzi (2019) for additional information. 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. No formal positional accuracy tests were conducted, nor are they applicable. No formal positional accuracy tests were conducted, nor are they applicable. The following steps were used in development of the model. For an in-depth discussion of processing, see Shope and Storlazzi (2019). Model results are presented in NetCDF format, accompanied by a README text file that lists the parameters used in each model run. 1. Select a suite of potential morphological parameters that may affect wave-driven sediment transport along atoll islands via literature review. After, testing, these were the atoll diameter, the atoll reef flat depth, the atoll reef flat width, and the atoll island width. Other variables were tested, but were found to have little control on transport patters or were unable to be appropriately modeled at the numerical wave model resolution. 2. Simulate incident wave transformations over the schematic atoll bathymetry using Delft3D-Wave (SWAN). The incident waves were kept constant at 3 m significant wave height, 10 s period, and coming from 0 degrees north. This process was repeated for each different bathymetry and each selected sea-level rise scenario (varying between 0 to +2 m). 3. Extract wave conditions along shore at each model output point nearshore, here defined as the model output point just offshore of a non-inundated model cell. 4. Use the Coastal Engineering Research Center sediment transport formula (e.g., Ashton and Murray, 2006 and Adams et al., 2011) to determine the sediment transport at each alongshore point, defining the alongshore sediment transport gradient. Calculate the divergence of the alongshore sediment transport to determine locations where the shoreline is eroding or accreting. 5. Use a low-pass filter to smooth the inputs into the CERC equation and the Erosion outputs to remove highly local trends that are generated by the model resolution and rectilinear nature. Sum the erosion/accretion values for each shoreline of the atoll island in question (Ocean-facing, lagoon-facing, or the longitudinal ends) to determine the next erosion or accretion for each shoreline type for each island for each morphology and sea-level rise scenario. 2018 Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. 20201019 U.S. Geological Survey VeeAnn A. Cross Marine Geologist Mailing and Physical

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Woods Hole MA 02543-1598 508-548-8700 x2251 508-457-2310 vatnipp@usgs.gov Performed minor edits to the metadata to correct typos. No data were changed. 20211013 U.S. Geological Survey Susan A. Cochran Geologist Mailing and Physical

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Santa Cruz CA 95060 831-460-7545 scochran@usgs.gov The model results presented are not for a particular geographic area. netCDF files are self-contained and attribute information may be found in the file itself. The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information. U.S. Geological Survey - ScienceBase Mailing and Physical

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Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov Zip file (Atoll_Schematic_NetCDFs.zip) contains output of model simulations in NetCDF format. Please read the accompanying Atoll_Schematic_NetCDFs_README.TXT file, which describes the naming convention and contents of the NetCDF files. 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. netCDF MATLAB R2018b Zip file contains model data in netCDF format. No compression applied 1152 https://www.sciencebase.gov/catalog/file/get/5be5f849e4b0b3fc5cf8c9ab?name=Atoll_Schematic_NetCDFs.zip https://doi.org/10.5066/P9U28JFO Files can be downloaded using the Network_Resource_Name links. The first link will begin a direct download of the NetCDF data. The second link points to a landing page with the data, metadata, and a README file. text TextEdit 1.13 text file that describes the accompanying NetCDF files No compression applied 0.089 https://www.sciencebase.gov/catalog/file/get/5be5f849e4b0b3fc5cf8c9ab?name=Atoll_Schematic_NetCDFs_README.txt https://doi.org/10.5066/P9U28JFO Files can be downloaded using the Network_Resource_Name links. The first link will begin a direct download of the README file. The second link points to a landing page with with data, metadata, and the README file. None. 20211013 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