Physics-based numerical model simulations of wave propagation over and around theoretical atoll and island morphologies for sea-level rise scenarios
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.
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Shope, James B., and Storlazzi, Curt D., 2019, Physics-based numerical model simulations of wave propagation over and around theoretical atoll and island morphologies for sea-level rise scenarios: data release DOI:10.5066/P9U28JFO, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.
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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.
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.
Date: 19-Oct-2020 (process 2 of 3)
Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.
Person who carried out this activity:
U.S. Geological Survey
Attn: VeeAnn A. Cross
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Date: 13-Oct-2021 (process 3 of 3)
Performed minor edits to the metadata to correct typos. No data were changed.
Person who carried out this activity:
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.
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What's the catalog number I need to order this data set?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.
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