Projected Seafloor Elevation Along the Florida Reef Tract From Deerfield Beach to Homestead, Florida—50 Years From 2014 Based on Historical Rates of Mean Elevation Change

Step 1: The original Miami 1/3 arc-second NAVD 88 Coastal DEM was downloaded from https://data.nodc.noaa.gov/cgi-bin/iso?id=gov.noaa.ngdc.mgg.dem:5166. The network common data format (netCDF) DEM file was converted to a tagged image file format (TIFF) using Blue Marble Global Mapper version 19.1.0. All remaining steps were completed with Esri ArcGIS Desktop Advanced version 10.6. Using the original TIFF, a footprint of the DEM was created with the "Reclassify (Spatial Analyst)" tool in ArcToolbox by replacing all old data values with 1 and the "No Data" value with 0 to create a raster file. Then, the "Raster to Polygon (Conversion)" tool was used to create a footprint of the original Miami DEM by converting the raster file to a polygon shapefile (SHP).

Step 2: The original Unified Florida Reef Tract Map version 2.0 polygon SHP file was downloaded from http://ocean.floridamarine.org/IntegratedReefMap/UnifiedReefTract.htm. Using Esri ArcGIS, the original habitat SHP file was modified using the "Clip (Analysis)" tool to clip the habitat SHP file to the extent of the original Miami DEM footprint (from Step 1) by specifying the habitat SHP file as the 'Input Features' and the DEM footprint SHP file as the 'Clip Features'. Then Artificial, Land, and Mangrove areas (ClassLv2) were removed from the habitat SHP file using the "Select by Attribute" tool to select the three habitat types and the "Editor Toolbox" to delete them.

Step 3: The original Miami DEM TIFF (from Step 1), was clipped to the extent of the modified habitat SHP file (from Step 2) using the "Clip (Data Management)" tool in Esri ArcGIS by specifying the Miami DEM TIFF as the 'Input Raster' and the modified habitat SHP file as the 'Output Extent'. The clipped TIFF was used to extract two shoreline contours with the "Contour List (Spatial Analyst)" tool by adding 'Contour values' for 0-meter (m) and -0.4 m contours. The shoreline contour SHP file was manually connected across inlets and gaps using the "Straight Segment" tool in the "Editor Toolbox" to draw straight lines between the seaward most points of channels or other breaks along the coastline. The backshore was removed from the contour SHP file by using the "Buffer (Analysis)" tool with a 'Distance Linear unit' of 1000 m. Then the shoreline contour was smoothed with the "Smooth Line (Cartography)" tool using the Polynomial Approximation with Exponential Kernel (PAEK) smoothing algorithm and a 50-m smoothing tolerance. Using the extended contour SHP file, a polygon SHP file was created using the "Feature to Polygon (Data Management)" tool by specifying the contour SHP file as the 'Input Features', to create the Coastal Clip SHP file. The clipped DEM TIFF was modified further using the "Clip (Data Management)" tool to remove coastal land areas by adding the DEM TIFF as the 'Input Raster' and the Coastal Clip SHP file as the 'Output Extent’, creating the Miami_ElevationSurface_OriginalClip TIFF.

Step 4: The clipped habitat SHP file (from Step 2) was modified by removing coastal land areas using the "Clip (Analysis)" tool with the habitat SHP file as the 'Input Features' and the Coastal Clip SHP file (from Step 3) as the 'Clip Features', creating the Miami_Habitat_Clip SHP file.

Step 5: Mean future elevation for each habitat type in the Miami_ElevationSurface_OriginalClip DEM was calculated by applying previously published mean elevation changes in the Upper Florida Keys (UFK) that were projected 50 years into the future from the year 2002 (Yates and others, 2018, https://doi.org/10.5066/P9CI9LNH). Mean projected elevation changes in the UFK were compiled by habitat type into a comma separated values (CSV) file using Microsoft Excel 2016.

Step 6: Using the Miami_Habitat_Clip SHP file, in Esri ArcGIS, individual polygon SHP files were created for each habitat type using the "Select by Attribute" tool and exporting each habitat type as a separate SHP file. Individual DEMs were created from the Miami_ElevationSurface_OriginalClip TIFF using the "Clip (Data Management)" tool to clip the full DEM to the extent of each habitat type SHP file by specifying the Miami_ElevationSurface_OriginalClip as the 'Input Raster' and the habitat type SHP file as the 'Output Extent'. The "Raster Calculator (Spatial Analyst)" tool was used to project future elevation change per habitat type by modifying individual habitat DEMs by adding or subtracting the corresponding 'Mean projected elevation change from 2002 Upper Florida Keys (m)' from the 50_Year_Miami_Seafloor_Projection_MeanElevation CSV file. For habitats present in the Miami_Habitat_Clip SHP file, but not present in the UFK (Dredged/Excavated, Ridge and Tidal Flats), the mean elevation change value for the total UFK study site was applied. Individual habitat DEMs were merged together using the "Mosaic to New Raster (Data Management)" tool with the 'Pixel Type' set to 32_BIT_FLOAT, 'Number of Bands' set to 1 and the 'Mosaic Operator' set to MEAN to create the final 50_Year_Miami_Seafloor_Projection_DEM_MeanElevation TIFF file.

Added keywords section with USGS persistent identifier as theme keyword.