| Description |
This data release contains foreshore slopes for primarily open-ocean sandy beaches along the United States portion of the Gulf of Mexico (Texas through Florida). The slopes were calculated while extracting shoreline position from lidar point cloud data collected between 2001 and 2018. The shoreline positions have been previously published, but the slopes have not. An alongshore reference baseline was defined, and then 20-meter spaced cross-shore beach transects were created perpendicular to the baseline. All data points within 1 meter (alongshore) of each transect were associated with that transect. For each transect, the points on the foreshore were identified, and a linear regression was fit through the foreshore points. Beach slope was defined as the slope of the regression. The regression was evaluated at the elevation of mean high water (MHW) to yield the cross-shore location of the shoreline. In areas where more than one lidar survey is available, the slopes from each survey are provided. Most of the slopes are for sandy beaches, but some transects cross seawalls or other structures that cause steeper slopes. The slope data files (slopeData_GulfCoast.csv and slopeData_GulfCoast.shp) contain beach slope, the location at which the beach slope data were calculated (the shoreline position), and the estimated uncertainty of the shoreline position. The reference line data files (referenceLine_GulfCoast.csv and referenceLine_GulfCoast.shp) contain information about the reference baseline, the cross-shore transects, and the MHW values used to estimate the shoreline location. Both file types *.csv (ascii files containing comma separated values) and *.shp (binary files supported by Esri known as shapefiles) contain the same information. Both file types are provided as a convenience to the user. [More]
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