Multibeam Bathymetry Data Collected in 2018 from Grand Bay and Point Aux Chenes Bay Alabama/Mississippi

The U.S Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC) conducted an ellipsoidally referenced survey using a multibeam echosounder within Grand Bay and Point Aux Chenes Bay, Alabama/Mississippi October 22-23, 2018. The survey is bridged between the former Sea level and Storm Impacts on Estuarine Environments and Shorelines project (SSIEES), which focused on the influence of marsh shoreline geometry on erosion and deposition patterns, and the current Estuarine and Marsh Geology Research Project (EMRG) which focuses on evaluating the linkage between marsh shoreline metrics and marsh geology. To facilitate mapping of the eroding marsh edges at locations of interest around the bay, the multibeam echosounder was horizontally tilted 62.5 degrees. This dataset includes the processed elevation point data (x,y,z), as derived from a 1-meter bathymetric grid, in the native format of the World Geodetic System of 1984 (WGS84). The data were transformed horizontally into the North American Datum of 1983 (NAD83) and vertically to the North American Vertical Datum of 1988 (NAVD88), using the GEOID12A model, and these files are also provided.