St. Marys River/Cumberland Sound, GA/FL (S170) BathymetricDigital Elevation Model (30 meter resolution) Derived From SourceHydrographic Survey Soundings Collected by NOAA

Bathymetry for St. Marys River/Cumberland Sound was derivedfrom six surveys containing 36,976 soundings. Five older,overlapping, less accurate surveys were omitted beforetinning the data. The average separation between soundings was42 meters. The six surveys used dated from 1934 and 1935. Thetotal range of sounding data was 1.2 meters to -20.7 meters at meanlow water. Mean high water values between 1.8 and 2.1 meters wereassigned to the shoreline. Five points were found that were notconsistent with the surrounding points. These were removed prior totinning. DEM grid values outside the shoreline (on land) were assignednull values (-32676).St. Marys River/Cumberland Sound has five 7.5 minute DEMs and asingle one degree DEM. The 1 degree DEMs were generated from thehigher resolution 7.5 minute DEMs which covered the estuary. ADigital Elevation Model (DEM) contains a series of elevations orderedfrom south to north with the order of the columns from west to east.The DEM is formatted as one ASCII header record (A- record), followedby a series of profile records (B- records) each of which include ashort B-record header followed by a series of ASCII integerelevations (typically in units of 1 centimeter) per each profile.The last physical record of the DEM is an accuracy record(C-record).The 7.5-minute DEM (30- by 30-m data spacing) is cast on theUniversal Transverse Mercator (UTM) projection. It provides coveragein 7.5- by 7.5-minute blocks. Each product provides the samecoverage as a standard USGS 7.5-minute quadrangle but the DEMcontains over edge data. Coverage is available for many estuaries ofthe contiguous United States but is not complete.