Shrnutí

Popis

Bathymetry for Ossabaw Sound was derived from eight surveys containing27,653 soundings. No surveys were omitted. The average separationbetween soundings was 56 meters. Seven of the eight surveys dated from1934. The remaining survey, located in the south, dated from 1974. The totalrange of sounding data was 1.8 meters to -17.1 meters at mean low water.Mean high water values between 2.1 and 2.3 meters were assigned to theshoreline. Six points were found that were not consistent with the surroundingdata. These were removed prior to tinning. DEM grid values outside theshoreline (on land) were assigned null values (-32676).Ossabaw Sound has seven 7.5 minute DEMs and two one degree DEMs. The1 degree DEMs were generated from the higher resolution 7.5 minuteDEMs which covered the estuary. A Digital Elevation Model (DEM)contains a series of elevations ordered from south to north with theorder of the columns from west to east. The DEM is formatted as oneASCII header record (A- record), followed by a series of profilerecords (B- records) each of which include a short B-record headerfollowed by a series of ASCII integer elevations (typically in unitsof 1 centimeter) per each profile. The last physical record of theDEM 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.