Summary

Description

Bathymetry for the Broad River was derived from twenty-three surveyscontaining 98,479 soundings. No surveys were omitted. The averageseparation between soundings was 50 meters. Nineteen surveys datedfrom 1931 to 1934. The remaining four surveys, located in thesouthern portion of the river, dated from 1971 to 1974.The total range of sounding data was 1.5 meters to -21.3meters at mean low water. Mean high water values between1.9 and 2.5 meters were assigned to the shoreline. Thirteenpoints were found that were not consistent with the surroundingdata. These were removed prior to tinning. DEM grid values outsidethe shoreline (on land) were assigned null values (-32676).The Broad River has eleven 7.5 minute DEMs and a single one degreeDEM. The 1 degree DEMs were generated from the higher resolution 7.5minute DEMs which covered the estuary. A Digital Elevation Model(DEM) contains a series of elevations ordered from south to northwith the order of the columns from west to east. The DEM isformatted as one ASCII header record (A- record), followed by aseries of profile records (B- records) each of which include a shortB-record header followed by a series of ASCII integer elevations(typically in units of 1 centimeter) per each profile. The lastphysical 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.