Cape Fear River, NC (S050) Bathymetric Digital Elevation Model(30 meter resolution) Derived From Source Hydrographic SurveySoundings Collected by NOAA

Bathymetry for the Cape Fear River was derived from seven surveys containing34,390 soundings. No surveys were omitted. The average separationbetween soundings was 54 meters. One survey in the south dated from 1934.The remaining six surveys dated from 1970 to 1975. The total range ofsounding data was 1.0 meters to -17.3 meters at mean low water. Mean highwater values of 1.2 or 1.3 meters were assigned to the shoreline. Five pointswere found that were not consistent with the surrounding data. These were removed prior to tinning.DEM grid values outside the shoreline (on land) were assigned null values (-32676).The Cape Fear River has seven 7.5 minute DEMs and four one degreeDEMs. 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.