Pamlico Sound, NC (S020) Bathymetric Digital Elevation Model(30 meter resolution) Derived From Source Hydrographic SurveySoundings Collected by NOAA

Bathymetry for Pamlico Sound was derived from Sixty-five surveyscontaining 648,402 soundings. Nine older, overlapping, less accuratesurveys were entirely omitted before tinning the data. The overlapfrom eight older, less accurate surveys was omitted prior totinning. The average separation between soundings was 104 meters.Ten surveys in the southwest dated prior to 1900. The remainingfifty-five surveys used dated from 1913 to 1980. The total rangeof sounding data was 0.3 meters to -21 meters at mean low water. Meanhigh water values between 0.1 and 0.6 meters were assigned to the shoreline.Twelve points were found that were not consistent with the surrounding data.These were removed prior to tinning. DEM grid values outside theshoreline (on land) were assigned null values (-32676).Update 2 (10/31/00): Seven additional surveys collected prior to 1900 havebeen digitized and have been included in the new update. These surveys were inthe Pamlico River and at the mouth of the Neuse River, as well as theWysocking Bay region. The previous update corrected an error in one of thehydro-graphic surveys where feet were registered as fathoms. Thesesoundings were near the mouth of the estuary. No soundings of greater than21 meters should be present within Pamlico Sound.A vector file delineating the regions were data are inadequate for quality 30mbathymetry have been included in the Zipped files in both Mapinfo [MIF] andArcView [SHP] formats.NOTE: These updated DEMs are NOT available for the 3 arc second version.Pamlico Sound has seventy-eight 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.