Mobile Bay, AL (G150) Bathymetric Digital Elevation Model (30meter resolution) Derived From Source Hydrographic Survey SoundingsCollected by NOAA

Bathymetry for Mobile Bay was derived from twenty-three surveys containing173,661 soundings. Older, overlapping, less accurate surveys were deleted.The average separation between surveys was 79 meters. The surveys used datedfrom 1960 to 1962. The range of soundings for the surveys was 0.6 metersto -32.9 meters at mean low water. Mean high water values between 0.3 and0.5 meters were assigned to the shoreline. Nine points were found thatwere not consistent with the surrounding data. These were removed prior totinning. DEM grid values outside the shoreline (on land) were assigned nullvalues (-32676).Mobile Bay has eighteen 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.