San Antonio Bay, TX (G290) Bathymetric Digital Elevation Model (30 meter resolution) Derived From Source Hydrographic Survey Soundings Collected by NOAA

Bathymetry for San Antonio Bay was derived from five surveys containing 32,829 soundings. Two older, overlapping, less accurate surveys were deleted before tinning. The average separation between soundings was 134 meters. The five surveys used dated from 1934 and 1935. The range of soundings was 0.2 meters to -12.2 meters at mean low water. Mean high water values between 0.2 and 0.4 meters were assigned to the shoreline. No points were edited out of the data set. DEM grid values outside the shoreline (on land) were assigned null values (-32676). San Antonio Bay has twelve 7.5 minute DEMs and a single one degree DEM. The 1 degree DEMs were generated from the higher resolution 7.5 minute DEMs which covered the estuary. A Digital Elevation Model (DEM) contains a series of elevations ordered from south to north with the order of the columns from west to east. The DEM is formatted as one ASCII header record (A- record), followed by a series of profile records (B- records) each of which include a short B-record header followed by a series of ASCII integer elevations (typically in units of 1 centimeter) per each profile. The last physical record of the DEM is an accuracy record (C-record). The 7.5-minute DEM (30- by 30-m data spacing) is cast on the Universal Transverse Mercator (UTM) projection. It provides coverage in 7.5- by 7.5-minute blocks. Each product provides the same coverage as a standard USGS 7.5-minute quadrangle but the DEM contains over edge data. Coverage is available for many estuaries of the contiguous United States but is not complete.