Summary

Description

Bathymetry for Tampa Bay was derived from eighteen surveys containing165,644 soundings. No surveys were omitted. The average separationbetween soundings was 74 meters. The surveys dated from 1945 to 1958 withabout 70 percent from 1957 or 1958. The range of soundings for the eighteensurveys was 3.7 to -23.8 meters at mean low water. Mean high water valuesbetween 0.6 and 0.9 meters were assigned to the shoreline. Fifty-ninepoints, mostly from the same survey, were not consistent with the surroundingdata and were removed prior to tinning. DEM grid values outside theshoreline (on land) were assigned null values (-32676).Tampa Bay has sixteen 7.5 minute DEMs and two one degree DEMs. The 1degree DEMs were generated from the higher resolution 7.5 minute DEMswhich covered the estuary. A Digital Elevation Model (DEM) contains aseries of elevations ordered from south to north with the order ofthe columns from west to east. The DEM is formatted as one ASCIIheader record (A- record), followed by a series of profile records(B- records) each of which include a short B-record header followedby a series of ASCII integer elevations (typically in units of 1centimeter) per each profile. The last physical record of the DEM isan 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.