Summary

Description

Bathymetry for Biscayne Bay was derived from twelve surveys containing149,227 soundings. The overlap from three older, less accurate surveys wasomitted before tinning the data. The twelve surveys used dated from 1930 to1993. Approximately 60 percent of the surveys were from 1934. Surveys from1980 to 1993 cover the eastern portion of the bay. The total range of soundingdata was 0.6 meters to -10.4 meters at mean low water. Mean high water valuesbetween 0.1 and 0.6 meters were assigned to the shoreline. Fourteenpoints 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).Biscayne Bay has fifteen 7.5 minute DEMs and a single one degreeDEM. 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.