Terrebonne/Timbalier Bays, LA (G210) Bathymetric DigitalElevation Model (30 meter resolution) Derived From SourceHydrographic Survey Soundings Collected by NOAA

Bathymetry for Terrebonne/Timbalier Bays was derived from twelve surveyscontaining 94,975 soundings. No surveys were omitted. The averageseparation between soundings was 115 meters. The surveys used dated from1934 and 1935. The soundings ranged from 0.3 meters to -16.8 meters at meanlow water. Mean high water values of 0.4 and 0.5 meters were assigned to theshoreline. Six points were found that were not consistent with the surroundingdata. These were removed prior to tinning. DEM grid values outside the shoreline (on land) wereassigned null values (-32676).Terrebonne/Timbalier Bays have twenty-three 7.5 minute DEMs and twoone degree DEMs. The 1 degree DEMs were generated from the higherresolution 7.5 minute DEMs which covered the estuary. A DigitalElevation Model (DEM) contains a series of elevations ordered fromsouth to north with the order of the columns from west to east. TheDEM is formatted as one ASCII header record (A- record), followed bya series of profile records (B- records) each of which include ashort B-record header followed by a series of ASCII integerelevations (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 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.