| St. Marys River/Cumberland Sound, GA/FL (S170) Bathymetric Digital Elevation Model
(30 meter resolution) Derived From Source Hydrographic Survey Soundings Collected
by NOAA |
| Bathymetry for St. Marys River/Cumberland Sound was derived from six surveys containing
36,976 soundings. Five older, overlapping, less accurate surveys were omitted before
tinning the data. The average separation between soundings was 42 meters. The six
surveys used dated from 1934 and 1935. The total range of sounding data was 1.2 meters
to -20.7 meters at mean low water. Mean high water values between 1.8 and 2.1 meters
were assigned to the shoreline. Five points were found that were not consistent with
the surrounding points. These were removed prior to tinning. DEM grid values outside
the shoreline (on land) were assigned null values (-32676). St. Marys River/Cumberland
Sound has five 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. |
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