Modeling of sheet flow and water surface levels in the wetlands of South Florida is very sensitive to changes in elevation due to the expansive and extremely low relief terrain. Hydrologists have determined minimum vertical accuracy requirements for the elevation data for use as input to hydrologic models. As a result, elevation data with a vertical accuracy specification of +/-15 centimeters (cm) relative to the North American Vertical Datum of 1988 (NAVD88) are being collected in critical areas using state-of-the-art differential global positioning system (GPS) technology and data processing techniques.
.cor comma delimited ASCII text file .asc ASCII text file reformatted to process into ARC/INFO coverage .e00 ARC/INFO coverage
Goulds missing .e00 file Homestead missing .cor file Pennsuco missing .cor file Perrine missing .asc file
The remianing data sets all have .asc, .cor, and .e00 files.
This elevation data is intended primarily for use in hydrological modeling. It is collected as high accuracy, "bare earth" ground elevation. That is, the data are restricted to ground elevations only. "Bare earth" in the Everglades swamp environment is generally considered to be the layer of "muck" which will support a one pound weight on a bearing surface of approximately 5.3 square inches (2.6 inch circle). In non-swamp areas it is actual bare ground.
1. Collection of GPS XYZ points in and around the Everglades swamp and environs using the helicopter-based Airborne Height Finder (AHF) developed by the USGS. Additional elevation data were acquired through contracted professional surveying services.
2. The GPS data is processed into an ASCII list of coordinates in column order of Point number and/or descriptor attribute data (maximum of 20 characters), NAD83 geographic XY coordinates, and NAVD88 elevation Z value. This file is transformed through NADCON (a conversion program available from the National Geodetic Survey, NGS) to NAD83 UTM XY and NAVD88 Z coordinates. The file is output as an ASCII text file and transferred on-site Reston, VA to a file server/ mass storage device.
3. The coordinates are then processed into an ARC INFO POINT COVER format. An annotation file is created and appended to the POINT cover file for the tabular elevation value of meters to the decimal value of 100th of meter (centimeter). This annotation value is later used to create the illustrated large area point plot file in GEO TIFF format.
4. The POINT cover is then transformed to other final distribution formats.
a. The POINT cover is exported into ARC/INFO Exchange Format (.e00) and transferred to a file server/mass storage device.
b. The POINT cover is used as input to ARC TOPOGRID to create the ARC GRID elevation file.
c. The ARC GRID cover is then used as input to ARC GRIDPAINT in combination with a color ramp and color map file to create the illustrated pseudo-color elevation plot.
Suite 107
U.S. Department of the Interior, U.S. Geological Survey, Center for
Coastal Geology
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