Greg Desmond 2003 Reston, VA U.S. Geological Survey http://sofia.usgs.gov/projects/elev_data/ The U.S. Geological Survey (USGS) is coordinating the aquisition of high accuracy elevation data. Three formats of the data are available for each data set: .cor files which contain complete lists of Global Positioning System point files, .asc files which are the same as the .cor files but have been reformatted to process into ARC/INFO coverages, and .e00 files which are the ARC/INFO coverages. The files are available in the same 7.5- by 7.5-minute coverages as USGS quadrangles. The elevation data is collected on a 400 by 400 meter grid. The elevations are referenced to the horizontal North American Datum of 1983 (NAD83) and vertical North American Vertical Datum of 1988 (NAVD88). This project is performing regional topographic surveys to collect and provide elevation data to parameterize hydrologic and ecological numerical simulation models that are being developed for ecosystem restoration activities. Surveying services are also being rendered to provide vertical reference points for numerous water level gauges. 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. 1995 Unknown ground condition In Work As needed -81.375 -80.125 26.75 25.125 none High accuracy elevation data mapping digital elevation data DEM elevation ISO 19115 Topic Category elevation imageryBaseMapsEarthCover 006 010 Department of Commerce, 1995, Countries, Dependencies, Areas of Special Soverignty, and Their Principal Administrative Divisions, Federal Information Processing Standard (FIPS) 10-4, Washington, D.C., National Institute of Standards and Technology United States US U.S. Department of Commerce, 1987, Codes for the identification of the States, the District of Columbia and the outlying areas of the United States, and associated areas (Federal Information Processing Standard 5-2): Washington, D. C., NIST Florida FL Department of Commerce, 1990, Counties and Equivalent Entities of the United States, Its Possessions, and Associated Areas, FIPS 6-3, Washington, DC, National Institute of Standards and Technology Broward County Collier County Miami-Dade County Monroe County USGS Geographic Names Information System Alligator Bay Andytown Big Boy Lake Black Hammock Big Lostmans Bay Blackwater Sound Chekika Island Chokoloskee Cooper City SW Coopertown Custard Apple Hammock East of Lone Palm Head Fifty Mile Bend Flamingo Forty Mile Bend Gator Hook Swamp Glades Goulds Grossman Hammock Harney River Hialeah SW Homestead Horseshoe Head Indian Camp Creek Joe Bay Lake Ingraham East Lake Ingraham West Long Island Long Pine Key Lostmans River Ranger Station Lostmans Trail Madeira Bay Mahogany Hammock Melaleuka Head Monroe Station North of Forty Mile Bend Ochopee Pa-Hay-Okee Lookout Tower Panther Mound Pavillion Key Pennsuco Perrine Royal Palm Ranger Station Royal Palm Ranger Station SE Shark Point Shark River Island Shark Valley Lookout Tower South of Coopertown South of Deem City Tarpon Bay Taylor Slough West Lake Whitewater Bay East Whitewater Bay West Big Lake West of Big Lake Coral Springs NE Fifty Mile Bend Gator Lake Greenacres City Lone Palm Head Loxahatchee Loxahatchee NW Loxahatchee SE Loxahatchee SW University Park West of Pennsuco none Central Everglades South East Coast SW Big Cypress none None. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data. Greg Desmond U.S. Geological Survey Project Chief mailing address

521 National Center

Reston VA 20192 USA 703 648 4728 703 648 4165 gdesmond@usgs.gov 8:30-4:30 ET M-F http://sofia.usgs.gov/exchange/desmond/demplot.jpg Plot of DEM data produced at 30 meter grid spacing JPEG http://sofia.usgs.gov/exchange/desmond/statusmap-big.jpg status map for elevation data JPEG GPS data converted to DEM's and ARC/INFO coverages by Vince Caruso. Data collection done by Charles Henkel, Gordon Shupe, Bob Glover, Ed Cyran, and Greg Desmond of the USGS and contractors. .cor comma delimited ASCII text file >.asc ASCII text file reformatted to process into ARC/INFO coverage >.e00 ARC/INFO coverage not available The following data sets have missing files: 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. Horizontal positions are established by GPS observations and are referenced to the North American Datum of 1983 (NAD83). The desired horizontal accuracy is +/- 15 centimeters. This level of accuracy is consistent with GPS differential techniques which use two stations - a high-quality dual-frequency GPS receiver base station and a roving GPS station. The density and accuracy of a given GPS data observation varies from a few meters to a few centimeters according to the Position Dilution of Precision (PDOP) in the study area. Generally if the PDOP is observed to be excessive, data collection is discontinued or the data are discarded. The PDOP is an indicator of the positional accuracy of the GPS that be can derived from the current GPS satellite geometry, which varies continuously. Generally the smaller the PDOP number, the higher the data quality. The PDOP is a permanent part of the recorded data and is also included in the post processing procedures during reduction of the GPS observations to NAD 83. Where possible, the GPS base station has an ellipsoid height to an accuracy of two centimeters relative to the Continuously Operating Reference Stations (CORS) or the High Accuracy Reference Network (HARN), both operated by the National Geodetic Survey (NGS). For all elevation data the vertical accuracy specification is +/- 15 centimeters and is referenced to NAVD 1988. 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. The process consists of the following steps: 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. Unknown Vince Caruso U.S. Geological Survey mailing address

521 National Center

Reston VA 20192 USA 703 648 4586 703 648 4614 vcaruso@usgs.gov South Florida - Everglades Raster Point Universal Transverse Mercator 17 0.9996 -81 0 500000 0 Coordinate Pair 400 400 meters North American Datum of 1983 Geodetic Reference System 80 6378137 298.257 North American Vertical Datum of 1988 .01 meters Explicit elevation coordinate included with horizontal coordinates Roy Sonenshein U.S. Geological Survey Database Manager mailing address

9100 NW 36th Street Suite 107

Miami FL 33178 USA 305 717-5824 305 717-5801 sunshine@usgs.gov High accuracy elevation data No warrantees are implied or explicit for the data ARCE 7.0 .e00 export-formatted interchange file in ASCII for input into ARC/INFO and ArcView 1 http://sofia.usgs.gov/exchange/desmond/desmondelev.html Log onto http://sofia.usgs.gov ASCII 1985 .asc comma delimited complete list of Global Positioning System (GPS) points 0.1 http://sofia.usgs.gov/exchange/desmond/desmondelev.html Log onto http://sofia.usgs.gov ASCII 1985 .cor complete list of GPS points reformatted to process into ARC/INFO 0.2 http://sofia.usgs.gov/exchange/desmond/desmondelev.html Log onto http://sofia.usgs.gov none 20041027 Jo Anne Stapleton U.S. Geological Survey mailing address

521 National Center

Reston VA 20192 USA 703 648-4592 703 648-4614 jastapleton@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998