Greg Desmond 200710 text files, shapefiles http://sofia.usgs.gov/exchange/desmond/desmondelev.html The High Accuracy Elevation Data Project collected elevation data (meters) on a 400 meter topographic grid with a vertical accuracy of +/- 15 centimeters to define the topography in South Florida. The data are referenced to the horizontal datum North American Datum 1983 (NAD 83) and the vertical datum North American Vertical Datum 1988 (NAVD 88). In some areas, the surveying was accomplished using airboats. Because access was a logistical problem with airboats, the USGS developed a helicopter-based instrument known as the Airborne Height Finder (AHF). All subsequent data collection used the AHF. Data were collected from the Loxahatchee National Wildlife Refuge, south through the Water Conservation Areas (1A, 2A, 2B, 3A, and 3B), Big Cypress National Park, the Everglades National Park, to the Florida Bay. The data are available for the areas shown on the USGS High Accuracy Elevation Data graphic at http://sofia.usgs.gov/exchange/desmond/desmondelev.html. The work was performed for Everglades ecosystem restoration purposes. The data are from 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 were also 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 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) were collected in critical areas using state-of-the-art differential global positioning system (GPS) technology and data processing techniques. 1995 2007 ground condition Complete As needed -81.5 -80.125 26.75 25.125 none High accuracy elevation data mapping digital elevation data DEM ISO 19115 Topic Category elevation 006 Department of Commerce, 1995, Countries, Dependencies, Areas of Special Sovereignty, and Their Principal Administrative Divisions, Federal Information Processing Standard (FIPS) 10-4, Washington, DC, 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, DC, 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 none South East Coast SW Big Cypress Cooper City SW Coral Springs NE East of Deem City East of Lone Palm Head Hialeah SW Lake Ingraham East Lake Ingraham West Loxahatchee NW Loxahatchee SE Loxahatchee SW North of Fortymile Bend Royal Palm Ranger Station SE South of Coopertown South of Deem City West of Big Lake West of Deem City West of Pennsuco Whitewater Bay East Whitewater Bay West Cooper City NE Monroe Station NE North of Deem City North of Fiftymile Bend North of Lone Palm Head South Miami NW West of Horseshoe Head Central Everglades USGS Geographic Names Information System Andytown Big Boy Lake Big Lostmans Bay Black Hammock Blackwater Sound Chekika Island Chokoloskee Coopertown Custard Apple Hammock Fiftymile Bend Flamingo Fortymile Bend Gator Hook Swamp Glades Grossman Hammock Harney River Homestead Horseshoe Head Indian Camp Creek Joe Bay Long Island Long Pine Key Lostmans River Ranger Station Lostmans Trail Madeira Bay Mahogany Hammock Melaleuka Head Monroe Station Ochopee Pa-Hay-Okee Lookout Tower Panther Mound Pavillion Key Pennsuco Royal Palm Ranger Station Shark Point Tarpon Bay Taylor Slough West Lake Shark River Island Shark Valley Lookout Tower Big Lake Gator Lake Greenacres City Lone Palm Head Loxahatchee University Park California Slough Deem City Everglades City Plover Key Sandy Key Weavers Station West Dixie Bend Alligator Bay none None. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data. Bob Glover U.S. Geological Survey mailing address

521 National Center

Reston VA 20192 USA 703 648-5056 rglover@usgs.gov http://sofia.usgs.gov/exchange/desmond/desmondelev.html map showing water conservation areas and greater Everglades region GIF http://sofia.usgs.gov/exchange/desmond/atlas/ map showing topographic quadrangles in the water conservation areas and greater Everglades region GIF Data collection done by Charles Henkle, Gordon Shupe, Bob Glover, Ed Cyran, and Greg Desmond of the USGS and contractors. Other project personnel include Vince Caruso, Gary Freeman, and Susan Price. compressed ArcGIS shapefile (.zip), comma-separated value file (.csv), and compressed .csv (.zip) The Grossman Hammock and Perrine quadrangles have helicopter AHF & airboat and truck data All verified and accepted data points are included in the files for the area 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 for creating digital elevation files consisted of the following steps: 1. Collection of GPS XYZ points in and around the Greater Everglades Region from the Water Conservation Areas (1A, 2A, 2B, 3A, and 3B), Big Cypress National Preserve, the Everglades National Park, to the Florida Bay, and environs using the following collection platforms: airboat and helicopter-based Airborne Height Finder (AHF) developed by the USGS. 2. The GPS data were transformed from NAD83 geographic X, Y coordinates and NAVD88 elevation Z valuse to NAD83 UTM X, Y and NAVD88 Z coordinates via "Corpscon for Windows" from the U.S. Army Corps of Engineers. http://crunch.tec.army.mil/software/corpscon/corpscon.html 3. The coordinate data were imported into a geographic information system to create multiple geospatial data formats. 4. Multiple formats of the data were posted to the SOFIA website. 5. This process was repeated for each quad-based file of data collected by the surveyors during the 12 year life of the project. 6. The ASCII text files containing more than 50,000 data records were aggregated and reformatted using custom shell scripts. These data were imported into ArcGIS (version 9.1) to create the the shapefile HAED_v01.shp available for download. 7. The associated .dbf files were opened in MS Excel and saved as the comma-separated values files which also are available for download. 200708 Susan D. Price U.S. Geological Survey mailing address

521 National Center

Reston VA 20192 USA 703 648 6692 sprice@usgs.gov Water Conservation areas and greater Everglades region Vector Entity point 57395 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 ELEV_M ground surface elevation in meters USGS X_UTM X UTM coordinate in meters for the data collection point USGS Y_UTM Y UTM coordinate in meters for the data collection point USGS QUAD_NAME The name of the USGS 1:20,000-scale topographic quadrangle in which the point falls USGS VEG_FS The vegetation observed by the surveyor at the data collection point. Vegetation types include Alligator Hole, Broadleaf Emergent, Cattail, Cypress, Floating Emergent, Hardwood, Lygodium, Melaleuca, Open Water, Palmetto, Pine, Sawgrass, Shrub, Slough, Tree Island, Wet Prairie, Wet Prairie/Slough, and Willow Shrub USGS SUR_METHOD type of surveying method USGS AHF Airborne Height Finder - a helicopter-based instrument used to access data points USGS AHF airboat data collected using an airboat to access data points USGS airboat SUR_INFO Characters 1-5 are the file name used by the surveyor during data collection. Characters 6-8 are the Julian date of the data collection. Characters 9-10 are the year the data were collected. Character 11 is a blank space. Characters 12-19 represent the date the data were released for publication and archive after the data have been collected, processed, edited, quality controlled, and approved for release. Character 20 is "Y" which means the data can be released. This is not the date the data were collected. During the 12 year lifetime of the project, data points were released as individual files (see SUR_FILE attribute) to match the published USGS 7.5-minute topographic quadrangle footprint. If new data were added to the quadrangle, the revision date was modified for ALL points in the quadrangle to reflect the latest revision date. At the completion of data collection, the individual quad-based files were aggregated to create the larger files now available for download USGS SUR_FILE file name used by the surveyor for internal data management purposes USGS Heather S.Henkel U.S. Geological Survey mailing address

600 Fourth St. South

St. Petersburg FL 33701 USA 727 803-8747 ext 3028 727 803-2030 hhenkel@usgs.gov helicopter & airboat No warrantees are implied or explicit for the data ASCII 1985 csv comma-separated values for the elevations in map area 2 4.5 http://sofia.usgs.gov/exchange/desmond/desmondelev.html File amy be downloaded form the SOFIA website zip unknown csv.zip comma-separated values for elevations in map area 2 file must be unzipped before use 0.7 http://sofia.usgs.gov/exchange/desmond/desmondelev.html File may be downloaded from the SOFIA website zip unknown shp.zip ArcGIS shapefiles and associated files for map area 2 file must be unzipped before use 1.7 http://sofia.usgs.gov/exchange/desmond/desmondelev.html File may be downloaded from the SOFIA website none 20071024 Heather Henkel U.S. Geological Survey mailing and physical address

600 Fourth Street South

St. Petersburg FL 33701 USA 727 803-8747 ext 3028 727 803-2030 sofia-metadata@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998