High Accuracy Elevation Data - TruckEntry ID: USGS_SOFIA_HAED_truck
Abstract: 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). The High Accuracy Elevation Data Project began with ... a pilot study in FY 1995 to determine if the then state-of-the-art GPS technology could be used to perform a topographic survey that would meet the vertical accuracy requirements of the hydrologic modeling community. The initial testing platform was from a truck and met the accuracy requirements. Data were collected in areas near Homestead, Florida. 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
These data are from topographic surveys to collect and provide elevation data to parameterize hydrologic and ecological numerical simulation models that were 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 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) were collected in critical areas using state-of-the-art differential global positioning system (GPS) technology and data processing techniques.
Data Set Citation
Dataset Originator/Creator: Greg Desmond
Dataset Title: High Accuracy Elevation Data - truck
Dataset Release Date: 2007-10-01T00:00:00.000Z
Version: Not provided
Data Presentation Form: text files, shapefiles
Other Citation Details: Data collection done by C. Henkle, G. Shupe, B. Glover, E. Cyran, and G. Desmond of the USGS. Others include V. Caruso, G. Freeman, and S. Price.Online Resource: http://sofia.usgs.gov/exchange/desmond/desmondelev.html
Start Date: 1995-01-01Stop Date: 1996-12-31
Quality Grossman Hammock and Royal Palm Ranger Station are included in both the helicopter AHF & airboat and truck datasets.
All verified and accepted data points are included in the files for each 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.
Access Constraints None
Use Constraints Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.
Data Set Progress
Distribution Format: Compressed ESRI shapefile (.zip); Comma separated value file (.csv) or (.zip)
Role: TECHNICAL CONTACT
Email: rglover at usgs.gov
521 National Center
Province or State: VA
Postal Code: 20192
Role: METADATA AUTHOR
Email: alicia.m.aleman at nasa.gov
Goddard Space Flight Center Code 610.2
Province or State: MD
Postal Code: 20771
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date: 2007-10-24
Last DIF Revision Date: 2018-07-03