|Home||Archived October 29, 2018||(i)|
The South landscape unit (representing approximately the southern third of WCA1) was further divided into two zones (east and west, termed "Southeast" and "Southwest") based on marked changes in slope and aspect data generated from a DEM of the South landscape unit as a whole. Division of WCA1 into 4 zones reduces errors estimated by comparing DEM modeled water depths with those measured by EDEN Principal Investigators in the field. Subdivision of the South landscape unit into east and west zones resulted in lower error estimates for the Southeast zone without significantly affecting (i.e., improving or degrading) the quality of the Southwest zone - an area where DEM modeling is most challenging. To reduce artificial breaks in elevation along WCA1 subarea boundaries, models were overlapped by 1 cell at these boundaries and, for the North, Central and South zone boundaries, overlapping model values were averaged. For the boundaries between the Southwest and Southeast zones, cell values were "blended" based on weighted distance from the boundary edge. Finally, points along the North / Central and Central / South zone edges were subjectively selected and changed by adding or subtracting 0.03 meters (3 cm) to particular cells based on nearby cell values. This slightly reduces apparent artifacts without drastically affecting the integrity of the model. The EDEN offers a consistent and documented dataset that can be used to guide large-scale field operations, to integrate hydrologic and ecological responses, and to support biological and ecological assessments that measure ecosystem responses to the Comprehensive Everglades Restoration Plan. To produce historic and near-real time maps of water depths, the EDEN requires a system-wide DEM of the ground surface.
U.S. Geological Survey, 201001, Everglades Depth Estimation Network (EDEN) January 2010 Digital Elevation Model (DEM).
Planar coordinates are encoded using Row and Column
Abscissae (x-coordinates) are specified to the nearest 400
Ordinates (y-coordinates) are specified to the nearest 400
Planar coordinates are specified in meters
The horizontal datum used is North American Datum of 1983.
The ellipsoid used is Geodetic Reference System 80.
The semi-major axis of the ellipsoid used is 6378137.
The flattening of the ellipsoid used is 1/298.257.
703 648-5543 (voice)
703 648-4165 (FAX)
These data were specifically created for the development of water depth information using interpolated water surfaces from the EDEN stage data network.
To create a realistic region-wide elevation model for EDEN purposes, the elevation data were segregated by Water Conservation Areas and National Park boundaries so that local trends could be isolated, sub-region specific interpolation models could be developed, and realistic breaks in elevation along sub-region boundaries could be imbedded in a final, region-wide DEM.
For the previous release of the DEM, subarea DEMs were produced using the geostatistical approach called "anisotropic ordinary kriging". This version is composed of new models created for each new EDEN subarea in Water Conservation Area 1 (WCA1) and for the new coverage in the southern portion of BCNP and the northwest corner of the ENP. For the latest iteration of the EDEN DEM "anisotropic universal kriging" was employed.
As with the previously released DEM, WCA1 surfaces were produced by removing all "upland" AHF points. However, in this version WCA1 "upland" was defined through a reclassification of the South Florida Water Management Vegetation Map rather than the Florida GAP map.
As the most challenging area from an elevation modeling standpoint, for this revision WCA1 was further subdivided into a total of 4 zones. First, boundaries between the North, Central and two South zones are based upon landscape units defined through the CERP Monitoring and Assessment Plan, Part 1 (Figure 3-20). Then the South landscape unit (representing approximately the southern third of WCA1) was further divided into two zones (east and west, termed "Southeast" and"Southwest") based on marked changes in slope and aspect data that were generated from a DEM of the South landscape unit as a whole. Division of WCA1 into 4 zones reduces errors estimated by comparing DEM modeled water depths with those measured by EDEN Principal Investigators in the field. Subdivision of the south landscape unit into east and west zones resulted in lower error estimates for the Southeast zone without significantly affecting (i.e., improving or degrading) the quality of the Southwest zone - an area where DEM modeling is most challenging.
A previously omitted area in the southern portion of the Big Cypress National Preserve (BCNP) and the northwestern corner of the Everglades National Park (ENP) has been filled.
Person who carried out this activity:
703 648-5543 (voice)
703 648-4165 (FAX)
Telis, Pamela, 2006, The Everglades Depth Estimation Network (EDEN) for support of ecological and biological assessments: USGS Fact Sheet 2006-3087, U.S. Geological Survey, St. Petersburg, FL.
Jones, J. W., 2001, Image and in situ data integration to derive sawgrass density information for surface-flow modeling in the Everglades: International Association of Hydrological Sciences, Wallingford, Oxfordshire, UK.
Desmond, G. B., 2003, Measuring and mapping the topography of the Florida Everglades for Ecosystem Restoration: USGS Fact Sheet 021-03, U.S. Geological Survey, Reston, VA.
U.S> Army Corps of Engineers, 2004, RECOVER: Monitoring and Assessment Plan (MAP) 2004 Greater Everglades Wetlands Module: U.S. Army Corps of Engineers, Jacksonville, FL.
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).
Source data (HAED) collected to better than +/- 15cm. Standard errors of cross-validation for the DEM range from ~7cm to ~21cm depending on the EDEN subarea.
Ground-surface elevation data were collected by the USGS at more than 50,000 points with an approximate spacing of 400 meters covering almost the entire Greater Everglades. The EDEN water-level network consists of hourly water-level data from 253 gaging stations (230 existing gaging stations and 23 new installations) and includes freshwater (nontidal) marsh gaging stations, boundary gages on canals, and coastal gaging stations operated by the Big Cypress National Preserve (BCNP), Everglades National Park (ENP), South Florida Water Management District (SFWMD), and USGS. The U.S. Army Corps of Engineers (USACE) and SFWMD recently documented or surveyed a majority of the hydrologic gages in the Greater Everglades to obtain correct values for converting water-level data from NGVD 29 to NAVD 88. The NAVD 88 datum is consistent in comparing water-level data across the Greater Everglades and computing accurate water depths.
The EDEN monitoring network includes ground-elevation measurements and continuous water-level data.
Are there legal restrictions on access or use of the data?
- These data were produced for EDEN operational water depth estimation and applications.
- The user is cautioned that this elevation model was produced specifically for EDEN applications and is based on input data of approximately 400m sample spacing and +/- 15cm vertical accuracy. No statement of appropriateness for uses other than that intended are implied.
727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)
No warrantees are implied or explicit for the data
|Data format:||zipped file of ArcINFO .e00 grid interchange format in format ARCG (version ArcGIS 9.1) .zip Size: 0.5|
|Data format:||The files contain pdf versions of the the EDEN DEM of January 2010 - one for a quick view and a second for print-quality in format Adobe PDF|
727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)
|Home||Archived October 29, 2018|