Aaron Higer
The EDEN network provides a framework to integrate data collected by other agencies in a common quality-assured database. In addition to real-time network, collaboration among agencies will provide the EDEN project with valuable historic vegetation and water-depth data. This is the first time these data have been compiled and analyzed as a collective set.
Price, Susan D.
Price, Susan D.
Higer, Aaron; palaseanu, Monica; Fujisaki, Ikuko; Mazzotti, Frank
1. Water-level data for all the EDEN gages is retrieved from an ftp server 2. Water-level data reported in NGVD 29 are converted to NAVD 88 3. Daily median water level is calculated 4. Linear interpolation is used to create boundary conditions along canals and levees 5. Radial Bias Function multiquadric interpolation of extended data (median water level from gages in marsh and interpolated values along canals) is used to generate continuous water level surfaces daily 6. The continuous water surface is predicted on the EDEN grid (400m x 400m) 7. Water depth is estimated by subtracting the EDEN ground digital elevation model (DEM) from the predicted water surface
The USGS retrieves water level data daily from 253 gaging stations including 225 telemetry-enhanced gages that record and transmit several water level values throughout the day, most hourly from recorders ranging from approximately 81 deg, 07 min 19 sec to 80 deg 13 min 05 sec West and from 25 deg 13 min 27 sec to 26 deg 40 min 47 sec North. An additional 28 gages do not have telemetry and are manually read and added to the network. All transmitted data are entered and stored in the National Water Information System (NWIS), a database operated by the USGS. There are a total of 240 gages used for water surface interpolation of the freshwater Everglades.
All gages in the EDEN network are operated and maintained by four separate agencies including Everglades National Park, South Florida Water Management District, Big Cypress National Preserve, and the USGS.
Water-level gaging stations have been surveyed, until recently, to the National Geodetic Vertical Datum of 1929 (NGVD 29); however, this datum has inconsistencies in the vertical network that have never been resolved for southern Florida. 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 the North American Vertical Datum of 1988 (NAVD 88). These and other data provided by BCNP and ENP have been used to create datum-correction values for the EDEN network gages, allowing historic water-level data to be converted from NGVD 29 the NAVD 88.
Three methods were used to determine the correcton for a gaging station: 1. Differential or basic Global Positioning System (GPS) - a highly accurate satellite-based surveying system 2. Optical survey - a traditional line-of-sight survey from points of known elevation; and 3. CORPSCON 1 version 6.0 - a program that interpolates the difference between ground elevation in NAVD 88 and NGVD 29 for a given location specified by latitude and longitude, and further refined by using the VERTCON version 2.5 grid modified by USACE Jacksonville District to incorporate the CERP vertical control network established in 2001-2002.
The Water Surfaces data in NetCDF has the following attributes: Creation Date, Conventions (version), Source (what software was used to write the file), Layer name, spatial reference (UTM Zone), Datum, Spheroid, Prime Meridian, Angular Units, Projection, Linear Units, False Easting, False Northing, Central Meridian, Scale Factor, Latitude of Origin, Grid Mappping Units, Starting Date (for the data), and Time Step Units. The data are also available as Geotiff files. The Daily Median Output Files contain 3 months of daily datsets. There are two files for each day: a "median" and a "median_reject". The "median" file is the one that was used to create the surface for a given day, the "median_reject" file contains a list of the gages not used for that day.
The Water Level (Gage) data for each area have a graphic showing the location of the gages and whether they are real time or non-real time and a list of the stations in each area. The information for each station includes station information, data links, data information, ground elevation/vegetation, and other information available for the station.
U.S. Department of the Interior, U.S. Geological Survey
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