Higer, Aaron; palaseanu, Monica; Fujisaki, Ikuko; Mazzotti, Frank
1. Water-level data for all the EDEN gages are 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.
The steps in preparing a daily surface from Everglades stage gaging stations are to collect the gaging station values as daily medians, create boundary conditions along canals/levees, generate the continuous surface using multiquadric radial basis function, and save the output into 400 meter output grids in netCDF and geoTIFF formats.
For each day that the surface is run, values for water stage are obtained from the USGS NWIS server for each gage listed in the EDEN master station list maintained by USGS, St Petersburg, Florida. Median daily values are calculated at each gage and stored in UTM, zone 17, NAD 1983 projection and datum, meter horizontal units. Vertical units are centimeters, NAVD 88. Where gage data is obtained in NGVD 29, it is converted to NAVD 88 using difference values for each gage. The difference values are provided in the EDEN master list.
Median stage values along specific canals are linearly interpolated every 200m between gages and extrapolated up to 3 kilometers beyond a gage when canals extend beyond the last gage. This interpolation/extrapolation will be used in the surfacing process to enforce boundaries at the canals between Everglades water conservation areas. The specific canals and the point locations interpolated/extrapolated in the canals are read from files maintained by USGS, St Petersburg, Florida.
Median stage for the day at each gage and each interpolated/extrapolated canal point location are combined as input for surface interpolation using the radial basis function routine in ArcGIS geostatistical analyst. The parameters are: Kernel Functions: Multiquadric; Parameter = 16.77 Neighbors to Include = 1 Include at least = 1 shape type = 8 sectors angle = 350 major semiaxis = 31000 minor semiaxis = 30000
A boundary data layer is used to clip the surface interpolation to the EDEN area. The surface interpolation is saved to an ESRI GRID with 400m cell resolution aligned to the EDEN grid data layer. The prediction grid value at each cell is obtained from the interpolation surface by assigning to the grid cell the prediction value that corresponds to the center position of the grid cell. Both the boundary data layer and the EDEN GRID are maintained by USGS, St Petersburg, Florida.
Interpolation surface GRID files for each day are converted to geoTIFF and CF compliant netCDF files for achieving. The netCDF files collect 3 months of daily surfaces together in each file.
950 Krome Avenue
The Daily Median Output text files provide the following information: the agency responsible for the data, the station id, X and Y location in UTM coordinates, median water values in cm, the year, month, and day of collection, Head or Tail gage, and area of data collection
U.S. Department of the Interior, U.S. Geological Survey
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