Home Archived October 29, 2018
(i)

South Florida Information Access (SOFIA)

Everglades Depth Estimation Network (EDEN) Water Surfaces Data

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:


What does this data set describe?

Title: Everglades Depth Estimation Network (EDEN) Water Surfaces Data
Abstract:
Spatially continuous interpolation of water surface across the greater Everglades is generated for daily mean values of the water level gages for the EDEN network beginning January 1, 1991. Surfaces are recorded as elevations in centimeters relative to the North American Vertical Datum of 1988 (NAVD 88). These surfaces are served on the web as GIS data layers.
  1. How should this data set be cited?

    Henkel, Heather, 201215, Everglades Depth Estimation Network (EDEN) Water Surfaces Data.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -81.3
    East_Bounding_Coordinate: -80.16
    North_Bounding_Coordinate: 26.75
    South_Bounding_Coordinate: 25

  3. What does it look like?

    <https://sofia.usgs.gov/eden/models/watersurfacemod.php> (JPEG)
    The graphic shows the area covered by the water surface data and the colors represent the differences in water surface elevation meters, The graphic is only representative of a single day, other maps will display differently.

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 01-Jan-1991
    Ending_Date: Present
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: digital files

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      Indirect_Spatial_Reference: greater Everglades

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 17
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -81
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using Coordinate Pair
      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.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.0001
      Altitude_Distance_Units: centimeters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    The CF-compliant metadata in the header of the NetCDF file provides spatial information for projecting the data into a GIS as well as the start date and time step for the time-series of data in the file. It also provides information about the conventions used for attributes in the dataset and the source software used to create the dataset.
    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. The files list one gage per line and the columns are tab-delimited. Gages are grouped alphabetically by agency.
    Prior to 5/14/12, the Daily Median Output Files "median" files contain a list of the stations that were used to create water surfaces for that day. The "median reject" files contain a list of the gages that were not used during the creation of that day's water surface. Starting on 5/14/12, a single daily median file combines the information in the previous two daily median files and includes information about the data type at each gage. The Data Type field informs users whether the water-level data is measured, estimated, dry, or missing at each gage. Gages with missing data are not used for that day's surfacing.
    Entity_and_Attribute_Detail_Citation:
    NetCDF Climate and Forecast (CF) Metadata Conventions, Version 1.0, 28 October, 2003 at <http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.0/>


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

    • Heather Henkel

  2. Who also contributed to the data set?

    Heather Henkel, USGS, runs the surface-water model that creates the daily water-level surfaces. Leonard Pearlstine, ENP, developed Version 1 of the surface-water model. Zhixiao Xie, FAU, developed Version 2 of the surface-water model.

  3. To whom should users address questions about the data?

    Heather S. Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov


Why was the data set created?

Spatially explicit hydrologic information can be critical in understanding and predicting changes in biotic communities in wetland ecosystems. Repeated field measurements, the traditional method of collecting water surface information, is labor intensive and doesn't produce spatially continuous data across large areas. For this reason the EDEN project was started to collect data from over 200 real time stage monitoring gages that automatically record and radio-transmit data. The project integrates existing and new telemetered water level gages into a single network. Combined with a high resolution ground elevation model it generates a daily continuous water surface and water depth for the freshwater greater Everglades.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    Date: 2008 (process 1 of 4)
    Surfacing Process for Version 1 of the surface-water model:
    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.

    Person who carried out this activity:

    Leonard Pearlstine
    Everglades and Dry Tortugas Parks
    South Florida Natural Resources Center
    950 Krome Avenue
    Homestead, FL 33030
    USA

    305 224-4228 (voice)
    305 224-4147 (FAX)
    Leonard_Pearlstine@nps.gov

    Date: 2010 (process 2 of 4)
    The water surfaces (Version 1) was created by the following steps: 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.

    Person who carried out this activity:

    Heather S. Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov

    Date: 2011 (process 3 of 4)
    Surfacing Process for Version 2 of the surface-water model: 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. In Version 2 of the model, separate subarea surfacing models are created for WCA1, WCA2B, WCA3B, and Pennsuco Wetlands because water levels in the boundary canal gages are not in hydraulic connection with the interior marshes for these subareas. In order to create subarea water surfaces, the interior gages are extrapolated outward using the radial basis function routine then clipped to the boundaries of the subarea and merged to the full domain model. 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.

    Person who carried out this activity:

    Zhixiao Xie
    Florida Atlantic University
    Geosciences Department
    Florida Atlantic University
    777 Glades Road
    Boca Raton, FL 33431
    USA

    561-297-2852 (voice)
    xie@fau.edu

    Date: 2011 (process 4 of 4)
    The water surfaces (Version 2) was created by the following steps: 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. Subarea models are created 6. 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 7. The subarea models are merged to the full domain model 8. The continuous water surface is predicted on the EDEN grid (400m x 400m) 9. 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 approximately 250 gaging stations most of which are 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. Some gages are manually read and added to the database on a quarterly basis. All transmitted data are entered and stored in the National Water Information System (NWIS), a database operated by the USGS. There are approximately 250 gages used for water surface interpolation of the freshwater Everglades. The number of gages used for the surfacing model is constantly changing as gages are installed and discontinued over time. 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.

    Person who carried out this activity:

    Heather S. Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov

  3. What similar or related data should the user be aware of?

    Pearlstine, Leonard Higer, Aaron; Palaseanu, Monica; Fujisaki, Ikuko; Mazzotti, Frank, 2007, Spatially Continuous Interpolation of Water Stage and Water Depths Using the Everglades Depth Estimation Network (EDEN): CIR 1521, Institute of Food and Agricultural Services, University of Florida, Gainesville, Fl.

    Online Links:

    Other_Citation_Details:
    accessed as of 12/29/2009
    Full text of the document is available at: <http://edis.ifas.ufl.edu/pdffiles/UW/UW27800.pdf>


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    EDEN real-time water surfaces are created using real-time (four-day delay) water level data for the EDEN network. Most data relayed by satellite or other telemetry have received little or no review. Inaccuracies in the data may be present because of instrument malfunctions or physical changes at the measurement site. A threshold comparison program eliminates daily values that appear erroneous (i. e. extremely high or low, extremely different from previous days). Subsequent review of the data may result in significant revisions to the data.
    Users are cautioned to consider carefully the provisional nature of the information when using provisional data.
    Within approximately 45 days after the end of each quarter (December 31, March 31, June 30, and September 30), finalized and approved water level data are provided by SFWMD and ENP at which time real-time EDEN surfaces will be replaced by provisional surfaces. EDEN surfaces created with final, approved water level data from all agency gages will be available in approximately May of each year for the previous year's water year (October - September). For the provisional water-level surfaces for the period 1990-1999, users are cautioned about the quality of the water-level surfaces for several subareas. 1) WCA2A for the period 1/1/1990 – 12/31/1999, most of the water-level data for gages in WCA2A were hindcasted. Resulting water-level surfaces show inconsistencies compared with surfaces post-2000 and will require further analysis. Water-level surfaces in WCA2A should be used with caution for this period until further analysis is completed and revised surfaces are generated. 2) WCA2B for the period 1/1/1990 – 4/27/1993, no data is available for the northern boundary structures (S144_T, S145_T, S146_T), therefore the water-level surfaces in WCA3B are not considered valid in the northern portion of the subarea. 3) Pennsuco wetlands, The surface for this subarea is modeled only when data for 5 or more gages is available.

  2. How accurate are the geographic locations?

    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).

  3. How accurate are the heights or depths?

    Source data (HAED) collected to better than +/- 15cm. Standard errors of cross-validation for the DEM range from ~7cm to 17cm depending on the EDEN subarea. This version is composed of new models created for WCA3N and the BCNP combined with the mosaic of two versions (i.e., eden_v002a for WCA1 and eden_v002c for all other EDEN subregions) that comprised EDEN_EM_JAN07. The previous mosaic was selected based on analysis of model performance in the water depth estimation process. The WCA1 surface was produced by removing all "upland" AHF points as defined by a reclassification of the Florida GAP process. For WCA1, the krigging model was developed based on statistics from the entire EDEN domain (the process for eden_v002a production). For each other EDEN sub-area (i.e., the other WCAs and the National Park) region specific krigging models were developed and applied.

  4. Where are the gaps in the data? What is missing?

    Data from all the gages were collected and evaluated for use in calculating the water surface for each day.

  5. How consistent are the relationships among the observations, including topology?

    Prior to 5/14/12, the Daily Median Output Files "median" files contain a list of the stations that were used to create water surfaces for that day. The "median reject" files contain a list of the gages that were not used during the creation of that day's water surface. Starting on 5/14/12, a single daily median file combines the information in the previous two daily median files and includes information about the data type at each gage. The Data Type field informs users whether the water-level data is measured, estimated, dry, or missing at each gage. Gages with missing data are not used for that day's surfacing.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: none
Use_Constraints: none

  1. Who distributes the data set? (Distributor 1 of 2)

    Heather S. Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov

  2. What's the catalog number I need to order this data set?

    Water Surfaces

  3. What legal disclaimers am I supposed to read?

    No warrantees are implied or explicit for the data

  4. How can I download or order the data?


  1. Who distributes the data set? (Distributor 2 of 2)

    Heather S. Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov

  2. What's the catalog number I need to order this data set?

    Water Surfaces Daily Median Output Files

  3. What legal disclaimers am I supposed to read?

    No warrantees are implied or explicit for the data

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 15-May-2012
Metadata author:
Heather Henkel
U.S. Geological Survey
600 Fourth Street South
St. Petersburg, FL 33701
USA

727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)
sofia-metadata@usgs.gov

Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.14 on Mon May 14 15:30:00 2012

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
This page is: http://sofia.usgs.gov/metadata/sflwww/eden_water_surfs.faq.html
Comments and suggestions? Contact: Heather Henkel - Webmaster
Last updated: 23 December, 2016 @ 01:48 PM (KP)