U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2006–3087

May 2006

Prepared as part of the Comprehensive Everglades Restoration Plan and the Greater Everglades Priority Ecosystems Science

The Everglades Depth Estimation Network (EDEN) for 

Support of Ecological and Biological Assessments

Printed on recycled paper

Introduction

The Everglades Depth Estimation 

Network (EDEN) is an integrated 

network of real-time water-level monitoring, ground-elevation modeling, and 

water-surface modeling that provides 

scientists and managers with current (1999-

present), on-line water-depth information 

for the entire freshwater portion of the 

Greater Everglades. Presented on a 

400-square-meter grid spacing, EDEN 

offers a consistent and documented dataset 

that can be used by scientists and managers 

to: (1) guide large-scale field operations, 

(2) integrate hydrologic and ecological 

responses, and (3) support biological and 

ecological assessments that measure 

ecosystem responses to the implementation 

of the Comprehensive Everglades Restoration Plan (CERP) (U.S. Army Corps of 

Engineers, 1999). The target users are 

biologists and ecologists examining trophic 

level responses to hydrodynamic changes in 

the Everglades.

Approach

Water depth is the 

difference between the 

water-surface elevation and 

the ground-surface elevation (fig. 1). To estimate 

water depths in the Greater 

Everglades, Geographical 

Information Systems (GIS) 

models were developed 

to determine the groundsurface and water-surface 

elevations for the freshwater portion of the Greater 

Everglades. Data to support 

the ground-elevation model 

include elevation measurements obtained at more 

than 50,000 sites (Desmond, 

2003). Data to support the 

water-surface model include 

continuous water-level measurements obtained at more than 250 sites. 

Technical aspects of the EDEN monitoring 

network and GIS models are presented in 

the subsequent sections.

Monitoring Network 

The EDEN monitoring network 

includes ground-elevation measurements 

and continuous water-level data. Groundsurface elevation data were collected by the 

U.S. Geological Survey (USGS; Desmond, 

2003) 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 (tidal) gages operated by the Big 

Cypress National Preserve (BCNP), Everglades National Park (ENP), South Florida 

Water Management District (SFWMD), 

and USGS (fig. 2). All gaging stations have 

telemetry equipment that provides data on 

a daily basis. Several of the new gaging 

stations are co-located where ongoing 

landscape studies have been conducted for 

several years. A 6-year (October 1, 1999, 

to September 30, 2005) dataset of baseline 

conditions was established for the EDEN 

water-level network prior to the implementation of CERP, offering scientists a single 

repository for historic, hourly water-level 

data.

Development of a water surface across 

the Everglades requires a consistent datum. 

Highly accurate ground-elevation data were 

collected using the North American Vertical 

Datum of 1988 (NAVD 88). 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 NAVD 88 datum is 

consistent in comparing water-level 

data across the Greater Everglades and 

computing accurate water depths. 

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 

Figure 1. Relation between the modeled surfaces. Modeled water-surface 

elevation minus modeled ground-surface elevation is the water depth at any 

point in time. Water depth may be adjusted by the ground surface as a result 

of the relation between vegetation in the cell and ground elevation.

400-meter cell

gs

gs

gs

MODELED WATER SURFACE

gs MODELED GROUND SURFACE

EXPLANATION

Water

depth Water

depth Water

depth

400-meter cell 400-meter cell

Actual ground

surface

Actual

water

surface

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 to NAVD 88. 

Three methods were 

used to determine the 

correction for a gaging 

station:

Differential or basic 

Global Positioning 

System (GPS)—A 

highly accurate 

satellite-based 

surveying system;

1.
Optical survey – A traditional lineof-sight survey from points of known 

elevation; and

CORPSCON1 version 6.0 – A program 

that interpolate 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 the USACE Jacksonville District to 

incorporate the CERP vertical control 

network established in 2001-02 (Rory 

Sutton, U.S. Army Corps of Engineers, 

written commun., 2005).

1

 Any use of trade, product, or firm names is 

for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

2.

3.

Ground-Elevation 

Model

The EDEN domain was 

broken into a large number 

of equal-sized rectangles 

(“cells”), which in total, are 

referred to as the “grid.” 

Characteristics of the grid, 

such as location of centroid, the representative area of the Everglades, elevation, and 

percentage of vegetation type, define the 

grid spatial parameters. The EDEN grid 

facilitates efficient GIS product development and distribution and allows for 

analysis of subsets of the grid or large-scale 

assessments at a system-wide level. The 

attribute information associated with grid 

cells can be expanded easily as new data 

are gathered or new information is derived.

Beginning with the first contoured 

surface created from the elevation data 

points in 1999 (http://sofia.usgs.gov), 

the ground-elevation model continues to 

be refined and used to improve water-depth 

estimates. The large number of elevation 

data allows for refinement of this model. 

The geostatistical technique of kriging 

was selected for the EDEN groundelevation model following extensive testing 

of multiple interpolation techniques. 

Kriging produced the lowest average error 

for validation of elevation points and 

provided useful diagnostic surfaces. To 

account for variations within subregions 

of the EDEN area, individual geostatistical 

models were created for each waterconservation area, ENP, and portions of 

BCNP. These individual models were 

combined to create a single, 400-meter 

resolution elevation model for the entire 

EDEN domain (fig. 2). 

Water-Surface Model

A water-surface model was developed 

in GIS using the EDEN grid described 

above. The model interpolates measured 

water levels from the EDEN continuous 

monitoring network to ungaged locations. 

Different interpolation methods, such as 

inverse data weighting, spline, kriging, 

radial basis functions (RBF) with regularize spline, and RBF with multiquadric and 

local weighted regression, were tested on a 

subset of the assembled water-level dataset. 

The RBF with multiquadric regression, the 

basis for the EDEN water-surface model, 

provided the best results. The model produces a continuous water-surface elevation 

BOUNDARY OF WATER

CONSERVATION AREA

HIGH LOW

ELEVATION GAGING STATION LOCATION AND AGENCY

SOUTH FLORIDA WATER MANAGEMENT

DISTRICT

BIG CYPRESS NATIONAL PRESERVE

EVERGLADES NATIONAL PARK

U.S. GEOLOGICAL SURVEY (freshwater nontidal)

U.S. GEOLOGICAL SURVEY (coastal tidal)

81°15 ́ 81°00 ́ 80°45 ́ 80°30 ́ 80°15 ́

25°15 ́

25°30 ́

25°45 ́

26°0  ́ 0

26°15 ́

26°30 ́

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

MIAMI-DADE CO

COLLIER CO

PALM BEACH CO

HENDRY CO

ATLANTIC OCEAN

GULF OF MEXICO

BROWARD CO

BROWARD CO

COLLIER CO

MONROE CO

MONROE CO

MIAMI-DADE CO EVERGLADES

NATIONAL

PARK

WCA 3A

WCA 3B

WCA 2B

WCA 2A

WCA 1

BIG CYPRESS

NATIONAL PRESERVE

INSET

Figure 2. Location of Everglades Depth Estimation 

Network (EDEN) gaging stations in southern Florida 

and the EDEN region ground-elevation model (excluding 

coastal areas) created by joining water-conservation 

areas (WCAs), Everglades National Park, and portions of 

Big Cypress National Preserve elevation models. Inset is 

detailed ground-water elevation data for WCA 1.

81°45 ́ 81°30 ́ 81°15 ́ 81°00 ́ 80°45 ́ 80°30 ́ 80°15 ́ 80°00 ́

25°15 ́

25°30 ́

25°45 ́

26°00 ́

26°15 ́

26°30 ́

26°45 ́

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

GAGING STATION LOCATION

HIGH LOW

ELEVATION

ATLANTIC OCEAN

GULF OF MEXICO

Figure 3. Example water-surface elevation from radial basis 

function multiquadric surfacing for a sample data.
AGENCY DATA SERVERS

NWIS DATABASE

SCIENTIST

MONITORING

STATION

NWIS WEB

EDEN WEB

FTP

Transmitted

Transferred Entered

Stored

Accessed

for any particular data within the period of 

record of the EDEN database. An example 

water-surface elevation from RBF multiquadric surfacing for a sample day is shown 

in figure 3. 

Internet Dissemination of 

EDEN Information

The information from EDEN is 

readily available to scientists, engineers, 

and water-resource managers through a 

webpage that integrates the real-time monitoring data and GIS model results (fig. 4). 

The purpose of the website is to integrate 

EDEN monitoring and modeling data and 

provide “one-stop shopping” for data with a 

consistent data format and documentation. 

The EDEN website is accessed through 

an interactive map showing the location of 

gaging stations in the network, and provides 

“clickable” access to gage data on a near 

real-time basis (generally within 24 hours). 

Data from water-level gages are transmitted 

by way of radio or satellite telemetry to the 

operating agency’s data servers. Data from 

BCNP, ENP, and SFWMD are then transferred to the USGS and entered into the 

USGS National Water Information System 

(NWIS) database. Once in NWIS, the data 

are available through the EDEN-NWIS web 

interface (http://fl.water.

usgs.gov/eden) where 

the data can be accessed 

as graphs, tables, or 

downloadable files. The 

EDEN website also 

provides station information, such as station 

descriptions (including 

NAVD 88 correction 

values), measured 

ground elevation, and 

vegetation in the vicinity of the gaging station. 

Ground-elevation 

and water-surface data 

as well as monitoring 

data for the Greater 

Everglades are available 

on the EDEN website. The generated maps 

of attributes for the EDEN grid are stored 

at the South Florida Information Access 

(SOFIA) website data servers (http://sofia.

usgs.gov) for retrieval by way of a specially 

created, PC-based EDEN user interface 

(EDENapps) as illustrated in figure 5. 

EDENapps is a downloadable utility to the 

Figure 4. Transmission, transfer, 

storage, and access of data from the 

water-level data collected in the field 

to website access by users. NWIS is 

National Water Information System. 

EDEN is Everglades Depth Estimation 

Network.

AGENCY DATA SERVERS

NWIS DATABASE

SCIENTIST

MONITORING

STATION

NWIS WEB

EDEN WEB

FTP

Transmitted

Transferred Entered

Stored

Accessed

Figure 5. EDENapps 

viewer screen. Shown 

is water depth for a 

user-specified area in 

the left-hand viewer, 

and water-level rate of 

change over a userspecific period of time 

for the same area in the 

right-hand viewer.

user’s desktop computer and offers two 

main features that allow users the ability to: 

(1) communicate with the server to obtain 

water-surface data, and (2) view, analyze, 

and format these data for their use. Initially, 
the interface is used to specify an area and 

dates of interest. These maps are collected 

from the SOFIA data storage server by the 

interface and displayed as an animation of 

water level over the specified period. The 

user then has options for examining the data 

in the interface, performing further analysis 

of the data within the interface, or exporting 

the data for external analysis and reports.

 Analyses of the water-level maps 

currently available in EDENapps include 

cell-by-cell measures of variability, rates 

of change (rate of water-level subsidence 

or rise), number of dry events, and slope. 

Each of these derived products is saved as 

spatially referenced GIS maps that can be 

displayed within EDENapps. The interface 

has two side-by-side viewers to allow for 

pairwise comparisons of the map products. 

Individual cells also can be selected, and a 

hydrograph of water surface or water depth 

can be generated at those selected locations. 

Future Plans for EDEN

Future plans for the EDEN network 

include finalizing the computation of water 

depths, refining ground elevations within 

EDEN 400-meter cells, integrating water 

depth and vegetation from other agencies, and extending the EDEN approach 

to coastal waters of the Everglades. Water 

depths are computed by subtracting the 

ground elevation (generated by the groundelevation model) from the water-surface 

elevation (generated by the water-surface 

model). The next version of EDENapp will 

have the utility to compute the average 

water depth for each EDEN cell.

Research has shown that relatively 

high-resolution data are needed to explicitly represent variations in the Everglades 

topography and vegetation that are important for landscape analysis and modeling 

(Jones, 2001). The EDEN project will 

provide a better representation of water 

depths if elevation variation within each 

400-meter grid cell can be taken into 

account. Patterns of land cover obtained 

from existing GIS coverages of vegetation 

classifications may be the best available 

representation of variation in local elevation. Land-cover classifications from the 

Florida Gap Analysis Program (FLGAP) 

dataset (Florida Cooperative Fish and Wildlife Research Unit, 2005) and the SFWMD 

(Rutchey and others, 2005) are being input 

to analyze the relation among land cover 

and elevation. Accurate elevation data 

points will be combined with land-cover 

data to establish average differences in 

elevation as a function of land-cover type. 

For these analyses, the land cover has been 

aggregated into six major communities: 

(1) slough or open water, (2) wet prairie, 

(3) ridge or sawgrass and emergent marsh, 

(4) exotics and cattail, (5) upland, and 

(6) other (mostly wetland shrub and 

wetland forested). Established relations will 

be used to proportion a grid cell into different depths as a function of modeled water 

surface and measured ground elevations. 

When the relation between vegetation 

communities and depth is finalized to better 

describe ground-elevation variations within 

a grid cell, water volume in each cell also 

will be generated. Other geospatial information, such as soils and water-quality data, 

will be integrated with hydrologic data from 

this and other projects on a public website.

The EDEN network provides a 

framework to integrate data collected by 

other agencies in a common quality-assured 

database. In addition to the real-time 

network, collaboration among agencies will 

provide the EDEN project with valuable 

historic vegetation and water- depth data. 

Scientists commonly collect water-depth 

and vegetation data when conducting 

biological field assessments. These data are 

then quality assured, properly compiled, 

and verified before being incorporated into 

the EDEN network to improve the waterdepth maps and ground-elevation data. 

About 60,000 observations of water depth 

with vegetation type are being compiled 

from the work of about 20 investigators 

covering the period from 1996 to 2004. 

Some data sites were sampled periodically, 

and other sites were sampled randomly. 

This is the first time these data have been 

compiled and analyzed as a collective set.

The EDEN network of analysis 

currently (2006) is for the freshwater 

(nontidal) portions of the Everglades. The 

EDEN network will be expanded to include 

the coastal (tidal) portions of the Everglades 

(fig. 2).

Application for CERP

EDEN’s real-time data approach 

coupled with biological models, such as 

Across Trophic Level System Simulations 

(ATLSS) and Habitat Suitability Indices 

(HSIs), should help scientists: (1) evaluate 

how well the simulated relations that drive 

both biotic and abiotic models reflect 

and anticipate real-world events; and 

(2) examine trophic-level responses to 

hydrodynamic change. In summary, EDEN 

provides the hydrologically based data 

that can be used to assess biotic ecosystem 

responses to hydrologic change within the 

Greater Everglades.

References

Desmond, G.D., 2003, Measuring and mapping the topography of the Florida Everglades for Ecosystem Restoration: U.S. 

Geological Survey Fact Sheet 021-03.

Florida Cooperative Fish and Wildlife 

Research Unit, 2005, Florida GAP 

Analysis Project web page: Accessed at 

http://www.wec.ufl.edu/coop/GAP/.

Jones, J.W., 2001, Image and in situ data 

integration to derive sawgrass density 

information for surface-flow modeling 

in the Everglades: Remote Sensing and 

Hydrology 2000, IHAS 267, p. 507-512.

Rutchey, K., Vilchek, L., and Love, Matt, 

2005, Development of a vegetation map 

for Water Conservation Area 3: West 

Palm Beach, South Florida Water Management District Technical Publication 

ERA #421.

U.S. Army Corps of Engineers, 1999, 

Central and Southern Florida Project 

Comprehensive Review Study: Jacksonville, Florida, Final Integrated Feasibility 

Report and Programmatic Environmental 

Impact Statement.

For more information, please contact:

Project Team Leader:

Pamela A. Telis

U.S. Geological Survey

701 San Marco Blvd.

Jacksonville, FL 32207

email: patelis@usgs.gov

University of Florida, 

Fort Lauderdale Project Team:

Dr. Leonard Pearlstine, Project Leader

Dr. Ikuko Fujisaki

Dr. Monica Palaseanu

Darcy Thomas

U.S. Geological Survey Project Team:

Paul Conrads, Columbia, SC

Heather Henkel, St. Petersburg, FL

Aaron Higer (contractor, ETI 

 Professionals, Inc.), Ft. Lauderdale, FL

Dr. John W. Jones, Reston, VA

Eduardo Patino, Ft. Lauderdale, FL

Roy Sonenshein, Ft. Lauderdale, FL

Arturo Torres, Ft. Lauderdale, FL

http://sofia.usgs.gov/projects/eden/