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Project Work Plan

U.S. Geological Survey Greater Everglades Science Initiative (Place-Based Studies)

Fiscal Year 2004 Project Work Plan 


Project Title: Geophysical Monitoring of the Southwest Florida Coast
Project Start Date: 1 Oct 2001 Project End Date: 30 Sept 2004
Project Funding: USGS Place-Based Studies Initiative

Principal Investigator: David V. Fitterman
Email address:
Phone: 303-236-1382 Fax: 202-236-1425
Mail address: USGS, Box 25046 MS 964, Denver, CO 80225

Other Investigator(s): Maria Deszcz-Pan
Email address:
Phone: 303-236-1317 Fax: 202-236-1425
Mail address: USGS, Box 25046 MS 964, Denver, CO 80225

Project Summary:

The development of ground-water flow models in the southern coastal area of Florida near Big Cypress National Preserve and Everglades National Park is a critical part of the Comprehensive Everglades Restoration Plan (CERP). Ground-water flow models are needed to plan and assess the success of the restoration effort. The utility of these models is dependent upon having reliable, high quality data with sufficiently high spatial sampling density to provide adequate information about subsurface geologic and hydrologic boundaries, as well as information on water quality. This project primarily makes use of helicopter electromagnetic (HEM) survey data to develop three-dimensional models of the resistivity structure of the subsurface. By combining geophysical and hydrologic information, the geophysical interpretations can be recast in hydrologic terms leading to valuable input for the modeling effort. The project has been very successful in this endeavor leading to a synthesis of the data.

With the collection of several HEM surveys in Everglades National Park spanning eight years, there is the opportunity to evaluate the utility of HEM surveys as a long-term monitoring tool of the effectiveness of CERP at modifying the hydrologic regime. Task 1, described below, addresses this issue.

In October 2001, additional funding was available to fly a small HEM survey to the east of Everglades National Park from highway US 1 over the Triangle Lands toward the Biscayne Bay coast and northward to Turkey Point. This data set has not been interpreted. With the development of the CERP C-111 Spreader Canal project, these data are of increased importance as they provide a very detailed look at the extent of saltwater intrusion in the area and the influence of existing canals and roadways on the hydrology. Interpretation of this data set can provide valuable information for the planning and assessment of the C-111 Spreader Canal project. This work is described in Task 2 below. Funding for this effort will be sought from the U.S. Army Corps of Engineers.

Project Objectives and Strategy:

The overall objective of this project is the collection of geophysical data that can be used to develop ground-water flow models of the area capable of modeling saltwater intrusion. This objective includes mapping of subsurface electrical properties of the aquifer and correlation of lateral variation in these properties to aspects of aquifer geometry and water quality that are pertinent to hydrologic model development.

Completion of combined ground and airborne geophysical surveys in Everglades National Park and Big Cypress National Preserve has shown the utility of these methods to map saltwater intrusion and provide geological information needed to develop ground-water flow models. The strategy that has been used is to interpret the HEM data as layered-earth resistivity models that slowly vary from place to place. Surface geophysical measurements (time-domain electromagnetic soundings) have been used to assist in this interpretation and provide an independent check on the HEM data. Borehole data in the form of formation resistivities and water quality sampling have allowed us to develop relationships for converting the interpreted resistivity-depth models into estimated water quality given as specific conductance (SC) or chloride concentration. This information is of great value to hydrologic modelers.

Potential Impacts and Major Products:

Water management decisions that impact Everglades restoration efforts, require high quality data and reliable hydrologic models. Traditionally these data for hydrologic models have been obtained through observation wells. In the Everglades, this approach is limited by the difficult access due to water which covers most of the area and to the limited number of roads. Airborne geophysical techniques provide a means of accessing large parcels of land and developing three-dimensional resistivity models of the area.


Inside the USGS collaborators have included Christian Langevin, who is developing the SICS and TIME hydrologic models; Raymond Schaffranek, who is responsible for the TIME (Tides and Inflows in the Mangrove Ecotone) model development; Tom Smith, who is working on studies of the mangroves; and Marc Stewart, while with Everglades National Park, worked on the influence of roadways on surface water flows and subsurface water quality. Outside the USGS collaborators have included: Robert Fennema, Freddie James, Robert Zepp, and Tom Van Lent of Everglades National Park; Robert Sobczak of Big Cypress National Preserve; Milton Switanek of the South Florida Water Management District.


Data, reports, and maps have been shared with Everglades National Park, Big Cypress National Preserve, the South Florida Water Management District, the U.S. Army Corps of Engineers, and the Miami-Dade County Department of Environmental Resources Management (DERM).


Title of Task 1: Evaluation of Restoration Monitoring Using Helicopter Electromagnetic Surveys
Task Funding: USGS Place-Based Studies Initiative
Task Leaders: David V. Fitterman, Maria Deszcz-Pan
Phone: 303-236-1382
FAX: 303-236-1425
Task Status (proposed or active): active
Task priority: high
Task Personnel: David V. Fitterman, Maria Deszcz-Pan

Task Summary and Objectives:

Helicopter electromagnetic (HEM) surveys from April 1994 through October 2001 provide an opportunity to evaluate the utility of HEM surveys for monitoring long-term changes in hydrologic conditions that can be influence by natural variations due to changes in rainfall. Four surveys covering the same flight lines exist, so that accurate comparisons the data can be made. If seasonal and multiyear changes can been detected and explained, then HEM surveys might provide a means of monitoring the long-term effect of Everglades restoration projects on ground-water quality.

Work to be undertaken during the proposal year and a description of the methods and procedures:

Selected flight lines from the various HEM surveys will be processed and interpreted using the same techniques. The data will then be compared to determine if temporal variations exist that are meaningful in terms of known hydrologic conditions such as seasonal variations in water flow and precipitations and interannual fluctuations in these conditions. If successful a long-term monitoring plan will be formulated.

Planned Outreach:

Work progress and results will be discussed with personnel from Everglades National Park, the South Florida Water Management District, and the US Army Corps of Engineers.

Title of Task 2: Geophysical Studies of the Triangle Lands-Turkey Point Coast
Task Funding: US Army Corps of Engineers
Task Leaders: David V. Fitterman, Maria Deszcz-Pan
Phone: 303-236-1382
FAX: 303-236-1425
Task Status (proposed or active): proposed
Task priority: high
Task Personnel: David V. Fitterman, Maria Deszcz-Pan

Task Summary and Objectives:

This task entails the interpretation of an helicopter electromagnetic (HEM) survey flown in October 2001, but never fully processed and interpreted here is reason to believe that existing roadways and canals have a dramatic influence on the hydrologic regime. Development of the C-111 Spreader Canal Project, which focuses on supplying more surface water to this area to prevent further saltwater intrusion will directly benefit from this information. Interpretations from this project will be of assistance in establishing the role of ground-water discharges to Biscayne Bay.

Work to be undertaken during the proposal year and a description of the methods and procedures:

This task will interpret the October 2001 HEM data set to a three-dimensional resistivity model delineating the extent of saltwater intrusion. Data from existing monitoring wells will be incorporated to establish the relationship between formation resistivity and specific conductance needed to estimate water quality at depth. Existing time-domain soundings in the region will be used to assist the interpretation, and if necessary additional measurements will be made.

Planned Outreach:

Interim products and final results of this task will be discussed and shared with the following organizations: US Army Corps of Engineers, Everglades National Park, Biscayne National Park, Miami-Dade County Department of Environmental Resources Management, South Florida Water Management District, and Florida Power and Light.


Task 1: This task looks at the ability of HEM surveys to monitor long-term changes in subsurface conditions. This work supports Restoration Goal 1A (Get The Hydrology Right) by establishing a baseline of what the hydrologic regime looks like now (SO2), and how the Everglades system will change due to restoration (SO4, SO5). This will be of value in predicting the effects of water management practices and assessing if the outcome agrees with the prediction. It will also help establish baselines as required by Restoration Goal 1B (Get the Water Quality Right) by providing snapshots of current water quality (SO2) at a sampling density not possible with wells. It will also provide input to Restoration Goal 2B (Ecologic Indicators) by providing a tool for monitoring long-term ecosystem change.

This task addresses the DOI Science Objectives concerning hydrologic and water quality issues by provide a means to assess long term changes over large areas.

Task 2: This task focuses on interpreting the HEM survey from the Triangle Lands-Turkey Point coastal area. It provides support to Restoration Goal 1A (Get the Hydrology Right) by addressing SO3 and the influence of man-made structures, such as canals and highways, on water levels and flows as seen in the subsurface water quality. It also addresses Restoration Goal 1B (Get the Water Quality Right) SO1 concerning how freshwater inflows affect water quality in coastal areas. Task 2 also addresses SO4 with regard to how restoration activity (C-111 Spreader Canal project) is expected to influence saltwater intrusion. Restoration Goal 3 (Foster Compatibility of the Build and Natural Systems) point SG1 (factors concerning saltwater intrusion) will benefit from this work.

With regard to DOI Science Objectives this task assists with hydrologic modeling of Biscayne Bay Coastal Wetlands and determining background conditions before the C-111 Spreader Canal becomes active. It directly provides information for the Combined Structural and Operations Plan (CSOP), which includes the C-111 Spreader Canal project and the need for water quality information and hydrologic models. It also assists the CERP Monitoring and Assessment Plan’s need for information on the role of submarine ground-water discharges to Biscayne Bay.

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