Project: Geophysical Mapping of Freshwater/Saltwater Interface

Web Site: http://sofia.usgs.gov/projects/geophys_map/

Location: Central Everglades, Southwest Coast / Big Cypress; Miami-Dade, Monroe, and Collier Counties

Principle Investigator: David Fitterman, fitter@usgs.gov, 303.236.1382

Project Personnel: Maria Deszcz-Pan, maryla@usgs.gov, 303.236.1317

Other Supporting Organizations: Everglades National Park, Big Cypress National Preserve and Fakahatchee Strand State Preserve

Associated Projects: Ground-Water Discharge to Biscayne Bay (http://sofia.usgs.gov/projects/grndwtr_disch/), Interrelation of Everglades Hydrology and Florida Bay Dynamics on the Ecosystem of South Florida (http://sofia.usgs.gov/projects/dynamics/), Southern Inland and Coastal Systems (SICS) Model Development, (http://sofia.usgs.gov/projects/sheet_flow/).

Overview & Status: This project focuses on the use of airborne and ground-based geophysical techniques to map the freshwater/saltwater interface (FWSWI) in the shallow aquifer system in and adjacent to Everglades National Park (ENP). Helicopter electromagnetic (HEM) surveys have been flown over large portions of ENP. These data have been supplemented with over 60 time-domain electromagnetic (TEM) soundings and geophysical borehole logs in nearly 20 wells. Through the joint use of these data, we have been able to develop a three-dimensional interpreted resistivity model of the area, as well as a correlation expression which allows the estimation of water quality (SC and chloride content).

Needs & Products: This project provided basic information needed to create ground-water models and test various restoration strategies and their impact on ground-water quality. Products to date include the following: The original study area is referred to as SICS. This is actually larger than the area of Eric Swain’s SICS project. A region to the west of the SICS area is referred to as WCST, which goes from near Tarpon Bay along the coast to Everglades City, This encompassing parts of Everglades National Park and Big Cypress National Preserve.

• HEM surveys SICS area, TEM soundings SICS area. Well logging SICS area
• TEM interpretation, HEM apparent resistvity maps HEM 3-D models
• Publications: Project Fact Sheet [Jun 1996]: Technical papers on HEM interpretation methods [1998], TEM interpretation report [Sep 1999], HEM 3-D model [Sep 2000]