Project Summary Sheet

Project: Ground Water Flow and Transport for the SICS and TIME Models

Web Sites: http://time.er.usgs.gov/; http://water.usgs.gov/ogw/seawat/

Location (Subregions & Counties): Central Everglades (including Florida Bay) & Southwest Coast/Big Cypress –Collier, Monroe, and Miami-Dade Counties

Funding (Source): USGS Place-Based Studies

Principal Investigator(s): Dr. Christian Langevin, langevin@usgs.gov, 305.717.5817

Project Personnel: Melinda Wolfert, 305-717-5855, mwolfert@usgs.gov; David Garces, 305-717-5849, dgarces@usgs.gov; Marc Stewart, 305-717-5847, mastewar@usgs.gov

Supporting Organizations: U.S. Geological Survey and National Park Service/Everglades National Park

Associated / Linked Projects: Tides and Inflows in the Mangroves of the Everglades; Southern Inland and Coastal Systems (SICS) Model Development; Across Trophic Level System Simulation; High Accuracy Elevation Data Collection; Land Characteristics from Remote Sensing; Geophysical Mapping of Freshwater/Saltwater Interface; Evapotranspiration Measurements and Modeling; Ground water-Surface Water Exchange Fluxes; Freshwater Flows into Northeastern Florida Bay; Water Flows to Southwest Coast of ENP; Land Margin Ecosystem Program; Groundwater Discharge to Biscayne Bay

Overview & Status: This project focuses on the development of a variable-density ground water flow and solute transport model to simulate flow and salinity interactions between surface water and ground water along the southwest Gulf coast and Florida bay boundaries of Everglades National Park. The first task of this project was to document the SEAWAT code, a computer program for simulation of variable-density ground water flow. The SEAWAT documentation has been published and the code is being distributed through the website listed above. The ground water model for the TIME area, which is being developed with the SEAWAT program, will be coupled with the surface water and transport TIME model, a two-dimensional overland flow and solute transport model. A 10-layer SEAWAT model has been developed and linked with the Southern Inland and Coastal System (SICS). A 10-layer SEAWAT model encompassing the TIME domain has been developed and is currently being calibrated with the latest airborne geophysical data and existing hydrologic data. Nested monitoring wells were installed at the data collection sites of three of the associated projects listed above. These sites include: New River near Chokoloskee, at the NEX1 ET monitoring site, and at the Upstream Taylor River freshwater flow site. At each site a shallow and deep well were installed and instrumented with a pressure transducer and conductivity probe that measure and record on 15-minute intervals.

Needs & Products: Surface water and ground water interactions play an important role in Everglades hydrology, particularly near the coast where the salinity of surface water can be affected by the underlying saline ground water. Airborne geophysical data indicate that saline ground water can extend inland from the coast by up to 20 kilometers. Upward leakage of this saline ground water can have a measurable effect on surface water flow and surface water salinity, an important parameter for Everglades restoration. Papers describing the SICS ground water model have been presented at local and national conferences. A journal article describing surface water and ground water interactions is in preparation for submission to a refereed journal. A report documenting the model will be published at the end of the project.

Application to Everglades Restoration: A critical goal in Everglades restoration is to get the water right. Numerical models are widely used by the Army Corps of Engineers, Water Management District, and other agencies to evaluate the hydrologic response of the Everglades to various restoration scenarios. These models do not have the ability to represent salinity and the processes that affect salinity. The purpose of this project is to further our understanding of surface water and ground water interactions and develop algorithms and simulation techniques that can be used to better predict the hydrologic response of the Everglades to restoration alternatives. In addition, the SEAWAT code is gaining wide acceptance throughout the south Florida modeling community and will probably be used for CERP projects, such as aquifer storage and recovery and other coastal projects that involve ground water simulation.