Project Summary Sheet

Study Title: A Coupled Surface Water and Ground-Water Model to Simulate Past, Present, and Future Hydrologic Conditions in DOI Managed Lands.
Study Start Date: Oct. 1, 2006 Study End Date: Sept. 30, 2009
Web Sites: See http://sofia.usgs.gov/people/wolfert.html for information on principal investigator.
Location (Subregions, Counties, Park or Refuge): South Florida, Miami-Dade & Monroe County, includes Everglades National Park & Biscayne National Park
Funding Source: USGS Greater Everglades Priority Ecosystems Science (GEPES) and ENP Critical Ecosystems Studies Initiative (CESI)
Other Complementary Funding Source: Department of the Interior Landscape funds, and South Florida Water Management District funding.
Funding History: FY07 (CESI, PES), FY08 (CESI, PES)
Principal Investigator: Melinda A. Lohmann
Study Personnel: Eric D. Swain, Christian D. Langevin, John D. Wang (University of Miami)
Supporting Organizations: None
Associated / Linked Studies: Biscayne Bay Coastal Wetlands Project, L31N Seepage Management Project, Everglades National Park Seepage Management Project, Combined Structural and Operational Plan (CSOP), including the C111 Spreader Canal Project, Additional Water for Everglades National Park and Biscayne Bay Feasibility Study, Florida Bay and Florida Keys Feasibility Study, Water Conservation Area 3 Decompartmentalization and Sheetflow Enhancement project, Lakebelt In-Ground Reservoir Technology Pilot Project, Landscape-Scale Science Needed to Support Multiple CERP Projects, GE PES project: Linking a conceptual karst hydrogeologic model of the Biscayne aquifer to ground-water flow simulations from Everglades National Park to Biscayne National Park-Phase 1, DOI Landscape Project: Flows to Coral Reefs, and SFWMD Project: Biscayne Bay Hypersalinity.

Overview & Objectives: The Comprehensive Everglades Restoration Plan (CERP) aims to reestablish predevelopment natural flows in the Everglades system and surrounding areas including Biscayne Bay. The changes proposed within this plan may cause significant alterations to the hydrologic conditions that exist in both Everglades National Park (ENP) and Biscayne National Park (BNP). System-wide, there are water management, water supply, and environmental concerns regarding the impact of wetland restoration on groundwater flow between the ENP and BNP and along the L-31 and C-111 canals. For example, restoration of wetlands may lead to increases in coastal ground-water levels and cause offshore springs in Biscayne Bay to become reestablished as a significant site of freshwater discharge in BNP. Accordingly, the CERP restoration activities may increase the rate of coastal groundwater discharge and aid transport of anthropogenic contaminants into the offshore marine ecosystem. Under this scenario, there is significant potential for habitat deterioration of many different threatened or endangered species of plants and animals that reside along the coastline of Biscayne Bay, in the Bay, or on the coral reef tract. In contrast to a surface water system which has been extensively compartmentalized and channelized, the Biscayne aquifer which flows under both ENP and BNP is continuous and not as amenable to partial domain simulation. A comprehensive model is needed to reliably and credibly assess the effects of groundwater flow and transport on both parks. Hydrologic conditions should be evaluated prior to substantial water delivery changes in order to protect these sensitive ecosystems. A numerical model that can simulate salinity and surface and ground-water flow patterns under different hydrologic conditions is an essential part of this effort.

The USGS developed a coupled surface-water/ground-water numerical code known as the Flow and Transport in a Linked Overland/Aquifer Density-Dependent System (FTLOADDS) to represent the surface water and ground-water hydrologic conditions in south Florida, specifically in the Everglades. The Flow and Transport in a Linked Overland/Aquifer Density-Dependent System">FTLOADDS code combines the two-dimensional hydrodynamic surface-water model SWIFT2D to simulate variable density overland flow (Schaffranek, 2004; Swain, 2005), the three-dimensional ground-water model SEAWAT to simulate fully-saturated variable-density groundwater flow (Guo and Langevin, 2002), and accounts for leakage and salt flux between the surface water and ground water (Langevin and others, 2005). The code was then applied to two major testing regions: 1) the Southern Inland and Coastal Systems (SICS) model domain (Swain and others, 2004) and 2) the Tides and Inflows in the Mangroves of the Everglades (TIME) model domain. The first application used code versions 1.0 and 1.1 which only utilized the SWIFT2D surface-water code. Later applications in the SICS area used version 2.1 (Langevin and others, 2005) where SWIFT2D was coupled to the SEAWAT groundwater model code. The second domain, TIME (Wang and others, 2007), utilizes the enhanced version 2.2 code, which includes enhancements to the wetting and drying routines, changes to the frictional resistance terms applications, and calculations of evapotranspiration. In 2006, FTLOADDS was modified again to represent Biscayne Bay and surrounding areas. The first objective of this project is to update and reconfigure the FTLOADDS modeling code to include all version modifications and enhancements in order to provide an easier transition for the coupling of models.

The second and principal objective of this project is to develop a comprehensive model by utilizing the established USGS TIME model application of the southern Everglades and linking it to a coupled surface and ground water model application of Biscayne Bay that is currently in development. This will provide one large sub-regional model that will give an integrated comprehensive assessment of how different scenarios will affect water flows in both Everglades National Park and Biscayne National Park. Once calibrated, additional simulations will be performed to estimate predevelopment hydrologic conditions and to predict hydrologic conditions under one or more of the proposed restoration alternatives, using inputs from the Natural Systems Model (NSM) (SFWMD, 1997A) and the South Florida Water Management Model (SFWMM) (MacVicar and others, 1984, SFWMD, 1997B.

Status: Project started in July FY07. 1.) Currently the recoding of FTLOADDS is 75% complete.

Recent & Planned Products: The current planned products include; an updated version of the FTLOADDS modeling code, a calibrated model that can be used by managers to evaluate different restoration scenarios, presentations on the model results, and an USGS Scientific Investigations Report or journal article.

Relevance to Greater Everglades Restoration Information Needs: Currently the TIME model is providing needed hydrologic data to the Florida Bay Florida Keys Feasibility Study (FBFKFS). When TIME is linked with the new model of Biscayne Bay, it will provide more detailed information in the northeastern portion of Florida Bay as well as exchange to the eastern metropolitan area. The large model will also provide inputs of freshwater flows and salinities that can be used for the CSOP evaluation as well as providing a linkage to the SFWMM model to estimate effects of restoration efforts on the C-111 spreader canal area. The model also provides estimates of overland flows within ENP, which can be used to evaluate the affects of the Water Conservation Area 3 Decompartmentalization and Sheetflow Enhancement project. When the model is linked to the NSM it will provide an estimate of pre-drainage conditions in both Biscayne National Park and Everglades National Park and display how the two systems interact. This will give needed hydrologic conditions, both in the surface water and groundwater, and salinity data needed for the Biscayne Bay Coastal Wetlands project and the Landscape-Scale Science Needed to Support Multiple CERP Projects. It will also provide water supply estimates to each park to mimic pre-drainage conditions for the Additional Water for Everglades National Park and Biscayne Bay Feasibility Study. Additionally the model will provide insight into the impact of the Lakebelt In-Ground Reservoir Technology Pilot Project on groundwater flows and help determine the effects on hydropatterns and water levels in Shark Slough for the L31N Seepage Management Project.

Key Findings: None at this time.