Melinda A. Wolfert¹, Christian D. Langevin¹ and John D. Wang^2
1U.S. Geological Survey, Florida Integrated Science Center, Fort Lauderdale, FL, USA
²Department of Applied Marine Physics, Rosenstiel School of Marine and Atmospheric Science, University of Miami, FL, USA

The Comprehensive Everglades Restoration Plan (CERP) aims to reestablish natural flows in the Everglades system and surrounding areas, including Biscayne Bay. The changes proposed within this plan may significantly alter existing hydrologic conditions in Everglades National Park (ENP) and Biscayne National Park (BNP). Surface-water runoff may be lessened as a result of restoration plans, which could result in less freshwater to the Bay and allow for increased periods of hypersalinity. Restoration of wetlands may also increase coastal aquifer heads and cause offshore springs in Biscayne Bay to once again become sites of freshwater discharge in BNP. Additionally, the CERP restoration activities may increase the rate of ground-water flow associated with contaminant loading into the offshore marine ecosystem. If contaminant loading is increased, the potential arises for habitat deterioration for the many different threatened or endangered species of plants and animals that reside within Biscayne Bay, along its coastline, and on the coral reef tract.

The U.S. Geological Survey is developing a coupled surface and ground-water model of Biscayne Bay and surrounding areas, including the urban and agricultural areas east of the Everglades. Freshwater discharges to the bay, salinity transport, potential causes of hypersalinity, and the groundwater flow rates and paths in the Biscayne aquifer can be simulated with the model. The model will be similar to the SICS (Southern and Inland Coastal Systems) and TIME (Tides and Inflows in the Mangroves of the Everglades) models in that the FTLOADDS (Flow and Transport in Linked Overland/Aquifer Density Dependent System) computer code will be used to simulate two-dimensional surface water flow in the coastal wetlands and adjacent estuary; variable-density groundwater flow and transport will be simulated in three dimensions. The current modeling effort does not include routing of surface water through the canal system. Coastal canal discharges will be applied as specified flux boundary conditions to Biscayne Bay, and canal stages will act as head-dependent boundary conditions for the underlying Biscayne aquifer. The finite-difference grid used for the simulations has a 500-m horizontal resolution and consists of a single surface-water layer and 20 ground-water layers (each 2.75-m thick). The current grid was designed to coincide with the TIME model grid; this feature facilitates joining the two models to address ground-water flow between ENP and BNP and to predict hydrologic conditions in the C-111 area. Time step lengths between 5 and 15 minutes are planned for the surface-water system and daily time steps are planned for the groundwater system. The model is being developed to represent hydrologic conditions, including the observed hypersalinity events in the bay, for the 9-year period from 1996 to 2004. Planned future applications of the model include linkage to the Natural Systems Model and South Florida Water Management Model to estimate past and future hydrologic conditions.

Contact Information: Melinda A. Wolfert, U.S. Geological Survey, 3110 SW 9^th Ave., Fort Lauderdale, FL 33315, Phone: 954-377-5955, Fax: 954-377-5901, Email: mwolfert@usgs.gov

(This abstract is from the 2006 Greater Everglades Ecosystem Restoration Conference.)

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