USGS - science for a changing world

Caribbean-Florida Water Science Center

  home   information/data   drought   flood   hurricane   models   nawqa   projects   publications   watercam   newsletter   about   contact
Hydrologic Modeling



Ask the director of the Florida Water Science Center Director a question.Ask Florida USGS

Coupled Groundwater and Hydrodynamic Surface-Water Modeling of Southern Florida

Project Chief: Eric Swain
Cooperator/Funding Source: Greater Everglades Priority Ecosystem Studies, U.S. Army Corps of Engineers, BRD Initiative
Period of Project: October 2008 Current

Problem Statement

Figure 1 – Studies supporting numerical model development.

Figure 1 –Studies supporting numerical model development.

Hydrologic conditions in south Florida require special numerical tools to simulate the close surface-water/aquifer connection, the transient nature of the low-gradient flow, and transport of dissolved salt at the coast. Accurate hydrologic simulations are needed for determining coastal outflow rates, distribution and concentration of saline waters, the interaction between hydrology and ecology, and to predict the effects of restoration efforts and climate change on coastal hydrology. Development of the FTLOADDS simulator has been underway since 1996 to help meet those needs, and considerable data has been compiled as input to simulate the complex hydrology of the Everglades, the coastal Biscayne Bay area, and the Ten Thousand Islands area.


  • Construct the FTLOADDS code by combining the three-dimensional groundwater flow and salinity transport code SEAWAT with the two-dimensional hydrodynamic flow and salinity/heat transport code SWIFT2D.
  • Develop the TIME model,  representing Everglades area
  • Develop the Biscayne model, representing Miami-Dade and Broward Counties and Biscayne Bay
  • Develop the BISECT model, integrating the TIME and Biscayne models for the entire south Florida peninsula
  •  Design physical experiments to evaluate the heat-budget terms for wetland environments that will result in more accurate temperature computations in the models. Laterally-insulated circular tank containing soil and water are exposed to environmental conditions and monitored to determine soil heat storage and albedo.


Figure 2 – Simulated effects of Hurricane Wilma on coastal salinity.

Figure 2 –Simulated effects of Hurricane Wilma on coastal salinity.


  • Simulate hypersalinity events in near-shore Biscayne Bay under varying water-management schemes;
  • Construct sea-level rise simulations with static rise values and also incremental changes in sea level and water management; 
  • Generate present and future rainfall simulations using downscaled global climate model data;
  • Develop hindcast simulation of early to mid-twentieth century hydrology with historic storm representations and computation of hydrologic effects on coastal mangroves;
  • Interface FTLOADDS hydrologic simulations with mangrove-hammock dynamic formulations to hindcast historic vegetation changes and forecast scenario outcomes
  • Utilize parameter estimation techniques to hindcast historic topography based on known vegetation configurations.
  • Apply smaller-scale hydrodynamic modeling to the Port of the Island, a marina inland from the Ten Thousand Islands area, to examine salinity and temperature effects on a manatee habitat.

Results of Various Studies

  • The BISCAYNE model has been applied to offshore hypersalinity analyses, demonstrating that surface water-delivery schemes have a substantial effect on Bay salinity.
  • Sea-level rise and downscaled rainfall simulations indicate future conditions have a much narrower salinity transition zone than current conditions.
  • The hindcast simulations show that historic storms can have a long-term effect on coastal salinity and mangrove habitats.
  • The physical experiments yielded albedo values which improved the heat transport simulations.
  • Three-dimensional representation of the Port of the Islands indicates salinity stratification is a major factor in manatee habitat suitability.


Information Products

Decker, Jeremy, and Swain, Eric, (planned), Three-Dimensional Hydrodynamic Flow and Transport Modeling to Assess Factors Affecting Thermal Properties of a Passive Thermal Refuge: Journal of Waterway, Port, Coastal, and Ocean Engineering

Lohmann, Melinda A., Swain, Eric D., Wang, John D., and Dixon, Joann, (planned), Evaluation of Effects of Changes in Canal Management and Precipitation Patterns on Biscayne Bay, Florida, Salinity, using an Integrated Surface-Water Groundwater Model: U.S. Geological Survey Scientific Investigations Report

Stith, B.M., Reid, J.P., Langtimm, C.A., Swain, E. D., Doyle, T.J., Slone D.H. Decker, J.D., and Patino, E., 2010, Temperature inverted haloclines provide winter warm-water refugia for manatees in southwest Florida; Estuaries and Coasts doi 10.1007/s12237-010-9286-1.

Swain, E.D., and Decker, J.D., 2009, Development, Testing, and Application of a Coupled Hydrodynamic Surface-Water/Ground-Water Model (FTLOADDS) with Heat and Salinity Transport in the Ten-Thousand Islands/Picayune Strand Restoration Project Area, Florida: U.S. Geological Survey Scientific Investigations Report 2009-5146, 42 p.

Swain, E. D., and Decker, J.D., 2010, A Measurement-Derived Heat-Budget Approach For Simulating Coastal Wetland Temperature With a Hydrodynamic Model: Wetlands, 30(3),p. 635-648.

Swain, Michael, Swain, Matthew, Lohmann, Melinda, and Swain, Eric, 2012, Experimental determination of soil heat storage for the simulation of heat transport in a coastal wetland: Journal of Hydrology 422–423, p. 53–62.

USGS Home Water Climate Change Core Science Ecosystems Energy and Minerals Env. Health Hazards

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: Webmaster
Page Last Modified: Thursday, 15-Dec-2016 17:45:19 EST