Numerical Strategies to Model Surface and Groundwater Interactions for the Biscayne Bay Coastal Wetlands Project Alternatives

WASH123D is a first-principle, physics-based numerical model that computes flow and transport in a watershed system that is conceptualized as a combination of 1-D channel network, 2-D overland regimes, and 3-D subsurface media. It has been selected as the tool to help evaluate the proposed alternatives of the Biscayne Bay Coastal Wetlands project that is one of the 40 projects included in the Florida Comprehensive Everglade Restoration Plan. In order to best rehydrate wetlands and reduce point source discharge to Biscayne Bay, rule-controlled coastal canal structures, rule-controlled pump stations, spreader swales, stormwater treatment areas, flowways, levees, culverts, roads, and backfilling canals are included in these project alternatives. Specified target freshwater flows for Biscayne Bay and the wetlands within the redistribution system are to be computed in each alternative, which will be used in performance measurement to determine the most adequate alternative for further investigation. In this paper, the numerical strategies to incorporate all the aforementioned hydrological features and processes included in the alternatives are presented. An example alternative will be used for demonstration.