Two-dimensional numerical simulation of the relationship between sinkhole lakes and ground water along the Central Florida ridge

An observation well network has been installed around a small lake in central Florida to investigate whether “plugged” sinkholes provide an avenue for contamination to reach potable water supplies in the Floridan Aquifer. Numerical modeling has been employed to evaluate the field data and a number of regional numerical simulations have been conducted to examine leakance from sinkhole lakes under a wide range of geologic settings typical of the central Florida ridge. Regional and site-specific numerical simulations indicate that leakance from lakes to the Floridan Aquifer occurs under the majority of geologic settings typical of the study area, regardless of the presence or absence of fractures and other high permeability conduits associated with solution or subsidence features. In particular, leakance through the lake bottom can be expected to occur where:the anisotropy ratio (Kh/Kv) 100, the hydraulic gradient _ 0.02, or a water table mound is absent on the regional downgradient side of the lake.