Tidal flushing of intracoastal bays Corpus Christi Bay, Texas Gulf coast, Sarasota Bay, Gulf coast of Florida
Contributions in Marine Science 25(25): 1-12
A numerical model is derived which describes the flushing of a coastal bay through tidal exchanges with the adjacent continental shelf. An expression for the renewal of bay water as a function of the number of elapsed tidal cycles involves a series of binomial coefficients which is equal in length to the number of tidal cycles. The model describes temporal variability in bay salinity,- or any other measure of water quality, and indicates an asymptotic approach to a final value equal to that characteristic of shelf waters. The model is applied to Corpus Christi Bay, along the central Texas Gulf coast, and to Sarasota Bay, on the Gulf coast of Florida. For tidal processes alone, and ignoring significant beat frequencies in the local tides, the model suggests that 50% of the water of Corpus Christi Bay will be renewed in from 155 to 1,400 tidal cycles, assuming 90% and 10% mixing of flood tide waters within the bay, respectively. It is concluded that meteorologically forced exchanges and, to a lesser extent, fresh water run-off are significant in supplementing the tidal flushing of Corpus Christi Bay and maintaining water quality. Model results suggest that tidal flushing is considerably more effective in Sarasota Bay. With 50% mixing of flood tide waters, half of the bay water will be renewed in 4 tidal cycles, and essentially all of the bay water will be replaced within 30 tidal cycles.