VARIABLE DENSITY FLOW AND SOLUTE TRANSPORT SIMULATION OF REGIONAL AQUIFERS CONTAINING A NARROW FRESH-WATER-SALTWATER TRANSITION ZONE

Variable density flow and solute transport simulation of aquifer systems containing narrow transition zones between freshwater and saltwater requires particular attention to certain aspects of the numerical method and its application to be successful. Typically, only cases involving wide transition zones have been simulated with variable density transport models. The major components of a successful approach are threefold. First, functionally consistent approximation of terms involved in fluid velocity calculations is necessary. Second, the simulator must be verified in a particular series of tests. Third, adequately fine spatial discretization is required when applying the simulator for spatial stability of the numerical transport solution and to allow accurate representation of narrow transition zones and the effects of low transverse dispersivity. The effectiveness of this approach is demonstrated through simulation of the flow of fresh and saline groundwater.