The effects of cut-off walls on repulsing saltwater based on modeling of density-driven groundwater flow and salt transport

Abstract:   A two-dimensional fully implicit finite difference model, which can be easily extended to three dimensions, is developed to study the effect of cut-off walls on saltwater intrusion into the aquifers. This model consists of a coupled system of two nonlinear partial differential equations which describe unsteady density-driven groundwater flow and solute transport. The numerical model is verified by the Henry problem. A good agreement between this model and the semianalitical solution of Henry problem shows the efficiency of this method for seawater intrusion problems. The effect of cut-off walls on reduction of saltwater intrusion in the Henry problem is investigated. Furthermore, the effect of geometric parameters of the cut-off wall such as depth and distance from the coast on repulsing saltwater is considered. Subsequently, the application of the presented model is considered to evaluate the effect of cut-off wall on repulsing salt water intruded by a pumping well located above the transition zone, which demonstrates that the cut-off wall has strong impact on repulsing saltwater intruded. For example, it repulses more than 45% salt water intruded by the discharge well in the Henry problem.