Control of seawater intrusion through a series of injection-extraction wells was studied using a vertically integrated, two-dimensional, sharp interface model. The model is based on the Galerkin weighted-residual technique and has been tested against the existing analytical solutions. The model is then cast in terms of the non-dimensional parameters, and a series of parametric studies are conducted to obtain the characteristic curves for the cases of a seawater extraction barrier alone and its combination with the freshwater injection barrier. These curves could be used to assess the effect of variations in the input parameters on the position of the seawater-freshwater interface toe position.