The Interface Between Fresh and Salt Groundwater: A Numerical Study

Present address: Laboratoire National d'Hydraulique, 6 quai Watier 78401 Chatou, France. In this paper the two-dimensional flow of fresh and salt waterthrough a homogeneous aquifer is considered. The two fluidsare assumed to be separated by a sharp interface. They differonly in their specific weight. This difference induces a flowin the aquifer which in turn causes a motion of the interface. We present a mathematical formulation of this problem whichconsists of a Poisson equation for the stream function coupledto a time evolution equation for the moving interface. The equationfor the stream function is solved by means of a finite-elementmethod while a predictor-corrector method (the S^ßscheme) is used for the discretization of the equation for theinterface.