On the Approximate Solution of Fresh Water-Salt Water Interface in Confined Aquifers

Abstract

A new method for solving the problem of the unsteady motion of the interface between fresh and salt waters in confined aquifers is presented, using the following three approximations : 1) The viscosity of salt water is equal to that of fresh water; 2) the compressibility of the granular skeleton of the medium and the compressibility of the fluid in the salt water region are equal to those in a fresh water region; 3) in the equation for the thickness of the salt water layer, the term containing the storage coefficient is ignored. The numerical solutions by the new method are compared with the ones obtained by solving directly basic equations. For the special case of non-pumping and one-dimension, an analytical solution is found. It is in good agreement with the numerical solution by SÁ DA COSTA and WILSON (1979), and LIU et al. (1981), and it is similar to the experimental result by BEAR and DAGAN (1964).