INTERSTITIAL WATER TRANSPORT MODEL IN AQUIFER SYSTEMS BY FINITE ELEMENT METHOD.

A finite element method is described for the solution of the Richards' equation governing the groundwater flow in variably saturated porous media. The dependent variable, the pressure head, is approximated over each isoparametric element using mixed linear, quadratic, and cubic base functions. This approximation reduces the problem to a set of matrix equations whose term associated with the temporal derivative is the mass matrix. The lumping of the mass matrix together with the application of explicit time integration schemes produces an efficient method of solution. The model is first tested by comparing its simulation with an exact solution for a simplified case. It is then further compared favorably with the experimental data. Refs. .