Modeling of Transient Two Dimensional Flow in Saturated-Unsaturated Porous Media

Abstract

We study the transient two-dimensional flow problems related to the recharge of groundwater using an approach based on the physics of water transfer in the whole domain, including both the saturated and the unsaturated zones. Such a domain is limited by the soil surface and by the lower impervious boundary of the aquifer. The flow problem is solved using a numerical iterative procedure based on the alternate directions implicit finite differences method. To simulate the water transfer in an unsaturatedsaturated porous medium, we developed a mathematical model based on a single flow equation used for both zones. To this end, the unsaturated and saturated zones are regarded as only one continuum and the Richards equation is used for both zones. The simulated results were validated by the calculation of the mass balance, then on values obtained by an experimental model of 160 cm length and 50 cm in height. The numerical model reproduces in a satisfactory way the experimental results giving the spacetime evolution of the level of water table.