Modeling Water and Containinant Transport in Unconfined Aquifers

Abstract

This chapter discusses modeling water and contaminant transport in unconfined aquifers. There are many available computer programs for investigating saturated and unsaturated water flow in porous media. These are usually based on a Galerkin finite element method that allows for such generalities as anisotropic and heterogeneous soil properties, general boundary conditions, and complicated boundary domains. However, the use of these computer codes to simulate long-time three-dimensional water transport in unconfined aquifers can take so much computer time that they become impractical to use. This is largely, due to the fact that even under homogeneous and isotropic conditions, the equations describing the flow in the unsaturated zone are highly nonlinear. Therefore, it is desirable to seek simpler models that retain much of the complexity and detail of the problem. While these approximating equations for the water and contaminant transport have significantly simplified the original formulation, nonlinearity remains and numerical techniques must be employed.