Numerical simulation for convection of contaminants in groundwater

Abstract

A numerical model which simulates the convective transport of conservative ions through groundwater aquifers is presented and discussed. The model uses the fully implicit, central finite difference technique to predict transient, two-dimensional areal groundwater level or piezometric head fluctuations, the corresponding flows, and the convective transport of conservative ions. The model uses the fully explicit finite difference technique to calculate the contaminant concentrations. The model neglects the dispersion portion of the convective-dispersion equation. Either square or rectangular grids which remain constant throughout the study period may be used. Simple longitudinal and radial flow problems are solved. In addition, criteria to assure convergence and stability of the model are developed theoretically and empirically. The sensitivity of the model to variations in grid size, time increment and seepage velocity are presented. The study was limited to confined aquifers. However, the model has been developed to handle unconfined aquifers also. The study was also limited to homogeneous and isotropic porous media.