THEORY OF SUBSURFACE WATER-BORNE SOLUTE TRANSPORT

The equations for the water mass balance and water-borne solute transport in a regional unconfined aquifer are presented. The aquifer is treated as a coupled saturated-unsaturated system with a time varying water table height and the evaluation of an accurate three dimensional specific discharge field is outlined. The numerical importance of the major transport mechanisms of a solute are shown to be reordered upon the transition from the local to the regional scale. A discussion is given of possible approximations that can be constructed from the convection-dispersion equation. © 1990.