THE EFFECT OF TRANSVERSE DISPERSION ON SOLUTI TRANSPORT IN SOILS

Most theoretical and experimental investigations of solute transport involve one-dimensional problems (i.e. soil column studies), whereas in reality many soil pollution problems concern transport and flow in more than one dimension. This study investigates two-dimensional transport, with emphasis on the contribution of transverse dispersion to solute transport. Three problems were studied with a finite element code. The first problem involved one-dimensional flow parallel to the interface of two layers with differing pore-water velocity. The early arrival of the solute at the end of the low-permeability layer and the increase in solute spreading for both layers, as a result of transverse dispersion, were demonstrated. The two other problems concerned transport of a pollutant from a point source and a diffuse source, respectively, located at the soil surface. The magnitude of the transverse dispersion coefficient influenced the region to which the pollution extended as well as the intensity of the pollution.