THE ONE-DIMENSIONAL APPROXIMATION FOR INFILTRATION IN HETEROGENEOUS SOILS

By using analytical solutions to the problem of one- and two-dimensional linearized unsteady infiltration from a strip source in a soil with saturated hydraulic conductivity varying exponentially in space, explicit criteria for the validity of the one-dimensional approximation are derived, in terms of parameters describing the soil type, the uniformity of the infiltrating source at the surface, and the soil heterogeneity. Numerical solutions for the linearized infiltration problem are developed for any variation of hydraulic conductivity in space. Extensive simulations suggest that for a sizable strip source and moderate variation of hydraulic conductivity, a set of independent neighboring soil columns represents well the multidimensional infiltration problem. The possibility of defining sufficient parameters controlling the accuracy of the one-dimensional approximation is discussed.