A Numerical Study of Steady Infiltration from a Single Irrigation Channel with an Impermeable Soil Layer

In this paper, steady infiltration problems into a homogeneous soil from a single trapezoidal channel are
considered. The horizontal part of the channel is impermeable. There is an impermeable soil layer underlying the homogeneous soil in some of the considered problems. These problems are governed by a Richards’ equation. The problems are studied by transforming the governing into a modified Helmholtz equation and solved numerically using a Dual Reciprocity Method (DRM). The method is implemented using MATLAB to obtain required numerical solutions or results. The numerical results indicate that at any point up to a certain level of soil depth, values of suction potential obtained from the problems all are about the same. From that level of soil depth, variations in values of suction potential are observed. For the soil without
impermeable layer, values of suction potential decrease as the depth of soil increases. On the other hand, for the soil with impermeable layer, the results indicate that the closer location to the impermeable layer, the higher values of suction potential.