Modelling overland flow with seepage

Abstract

The hydraulics of flow in thin sheets on the soil surface during rainfall is an essential component in the study of soil erosion and conservation, design of surface drainage systems and in the solution of sedimentation problems. Overland flow conditions are significantly affected by infiltration (exfiltration) and percolation through the soil, both varying in time and space. A time-dependent model developed for analyzing the problem of overland flow on infiltrating surfaces is the subject matter of this paper. Infiltration (exfiltration) is computed using a finite element submodel for Darcian flow through porous media. The computed flux across the soil surface becomes input to an overland flow submodel which uses a combination of the finite element and finite difference techniques. The computed depths of overland flow and water table positions in the soil layer are compared with experimental results.