Rain Induced Infiltration Into Soil With Dynamic Surface Seals

For the purpose of developing infiltration equation under a dynamically sealing soil surface Richards' equation of unsaturated flow for a two layered system is considered. An analytical approach based on the concept of dynamic wetting front is utilized to form the basis of transport process in a substrate whereas a kinematic approximation is utilized in the surface seal. First, the general solutions of unsaturated flow with appropriate boundary conditions are developed, which consist of concentration and flux boundary values. Richards' equation in the domain of the seal is approximated by a kinematic approach which yields a closed-form solution permitting the satisfaction of continuity of transport conditions between the seal and the substrate. Further analysis of the resulting set of equation yields a nonlinear integral equation. Solutions of the integral equation show direct dependence on physical parameters pertaining to the seal and the substrate as well as the rain characteristics. Results of the present model are compared with the available experimental data of cumulative infiltration pertaining to sealing soils under various rainfall regimes.