Modeling infiltration responses of layered soil column under rainfall conditions

Based on the developed Green-Ampt approach by Xuefeng Chu, the infiltration responses of 5 groups of layered soil column with different topsoil under rainfall conditions were numerically studied in this paper. Numerical experiments were carried out on the 120cm high soil columns with 4 layers subject to the rainfall amount of 200mm. It has been found that the cumulative infiltration and average infiltration rate show positive relativity with the saturated hydraulic conductivity of topsoil, while negative relativity is found for runoff. The occurrence of runoff is more earlier when infiltration capability is less or rainfall rate is greater. The position of wetting front varies widely. The wetting front can reach nearly 60cm depth for sand-topsoil, while less than 10cm depth for clay-topsoil. The actual infiltration rate may change sharply when the wetting front reach the interface of two different layers, which is induced by different saturated hydraulic conductivities and suctions of different soil layers.