Simulation of Water Movement in Unsaturated Remolded Loess Under Ponding Infiltration and Rainfall Infiltration

Abstract:

In order to simulate the water movement in the unsaturated remolded loess under ponding and rainfall conditions, an improved infiltration model based on the modified Green-Ampt model and the model proposed by Wang Wenyan et al., which can reasonably consider the effect of suction at wetting front and the water content profile, was proposed. The reliable method for determining the parameters needed in the model based on the modified GreenAmpt model and the numerical method for solving Richard’s equations was also recommended. The research results show that the improved model can more accurately predict the movement of wetting front and the water content change at measured points in the onedimensional ponding infiltration test, compared with the modified Green-Ampt model and the model proposed by Wang Wenyan et al. When the unsaturated hydraulic conductivity function was determined directly by the improved wetting front advancing method in the ponding infiltration test, the results are closer to the measured values compared with those parameters indirectly determined by the saturated permeability test and water retention curve. For rainfall infiltration, the water profile after runoff obtained by the improved model is similar to that obtained by the numerical method, especially for the soil with a higher dry density.

Key words:unsaturated loess; rainfall; infiltration; modified Green-Ampt model; wetting front advancing method