Simulation of infiltration over layered and crusted alfisols under unsteady rain
1989
Varshney, Peeyush
Model for analyzing water infiltration into layered soil profiles with crusting phenomenon, under rainfall application is developed, using the Green and Ampt approach. The model developed predicts the reduction in infiltration rate caused by surface sealing/crusting and the consequent behaviour of infiltration in layered profile, the time at which surface saturation occurs and describes the infiltration thereafter. Prior to surface saturation stage, the infiltration rate in the soil is equal to the rain application rate. The model contains seven measurable input parameters, which are based on properties and initial soil profile conditions. The key parameters of the model namely, saturated hydraulic conductivity, effective wetting suction front, were measured by Guelph Permeameter and Air-Entry Permeameter simultaneously. The moisture content deficit was determined by the gravimetric method of oven drying. The model results are compared with the results obtained from a rainfall simulator field data, on three different soil textures with 75, 85 and 95 % sand. Effect of surface sealing decreases as sand content in the soil profile increases. Predicted results of the model and the observed results from the rainfall simulator showed in limited cases good agreement and proved the applicability of the Green Ampt approach to incorporate various ameliorating measures which can control this soil crusting phenomenon and predict accurately the infiltration behaviour in the soil under diversified field conditions.
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