Infiltration-Discharge of Rain Water and Translation Phenomena in Soil

Abstract

Infiltration-discharge of rain water and translation phenomena in soil were investigated by the numerical analysis based on a one-dimensional infiltration model. A simple approximate formula for the piezometric head and water content distribution in soil in the steady state was obtained. Computational results in the unsteady state indicated that the vertically downward speed of wetting front is generally much larger than that of tracer, which is assumed to be injected together with the rain water through the top of the soil. Theoretical consideration was then made to relate the movement of wetting front and that of tracer front with the translation phenomena in soil. Finally, numerical analysis was made for various precipitation intensities, under various initial soil moisture conditions and various different soil properties. The speed of wetting front becomes closer to that of tracer as the precipitation intensity gets larger, the initial soil moisture smaller, the grain size of soil smaller and the uniformity coefficient of soil larger.