The effect of initial moisture content and infiltration quantity on redistribution of soil water

Abstract

The effects of initial moisture content and infiltration quantity on redistribution of water were studied in a loam, a fine sand, and a coarse sand. Moisture profiles during redistribution were obtained by gamma ray attenuation. Measured values of the hydraulic properties of these soils were used to calculate fluxes at the transition from drainage to wetting. The results were used to check a recent analysis of Peck. Gravity effects dominated in both sands, while in the loam capillary effects dominated at the smaller initial moisture contents and infiltration quantities. In all materials, increasing initial moisture content or infiltration quantity increased the contribution of gravity to the flux at the transition, and decreased the contribution due to capillary potential gradients. For a particular material, it depends on the magnitude of these fluxes whether mean moisture contents in the draining zone will be higher or lower at increasing values of initial moisture content or infiltration quantity.