Determination of purple soil unsaturated hydraulic properties based on soil water redistribution in laboratory

Through conducting experiments of soil water redistribution in laboratory, an approach of determining soil unsaturated hydraulic conductivity and diffusivity based on the redistributions of soil water, and its applicability on three different textural purple soils were discussed. The results show that the purple soil unsaturated hydraulic diffusivity based on the redistributions of soil water both vertically and horizontally is in good agreement with the measured values and its unsaturated hydraulic conductivities determined by the same method deviate greatly from the mesured values. However, the ones determined by combining one-dimension redistributions of soil water with measured soil water retention curve agree well with the measured values. Differentiation between unsaturated hydraulic diffusivity and unsaturated hydraulic conductivities detemined by the differnet function relationships between soil moisture of wetting front and average moisture of wetted zone is not significant. In addition, this approach for determining soil hydraulic parameters based on soil water redistribution is more suitable for the lower soil moisture.