On the Improvement of Hydraulic Conductivity Function in Van Genuchten-Mualem Model

Abstract

Hydraulic conductivity (HC) is deduced indirectly from soil water retention curves (SWRC) by Mualem model, but the mathematical calculation in the Mualem model is sensitive to integration interval near saturation. After the van Genuchten model fit actual SWRC, the van Genuchten-Mualem (VGM) HC is integrated simply by an analytical function for unsaturated soils. However the analytical solution on VGM HC results in the rapid change of HC near saturation. For unsaturated soils sampled in Korea, SWRCs and unsaturated HCs were obtained by experiments. The HC experiments were compared with the HC models from the SWRCs. As a result, VGM models of HC function underestimate the unsaturated HC and show rapid reduction near saturation. It is found that a modification in VGM model should be required to predict accurate HC functions.