| Two material properties of the unsaturated flow such as the soil-water characteristic curve and the unsaturated hydraulic conductivity are the keys to solve the problem related to the unsaturated soil behavior. Several researchers developed the mathematical models to predict the soil-water characteristic curve and the unsaturated hydraulic conductivity.; In this study, the methodologies of determining the soil-water characteristic curve and the unsaturated hydraulic conductivity by pre-existing models such as the Brooks and Corey model, van Genuchten model, and the Fredlund and Xing model are reviewed. In order to examine universal validity of the unsaturated hydraulic conductivity functions of pre-existing models, the computer code UNSAT-H is used. From results of simulation by the computer code UNSAT-H, it was concluded that different approach to obtain the unsaturated hydraulic conductivity function is needed, because the existing models can not predict the behavior observed in some experiments. Therefore, inverse problem solution with the computer code PEST is used to estimate parameters of the unsaturated hydraulic conductivity function with the suction-saturation experimental measurements based on flow pump technique. Throughout the computer code PEST with UNSAT-H, the more reasonable unsaturated hydraulic conductivity function is obtained than by the pre-existing models. |
