The unsaturated soil hydraulic properties are essential data to predict the seepage behavior in the vadose zone. In this paper, a new experimental methodology of determining unsaturated soil hydraulic properties is proposed. The soil hydraulic properties are assumed to be represented by van Genuchten's closed-form expressions. Unknown parameters of this model are identified by using a optimization techniques. The optimization approach is nonlinear least-squares algorithm in corporating finite element analysis of one-dimensional nonsteady seepage flow. The advantages of the methods are in the possibility of identifying the optimal unsaturated soil hydraulic properties and diminishing experimental time. To evaluate availability of our proposed method, experimental results which are determined by proposed methods and conventional method are compared for decomposed granite soil.
unsaturated hydraulic properties