Abstract
A new parameter estimation methodology of determining unsaturated soil hydraulic properties from laboratory transient outflow experiments was investigated. In this method saturated hydraulic conductivity and unsaturated soil hydraulic properties in van Genuchten's equations are estimated by Genetic Algorithms incorporating finite element solution of Richards equation. Measured soil water pressure and cumulative outflow data as a function of time were used to evaluate the objective function. The utility of our proposed method is demonstrated using experimental data for Japanese decomposed granite soil. An excellent agreement between optimized and independently measured soil water retention data and saturated hydraulic conductivity were found.
