17-Determination of Unsaturated Soil Parameters from Infiltration Experiment Using Inverse Procedure.

Abstract

The inverse problem of determining unsaturated soil hydraulic properties from one-dimensional, transient infiltration event is analyzed. Hydraulic properties are assumed to be described by Van Genucheten's (1980) model. Unknown parameters in the model are estimated from observed infiltration rates during transient flow by numerical inversion of the unsaturated flow equation. The inverse problem is solved using Levenberg-Marquardt method. It is observed that, the inverse procedure estimates the unsaturated soil parameters quite accurately and the parameter estimates are comparable with the obtained by direct measurement. It is concluded that, inverse procedure can be effectively used to estimate unsaturated soil parameters from infiltration experiment.