ABSTRAKT

This work deals with the solution of an inverse problem of parameter estimation involving the water transfer in an unsaturated porous medium as described by the Richards equation. The physical problem involves the drainage in an initially unsaturated porous 1D medium using a multistep outflow experiment. Using cumulative outflow volume and/or soil water pressure head measurements taken inside the medium, we have simultaneously estimated the parameters appearing in the formulation of the water retention θ and the hydraulic conductivity. The inverse problem is based on the Levenberg–Marquardt minimizing method of the least-squares norm with simulated measurements. The analysis of the sensitivity coefficients shows that it is possible to estimate simultaneously a certain number of parameters. It is found that the best position for measuring the soil water pressure head in order to estimate parameters is 5 cm below the soil surface.