Numerical Methods for Estimating the Soil Hydraulic Properties and the Wetting Front in the Soil

The unsaturated zone in the soil generally plays an important role in the transfer of water and pollutants in the underground environment. To simulate the water flow in this area, the relationships that express the variations of the water content and the hydraulic conductivity of the soil as a function of the pressure must be defined. In this context, determination of the hydrodynamic parameters constitutes an essential step for any study of the water and solutes transfers in the unsaturated zone. The purpose of this article is to identify the soil hydrodynamic parameters by direct method and inverse method, from the infiltration data by using the disc infiltrometer. These two methods of the characterization were applied on two plots: a plot of R'mel, sandy soil, and a M'risa plot, clay-loamy soil in northern Morocco. The results of the analytical and numerical modeling reproduced correctly the experimental measurements. A performance analysis of the models used was implemented to study the reliability of the estimated parameters. The values of RMSE approximate to 0.20 and R-2 approximate to 0.90 show that the inverse method remains a robust and accurate method for determining the soil hydrodynamic parameters compared to other conventional methods.