Estimation of Soil Hydraulic Properties of Basin Loukkos (Morocco) by Inverse Modeling

Management of groundwater resources is very important for economic development in arid and semi-arid lands. Unsaturated zone plays an important role in the fate of pollutants in the soil. Modeling of water flow in the vadose zone uses methods and techniques of soil physics. To describe and predict the behavior of water and solutes in unsaturated soil, knowledge of the soil hydraulic parameters is essential. The aim of this work is to evaluate the soil hydraulic parameters by direct and inverse methods from field measurements of cumulative infiltration and water contents. The inverse approach used here combined the numerical solution of the Richards equation two-dimensional with a Levenberg-Marquardt algorithm of optimization. Field experiments, using the disc infiltrometer, were conducted out in the Rmel area, sandy soil, in the Loukkos Basin located in northern Morocco. In this study, numerical and experimental results show that the simulated values are much closer to the measured values with a high correlation (R2 ≈ 0.92, RMSE ≈ 0.146). Indicating that the model used here is efficient to estimate the soil hydraulic parameters by inverse modeling. Furthermore, the sensitivity analysis showed that the saturated conductivity (Ks) is sensitive to estimate with respect to other parameters.