Unsaturated Soil Hydraulic Properties Identification using Numerical Inversion and In-Situ Experiments from Mnasra Area, Morocco

Abstract

In soil physics, accurate estimation of hydrodynamic properties is essential for effective groundwater management. Experimentally, determination of these properties in the laboratory or in-situ conditions is difficult step, long and may involve uncertainties significant for the vast majority practice use. Frequently, inverse methods were established to determine accurate parameters in the field scale based on measured soil moisture and hydraulic conductivity over time and depth. These inversions methods involve hydraulic soil-models using adapted optimization algorithms that ensure a best combination of parameters minimizing a cost function. In this work, direct and inverse optimization approaches has been proposed to estimate the effective hydraulic parameters, based on the temporal description of the soil physical and hydraulic parameters using field water content measurements from located in Mnasra area (northwest of Morocco). The Levenberg Marquardt optimization algorithm coupling with the vadose zone model (VZM), numerical code in Fortran, has been used to inverse estimation of hydraulic parameters based on transients soil water content measurements. These uses have been conducted using temporal measurements of soil moisture in depths: 20, 40, 60 and 80 cm. The estimated properties are in good agreement with those measured in-situ. Overall, it was concluded that this technique can greatly widen the range of hydrological problems admissible for inversion and can be used for many applications in hydrologic engineering, either alone or in conjunction with traditional techniques.