Estimating of Soil Saturated Hydrodynamic Using Numerical Inverse Model

The saturated hydraulic conductivity K and the effective porosity fare two important input parameters needed for lateral drainage spacing design and many other applications. The current design procedure is based upon calculation of the lateral spacing, using some average values of saturated K and f within the area to be drained. This procedure causes error in most of the cases. Numerical modeling is a powerful tool in simulating water table around drains. The objectives of this study were to simulate water flow toward drains and to simultaneously estimating K and f using the optimization process within the inverse problem technique. To collect the necessary data of spatial and temporal water table monitoring, a physical drainage model was established in the laboratory and carefully packed with a sandy loam soil. Different data sets from the conducted experiments and literature were used for calibration, using the inverse problem technique. The proposed approach that is based upon measuring water table profiles at different times was then evaluated with both constant and variable f The estimated values with the proposed approach indicated reasonable agreement with the measured data. With variable effective porosity, the method was even more accurate to predict the water table profiles. Also, the inverse problem method provided good agreement compared to the ones obtained by employing the average soil saturated hydrodynamic properties.