Numerical modelling of flow in variably saturated porous media with fluctuating shallow water tables

The paper discusses various models which have been proposed to simulate the hysteresis of the water retention curve. Three of these models were implemented into a finite element computer program for flow in variably saturated porous media and were applied to the solution of transient flow through a soil column subject to drying-wetting cycles. The performance of these models was assessed through comparisons with previously published experimental results. A linear hysteresis model was shown to reproduce satisfactorily the experimental results, although it was simple to implement and required minimal experimental data to be formulated. Overall, the results indicate that the fact of including hysteresis in the numerical model improved the predictions with respect to the case when single-valued functions were used.