Abstract
Previous experimental studies of capillary barriers have identified highly hysteretic soil moisture retention characteristics in the materials used. In this study, numerical modelling is used to analyse the role of soil moisture hysteresis in capillary barrier functioning. Comparisons between published experimental results and model simulations indicate that soil moisture hysteresis was a necessary inclusion in the modelling approach to adequately reproduce pore water pressure distributions and the timing of breakthrough occurrences. Under hypothetical intermittent infiltration and evaporation conditions, the predicted volumetric water content in the moisture retention layer was significantly different for hysteretic and nonโhysteretic models. The hysteresis effect was found to be dependent on the nature of infiltrationโevaporation cycling, although the predicted volume of flow through the hysteretic barrier was lower than that of the nonโhysteretic case, regardless of the nature of the cyclic upper boundary conditions. For practical engineering designs, where the water leakage through the barrier is the primary concern, the inclusion of soil moisture hysteresis in numerical modelling is needed. Copyright ยฉ 2009 John Wiley & Sons, Ltd.