Modeling slope rainfall-infiltration-runoff process with shallow water table during complex rainfall patterns

Abstract Limitations in current infiltration modeling approaches hamper the evaluation of the effects of complex rainfall pattern and slope gradient on soil infiltration and runoff in presence of a water table (WT), although they can markedly alter the hydrologic processes. To fill the gap, the Smith et al. (1993)’s infiltration model was modified, and a modeling framework was then developed to simulate the rainfall-infiltration-runoff process in presence of a WT. The model was tested against experimental infiltration and runoff data at two different constant inflow rates and WT depths. Good agreements between the modeled and observed results were found in infiltration and runoff rates for two cases. The model was evaluated under complex rainfall patterns and the results showed that the model performs well in the infiltration rate and the soil water redistribution predictions. With an increasing of slope gradient, the decrease of runoff rate tends to become more prominent under steady rainfall pattern, but the trend becomes more complicated under complex rainfall patterns. The model was compared with Hydrus-1D and Shallow Water table Infiltration Algorithm (SWINGO) and found that both the model and Hydrus-1D can well predict the soil infiltration rate and soil water redistribution in presence of a shallow WT for the silt loam, sandy loam, and clay. SWINGO is likely to overestimate the ponding time and the infiltration rate but underestimate the time to column saturation for clayey soils with a shallow WT. The model is expected to produce a more realistic and accurate approach for infiltration and runoff prediction in presence of a WT.