Ponded Infiltration into Soils Bounded by a Water Table

A simple model of ponded infiltration into homogenous soils bounded by, and at steady state equilibrium with, a water table is presented. The model parameterizes the wetting front profile as a tension‐saturated zone above a zone in which the moisture content decreases linearly with depth. Application of the model requires numerical evaluation of an integral relating the time since the onset of ponding to the infiltration rate or wetting front position. Wetting fronts predicted by the simplified model compare favorably with laboratory measurements of Vachaud and Thony (1971) and, for a wide range of soil types, with those predicted by finite‐element integration of the governing flow equations. The presence of a shallow water table causes the infiltration rate to decrease faster than it would under semi‐infinite conditions with uniform initial moisture content. Infiltration equations for soils bounded by water table may be used in distributed hydrologie models and other applications where the shallow position of the water table significantly affects the partitioning of precipitation forcing during storms.