A deterministic-empirical model of the effect of the capillary fringe on near-stream area runoff .1. Description of the model

This paper describes the development of a deterministic-empirical model that can simulate total streamflow and the components of the stream hydrograph in near-stream wetland regions. The model treats the watershed in terms of three zones with differing storage characteristics, and accommodates the dynamic flow system that occurs owing to the influence of the capillary fringe. It accounts for the expansion and contraction of near-stream saturated regions, the large and rapid rise in the water table and the development and decay of the water-table mound, which result from the decreasing storage capacity toward the stream. The overland flow and the groundwater flow components of the stream are calculated accounting for the increased hydraulic gradient toward the stream and the development and expansion of the seepage face. Using relatively modest input, the model incorporates the effect of the capillary fringe mechanism for the purpose of improving the runoff prediction capability in shallow water-table regions.