PHYSICAL MODEL OF THE HYDROLOGY OF SLOPING HETEROGENEOUS FIELDS

A model simulating water flow and storage in a 2-dimensional section of a sloping field, in which surface runoff, infiltration, evaporation, unsaturated soil moisture movement and groundwater flow are represented as a series of interacting 1-dimensional processes, was adapted to cases of horizontally heterogeneous fields. The model is illustrated in a series of simulation trials with variously constituted hypothetical fields of loam and clay soils, subjected to a 108-mm rainstorm. Runoff was found to depend on the fraction of the slope occupied by clay, and on the relative location of the clay (wether upslope or downslope with respect to the loam). Ground-water recharge was found to be greater in the loam, as was the rate of lateral drainage. The capability of the model is discussed. - Authors