Simplified modelling of areal average infiltration at the hillslope scale

Two models for estimating expected areal-average infiltration rate, (I) over bar, at the hillslope scale are presented. The first relies upon the condition of a negligible infiltration of surface water running downslope (run-on process) into a previous heterogeneous soil. It is an adapted version of an earlier semi-analytical model. The second incorporates the run-on process and is based on a Jumped approach that uses an effective saturated hydraulic conductivity. This latter was parameterized in terms of the main characteristics of rainfall and soil. Both the models were tested by comparison with the results carried out by Monte-Carlo simulations over different soil types. It was found that the first model simulated (I) over bar with maximum errors in magnitude typically less than 10%. The second model provided similar errors in the total volume of overland flow, and the rising limb of the hydrograph experienced a distortion. Lastly, satisfactory results were obtained by comparing the model without run-on with an empirical approach particularly accurate for fine-textured soils. Copyright (C) 2002 John Wiley Sons, Ltd.