Simulation of Rainfall - Run-Off Relationships in an Arid Area as a Means for the Characterization of Hillslope Flows / הדמייה של יחסי נגר-גשם באזור צחיח כאמצעי לאיפיון הזרימה המדרונית

This paper demonstrates a computer-produced deterministic simulation model which was developed in order to illustrate the runoff response to rainfall on arid hillslopes. The model is based on the Hortonian approach to overland flow generation. It takes into account the spatial variability of surface properties and rain characteristics. The hillslope is divided into N compartments parallel to the contours. Within each compartment processes associated with overland flow generation are simulated: rainfall, infiltration, evaporation and soil moisture losses. Although these processes occur simultaneously, they do not necessarily occur at the same intensities. The computer determines the depth of water which accumulates over short intervals of time on the surface of each compartment and transfers this water at the end of each interval to the adjacent compartment further down the hillslope. The model permits an evaluation of overland flow yield on arid hillslopes of known surface characteristics under various rainfall conditions. Simulations of partial area contribution using various rainfall conditions and surface properties may also be performed with the model.