Prediction of the runoff production dynamic and analysis of the effects of slope and range cover type using process based WEPP model

The ability of rangeland hillslope to runoff production is contributed to two key factors including surface geometric and vegetation cover composition Different models was developed for simulating runoff production based on geometric and physical and vegetation properties that can estimate runoff production. This research was conducted to evaluate the ability of hillsope version of process based WEPP model in prediction of runoff production dynamic in different slope angle (25, 35 and 45 %) and different rangeland type. Runoff collection plots were established in Kabode area in Gharasoo watershed with 3×10 meter dimension in three replications and in three rangeland type. Climatic data including rainfall and temperature was recorded on site and the others including wind velocity and direction, solar radiation and dew points prepared in Kermanshah synoptic climate station. Runoff simulation was done as single storm using v2008.9 version of WEPP model. Results indicated that maximum prediction accuracy was made in 45% sloe. The model estimation error was as underestimation and the nonlinear relationship was existed between predicted and measured data. Model has good advantages in simulation the land cover type and management condition effects on production of runoff and water harvesting.