Efficiency Assessment of Rangeland Hydrology and Erosion Model (RHEM) for water erosion quantification (Case Study: Sangane Watershed-Iran)

Computer simulation models are becoming increasingly popular for predicting soil loss through quantification of the processes of detachment, transport and deposition of eroded soils. To assess the effects of different management practices on soil erosion and to select the best management practices, application of models (especially process-oriented models) and their validation is considered a positive step. In this research, the Rangeland Hydrology and Erosion Model (RHEM) was evaluated using soil erosion measuring plots and the recorded rain in Sangane Research Station, Khorasan Razavi Province of Iran. The model was run and the predicted runoff and sediment yield values were compared with measured runoff and sediment yield values. Then sensitivity analysis and calibration were done on sensitive parameters and model was run with calibrated parameters. In the calibration period the, the model efficiency (ENS) values and the coefficient of determination (r2) were 0.92 and 0.95 for sediment, and 0.60 and 0.70 for runoff, respectively. In validation period, the (ENS) values and (r2) values in 99% Confidence level were 0.70 and 0.84 for sediment and 0.11 and 0.65 for runoff, respectively. Our research indicated that the results of model were acceptable in 99% confidence level for sediment and could be used withreasonable confidence for soil loss quantification in the Sangane watershed and the other rangeland watershed with similar condition.