Evaluation the Efficiency of MUSLE Model in Sediment Load Estimation Resulting from Individual Rain Events in Doviraj River Sub-Basins, Ilam Province

Most of our country is located in arid and semiarid climate which have high soil erosion and sediment production, therefore, the study of soil erosion and sediment yield and also evaluation of the effective factors on sediment production are very important in proper management of a watershed. The aim of present study is the efficiency evaluation of MUSLE model in sediment estimation in the storm scale and also its modeling based on storm and runoff characteristics in four sub-basins of Doviraj River watershed in Ilam Province, which finally an optimized model is given for estimation of sediment resulted from the storm. Two storms in different dates (2012.11.22 and 2013.1.30) are used in this research. Results indicate appropriate correspondence in calibration stage between the observed and estimated sediment yield in four sub-basins. But, in validation stage, a high difference between observation and estimation in 1, 2 and 3 sub-basins was observed compared to the 4th sub-basin. The reason of inefficiency of the model in validation stage is related to the vastness of sub-basins. In order to present the appropriate model of the whole area the regression relation has been used, in which the power of runoff factor changed from 0.56 to 0.34, which has a high correlation coefficient. In this case if the other sub-basins of Doviraj watershed have similar vegetation cover, physiography and geology conditions, the modified MUSLE model can be used.