Determining the Most Appropriate Method to Estimate Sediment Delivery Ratio in Shirin Darreh Dam Basin

In this study, sediment load in Shirin Darreh Dam basin was estimated based on hydrological, UNESCO and FSM methods. Comparison between the total deposited sediments in the reservoir (17 Mm3) and results of the three methods showed the hydrological and FSM methods with the estimated value of 1158000 and 5565000 m3/year were the most proper and the most improper ways to sediment load estimation, respectively. Annual erosion intensity based on EPM was obtained about 1426300 m3/year, and the actual sediment delivery ratio was calculated about 0.78. The predicted sediment delivery ratio based on the results of EPM method and the three methods of total sediment load, and some of empirical models, was calculated. The results of the calibration showed that the hydrological method and the empirical model, in which the slope is the most important factor to obtain the sediment delivery ratio, with minimum error and maximum accuracy were the most proper methods.