Determination of sediment yield of watershed basins based on sensitivity to erosion of geological formations

The erosion rate ranking of geological formations can be a useful way for identifying and prioritizing the watershed sub-basins and it is important in view of decision making and management of the watersheds. Therefore, the present research was conducted with the aim of prioritizing the implementation of soil conservation operations in the Hablehrood sub-basins in northern Garmsar based on the degree of sensitivity of rock units to erosion. The method is based on the expert opinions and rainfall simulator experiment and comparison of the obtained results with erosion and sediment estimations of empirical models such as PSIAC, EPM and SWAT. Results showed that erosion rate ranking of the sub-basins based on the results of rainfall simulator conformed to the output of the three mentioned models in 12 sub-basins of 21 sub-basins and in other six sub-basins with two models, and in the remaining three sub-basins, it only conformed to one model output. Rainfall simulation results showed the highest correlation with the PSIAC model with a specific sediment yield of 9.2 t km-2 and based on the results of the observation data of the Bonkouh sediment-debit station, a special sediment of 8.02 t km-2 without considering the bedload, it became clear that the PSIAC model provided the most reliable estimate of sediment yield. Thus, matching the results of rainfall simulator in the erosion rate ranking of sub-basins with the PSIAC model shows that the rainfall simulator study on lithology units quite reliable with a 90% confidence level for erosion ranking classification of sub-basins and it can be used in similar basins.