A Study on the Suspended Sediment Yield in River Basins of Iran

A wide range of estimated soil erosion in Iran is reported in different references. In addition, there is no acceptable priority of erosion rate and sediment yield among the main basins of Iran. In this research Suspended Sediment Yield (SSY) and soil erosion are estimated about 350 and 1000 million ton per year respectively for the country. Average specific SSY are also calculated 214 t/km2/yr using 209 hydrometric stations records. The maximum average specific SSY are observed in Hamoon-e-Jazmoorian, Minab and Baloochestan-e-Jonobi, and Maroon and Zohreh second order basins with more than 700 t.km-2. Three significant regression equations are developed between SSY with area, mean annual discharge and specific discharge. This study shows that specific SSY is proportionally related to area, which means relatively higher erosion rates in piedmonts and hilly land to high mountains. Primary study of watersheds with more than 1000 t/km2/yr specific SSY shows that the susceptible geological formations, landslides and vegetation cover play important roles on specific SSY.