Watershed Management and its Effect on Sedimentation in Doroudzan Dam

Doroudzan Dam which is located in south of Iran is an earth dam with the reservoir capacity of 993 MCM. It supplies the demand water for Shiraz city with 2000000 population and irrigation of 1100 km2 down stream agricultural land as well. Due to the importance of this dam in regional development increasing the period of operation of it, is on priority. The large amount of sediment load entering the reservoir is the greatest factor threatens the useful life of this dam. Dead storage of dam is estimated about 133 MCM for 50 years. Decreasing the amount of sediment load, watershed management operations such as creating mechanical structures like check dams, terraces, and biomechanical operation like vegetation and training to residents has been applied to upstream lands since 1980. In this article the watershed management operations are investigated and to evaluating the results of these operations, the amount of sediment load entering the reservoir before and after the watershed management operations, has been considered by the data of Chamriz hydrometric station that is located in the upstream of the reservoir, and the results of hydrographic surveying that has been done in 1995 and 2003 in reservoir.