Abstract

Due to the settlement of large quantities of transported sediment by the Sefidrud River flow, during the last few years more and more problems have arose to the reservoir. A critical issue to be addressed in any reservoir emptying or flushing operation is that of the downstream impacts. Barrages and intakes are installed on the Sefidrud River, downstream of the dam, to divert reservoir releases to irrigators. These intakes and canals cannot tolerate heavy sediment loads, since this would create serious sedimentation problems within the irrigation system. During the last 24 years (1980 to 2004) the flushing operation has created biological and ecological changes in the river and its command areas. Some of the causes and obtained results are presented in this paper.

Keywords: Downstream Impacts, Flushing Operation, Sefidrud Management, Sefidrud Reservoir.