157. Silt Management in Rangit Power Station

River Rangit originating from Talung Glacier is one of the major tributaries of river Teesta in the state of Sikkim. Like other Himalayan rivers, the silt content in this river is very high resulting in loss of storage capacity of Dams built across it. Rangit reservoir upstream of Rangit Dam for hydropower generation had a reservoir length of 1.609 kms and a live capacity of 1.175 Million cubic meters when constructed in 1999. Due to storage effects of Dam and rapid urbanization and development activities in the catchment area, the capacity has now reduced to 1.033 million cubic meters. This has not only affected storage required for peak power generation during the lean flow period but also the performance of hydro turbines (3x20MW) at surface Power House, and also the flood management is affected seriously resulting in higher reservoir levels for comparatively lower inflows. This paper deals with the problems of sedimentation in the Rangit reservoir and its regular flushing during high flow period to gain some of the lost capacity.