The sedimentation of a small reservoir Itiquira A case study

A sedimentation study carried out for the basic design of Itiquira hydroelectric power plant reservoir in Itiquira River, situated in the State of Mato Grosso, Brazil, is described. Using local sediment discharge data and Churchill’s Trap Efficiency Curve, which is recommended for small reservoirs, a 12 years useful life was obtained. Furthermore, to take into account the increasing of sediment transport during time, a methodology was applied, leading to an annual growing of about 16%, which would reduce the silting time of the reservoir to just 8 years. The effect of a 50 years of return period flood was studied, showing that the small reservoir could be completely silted in only 80 days. In order to guarantee the operation of the plant, a bottom outlet and silting chamber designs, both adequately positioned, were suggested.