Assessment of sedimentation status and trap efficiency of Wyra reservoir

ABSTRACT Sediment deposition is an inherent phenomenon of any reservoir which causes considerable storage loss thereby disturbing the economy of the community for which the reservoir is intended to serve. Failure to take adequate remedial measures to control sedimentation would result in huge loss in storage capacity. Present paper provides the analysis of the field studies using the hydrographic surveys which were conducted on the Wyra Project, a medium irrigation reservoir built across Wyra, a tributary of river Krishna. The surveys were conducted during the period when the reservoir receives good rains. The principal objectives of the study are to assess sedimentation status, annual sedimentation rate in the reservoir and to estimate the trap efficiency (Te) of the reservoir. The ‘Te’ is useful for predicting the remaining useful life span of the reservoir and the pattern of sediment deposition in the reservoir. Te is also useful in regulating the irrigation water, generation of hydroelectric power and management of sediment treatment plans. Analysis of the results showed that there is a loss of about 27.66 Mm3 (39.47%) in the storage capacity of the reservoir. The sedimentation rate was about 6.86 ha.m/100 km2/year, which is higher than what was considered at the planning stage.