Tarbela reservoir has experienced severe sedimentation, leading to the loss of one third of its total volume due to the accumulated sediment deposits. In addition to losing the volume and thus capacity to regulate the flow for irrigation, the advancing sediment deposits potentially present a threat to the operation of the dam. Rising sediment levels near the dam may block the low-level outlets and impede their continual operation. Sand-sized sediment are starting to pass into the hydropower intakes and this will cause abrasion of turbine blades, leading to increasing cost of maintenance and time when the turbines are out of operation.
HR Wallingford has contributed with designing data collection campaigns, analyses of sediment inflow into the reservoir and advised on possible future sediment management strategies. To quantify the impacts of different future scenarios, we used a selection of 1D, 2D and 3D computer models to simulate sedimentation process in the reservoir at various levels of detail. The typical outputs of the models included prediction of storage loss, annual variation in sediment inflow and outflow, locations, depths and composition of deposited sediment and amount and composition of sediment outflow through different structures.
HR Wallingford has been looking into the sedimentation issues and their solutions in a number of projects listed below.