Experimental and numerical simulations of the hydraulic flushing of reservoir sedimentation for planning and design of a hydropower project

Hydropower projects located on rivers transporting heavy sediment loads require design and operation criteria based on sediment management as a means of sustaining the project life. Sediment management is achieved by designing projects as a run-of-the-river scheme, with provision for drawdown flushing, noting hydraulic model simulations are essential for optimizing the design of these projects. Sediment deposition levels are generally predicted with long-term simulations using 1-D numerical models, as well as experiments with scaled physical models that simulate drawdown flushing. The present study presents experiments with scaled model and 3-D numerical model simulations conducted for hydraulic flushing of a reservoir. Experiments were conducted for various durations and discharges to finalize the intake alignment and optimize the flushing. The results of the 3-D numerical model simulations are in agreement with the results of the experimental study (4%–6% variation). The results also indicate a combination of a 1-D numerical model for sedimentation and a 3-D numerical model for flushing can be effectively used to simulate the sedimentation and flushing of reservoirs during the planning and design stages.