Experimental study with hydraulic modeling of a reservoir desilting operation using a sediment bypass tunnel

The storage volume of reservoirs is highly susceptible to the effects of sedimentation. This study investigated the Wushe reservoir in Taiwan, the volume of which dropped to just 31.9% of its original capacity in 2016. Our focus is the improvement of desilting operations via scale model experiments involving a sediment bypass tunnel. The experiment parameters included inflow and outflow boundary conditions, sediment discharge, and the shape of particles used in the scale model (i.e., matching those in the real-world location). This study also performed numerical modeling to select upstream inflow boundary conditions for the experiment. The results revealed that the proposed desilting strategy using a sediment bypass tunnel would not only be more effective than the existing outlet in terms of sediment release, but would also provide economic benefits over dredging. The return on investment should be evident within 8–21 years, depending on the scale of the typhoons that strike. There seems little doubt that a sediment bypass tunnel is the best approach to preserving reservoir storage capacity and relieving concerns of an impending water crisis.