Author(s): Peng An Chen; Sameh A. Kantoush; Tetsuya Sumi; Doan Van Binh; Sebastien E. Bourban; Riadh Ata
Linked Author(s): Doan Van Binh, Riadh Ata
Keywords: TELEMAC-3D; Turbidity current venting; Venting efficiency; Multiple outlets operation
Abstract: Operating different reservoir outlets is a challenging decision-making process balancing the releases of turbidity currents with the maintenance of clear water circulation within the reservoir. Experimental model tests for the Shihmen Reservoir in Taiwan were conducted to investigate the venting of turbidity currents for existing outlet facilities and additional proposed sediment bypass tunnels. In this study, a three-dimensional numerical model, based on TELEMAC-3D, was validated and used to predict the venting operation and the behavior of turbidity current within the reservoir under multiple outlet conditions. Various turbidity current characteristics, including the plunging location (from cross-section 29 to 24), head velocity (around 0.09 m/s), arrival time at each outlet and muddy lake evolution, were analyzed under different scenarios. The results confirm that the upstream bottom outlets' operation leads to delayed arrival of the turbidity current at the dam’s outlets. This is critical information for downstream outlets' operation. Moreover, additional release of sediments delays further the formation of the muddy lake near the water supply intake, which means additional clear water could be supplied during flooding events. To choose the balance between water storage and sediment desiltation under water resource avail-ability, a suitable venting strategy is here proposed with a schedule of outlet operation. This study has shown that one outlet operation, which is the highest order outlet, is ap-propriate under the 2021 drought event. In contrast, under abundant water resources conditions, one can operate all of the sediment venting outlets to provide 66.36% venting efficiency and a 19.5% supplementary delay in the clear water supply. To conclude, un-derstanding the most efficient de-siltation strategy without wasting extra water resources is valuable to reservoir management.
DOI: https://doi.org/10.3850/IAHR-39WC252171192022720
Year: 2022