Modeling and Analysis of Turbidity Currents in a Reservoir with the Dredged Guiding Channel

Zengwen Reservoir, the largest water resource in Taiwan, has been seriously impacted by sedimentation, contributed mainly by typhoon floods. Therefore, it is chosen as a case study to investigate the effectiveness of an integrated reservoir management strategy of sediment routing and removal by constructing a dredged guiding channel to route turbidity currents generated during typhoon floods. The strategy is evaluated by simulating flood events of four return periods using a 3D numerical model, the effectiveness of which, with and without the dredged guiding channel, is compared in terms of the venting efficiency of reservoir outlets and the arrival time of turbidity currents. The numerical model is calibrated using the laboratory data and validated using the physical model and field data. The simulated results show a significant increase in the venting efficiency and a decrease in the arrival time of turbidity current for all the flood events in the presence of a dredged guiding channel. In addition, results also aid in predicting trapping efficiency based on the Brune curve trend for different capacity inflow ratios for single flood events. The findings demonstrate the feasibility and effectiveness of the integrated reservoir management strategy in the field before high-intensity flood events.