Simulation of River Morphology Change due to Reservoir Desiltitation Operation

The formulation of the reservoir desiltitation strategy has been addressed as an essential issue worldwide because the water resources crisis has become serious in recent years. The sediment-releasing operation using the current sluice gates or the bypass tunnel during flooding events can slow down the reservoir deposition and keep the storage capacity. However, the variation of downstream river morphology inevitably affected the channel stability due to the reservoir sediment-releasing operation. The sediment transportation downstream of the reservoir needs to be further investigated to determine the potential risk. This study adopted a calibrated two-dimensional numerical model, SRH-2D, to investigate the river morphology in the Tamshui River in northern Taiwan, East Asia. Three different typhoon events, Typhoon Hinnamnor, Soudelor, and Aere were considered slight, moderate, and severe scenarios. In addition, the original operation, sediment releasing, and bypass joint operation could be represented as the lowest, medium, and highest sediment released rate situation. The simulation shows the erosion and deposition location of different typhoon events and reservoir operations to highlight the potential disaster hotspot. As a result, this research can be a reference to reservoir management to adjust the operation principle to obtain the balance between reservoir storage capacity and downstream river stability.