Investigation on plunge point location and turbidity current movement in the Shihmen Reservoir

Abstract

Since the completion of a reservoir, sedimentation process decreases reservoir storage and woody debris affects the operation of power plant in many montane areas, especially in the northern Taiwan. As turbid density current travelling through a reservoir, successful operation of a sluicing outlet depends on accurate prediction of sediment transport. Insitu measured data of sediment concentration distribution during sediment release operation through bottom outlets can help understand sediment-sluicing efficiency from the reservoir. However, field measurement of the turbidity current in a reservoir is relatively difficult because of large water depth, an unsteady fluid mechanism, and harsh environments during a flood. The Shihmen reservoir is important for water supply, irrigation and flood control in northern Taiwan. Empirical equation is considered to estimate the plunge point location of turbidity current and verified with the field observations. A user interface is developed in this study to display the plunge location, movement velocity, body thickness and sediment concentration of turbidity current. For turbidity current venting, the plunge point location and turbidity current movement estimation can provide real-time information to assist the operations of bottom outlets and sediment bypass tunnels. In the future, coping with rainfall runoff prediction, the prediction of turbidity current movement can also expect to improve the desiltation operation of the Shihmen reservoir. The study results can be applied to the related disaster prevention issues on water resources sustainable, reservoir sedimentation and water treatment capacity.