New criterion for predicting turbidity current formation in reservoirs Seminar

Sediment deposition is a big problem that affects the lifespan of reservoirs on heavily sediment-laden rivers, and to release sediment through venting turbidity currents is an important measure to reduce the sedimentation rate in a reservoir, especially at the initial operation stage of the Xiaolangdi Reservoir. The occurrence of the plunge point means the formation of a turbidity current, and the research into the prediction of turbidity current formation can help to better understand its movement characteristics in a reservoir. Qualitative descriptions and quantitative calculation methods for the prediction of turbidity current formation are summarized firstly in this study, which indicates that existing prediction methods are usually based on the sediment-laden flows with low concentrations or developed according to the part auto-correlation between the densimetric Froude number and the incoming sediment concentration, and these methods are inapplicable to predict the formation of turbidity currents in the Xiaolangdi Reservoir. The momentum equation for the motion of turbidity current is then deduced, and the effect of non-uniform vertical distribution of velocity on the formation of plunge point is investigated. Finally, a new criterion for predicting the formation of turbidity currents is proposed herein, and its predictive accuracy is validated by lots of flume and field measurements. Validated results indicate that the proposed formula can be used to predict the formation of turbidity currents in the Xiaolangdi Reservoir.