Control of Turbidity Currents in Reservoirs by Solid and Permeable Obstacles

Abstract

Turbidity currents are often the main process for the transport and deposition of the sediments in narrow, alpine reservoirs. These underwater avalanches with high concentration of suspended sediments follow the thalweg of the lake to the deepest area near the dam, where the sediments can affect the operation of the bottom outlet and the intake structures. To control the sedimentation within the reservoir, the effects of solid and permeable obstacles on the turbidity current were investigated with physical experiments and numerical simulations. In the physical experiments, the velocity distributions as well as the spatial and temporal evolution of the deposits were measured. The investigated measures were also simulated by means of a two-dimensional numerical model, based on the flow solver CFX-4.4. The investigations showed that turbidity currents can be influenced effectively by properly designed constructive measures. Based on the results of the physical experiments and numerical simulations, some design recommendations for solid and permeable obstacles are proposed.