NUMERICAL SIMULATION OF TURBIDITY CURRENT IN RESERVOIR

I. INTRODUCTIONWhen a sediment--laden flow reaches the backwater zone of a reservoir, the suddenreduction of flow velocity causes sediment particles to settle toward the river bed. Undercertain circumstsnces, it will plunge and form a layer of sediment--water mixture flowingbeneath the water surface. This flowing layer is called the turbidity current. A turbiditycurrent is relatively stable and has important impacts on reservoir sedimentation.In the case of deep reservoirs, due to temper…

NUMERICAL SIMULATION OF TURBIDITY CURRENT IN RESERVOIR

Turbidity current is one of the most important phenomena that occurs in a reservoir. It is able to carry tremendous amounts of fine sediment over a long distance and has significant impacts on the spatial distributions of sediment deposition in a reservoir. Layer-inte- integrated equations were applied in this study to simulate the hydraulic characteristics of a gradually varied turbidity current. Small disturbance theory was used to analyze the locations of the boundary conditions, and a series of experiments were conducted to calibrate and verify the model. Sensitivity analyses were also performed to Study the impacts or water entrainment coefficient, total resistance coefficient and transport-capacity concentration of suspended sediment. It was found that supercritical turbidity current occurs when the densimetric Froude number is greater than 0.88, and the boundary conditions have to be as- signed at the upstream end. For the case of the turbidity current without erosion or deposition, variations of the water entrainment coefficient and total resistance coefficient will only change the longitudinal variation rate of the hydraulic characteristics of the turbidity current. For the case of the turbidity current with erosion or deposition, transport-capacity concentration is the only parameter that affects the trend of the turbidity current.