Field measurements of sediment transport in the permanent backwater region of the Three Gorges Reservoir
Since the impoundment of the Three Gorges Reservoir, it is measured that many fine sediments have deposited in the permanent backwater region, influencing the navigation seriously. For example, the depth of siltation at the Huang huacheng reach has exceeded 50 meters, and the navigation has been forbidden at the low water levels. Despite the numerous relevant studies, there is still a need to carry out further studies on the fine sediment transport in the Three Gorges Reservoir. Through the combination of synchronous measuring equipment of flow velocities and suspended sediment concentrations, water sampling equipment and underwater camera system, a velocity and sediment measuring system is developed. Field measurements are conducted from July 18th to August 2nd 2012 at the Zhongxian and Fengjie reaches, thirteen sections are selected, a total of 41 vertical lines with 320 points are measured. The suspended particles are shown mostly silt and the median diameters keep almost the same along the water depth. The sediment concentrations are plotted against the Rouse equation, illustrating that the concentrations don‘t fit the Rouse equation at low velocities, but gradually agree the Rouse equation well with the increase of velocities. According to field sampling results, the sediment concentrations are calibrated against the backscatter acoustic intensities of ADV. The relationship presents linear in double logarithmic coordinates, and a formula for calculating sediment concentrations is given finally. Then the instantaneous sediment concentrations and flow velocities are synchronously obtained and thereby the turbulent and sediment diffusion coefficients, indicating that the turbulent diffusion coefficients are much bigger than the sediment diffusion coefficients, which is thought because of the large scale vortex motion. The sediments on the bed are fluid muds observed by the underwater camera system, showing the high-velocity and intermittent movements due to the large water depth and turbulent bursting phenomena. This study shows a basic situation of the fine sediment transport in the Three Gorges Reservoir, laying the foundation for the further related studies.
field measurement sediment transport velocity and sediment measuring system the Three Gorges Reservoir
W.J.Li J.Wang S.S.Zhang
National Inland Waterway Regulation Engineering Research Center, Chongqing Jiaotong University, Chon Key Laboratory of Ministry of Education for Hydraulic and Water Transport Engineering, Chongqing Jia
国际会议
The 3rd Biennial ISRS Symposium Achieving Healthy and Viable Rivers (ISRS)第3届国际河流大会
北京
英文
584-591
2013-08-05（万方平台首次上网日期，不代表论文的发表时间）