Abstract:

Laomukong navigationpower junction is the first level of the navigation hydropower cascade development project located between Leshan and Yibin on the Minjiang River. It is a comprehensive water conservancy project which is based on shipping and integrated avionics, combining flood control, water supply, environmental protection and tourism. In this paper, a twodimensional mathematical model was established for sediment and river flow. The model consists of the flow equation, nonequilibrium suspended sediment transport basic equation and the bed deformation equation. To prove the similarity, water level and crosssection velocity distribution were verified based on the measured data. According to the water and sediment data of Laomukong, including the suspended particle gradation, bed load gradation and the scheduling mode of the reservoir, 3 representative years (low water 1971, ordinary 1979, ample flow 1985) were selected to constitute the cycle. The reservoir sedimentation in different periods was calculated after the completion of the reservoir. Based on the calculations, we analyzed the distribution of the sediment deposition, mainly about the sediment deposition and siltation thickness in the key parts. Then a preliminary analysis was made on the reasons of sediment uneven distribution and the relationship between sediment and scheduling mode of reservoir. Due to the aggradation of the reservoir, it is necessary to discuss how the change of reservoir level affects on Leshan city and the Leshan Giant Buddha in different flood frequencies. According to the computation of sedimentation, an analysis was made on the influence of reservoir sedimentation on port construction environment. The comparison of the values of physical model and numerical simulation indicated that the twodimensional mathematical model for sediment could well simulate the process of sediment deposition in the reservoir. The results of the paper showed that: (1) the model can simulate the movement of water flow and the process of sediment deposition; (2) the sediment deposition mainly occurred in the reaches between Laojiangba and Laomukong, and the sedimentation volume accounted for 85 percents of the total; (3) after the sedimentation in the reservoir, flood in different frequencies does not have an impact on Leshan city and Leshan Giant Buddha