Research On The Evolution Characteristics And Waterway Regulation Measures Of Shoals At The Bend Transition Region Of The Downstream Of The Hydropower

The rivers in the western mountainous areas of our country are rich in water resources and have great potential for development.With the continuous construction of the Jialing River hydraulic complex,the level of the Jialing River waterway has been improved,and it has assumed an important role in the development of inland waterway shipping.At the same time,hydropower energy has also been widely used.However,after the operation of the hydraulic complex,the water flow and sediment concentration of the discharged water will change,and the evolution of the riverbed downstream of the hydraulic complex will change to varying degrees.The Banjiubei transition shoal is located about 2.5km downstream of the Caojie Power Station on the Jialing River.Due to the construction of the Caojie Junction and the impact of sand mining activities in the channel,the flow conditions in the channel have changed greatly,and the navigation conditions of the channel have deteriorated.The thesis base on the Banjiubei transition shoal of the Jialing river channel comprehensive improvement project,this thesis uses the measured riverbed data and hydrology data,combined with the two-dimensional mathematical model to analyze the water flow conditions of the project river section and the evolution process of riverbed erosion also the sedimentation before and after the operation of the hydraulic complex.The navigability characteristics of the Banjiubei shoal,the improvement effect of different schemes,after the scheme,the riverbed evolution and the influence of the project operation were analyzed,and the following conclusions were obtained:(1)Through the analysis of river bed evolution,it is found that the shoreline,swale and channel of the project river have been basically stable for many years.Different degrees of sedimentation.Due to the impact of sand mining activities,the water flow of the main channel in dry season is reduced,and the sand-carrying capacity of the water flow is weakened,and there are different degrees of sediment deposition in the channel.(2)According to hydrology data,after the operation of the hydraulic complex,the flow in the flood season will be leveled,the frequency of major floods will be reduced,and the amount of sediment runoff will be greatly reduced.The change of the riverbed before and after the operation of the hydraulic complex was analyzed.After the operation of the hydraulic complex,there was riverbed scour in the channel within a range of nearly 2km,and the degree of the scour was relatively deep.The beach was washed away,and the Zhongqi sand beach was washed away.(3)Drawning up three kinds of Banjiubei Shoal remediation schemes,and two-dimensional water and sediment mathematical simulation research was carried out,the remediation effects of each scheme were compared,and the evolution of riverbed scour and siltation under the two schemes with better remediation effects were simulated,and the analysis was carried out.Based on the navigation conditions of Jiubei Shoal and the stability of the navigation channel after the regulation,the optimal shoal regulation measures are proposed.