Research On The Channel Evolution And Control Scheme Of The Ma'anshan Reach Of The Yangtze River Under The Change Of Water And Sediment

With the impoundment and operation of the Three Gorges Reservoir,the discharge of clear water has changed the long-term water and sand conditions.The erosion and deposition of the main stream of the middle and lower reaches of the Yangtze River will undergo great changes.The economic and social development of the coastal areas has a significant impact.With the increasing progress and development of our country's society today,the urban structure is gradually being improved,all of which have put forward new and higher requirements for the governance of the Yangtze River and river courses.Through historical data collection,actual measurement data collection,prototype observation and data analysis,a comprehensive analysis of the characteristics and geological evolution law of the studied reach and its influencing factors have been carried out.This paper analyzes and predicts the evolution trend of the river bed in the Ma'anshan reach.Starting from the actual needs of life,it puts forward the actual governance problems and needs of the Ma'anshan reach under the current social situation.In response to the above problems and needs,a combined improvement plan for the Ma'anshan reach is proposed,and the plane two-dimensional mathematical model of water flow and river engineering model tests are used.Means,from the five aspects of river regime,flood control,shipping,shoreline,and ecological requirements for effect analysis.The main content of the research and the innovation results are summarized as follows:1.Analysis reveals the law of river course evolution in Maanshan RiverAfter collecting a large amount of relevant data such as the shoreline,deep channel line and navigation channel of the Ma'anshan reach of the Yangtze River,the author analyzed the historical evolution and recent evolution of the reach,and then summarized the evolution law of the reach.It is preliminarily believed that the beaches and deep troughs will continue to move downwards in response to the upper and lower transitional sections of the mainstream.After this process is completed,the two begin to rise simultaneously.This downward movement plus the rise is called a whole evolution cycle.In the year of flood,Ma'anshan The pace of evolution of the river reaches is accelerated,and the evolution cycle is shortened.In addition,revetment projects that increase the ability of the riverbed to resist erosion will slow down its evolution speed and extend its evolution cycle.2.Prediction of the channel evolution trend of the Ma'anshan reachBased on the analysis and understanding of the evolution of the typical straight branch of the Maanshan reach of the Yangtze River,the author believes that the mainstream inflow conditions of this reach will remain basically stable,and the left and right branches of Jiangxinzhou will maintain the left branch as the main branch,and the right branch as the branch branch.The diversion pattern of Xiaohuangzhou branch is "Left main and right branch";its Xiaohuangzhou branch will also maintain the diversion pattern of "Right main and left branch",but the diversion ratio of Xiaohuangzhou left branch is still tending to increase.3.Research on the demand for river regulation of the Ma'anshan reachThrough the study of river regime stability,flood control safety,waterway scale,shoreline utilization,eco-friendliness,etc.,the actual governance needs of the Maanshan reach under the current social situation are put forward.It is believed that the river regime: control the left margin of Jiangxinzhou and Niutunhe beach collapsed,slowing down the transition section of Jiangxinzhou left branch,stabilizing the central bank and Xiahejiazhou,restricting the development of the branch between Xintan and Xiahejiazhou and Jiangxinzhou;increasing the inflow of the Xiaohuangzhou transition section,Hinder the development of the left branch of Xiaohuangzhou.In terms of flood control: strengthen the river bank line,improve the level of dike,and avoid the occurrence of bank collapse;it is necessary to give full play to the flood discharge capacity of the main,branch,beach land,etc.,reduce the morphological resistance of the river,and fully ensure the unobstructed flood discharge of the river.In terms of shipping: stabilize the main flow of the left branch of Jiangxinzhou and the beach,increase the diversion ratio of the right branch of Xiaohuangzhou,maintain the stability of the navigation channel,and increase the minimum width of 10.5m in the transition section of the heart beach and the transition section of Xiaohuangzhou.The demand for shoreline protection and utilization can be summarized as follows: restrain or slow down the transition section of Jiangxinzhou left branch and the downward movement of beach tail of Niutunhe,ensure the utilization of deep water shoreline in Zhengpu Port area on the left bank of Jiangxinzhou left branch,and ensure Xiaohuangzhou Large and medium-sized enterprises such as Ma'anshan Port on the right bank of the right bank are operating normally.The ecological requirements are summarized as follows: setting up finless porpoise protection areas to ensure smooth migration channels for Chinese sturgeon and other fishes,without siltation of the channels,and reducing the occurrence of human activities during the migratory period.4.Research on comprehensive improvement plan for river improvement of Ma'anshan reachPropose a proposed layout project with reference value,analyze the hydrodynamic aspects of a single project by establishing a two-dimensional mathematical model of the water flow,and then use the movable bed river model test to carry out the combined plan of the single project.Research on the effects of five aspects: river regime,flood control,shipping,shoreline protection and utilization,water ecology and water environment.After verification,the scheme: after the construction of the pinch groove sealing project between the heart beach and the lower Hejiazhou,the upper Hejiazhou left margin submerged dam project,the Xiaohuangzhou diversion dam project,the Xiaohuangzhou left branch submerged dam project,the Ma'anshan River.The multi-objective needs of the segment can be met.