Study On The Utilization Of Channel Water Depth Resources In The Yibin-Chongqing Riverway Of The Upper Reach Of The Changjiang River Under The Condition Of Daily Adjustment Unsteady Flow

The Changjiang River Economic Belt has become one of the regions with the strongest comprehensive strength and the greatest strategic support in China.Accelerating the development of inland water transportation of the Changjiang River is of great significance for building a modern comprehensive transportation system,adjusting and optimizing the industrial layout along the Changjiang River and the region,and promoting the coordinated development of energy conservation and emission reduction and regional economy.However,in the Yibin-Chongqing riverway of the upper reaches of the Changjiang River,due to the influence of unsteady flow with daily regulation of cascade junctions,the water depth of the channel increases,which increases the difficulty of channel maintenance.During the dry season,the water depth of the channel is small,especially in the dangerous section of the navigation beach,so the navigation quality is not ideal.To improve the quality of navigation of Yibin-Chongqing riverway and shipping efficiency,need for daily regulation unsteady flow along the propagation law is studied,using unsteady flow wave time channel depth is relatively larger conditions for navigation of ships,made shipping under the condition of guarantee of cargo capacity continuously through the obstruction beach risk,achieve the goal of the depth of the water resources make full use of.The main work of this paper is as follows:(1)A one-dimensional unsteady flow mathematical model is established,which is suitable for the characteristics of long-distance and multi-tributaries in the Yibin-Chongqing section of waterway.The Preissmann implicit difference scheme is used to discretize the Saint Venant equations,which solves the problem that the calculation results of long distance unsteady flow mathematical model are easily scattered.The catch-up method is used to solve the difference equations,and the solution method of catch-up coefficient at the junction of tributaries is clarified,which breaks through the obstacle of unsteady flow calculation under the condition of multiple tributaries.The measured data were used to verify the calculation results of the model,and the calculation accuracy met the requirements.(2)Reveal the spatial and temporal distribution characteristics of water depth resources in the Yibin-Chongqing riverway.In this paper,the daily variation of water depth and the variation law of water depth during the peak period are obtained,the tonnage of the main navigational vessels in the channel along the Yibin-Chongqing section is determined,and the indexes for the full utilization of water depth resources are established.(3)A scheme for the utilization of water depth resources is put forward for the risk of obstructing the navigation beach in the channel between Yinbin and Chongqing.The function relation between the propagation time and the propagation distance of the unsteady flow is fitted,and the time of the unsteady flow to the key obstruction beach risk along the passage is calculated by using the relation.The optimal navigable time of ships in Yibin is established,which shows that the optimal navigable time of ships in Yibin is closely related to the flow value of Yibin.The average speed of unsteady flow propagation in each section with obstruction to navigation is calculated,and it is revealed that when the ship starts from Yibin in the best navigable period and the sailing speed is equal to the average speed of unsteady flow propagation,it can realize the continuous passage of all the key obstruction to navigation in the Yibin-Chongqing riverway.