Dynamic Simulation And Refined Operation Of Water Flow And Quality In The North-south Main Pipeline Network Of The Han River To The Wei River

The Han to Wei River Diversion Project,known as the South to North Water Diversion Project in Shaanxi Province,is a key project to solve the water resource shortage in the Guanzhong region.The water resources of the Huangjinxia Water Conservancy Hub and Sanhekou Water Conservancy Hub in the Han River Basin are transported through the Qinling Water Diversion Tunnel to the Huangchigou Water Distribution Hub,and then through the northsouth main pipeline network and water distribution facilities in the Guanzhong region,the water resources are transported to the water supply targets.The regulation and storage capacity of the water pipeline network is limited,and the water cannot be stored in large quantities within the pipeline.Therefore,the flow of water discharged from the Huangchigou Water Distribution Hub to the north-south main line needs to be in a dynamic equilibrium state at all times with the water intake process at various water outlets along the main line.Once the discharge process does not match the water intake process,it will lead to pipeline blockage.To maintain the safe operation of the project,water withdrawal facilities are used for water withdrawal operations,but this greatly reduces the economic efficiency of the project operation.The water in the pipeline is transported downwards by gravity and is not actively controlled by humans.At the same time,water quality pollution incidents are prone to occur at key hubs,and the migration process of pollutants within the pipeline is not clear.The purification effect of water withdrawal facilities on mainline pollutants is not clear.Therefore,exploring the hydraulic characteristics,water quality transport characteristics,and refined operation process of water transportation and intake in pipelines is of great significance for the safe operation of engineering.The long-distance water transfer project from Han to Wei in the second phase of the Guanzhong water receiving area has been taken as the research object.HD hydrodynamic module,AD convection diffusion module and ECO lab water quality simulation module in MIKE model are used to conduct Dynamic simulation of flow characteristics,flow evolution and water quality in the north-south trunk water transmission pipeline network and explore the refined operation process of Dynamic equilibrium of water transmission and distribution,so as to maintain the stable operation of the project.The main achievements are as follows:(1)Introducing the Princeton Virtual Narrow Slot Method into the MIKE HD model,organically coupling the non pressure tunnel with the pressure pipeline,simulating the water surface profile of each section of the north-south main line under the second phase operating conditions and the designed maximum water delivery capacity.In the non pressure water delivery tunnel section,the water surface profile did not reach the top of the tunnel,and the project was in a safe operating state,consistent with the design,verifying the rationality of the model.(2)The evolution time of each section of the North-South trunk line under different water flow is simulated and calculated,and the flow evolution law of the North-South trunk line is based on AD model.(3)Couple the AD module with the ECO lab module,to s imulate the water quality change of the north and south trunk lines under different Point source pollution,and combine the water returning function of the water returning facilities,formulate the water returning rules to drain the polluted water out of the trunk line pipe network,so as to achieve the purpose of purifying the water body.The simulation results show that the southern trunk line has a strong water purification ability,while the northern trunk line has a weak water purification ability.The main reason is that the maximum return flow rate of each trunk line outlet is different from the proportion of the trunk line flow rate.The larger the return flow rate,the stronger the purification ability.(4)Simulate the damage degree and countermeasures to the balance state of water transmission and distribution in the North-South trunk line caused by an emergency such as surge or sudden decrease of water intake flow.Based on the flow evolution concept of "first and then combined",the refined operation process of Huangchigou discharge is calculated and combined with the regulation and storage effect of the rear positioning bleeder,which greatly reduces the adverse impact of emergencies and provides technical support for engineering operation under different working conditions.