Study On Regulation Of Branch Channel And Shoal In Fluctuating Backwater Area Of Reservoir

Channel upgrade renovation is in full process.Reservoir change backwater to distinguish system is a kind of common river type in our country.The type river is located in the backwater reservoir changes under the influence of reservoir operation scheduling present a dual characteristic of natural river channel and reservoir.Influenced by water flow and sediment conditions,the riverbed evolution is complex,often appear shoals obstruction,regulation is difficult.The beach,main show is curved,shallow,risks,such as integrated features.The changes of the three gorges reservoir,the streamwise part of the channel is still a classIII,short of "golden waterway" planning requirements.For this class of bank risk regulation should be based on the analysis of the river channel evolution law,the regulation principle,regulation parameter selection and the building layout and so on comprehensive consideration.In this paper,reservoir of Three Gorge changes the streamwise chetingqi channel based on the reservoir change backwater branching river shoal regulation research.By using historical data,mathematical model and the method of combining physical model study of the law of riverbed evolution,beach risk causes and mechanism,navigation-obstructing characteristics were analyzed,and the river regulation scheme are put forward.Reservoir of Three Gorge operation after 175 was used in the beach paragraph affected by water,low water level reservoir runtime appear a rapid obstruction at xiannanhai beach.Beach period of interannual thalweg convex concave position,beach groove position is relatively stable,no ChanXiangChong silting law as a whole.3.5 m isobath all fronts,the minimum air 100 m wide,to fulfill the requirements of class II channel from the channel size.Narrow section during dry the surface,but the beach water,steep slope,combined with the outlet section of the sheet pile of spur dike and car pavilion moraine tail confrontation,bend narrow channel,channel within the flow regime is poorer,water flow is urgent,reflux and more water.Zhajiao beach bed basically stable,but due to recent sand mining fishing moraine,the pile of tail bed face down pile in the left tank water straight,but less,water diversion.Right groove deep water,but was bent,and the right has am moraine mouth,Angle of rock and slag heap in respectively with moraine brain,moraine wing standoff,narrow slot,low water velocity,slope steep and cross flow and scissors water,large ships ascending difficulty.In this paper use the MIKE21 two-dimensional planar flow calculation software and the physical model test on the corresponding experimental study.According to reach the recent topographic map and the observed hydrological data model and the frictional surface,flow velocity,flow and split ratio similarity verification.In the validation by physical model and mathematical model on the basis of reasonable solution experiment was carried out,and scheme comparison to determine the final plan.Branching river beach group of regulation,insurance regulation tend to affect the downstream beach upstream section,in order to avoid the influence of this study is the first treatment was studied for Three Gorge beach paragraph,and then to small beach period of regulation.The results showed that: Xiaonanhai beach duan zaisheng plate pile built two downstream dam,latent dam crest elevation respectively under the design water level of 6.0 m and 6.5 m,reduce car pavilion moraine lock car pavilion moraine dam height of 171.2 m and dredging right wing and the right stone bowl and car pavilion moraine section of the channel,dredging the bottom elevation of 168 m;Zhajiao beach open on the left bank Singapore airlines groove Angle of beach,channel width of 80 m,dredging water level under the design water level 4m.Construction of moraine dam dam head and three teeth long dam,dam in the design of high water level more than 2.5 m.Scheme after the river regime basically under control,the mainstream swing is restrained,full of flow smooth,flow regime is good,the risks to eliminate obstruction beach navigation flow condition improved significantly,basically stable channel.Meet the requirements of class II channel.