Study On Parameters Of Navigational Channel Regulation Of The Middle Yangtze River After Impounding Of Three Gorges Reservoir

The Yangtze River is the longest river in our country, which is the significant channel through east to west, Navigable mileage is accounted for53%while the water volume is accounted for80%. The middle reaches of the Yangtze River is900km from Yichang to Poyang Lake, Hukou, the water transport condition is extremely advantageous, it is an important link making the East, middle, West of China together, it is the bases of the western development, it is also the important support for the sustainable, rapid development of economic. Keeping Yangtze waterway unimpeded and safe will increase the material exchange and economic exchanges between the East and West, which is benefit for the social and economic development of our country. However, the middle reaches of the Yangtze River have many shoal patch, this problem has not been solved, it is becoming the "bottleneck" for transportation on the yangze river, so we must take action to deal with it.Before manage the Yangtze River comprehensive, we should determine the navigable water level and regulation parameters, Channel regulation parameters. Design water level, waterway regulation parameters are closely related to many factors such as the channel distortion, low water flow. The designing water level impacts the shipping benefits and the cost of Channel construction and Channel maintenance. The determination of waterway regulation parameters influence the engineering cost and effect.Since2003, because of the three gorges reservoir’s impoundment, the water and sediment process in the middle reaches of the Yangze river is determined by artificial regulating, Flow’s leveling, clean water’s washing, riverbed’s changing. so the low water level and beach trough structure changed, then designing water level and the waterway regulation parameters are difficult to determine, which impedes the implementation of the project in the middle reaches in Yangze river. Above, the study of how to determine the waterway regulation parameter in the middle reaches of Yangze river is necessary.This article explains the trends of the rectification parameters in yangze river through considering the changing of water and sediment process and the changing of the terrain by under Three Gorges reservoir. Then find the way to determine the designing water level under the Reservoir regulation and riverbed sedimentation condition. The downstream of the hydro-junction has two characteristics:unsteady sediment transport and unidirectional cutting bed. We has reduced the formulary of calculating the width of channel regulation line, and analysed the parameters in this formulary. To find out the formulary of calculating the width of channel regulation line in middle reach of yangze river, we have made the formulary combined with the feature of middle reach of yangze and put forward the concept of remediation cross-section, using the proved parameter in the downstream of three gorges reservoir. Provides the basis for determining the remediation parameters in the middle reach of yangze by considering the reduction of sand and the acceleration of withdrawal water.This passage focuses on the following aspects:(1) The differences of the river evolution under the three gorges reservoir operating. Because of the three gorges reservoir, the recession of water is expediting and the sands become less on October. The bed below is washing out for long distance and for long time. So low water level is drawdown, channel depth becomes deeper. The strong impact of the river may appears the steep slope and flow anxious problems, the dandy river’s width becomes wider. All above will make the mainstream awe.(2) Method for determining the designing water level. On the basis of summing the method for determining the design water level before impoundment, put forward a better method after impoundment:deducing design water level by the design flow. So we can determine the midstream hydrological station designing water level for15years after the Three Gorges reservoir completion. Determine the designing water level of the hydrological station comparing the different designing water level by different methods. At last, the Power stations also affect water levels, so make same amending is necessary.(3) The determining of regulation line width. We have summarized the method of determining the regulation parameters. And put forwards some optimization ideas, determined the method for the regulation water level, put forward the idea of combining regulation line and rectification section in the Channel regulation. All above is according to the three-dimensional condition to adjust and control the river. We can consider the influence of the flood and the dry water which is overall for a river’s development. To make the river steady and governance the river comprehensive, studies on physical experiment and verify the formula will make it more reasonable.(4) The usage of method for determining regulation parameters. We can put this improved method in the significant erosion period (Lotus pond channel) and Weak erosion period (Guniu Sha channel) on the downstream of The Three Gorges reservoir. Then discuss how adaptable the regulation parameters it is when facing the lesser sand and the accelerated water Withdrawal. To prove the new method for determining regulation parameters mentioned above is better after running Three Gorges Reservoir.