Study On Improvement Measures Of A Navigation Channel For Typical Long River Reach (Daijiazhou Reach)in The Middle Reaches Of The Yangtze River

The regulation of the long reach with multi-channel in the middle and lower reachesof the Yangtze River has become a very important problem for the navigationdevelopment. On the basis of the long reach of the middle reaches of the Yangtze River-Daijiazhou reach waterway project, applying the on-site research, data analysis,numerical simulation and physical model test, the evolution characteristics of the typicalriver bed were analyzed. Focusing on the macro management of the waterway, the targetriver pattern for the regulation, the he regulation timing and channel regulation ideaswere studied,and the renovation ideas were ultimately proposed under the actualcontrol measures. The main contents and conclusions are drawn as follows.(1) Theanalysis results of the reach evolution show that the timing of taking the round branch asthe main navigable branch for the channel regulation of the Daijiazhou reach is favorable,whilethe timing of taking the straight branch as the main navigable branch for theDaijiazhou reach channel regulation is not very favorable. However, it is concludedthrough comprehensive comparisons that the straight branch should be selected as thelast target river pattern for the channel regulation of the Daijiazhou reach.(2) On thebasis of riverbed evolution analysis, the general idea of the typical long river channelregulation is proposed as follows: The straight branch of Daijiazhou reachis taken as themaster navigable channel in dry season, the high water routes and low water routes areall attributed to the straight branch. In the mean time, the Ba River channel, as theentrance of the straight branch, should be improved, so that the difficulties of channelmaintenance can be reduced and eliminated.(3) A two-dimensional mathematical modelof the total sediment (TK-2DC) suitable for the long reach with complex river boundarywas applied to investigatethe flow along the Dajiazhou reach. Through the analysis ofdiversion flow characteristics around the delta head in the bending and branching riverreach, the concept of diversion flow plane was presented. The characteristics of flow andsediment tansport, and the regulation plans were studied through numerical simulationtests.(4) Based on the riverbed evolution analysis andthe simulation results of the flowand sediment movement, the regulation plans of the Daijiazhou reach are proposed.Furthermore, the physical model tests of fixed bed were carryied out for in-depthresearch of the regulation measures,and the final proposal for the overall regulation plansof the river reach and regulation measures by stages and were presented.