Experimental Study On Evlution Of Branching Reach With Bend

Bending-widen-braided river reach is a more specific type of the river widespread in mountain rivers in southwest China, in the upstream of Yangtze River there are Shenbei mouth Fengji Shingle, Tonggu Beach, Wayao Beach, Luoguo Beach and Diaoyu Mouth which belong to this river type, the navigation Characteristics are curved, shallow, dangerous, which is one of the most complex rapids in the channel regulation. According to the current status of mountain river channel regulation and engineering of the actual needs, it is necessary to study the navigation brought by such bending braided river through qualitative experiment.This paper is based on the background of transport infrastructure projects "Mountain River inlet bending mechanism of relaxation and Renovation", analyzed the Yangtze River upper reaches of mountain bending braided river prototype data, based on the relative position of low water main channel in the relax reach, the mountain bending braided river is divided into two categories, one is that low water main channel is lied on the bottom of the convex bank and the other is on the concave bank. It is studied by the fixed-bed sediment transport generalized model for the evolution of river erosion and deposition characteristics.Based on preliminary results of bending widening mobile bed test, analyzed water and sediment flow processes, nodes form around inlet riverbed morphology and the relative height of the river regime evolution, the boundary conditions of the test is determined.The evolution of low water main channel is lied on the bottom of the convex bank says the channel is in equilibrium after many water and sediment flow processes.The same water and sediment flow processe of right channel presents evolution law of flood deposit and dry wash. The evolution of extent between different processes is not large. According to the evolution of characteristics that shows in slot import of the right, in the central and in the export navigation and siltation problems exist.The right channel of the second category inlet that low water main channel lies on the concave bank shows the channel is accumulated siltation after many water and sediment flow processes and the evolution of the right slot for the support of smaller sub-flow inlet. Natural rivers such as Degan dam, Furong dam, Guxian dam and so on mostly weak or Braided convex bank branch in the flood diversion of the river only. The left main tank inlet flow rate greater than the drop may be formed in the lower rapids navigation and rapids.In the generalized model the channel is in equilibrium, based on the main channel of navigation and features for the low water, for different types of channel regulation program comparative test, the results show that the first category inlet in the right slot import, center and export exist navigation problems, using diversion dike at the head of central bar and the right concave groove spur dikes in the remediation program was better regulation. The second category inlet transition section of the main channel in the lower low water may form jet navigation and rapids.The results of evolution and features of navigation of bending-widen-braided river reach have been well proven on the regulation practice of Tonggu Beach and Fengji Shingle in the upstream of Yangtze River.