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1 河势基本情况 长江南京河段八卦洲汊道属鹅头型汊道。左汊为支汊,长21.7 km,半个世纪以来,一直处于不断衰退中,其近期演变格局为:洲头不断崩退,河道沿程不均匀收缩,沿程和局部阻力增加,河床淤积,分流比减小,河形向弯曲发展。使八卦洲左汊分流比减少的主要原因有2个:上游分流区主泓的变迁和左、右汊阻力比变化。 50年代以来,上游分流区主泓总的变化趋向是左摆、下移,-20m槽尾逐渐指向左汊进口段,这一河势条件是维持左汊能长期保持一定分流
A basic situation of the river The Nanjing section of the Yangtze River Gossamer Chau Road is a goose head road. The left bank is a branch with a length of 21.7 km. It has been in a downturn for half a century. Its recent evolution is as follows: the recurring collapse of the headland, the uneven shrinkage along the river course, the increase of resistance and local resistance, the siltation of the riverbed, Shunt ratio decreases, the river to bend development. There are two main reasons for the decrease of the diversion ratio of Zuyi in Gouzhou Island: the change of the main upstream of the upstream diversion zone and the change of resistance ratio of left and right 汊. Since the 1950s, the main trend of change in the main diversion zone is left-swinging and down-going, and the tail of -20m gradually points to the left-hand import segment. This river condition is to maintain a certain diversion for a long time