中文摘要：

近年来,随着来水来沙条件的改变,南京八卦洲汊道左汊衰退速率又有所加快,并已多次观测到12%左右的分流比。采取一定的工程措施可以对左汊的分流比进行改善,但工程在改变汊道首部分流比的同时也改变了分沙比。分沙比的改变对于整治工程的实施效果,以及下游河道的走势,特别是左汊的河床冲淤变化有一定的影响。针对改善左汊分流比的工程措施,运用二维水沙数学模型,计算分析了导流坝、切滩、疏浚等工程措施对汊道河床冲淤的影响。结果显示,3个月冲淤计算后,工程措施对左汊分流比均有较大改善,且在工程附近河床的冲淤也有较明显的变化。

英文摘要：

In recent years, the recession of the left branch of Baguazhou braiding channels in Nanjing of Yangtze River has accelerated with the variation of water and sediment conditions , and the split ratio of the left branch has reduced to 12 %. River engineering treatments and structures can improve the split ratio of the left branch, while the diversion ratio of sediment will be changed too, which may generally affect the improvement effect of engineering measures and the trend of downstream river channel, especially the deposition of the left branch. For the engineering measures to improve the split ratio of the left branch, this paper analyzes the impact of diversion dikes and dredge in the left branch on the progress of riverbed deposition with a 2- D flow and sediment mathematical model. The results show that split ratio of the left branch generally increase and there is also significant erosion around the engineering structures. It can provide some advice for the further improvement of engineering measures.