南北港汊道是长江口的主要汊道,由三部分组成:分汊口段、南北港段和横沙以下水下三角洲段。其中分汉口段自七丫口至吴淞长约34公里,河宽由10公里扩宽至15公里,宝钢码头即位于其间,连同上游白茆沙河段通常称为南支。

The South-North "Waterway is a main fork reach of Yangtze River, it consists of three regions: (1) the fork reach; (2) the main braided channel; (3) the mouth bar re-gion.Based on the historical charts and hyddrological surveys, this paper dealts with the characteristics on the distribution of discharge and bed material load transported and analyzes fluvial process of the fork and braided channel.The paper points out that the oscillation of the main channel in the fork reach-brings about the change of the transported bed material load distribution ratio in the South-North "Waterway, thus causes the banks in the South-North Waterway subject to scouring and silting, Furthermore it also causes the flow condition changes in the-fork reach and conversely makes the main channel oscillates.According to the analysis, the basic reason which causes all of the changes descri-bed above is that the equilibrium condition between the flow and sediment transporta-tion is destroyed. In addition, wide river b?d and sandbank with characteristic loose material boundarv condition of channel in fork reach are other reasons.