近百年来长江河口航道拦门沙的形态演变特征

长江河口航道拦门沙对长江航运、泄洪以及上海港的建设具有重大的影响。通过近百年来历史资料和最新图件中北支、北港、北槽和南槽拦门沙河段的主泓剖面与平面图，分析近百年来4 个入海航槽拦门沙的形态演变特征。经分析发现：近100 年来，北支拦门沙由口外向口内逐渐移动并演变为口内巨型沙坎；北港拦门沙滩顶向下游移动了近30 km，2001 年后北港拦门沙河段开始有心滩发育；北槽拦门沙有两个明显的滩顶，但至2010 年这一显著特征消失；南槽拦门沙滩顶呈双峰型-多峰型-单峰型变化趋势，且滩顶向下游移动了约14 km。显然，除了北支拦门沙演变与崇明岛大规模围垦、北槽拦门沙演变与深水航道直接相关外，北港、南槽拦门沙演变特征主要与长江深水航道整治工程、横沙东滩圈围以及青草沙水库等大型工程影响有关。

Morphological Evolution of Mouth Bars of the Yangtze Estuarine Waterways in the Last 100 Years

The mouth bar in the Yangtze estuarine waterways has significant influences on the transportation of the estuary, flood discharge and the construction of Shanghai Port. In this paper the morphological evolution and its mechanisms of mouth bars of the Yangtze estuarine waterways are studied by analyzing hundreds of years of historical data and the latest profile maps of some main mouth bar channels in the Yangtze Estuary. The results are shown as follows: The mouth bars in North Branch move gradually from outside of the mouth to inside and form a huge sand bar. In North Channel, the top of mouth bar migrates down-stream about 30 kilometers, and a channel bar has been developing since 2001. Two mouth bar tops had ever exited in North Passage, which disappeared in 2010. The top of mouth bar in South Passage migrates to down-stream about 14 kilometers and the number of tops increases at first and then reduces to only one now. According to these analysis results, we can conclude that the evolution of mouth bar differs from that of the location. In North Branch it is directly related to large reclamation in Chongming Island, but in North Passage it has a close relationship with the Yangtze Estuary Deepwater Channel Regulation. However, the evolution of mouth bar in North Channel and South Passage is not only in connection with the Yangtze Estuary Deepwater Channel Regulation, but also with the reclamation in East Hengsha Shoal and the Qingcaosha Reservoir.