长江口南、北港分汊口演变与治理

Process and regulation of bifurcation of Southern and Northern Waterway in Yangtze River estuary

按输水输沙特征,中等潮汐长江口多年来保持“三级分汊,四口入海”地貌形态格局。第二级南、北港分汊口问题已成为当今发展重要障碍之一。近百年来南、北港分汊口呈周期性冲淤演变,1971年前后共约10年,中央沙头石头沙西10 km左右的分汊口位置最佳,河势归顺,河床稳定,南、北港都畅通。现今分汊口正处于剧烈变动时期,分汊口治理,南支及其下游河段的开发与工程须认真考虑其影响与对策。

According to its characteristics of water and .sediment transport, the Yangtze River estuary with medium tide keeps the geomorphololgical pattern of ＂3 bifurcations and 4 outlets＂ many years. The problem of the second bifurcation of the Southern and Northern Waterways becomes one of the main obstructions against further development. The erosion and silation processes of the second bifurcation have alternated periodically in the recent century. The best site for bifurcation stood at the west end of the ＂Central Shoal＂, about 10 km from ＂Shi-tou＂ Bar at 1971, when the river situation was ideal for training, the river course was stable and the navigation of beth Southern and Northern Waterways was notimpeded. As the second bifurcation now is during extreme changing years, main effects and and training of the Southern Branch and its lower reaches must be seriously considered. for further development