长江河口南北槽分流口工程及瑞丰沙地形变化对分流比的影响

Influence of the diversion project and bathymetric change of Ruifeng Shoal on the flow diversion ratios in the South and North Passage of Yangtze River Estuary

分析了南北槽分流口河段的地形特征及其在人类活动影响之下的演变过程,利用高分辨率FVCOM模型研究了分流口潜堤工程的修建、潜堤方向的偏转以及分流口上段瑞丰沙地形变化等因素对南北槽落潮分流比的影响.结果显示,现有的分流口潜堤对北槽落潮分流比的影响较小.潜堤向北偏转时北槽落潮分流比减小,向南偏转时增加,潜堤向南偏转对分流比的影响大于北偏.瑞丰沙中沙基本消失、下沙萎缩及南港主流的北偏有利于水流进入北槽,从而明显增加北槽上段面落潮分流比.而由于横沙通道对水通量的调节,北槽下断面落潮分流比增加甚微.

This paper analyzes the bathymetric characteristics and the evolution processes affected by human activities in recent years at the bifurcation of the South and North Passage in the Yangtze River Estuary. A high-resolution FVCOM model is used to investigate the impact of the diversion project, the direction of submerged dike and the bathymetric change of Ruifeng Shoal on the ebb flow diversion ratios of the South and North Passage. The results show that the construction of the submerged dike at the bifurcation head has limited influence on the ebb flow diversion ratio of the North Passage.The ebb flow diversion ratio of the North Passage decreases when the submerged dike deflects northward and vice versa; however, the influence of the southward deflection is greater than that of the northward deflection. Scouring of the middle and lower Ruifeng Shoal and the northward shift of the mainstream are favorable for the flow entering the North Passage, which increases the flow diversion ratio of the North Passage in the upstream cross-section. Due to adjustment of the water flux in HengSha channel, the flow diversion ratio of the North Passage is slightly increased in downstream cross-section.