长江口北支河段碍航特性及治理思路

Characteristics of navigation-obstruction and regulation idea of the North Branch of the Yangtze Estuary

近年来随着一系列圈围和护岸工程的实施,长江口北支河道边界逐渐固定,河床整体处于缓慢淤积状态,但局部滩槽变化仍较大,航道条件相对复杂。基于实测地形资料,分析1997年以来北支河段的河床演变特征及碍航特性,结合近期北支河段水深条件,提出北支航道采取上中下河段“联动治理,分级通航”的治理思路。崇启大桥上游河段水深多为3~5 m,3 m深槽仅在崇头附近中断,建议该段利用自然水深布置航道,局部浅区开展疏浚。崇启大桥下游河道展宽明显,河宽达5~10 km,加之江心滩冲刷萎缩,漫滩流增加,不利于航槽水深的维持,建议在主槽南侧采取必要的整治工程,同时开展江心滩守护工程,稳定航道边界,维持航槽水深。

With the implementation of large-scale reclamation projects and bank-protection works in recent years,the boundary of North Branch of the Yangtze Estuary gradually maintains stable.In general,the North Branch slowly undergoes sedimentation,but the remarkable channel evolution still occurs in some local regions with its complex navigation conditions.Based on the topographic data,we analyze the characteristics of channel evolution and navigation-obstruction of the North Branch since 1997,and propose the regulation idea of“linkage regulation and hierarchical navigation”in the upper,middle,and lower reaches of the North Branch channel.The water-depth of the upper reach of Chongqi Bridge mostly ranges from 3 m to 5 m,with the groove deeper than 3 m only being interrupted near Chongtou.It is suggested to arrange the channel with natural depth in the upper reach,and dredge in some shallow areas.The lower reach of Chongqi Bridge is widened,with the water-width from 5 km to 10 km.Also,the floodplain flow increases because of the erosion and shrink of the central bar,and it is not conducive to the maintenance of channel depth.It is suggested that the regulation works should be taken on the south bank,and the protection project of the central bar is carried out to stabilize the channel boundary and maintain the channel depth.