长江口福姜沙河段近期河势演变分析

Recent river evolution of Fujiangsha section of Yangtze estuary

长江口福姜沙河段属于复杂的分汊型平原河道,江中沙洲、暗滩交替分布。河床受径流和潮流共同作用,在江面宽阔河段涨落流路分歧,主槽分汊,多处航段12.5 m水深不贯通,宽度不足200 m,是海轮入江的碍航河段。交通运输部计划在十二五期间开始实施长江南京以下12.5 m深水航道建设。本河段航道建设治理思路为顺应河势,维持分汊型,守护双涧沙沙体,稳定航槽。利用实测资料为福姜沙河段航道治理目标进行河床演变分析,分析可知:随着水文年的周期性变化,河道沙体和汊道及汊道间兴衰更替,给航道稳定性带来不利影响,说明了双涧沙守护的必要性;福北、福南水道受岸线约束,航槽稳定,航深通过疏浚虽能达12.5 m,但宽度很难满足;从河势变化趋势来看,福中水道弯曲度适中,主槽宽阔,且呈冲刷发展趋势,利于航道建设。

FJS （Fujiangsha） section of the Yangtze estuary with braided shoals distributed in the channel, is a complicated and bifurcated plain river. River bed nearby, impacted by runoff and current flows, is divided at the wide river sections. The main passage is bifurcated and the 12.5 m deep contour breaks at many navigation sections. So FJS section becomes an obstructed river for vessels sailing. The Ministry of Transport intends to implement construction of 12.5 m deep-water navigation channel under Nanjing during the“Twelfth Five-Year Plan”period. The principle of the control project is“Following river evolution;Keeping originally as bifurcated;Protecting SJS （Shuangjiansha） shoal;Stabilizing the navigation channel”. Based on the measured data, we analyze the river regime evolution. The results show that：1） With the cyclical change of the hydrological year, sand bodies and inlets will be replaced by each other over and over again which has negative impact on the navigation stability so that there is great necessity of SJS shoal protection project;2） Due to the restriction of shore lines, navigation channels in Fubei and Funan waters stay stable, besides, the depth can be deepen to 12.5 m contour by dredging measures while the width of the passage cannot be guaranteed;3） According to the river regime evolution, Fuzhong passage, with a wide main channel and a moderate turning curvature, has a trend of erosion which is to make a better navigation condition.