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长江口为典型的多级分汊中等潮汐河口,口门宽阔、径潮流强劲、泥沙运动复杂、河槽交替多变,给河口综合治理带来困难。长江口各分流汊道演变过程中,此消彼长是永恒的主旋律,其产生、发展、扭曲、萎缩、消亡具有周期性演变规律。为发挥长江黄金水道的优势,促进国民经济发展,长江口先后实施了深水航道治理工程、南北港分流口处的新浏河沙护滩和南沙头通道限流工程,以及中央沙促淤圈围工程和青草沙水源地工程等,南北港和南北槽分流口河段得到有效控制,对长江口未来的演变产生深远影响。基于南北港分流口以下丰富的地形、水文现场资料,对近年来南港地形演变进行了深入分析,在肯定工程稳定河势的同时,认为目前南北港分流口以下,尚存在南港主流偏离南岸致使发生近岸淤积,以及瑞丰沙中下段沙体刷深导致水流分散,不利于河势稳定等问题。并探讨了长江口“先下后上”治理模式的优缺点,建议在长江口河势尚未发生较大变化时,站在整体的高度,综合考虑河势、航道、水土资源、防洪潮及排灌、生态环境保护等诸多因素,尽快实施长江口综合整治工程。
The Yangtze Estuary is a typical multi-level sub-tidal middle tidal estuary, with wide mouth, strong tidal current, complex sediment movement and alternating river channels, which make it difficult to comprehensively manage estuaries. During the evolution of the diversion routes in the mouth of the Yangtze River estuary, the shift from one economy to another is the eternal theme, and its production, development, distortion, atrophy and demise have a cyclical pattern of evolution. In order to give full play to the advantages of the golden waterway in the Yangtze River and promote the development of the national economy, the Changjiang Estuary has implemented the deepwater channel regulation project, the new Liuhe Sandy Beach and the flow control project of the Nansha Head Channel at the diversion outlets of the North and South ports, Engineering and Qingcaosha water source project, the north-south port and the north-south channel diversion outlet are effectively controlled and have a profound impact on the future development of the Yangtze Estuary. Based on the abundant topographic and hydrological data below the diversion outlets of South and North ports, the evolution of the topography of South Harbor in recent years has been deeply analyzed. While affirming the stable river regime, it is believed that below the diversion mouth of North and South ports, Near-shore siltation, as well as the lower reaches of the Ruifengsha sand brushing deep water flow diversion is not conducive to the stability of the river. And discussed the advantages and disadvantages of the Yangtze River Estuary “before and after the last” mode of governance, it is proposed to stand at the overall height when the river mouth of the Yangtze Estuary has not changed much, considering the river potential, waterway, land and water resources, flood control And irrigation and drainage, ecological and environmental protection and many other factors, as soon as possible the implementation of the Yangtze River Estuary comprehensive renovation project.