中文摘要：

南槽作为长江口入海四口之一,是长江水沙输运向海的主要通道。在长江入海水沙急剧变化和长江口大型涉水工程的影响下,南槽的动力地貌过程成为当前长江河口研究的重点内容之一。分析和揭示近50年来南槽的动力地貌变化过程对理解长江河口响应人类活动和自然驱动作用的变化具有重要意义。基于此,本文通过1959~2013年长时间序列的南槽地形资料,研究长江入海水沙变化及南槽落潮分流分沙比影响下的南槽动力地貌演变过程。结果表明,南槽在1989年江亚南沙并滩前后呈现两种不同的地貌演化阶段：江亚南沙并滩前,南槽普遍发生淤积,两侧浅滩不断淤涨,河槽总体呈缩小态势,河槽拦门沙呈现＂双峰＂状态;江亚南沙并滩后,南槽呈现出＂上段冲蚀加深、中段微冲、下段河槽束窄、两侧浅滩淤积＂的状态,拦门沙向＂单峰＂发展。此外,周边涉水工程的实施对近期南槽地貌的冲淤演变过程有较大的影响。

英文摘要：

As one of the four outlets of the Yangtze Estuary into the East China Sea,the South Passage（ SP） was the main channel of the water and sediment transportation before the Deep-Water channel Regulation Project operation. But in recent decades,under the influence of changes in water and sediment discharge and large-scale hydraulic engineering projects,the morphodynamic processes of the SP have undergone tremendous changes. It is obvious that the analysis and determination of the morphodynamic processes of the SP in the recent periods has important significance for understanding the response of the Estuary to anthropogenic actions and natural forcing. The results indicate that there were two distinct evolutionary phases of the SP associated with the connection of the Jiangyanan shoal to the Jiuduan shoal（ CJSJS） before and after 1989. Before the CJSJS in 1989,due to the relatively stable water and sediment supply conditions,the SP had wide siltation on both sides of the shallow tidal flats,and the overall river channel was narrowed,and there were two different parts in the mouth bar in those years. However,after the CJSJS in 1989,the SP showed an abnormal appearance with ＂deepened erosion of the upper segment,slight erosion of the middle segment,narrowing of the lower segment and siltation at the two sides＂,thus leading to the disappearance of the first part of the mouth bar. Moreover,there are close relationships between the morphodynamic processes of the SP in recent years and the operation phase of the engineering distributed around SP.