镇扬河段位于长江下游感潮段,为典型的分汊河道,长期以来其河道演变复杂多变。基于历史文献、古地图、近现代地形测图及水文资料等资料,分析了镇扬河段长期演变规律。研究表明:西汉之前镇扬河段为长江河口,泥沙在古河口逐渐落淤,北岸边滩发育,河道总体南移、河宽缩窄,江中泥沙落淤并逐渐发育为稳定沙洲,形成世业洲汊道与和畅洲汊道。历史时期,河道水力和输沙特性是河道形成和演变的主要因素,南北两岸节点为控制河势的关键;20世纪50年代后,镇扬河段河道形态相对稳定,近期演变主要表现为汊道段河势格局的调整,河道内各类工程的建设等人类活动成为影响河床演变的重要外因。

As a typical bifurcating channel in the tidal reach of the lower Yangtze River(also known as the Changjiang River), the Zhenjiang-Yangzhou Reach has experienced long-term complicated evolution. By examining historical documents, ancient maps, modern topographic mapping, and hydrological data, we analyzed the long-term evolution of the Zhenjiang-Yangzhou Reach. According to our findings, prior to the Western Han Dynasty, the Zhenjiang-Yangzhou Reach served as the mouth of the Changjiang River. Sediment gradually accumulated in the ancient estuary, giving rise to the development of a sandbar along the north bank. The river channel generally shifted in a southerly direction, resulting in decreased river width. The sediment deposition eventually stabilized, forming the Shiye sandbar branching channel and the Hechang sandbar branching channel. Throughout history, hydraulic power and sediment transport characteristics played a key role in shaping and transforming the river. River nodes located on both the north and south banks played an essential role in controlling the river’s flow regime. Since the 1950s, the channel morphology of Zhenjiang-Yangzhou Reach has been in a relatively stable state. However, recent developments have shown adjustments in the flow regime within the branching channel. Human activities, such as the construction of various projects in the river, have become important external factors influencing the evolution of the riverbed.