末次盛冰期以来长江河口段河道演变研究综述

An Overview of the Research on Channel Evolution in the Yangtze River Mouth Region Since the Last Glacial Maximum

末次盛冰期以来,由于海面发生大幅度的变化,长江河口段经历了深切古河谷形成—古河谷充填—三角洲发育的河床演变过程。海陆相互作用是河口段河道演变的主要影响因素。综合分析了对河口段河道研究的成果,着重对长江河口段古河谷的形成与充填、最大海侵以来的河床演变、古河谷的沉积层序与沉积相及研究的方法进行了综述。过去对古河谷宏观的趋势研究及单个钻孔的研究较多,宏观与微观结合的不够,专门研究古河谷河形的成果很少。今后应注重宏观与微观研究的结合;根据系列钻孔剖面,分析、恢复古河谷河型;根据河型、沉积物特征等,估算古长江流速、流量;加强高分辨率研究、定性与定量研究相结合,探讨环境变化与河道演变的关系和规律。

Since the Last Glacial Maximum, the riverbed of the Yangtze River mouth region has evolved from the shape of the deep incised-valley to the filling of the palaeo-valley and to the delta development because of the great change of the sea level. The interaction between Sea and Land is the main factor which has affected the evolution of the channel of the Yangtze river mouth region. The research achievements on the channel of the Yangtze river mouth were analyzed. The shape and filling, the riverbed evolution since the transgression Maximum, the sedimentary sequence and sedimentary facies of the ancient valley of the Yangtze river mouth region were focused on. A lot of macroscopical studies and single core studies were made. Macroscopic and microcosmic studies were seldom combined. Few shapes of ancient valley were particularly studied. Great importance should be attached to macroscopic and microcosmic combination. The shape of ancient valley was resumed on the basis of series core section analysis. According to the sedimentary characteristics, the flow velocity and discharge were estimated. The high-resolution study, quantitative study and comprehensive study will be increased. The relationship and the law between the environmental change and the channel evolution will be reinforced.