鄂西清江下游中更新世晚期以来的河流演化

随着水利水电和旅游经济的发展,清江流域已成为众多学科研究关注的热点,清江的形成与演化也得到了学术界重视。探讨清江的河流演化有助于研究地质灾害的发生机理,为当地减灾防灾工作提供理论支撑。在清江下游多处河段存在以双底谷中谷为代表的古宽谷,它们呈线状连续分布,与现今河道大致平行,是清江下游河道变迁的重要证据。通过古宽谷内的代表性河流阶地年龄数据,可以较为准确地梳理出河流演化过程的时间序列。从清江下游的双底谷中谷和其中的河流阶地的系统调查研究入手,通过自然历史分析法和类比法,结合阶地物质光释光年代测试方法,重建了中更新世晚期以来清江下游大致的河流演化过程,同时提出山地河流演化存在去直取弯、袭夺归并和变换的特点,指出地壳差异隆升是导致河道变迁的主要因素,提出通过河流演化过程的研究探讨岸坡稳定性的思路。

Evolution Process of the Downstream of Qingjiang River Since Late Middle Pleistocene in Western Hubei Province

With the development of water resources,hydropower and tourism economy,the study on Qingjiang river has become a hot spot in many disciplines,and the formation and evolution of Qingjiang river were also paid academic attention to.The study on Qingjiang river evolution can contribute to investigate the pathogenesis of geological disaster,and thus provide theoretical support for local disaster prevention and mitigation.There are many ancient valleys represented by double-bottom valleys in some reaches of the downstream of Qingjiang river,which show linear continuous distribution,and the connection of these ancient valleys parallel to the current river.These double-bottom valleys are the direct evidences of river bed change of Qingjiang river.The ages of the river terraces can date the time series of the river evolution accurately.Based on analysis of the characteristic double-bottom valleys,and dating of the river terraces in the key locations,series of migration of valley in the downstream of Qingjiang river since late Middle Pleistocene were evaluated.Furthermore,the paper points out that mountain rivers may be characterized by abandoning line to choose curve,and merging each other,and transferring gradually.The result shows that difference in crustal uplift is the main reason of the valley change,and underground river communication may be another capture mode.The paper also points out that the slope stability should be discussed based on river evolution.