关键词: 清江下游, 鄂西, 双底谷中谷, 河流阶地, 河流演化

Abstract:

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. 

Key words: downstream of Qingjiang river, western Hubei Province; , doublebottom valley, river terrace, river evolution