ABSTRACT
River bed change and evolution of the Yangtze River in Chongqing reach received much attention for at least two aspect reasons, the waterway navigation condition, as well as the sedimentation in the Three Gorges Reservoir (TGR). In this study, river bed variation of Chongqing reach was analyzed by an observed profile diagram in recent years after the operation of TGR. Roughly three types of variation were identified, (1) relative stable cross-sections with slight changes both seasonal and annual, (2) stable in seasonal while with intense variations interannual, (3) unstable cross-sections which with not only seasonal changes but also significant changes in different years. River bed evolution is the result of many comprehensive factors such as the regulation history of the river, bank and boundary conditions, and river bed constitutions, and so on. Further comparison shows that human activities such as gravel and sand mining, waterway regulation engineering were the principle fact for the river bed variation in Chongqing reach, result in abrupt changes in a short time. It is suggested that human activities must be considered for analyzing the sedimentation process of the Yangtze river reservoir.
