Abstract: Luxikou reach is a typical goose-head braided channel in the middle and lower reaches of Changjiang River. Before the impoundment of the Three Gorges Project, channel evolution shows periodic tendency due to flow deflecting caused by single-side node in inlet of channel and bend circulation effect. After the impoundment, the evolution regularity of scouring and silting changes under the influences of water and sediment in upper reach and human activities. According to theoretic analysis and measured data, we carry out research the periodic evolution of Luxikou goose-head braided reach. The results show that periodic evolution still exists, and adjustment of scouring and silting even speeds up due to the decrease of incoming sediment from upstream. Furthermore, the head of Xinzhou sandbar suffers severe erosion, and erosion ditch occurs. Meanwhile, sediment deposition is serious in the inlet of Zhigang, which leads to adjustment of flow distribution pattern and bad channel condition. After the implementation of artificial waterway engineering, the river regime gradually tends to be stable , but the inherent effect on cyclical evolution of river reach still exists, bringing out a negative effect on navigation conditions and regulation projects.

Key words: goose-head braided channels in Luxikou reach, evolution of river bed, periodicity, adjustment of scouring and silting, mechanism study