Abstract:

According to observed data of hydrology, sediment and topography of the bending braided channel at Wuhan’s Tianxingzhou reach in the middle Yangtze River, we analysed the changes of flow dynamic axis, flow velocity and sediment concentration distribution in the presence of varying flow and sediment. We also expounded the interaction between runoff and sediment load and fluvial processes, and predicted the evolution trend. Results suggest that the flow dynamic axis in river diversion zone shifts to the left with the flow increasing, giving rise to favorable conditions for the left branch and a long-term braided river pattern. But as the incoming sediment from the upstream reduces remarkably, erosion in the right branch is more severe than that in the left branch, favorable for the right branch to maintaining as the main branch.

Key words: Three Gorges Reservoir, braided channel, riverbed evolution, runoff and sediment load, flow dynamic axis