Spatiotemporal evolution of longitudinal profiles of channel thalweg in the Jingjiang Reach of the Middle Yangtze River
The evolution process of the thalweg is of great significance for the study of riverbed evolution and channel adjustment.To investigate the spatiotemporal evolution of longitudinal profiles of channel thalweg in the Jingjiang Reach after the operation of the Three Gorges Reservoir,based on the measured thalweg elevation data of 173 sections from 2002 to 2020,this study compares the spatiotemporal changes in thalweg elevation o-ver the past 18 years,and analyzes the causes for these changes in combination with the variation of incoming flow and sediment.The results show that the channel thalweg in the Jingjiang Reach is generally scouring and downcutting since 2002.In particular,the thalweg elevation downcutting further exacerbates after 2008,but there will be deposition occurred when there is extremely high incoming flow and sediment flux.The average scouring depth in the upper Jingjiang Reach is 4.62 m from 2002 to 2020,but the riverbed is alternately scoured and deposited in the Lower Jingjiang Reach.The relative erosion-deposition strength in the upper Jingjiang Reach is less than 10％,which is smaller than that of the lower Jingjiang Reach.The main reason for this is that the riverbed in the Zhijiang Reach is mostly composed of coarse sand and gravels with strong erosion resistance,which to some extent limits the development of scouring.While the riverbed in the lower Jingjiang Reach is mostly composed of medium fine sand,which is vulnerable to scour.
channel thalweglongitudinal profileriverbed scourwater and sediment variationerosion-deposi-tion strength
万方数据
维普
