Variation in the hydraulic geometry of the middle Yangtze River after the Three Gorges Project operation
The operation of the Three Gorges Project(TGP)has changed the flow and sediment regimes in the river below the dam,the riverbed in the middle reaches of the Yangtze River(MYR)has been continuously scoured,and the hydraulic geometry of the MYR has been adjusted accordingly.The Zhicheng-Hankou sub-reach of the MYR was chosen as the research object,and the variation characteristics of hydraulic geometry of different sections in the MYR were analysed according to the measured data from 2003 to 2017.The results showed that:1)After the TGP operation,the bed erosion from Zhicheng to Hankou was mainly concentrated in the low-flow channel.The adjustment range of the water surface width was mainly concentrated in the low-flow channel,and the maximum variation in the width reached 400 m under the same discharge.The width-depth ratio at each station decreased under the same discharge.2)The water depth increased under the same discharge at each station,with the flow velocity decreasing.The bed erosion in the Jingjiang River reach is intensive,leading to a more significant variation in the range of water depth and the relationship between velocity and discharge.Due to the gradual weakening of scour intensity,the variation range of water depth and the relationship between velocity and discharge became smaller year by year,and the variation range decreased by more than 25％from Phase Ⅰ(2003-2006)to Phase Ⅳ(2014-2017).The erosion intensity in the Chenghan reach was small,only 54％of that of Jingjiang River reach.The variation ranges of water depth and the relationship between velocity and discharge were small,and the change law was not obvious year by year.
alluvial rivers hydraulicshydraulic geometryflow-sediment conditionsthe middle reaches of the Yangtze RiverThree Gorges Project
NETL
NSTL
万方数据
