383 / 2024-03-05 14:53:28
Study on the Burst conditions of bend cutoff in the Lower Jingjiang of the Middle Yangtze River
meandering rivers,bend cutoffs,river management
摘要录用
Ya Liu / Changjiang River Scientific Research Institute
Shiming Yao / River Research Department; Changjiang River Scientific Research Institute; Key Laboratory of Ministry of Water Resources on River and Lake Regulation and Flood Control in the Middle and Lower Reaches
Xiaohu Guo / Changjiang River Scientific Research Institute
     Natural rivers are dominated by meandering channel Pattern. The associated channel migration involves progressive changes of channel position overtime as well as abrupt and rapid changes .Due to the roughly- equilibrium sediment transport in nature, meandering river often shows the characteristics of "concave scouring and convex silting".With the continuous development of the curve, the curvature of the river channel is further increased, which often leads to the occurrence of bend cutoff when encountering overbank Flood. Due to the suddenness and uncertainty of these changes, it is difficult to predict the specific time and process of such events.

     The Lower Jingjiang of the middle Yangtze River is a typical meandering river, with occurence of many natural bend cutoffs in history. In the 20th century, there were two demonstrable natural cutoffs: Chibakou cutoff occured in 1909 and Shatanzi cutoff occured in 1927. And two artificial bend cutoffs were implemented this time. The cutoffs shortened the length of the river,lowered the upstream flood level, and stabilized the river regime. And also, several negative effects such as damage to the flood control projects and loss of wetland resources are gradually emerging.

In this paper, Shatanzi cutoff is studyed through detailed analysis of the measured data, with particular attention to factors that may trigger cutoff. it is concluded that the planform with large curvature is the basic condition for the natural cutoff, and that sufficient flood time and large water surface gradient are the burst hydraulic factors of natural cutoff.

     Based on the current river regime of the lower Jingjiang and the relationship between Jingjiang and Dongting Lake, it is estimated that when the inflow of the Lower Jingjiang  exceeds 40000 m3/s for more than 3 days, with relatively small  outflow of the Dongting Lake concurrently, there's a strong possibility that natural cutoff occur at the Baxingzhou bend. This conclusion may provide reference for cascade reservoirs operation in the main stream of the Yangtze River and the Dongting Lake basin and comprehensive management of the Lower Jingjiang.

 
重要日期
  • 会议日期

    10月14日

    2024

    10月17日

    2024

  • 09月30日 2024

    初稿截稿日期

  • 10月17日 2024

    注册截止日期

主办单位
国际水利与环境工程学会亚太地区分会
承办单位
长江水利委员会长江科学院
四川大学
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