Impacts of grade control structures on riverbed degradation  

作　　者：Weiming Wu Ruihua Nie Kai Wei Bruce W.Melville Asaad Y.Shamseldin Lu Wang 

机构地区：[1]State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resource and Hydropower,Sichuan University,Chengdu 610065,China [2]National Key Laboratory of Bridge Intelligent and Green Construction,Southwest jiaotong University,Chengdu 611756,China [3]Department of Civil and Environmental Engineering,The University of Auckland,Auckland,New Zealand

出　　处：《International Journal of Sediment Research》2025年第1期108-118,共11页国际泥沙研究(英文版)

基　　金：This work was funded by the National Natural Science Foundation of China(Nos.U20A20319,52279074);the Sichuan Science and Technology Program(No.2023NSFSC1989).

摘　　要：Sediment flux of many rivers has been significantly reduced due to human activities caused by economic development,leading to increasingly severe riverbed degradation.To prevent riverbed degradation,grade control structures(GCSs)have been widely applied in degrading channels.Existing studies have not provided a good understanding of the effects of GcSs on flow characteristics and bed morphology in degrading channels,limiting the management of degrading channels.A series of flume tests with no sediment supply are conducted to investigate the effects of GCSs on upstream water levels and riverbed morphology in degrading channels.The experimental results indicate that:(1)in the initial stage of degradation,the water surface slope in the backwater reach is linearly and negatively correlated with the GCs-height Froude number,based on the average flow velocity upstream of the backwater reach due to GCS and the height of GCS:(2)the effective protection bed length upstream of GCS is approximately equal to the length of the reach where the flow velocity is less than the critical velocity for sediment motion in the backwater zone;(3)for sequential GCSs,the effective protection bed length will decrease if GCS is located in the backwater reach of the downstream GCS.A semi-analytical calculation method of the effective protection length and equilibrium bed profile upstream of Gcs in degrading channels is proposed based on the critical condition of sediment motion and weir flow formulas.The computed values by the proposed calculation method agree well with the experimental data of the present study.

关 键 词：Grade control structure(GCSs) Riverbed degradation Base level Effective protection bed length 

分 类 号：TV1[水利工程]