Long-term evolution of meandering channel planforms in response to the mean annual flow and width-depth ratio  

作　　者：Xiaolong Song Haijue Xu Yuchuan Bai 

机构地区：[1]State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation,Tianjin University,Tianjin,300350,China [2]Institute for Sedimentation on River and Coastal Engineering,Tianjin University,Tianjin,300350,China

出　　处：《International Journal of Sediment Research》2024年第1期131-143,共13页国际泥沙研究（英文版）

基　　金：the National Natural Science Foundation of China(Grant Nos.51879182 and 51979185);the Science and Technology Planning Program of Tianjin,China(Grant No.21JCQNJC00480).

摘　　要：A depth-averaged linearized meander evolution model was used to numerically evaluate the spatiotem-poral evolution of the meandering channel centerline in the plane at various mean annual flows and width-depth ratios for capturing the overall average trend of the meandering channel planform.This analysis was done to better understand the consistent responses of the river morphology to possible future tectonic and climatic changes.The computational cases included an idealized sine-generated meandering channel with a moderate maximum deflection angle and a typical natural meander for the Jiyun River in China.The study results showed phased development and response characteristics of the meandering channel centerline(to the mean annual flow),along with increases in the specified mean annual width(B)-depth(H)ratio(represented by B/H).First,the spatial meander straightening trend over time weakened during Phase 1(B/H≤16.5)and gradually changed to a meander developing trend during Phase 2(16.5<B/H≤27)with an overall insensitivity to the flow magnitude.Second,starting from the downstream tail during Phase 3(27<B/H≤28.9),the symmetric development form along the transverse direction(perpendicular to the mean flow direction)was disrupted,while flow effects were highlighted when the mean annual B/H exceeded 28.Finally,an obvious onset and jump process of the channel sensitivity in response to flow occurred during Phase 4(28.9<B/H≤29.5).These event characteristics are very similar to the transition from laminar to turbulent flow in fluid mechanics.This study provides insights for more in-depth exploration of meandering mechanisms and technical support for effective river management.

关 键 词：Long-term average trend Meandering channel planform Mean annual flow Width-depth ratio River management 

分 类 号：TV135[水利工程—水力学及河流动力学]