李志威, 文杰, 陈帮, 鲁瀚友, 胡旭跃. 黑河下游颈口裁弯后河道三维水流结构研究[J]. 水科学进展, 2022, 33(2): 286-297. DOI: 10.14042/j.cnki.33.1309.2022.02.012
引用本文: 李志威, 文杰, 陈帮, 鲁瀚友, 胡旭跃. 黑河下游颈口裁弯后河道三维水流结构研究[J]. 水科学进展, 2022, 33(2): 286-297. DOI: 10.14042/j.cnki.33.1309.2022.02.012
LI Zhiwei, WEN Jie, CHEN Bang, LU Hanyou, HU Xuyue. Three-dimensional flow structure of a meandering channel after neck cutoff occurred in the Lower Black River[J]. Advances in Water Science, 2022, 33(2): 286-297. DOI: 10.14042/j.cnki.33.1309.2022.02.012
Citation: LI Zhiwei, WEN Jie, CHEN Bang, LU Hanyou, HU Xuyue. Three-dimensional flow structure of a meandering channel after neck cutoff occurred in the Lower Black River[J]. Advances in Water Science, 2022, 33(2): 286-297. DOI: 10.14042/j.cnki.33.1309.2022.02.012

黑河下游颈口裁弯后河道三维水流结构研究

Three-dimensional flow structure of a meandering channel after neck cutoff occurred in the Lower Black River

  • 摘要: 黄河源黑河下游于2018年7月汛期发生1次颈口裁弯的极端地貌过程,裁弯河段的水流结构发生强烈调整,开展原型观测裁弯后河道水流结构具有重要科学意义。2019年和2020年采用声学多普勒流速剖面仪对裁弯河段共计45个横断面进行野外测量,对比分析裁弯后河道三维水流结构与环流强度。结果表明:受河道形态、边界条件、水文条件等因素影响,裁弯口上游顺直河段的水流结构受颈口裁弯的影响较小,而弯道段水流结构于裁弯后明显调整。具体表现为颈口裁弯对顺直河段的流速、环流强度空间分布无较大影响,会改变弯顶段最大流速的横向分布和环流结构的断面分布、影响分离区的规模和分布位置。研究结果加深了颈口裁弯后水流结构调整对牛轭湖淤积、分离区河床冲淤以及新河道冲刷影响的认识。

     

    Abstract: Neck cutoff as an extreme geomorphic process, occurred in flood season of July 2018 in the lower Black River in the Yellow River Source region. Neck cutoff strongly adjusting flow structure is of great importance to understand the hydrodynamic mechanism of meander cutoff. Acoustic Doppler Current Profiler (ADCP) was used to conduct field measurements on a total of 45 cross-sections in May 2019 and August 2020 in order to compare and analyze three-dimensional flow structure in different cross sections. Results demonstrated that due to the influence of channel shape, boundary conditions, hydrological conditions and other factors, the flow structure in the upstream straight reach is less affected by the neck cutoff, while the flow structure of the bend section is obviously adjusted after neck cutoff. The specific performance is that the neck cutoff has little effect on the spatial distribution of velocity and circulation intensity in the straight reach. It will change the transverse distribution of the maximum velocity at the top of the bend and the section distribution of circulation structure, and affect the scale and distribution position of the separation area. The results also deepen the understanding of the impact of flow structure adjustment after neck cutoff on deposition of oxbow lake, scouring and depositing of riverbed in separation area and scouring of new channel.

     

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