| 引用本文: | 江青蓉,夏军强,周美蓉,王英珍.黄河下游游荡段不同畸形河湾的演变特点.湖泊科学,2020,32(6):1837-1847. DOI:10.18307/2020.0623 |
| JIANG Qingrong,XIA Junqiang,ZHOU Meirong,WANG Yingzhen.Evolution process of different abnormal river bends in the braided reach of the Lower Yellow River. J. Lake Sci.2020,32(6):1837-1847. DOI:10.18307/2020.0623 |
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| 摘要: |
| 1980s中期以来，黄河下游游荡段经常出现畸形河湾，分析其演变过程及特点对游荡段治理具有重要意义.本研究采用黄河下游游荡段的遥感影像和实测断面地形资料，描述了不同畸形河湾的演变过程并分析其河湾形态参数和断面形态的变化.研究表明，黄河下游游荡段的畸形河湾具有演变周期短、扭曲程度较大和易发生自然裁弯等特点.游荡段不同位置畸形河湾的演变特点不同：游荡段上段的畸形河湾演变缓慢，裁弯历时长；中段的畸形河湾演变速率较高，河湾扭曲程度大；下段的畸形河湾演变速率高，容易发生自然裁弯.河湾形态参数可反映畸形河湾的演变过程，其变化特点与畸形河湾的形成和裁弯过程相对应.在畸形河湾形成过程中，曲率半径和河湾间距减小，弯曲度、水流夹角和河湾振幅增大.游荡段3个畸形河湾弯曲度的最大值分别为1.20、2.10和1.61，反映了不同畸形河湾的扭曲程度.“Ω”形畸形河湾裁弯后的曲率半径、水流夹角、河湾振幅和河湾间距约为其演变过程中最值的605%、59%、27%和133%.“M”形畸形河湾裁弯后水流夹角、河湾振幅和河湾间距约为其最值的37%、83%和152%.在畸形河湾形成时期，伊洛河口断面位于畸形河湾凹岸侧的滩地以94 m/a的速率崩塌.裁弯后，河槽冲刷，两岸滩地崩退，河槽展宽速率为148 m/a.河床底部的冲刷从深泓点逐渐向两边发展. |
| 关键词: 畸形河湾 演变过程 平面形态 黄河下游 游荡段 遥感影像 |
| DOI：10.18307/2020.0623 |
| 分类号: |
| 基金项目:国家自然科学基金项目（51725902，51579186）和国家重点基础研发计划项目（2017YFC0405501）联合资助. |
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| Evolution process of different abnormal river bends in the braided reach of the Lower Yellow River |
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JIANG Qingrong, XIA Junqiang, ZHOU Meirong, WANG Yingzhen
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State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, P. R. China
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| Abstract: |
| Since the mid-1980s, the braided channel reach of the Lower Yellow River has formed some abnormal river bends. Analysis of the evolution processes and characteristics of abnormal river bends are of great significance for the regulation of the braided reach. Based on the remote sensing imagery and the cross-sectional topography, this study describes the evolution processes of abnormal river bends and variation of morphological characteristic parameters. The result shows that the abnormal river bends in braided channel reach of the Lower Yellow River have the characteristics of short evolution duration, high distortion level and prone to natural cutoff and the bends in different location have different evolution characteristics. The first bend in the upper braided reach evolves slowly and the cut-off period is long. The second bend in the middle braided reach evolves rapidly and highly distorted. The third bend in the lower braided reach evolves rapidly and is prone to generate natural cutoff. Variation of river bend morphology reflects the evolution process of three abnormal river bends, which are corresponding to the bend formation and cutoff processes. The formation of the abnormal river bend is a process in which the curvature radius and river bend spacing decreases, and the bend curvature radius, angle of water flow and bend amplitude increase. The maximum curvature radius of the three bends in the braided reach are 1.20, 2.10 and 1.61, respectively, reflecting the distortion degree of different bends. After cut-off, the curvature radius, angle of water flow, bend amplitude and river bend spacing are about 605%, 59%, 27%, and 133% of the extreme value during the evolution of the “Ω” shape river bend. For “M” shape river bend, angle of water flow, bend amplitude and river bend spacing after cutting are about 37%, 83%, and 152% of their extreme values. The cross-sectional profile at the Yiluo River outlet reflected that the beach on the concave bank of the river bend continuously collapsed at a rate of about 94 m/a during the formation period of abnormal river banks. The cut-off has a great influence on the cross-sectional profile. After cut-off, the beaches on both bank collapsed, and the river channel widen at a rate of 148 m/a. The erosion at the riverbed developed from the deep point to its two sides. |
| Key words: Abnormal river bends evolution processes bend morphology Lower Yellow River braided reach remote sensing images |
