| 1990年以来黄河第一湾齐哈玛河段砾质网状河的演变特征 |
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| 引用本文： | 高超,王随继.1990年以来黄河第一湾齐哈玛河段砾质网状河的演变特征[J].地理学报,2018,73(7):1352-1364. |
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| 作者姓名： | 高超 王随继 |
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| 作者单位： | 1. 中国科学院地理科学与资源研究所 中国科学院陆地水循环及地表过程重点实验室,北京 1001012. 中国科学院大学资源与环境学院,北京 100049 |
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| 基金项目： | 国家自然科学基金项目(41571005, 41271027) |
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| 摘 要： | 黄河第一湾的网状河型因其砾石质的河床质而与砂床质网状河明显不同,但是其具体的冲淤特性、河道与河间地的稳定性等是否与砂质网状河具有相似之处,尚待揭示。以齐哈玛乡主河道长约为12 km的砾石质网状河段为研究对象,利用1990年、2001年、2013年和2016年共4期Landsat遥感影像数据和2011年与2013年两期Google Earth高分辨率图像数据,结合野外采样观测分析其1990-2016年间的平面形态变化与沉积特征。结果表明：砾石质网状河整体具有很高的稳定性,众多分支河道与河间地无明显冲淤现象。网状带面积仅增加2.43%,陆地与水体面积比例接近1∶1;网状带部分小型河间湿地及河间岛屿呈现碎片化现象,导致河间湿地个数逐渐增加,最大增加率为62.16%。河道主流线长期左右迁移交替变化,且变化率相对稳定,受主流线迁移的影响,主河道内部河间岛屿形态变化较大,其河岸变化率为5 m/a。网状河众多支河道非常稳定,平均河宽变化率仅为1 m/a左右。河岸沉积物以细砂或粉砂为主,黏土含量较高,粒度分布曲线呈现多峰,这与砂质网状河流河岸以泥质沉积物为主略有不同,但河岸及河间湿地茂密的植被保护了众多分支河道免受侵蚀、维持了河道的稳定性,这也是砾石质网状河流体系具有高稳定性的重要原因。
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| 关 键 词： | 砾石质网状河 网状带 河间湿地 主流线 沉积物 黄河 |
| 收稿时间： | 2017-06-05 |
Evolution characteristics of the gravel-bedded anastomosing river at the Qihama reach in the First Great Bend of the Yellow River since 1990 |
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| GAO Chao,WANG Suiji.Evolution characteristics of the gravel-bedded anastomosing river at the Qihama reach in the First Great Bend of the Yellow River since 1990[J].Acta Geographica Sinica,2018,73(7):1352-1364. |
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| Authors: | GAO Chao WANG Suiji |
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| Institution: | 1. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China2. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | The anastomosing river located at the First Great Bend of the Yellow River is different from other sand-bedded anastomosing rivers because of its gravel-bedded materials. So, it needs to be revealed whether its specific characteristics have a similarity with the sand-bedded anastomosing river, in terms of erosion and deposition, the stability of channel and interchannel wetlands, and so on. Based on four remote sensing images in 1990, 2001, 2013, and 2016 and two Google earth images in 2011 and 2013, combined with field sampling and observations, the Qihama anastomosing river reach with a main channel length of about 12 km was selected to analyze the variations of channel planforms and sedimentary characteristics in the period 1990-2016. The results show that the gravel-bedded anastomosing river has a high stability as a whole, and there is no obvious bank erosion and deposition for varied channels and wetlands. During the past 26 years, the anastomosing belt area increased by 2.43%, and the ratio of land to water area was close to 1:1. The number of wetlands increased gradually with the highest increasing rate of 62.16% due to the fragmentization of some small interchannel wetlands. Talweg migrated to the left or the right alternately in a long period of time, and the migration rate was relatively stable. Due to the influence of talweg migration, the change of islands in the main channel is large and the bank shift rate of the main channel was about 5 m/a. The network composed of secondary channels is very stable and the channel average migration rate was only about 1 m/a. The sediments in the bank columnar sections are mainly composed of fine sands or silts, and the clay content is relatively high. Besides, the grain-size distribution presents a multi-peak curve, which is little different from the muddy sediments in bank columnar sections of sand-bedded anastomosing rivers. However, the dense vegetation on the riparian and interchannel wetlands protects the anastomosing channels in the study river reach from being eroded, and maintains the stability of the channels, which is also an important factor contributing to high stability of the gravel-bedded anastomosing river system. |
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| Keywords: | gravel-bedded anastomosing river anastomosing belt wetlands talweg sediments Yellow River |
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