地理学报(英文版)

›› 2013, Vol. 23 ›› Issue (5): 833-848.doi: 10.1007/s11442-013-1047-1

• Special Research on Sanjiangyuan • Previous Articles     Next Articles

Analysis of controls upon channel planform at the First Great Bend of the Upper Yellow River, Qinghai-Tibet Plateau

LI Zhiwei1, WANG Zhaoyin1, PAN Baozhu2, DU Jun1, Gary BRIERLEY3, YU Guo-an4, Brendon BLUE3   

  1. 1. State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China;
    2. Changjiang River Scientific Research Institute, Wuhan 430010, China;
    3. School of Environment, University of Auckland, Private Bag 92019, Auckland, New Zealand;
    4. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
  • Received:2012-05-30 Revised:2013-03-28 Online:2013-10-15 Published:2013-10-15
  • Contact: Wang Zhaoyin (1951-), Professor, E-mail: zywang@tsinghua.edu.cn E-mail:zywang@tsinghua.edu.cn
  • About author:Li Zhiwei (1984-), Ph.D Candidate, specialized in river dynamics. E-mail: lizhiwei11@mails.tsinghua.edu.cn
  • Supported by:

    International Science & Technology Cooperation Program of China, No.2011DFA20820; No.2011DFG93160; Tsinghua University, No.20121080027; National Natural Science Foundation of China, No.51209010

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Abstract:

The 270 km long section of the Upper Yellow River at the First Great Bend is comprised of single channel and multiple channel systems that alternate among anastomosing, anabranching, meandering and braided reaches. The sequence of downstream pattern changes is characterized as: anastomosing-anabranching, anabranching-meandering, meandering-braided and braided-meandering. Remote sensing images, DEM data and field investigations are used to assess and interpret controls on these reach transitions. Channel slope and bed sediment size are key determinants of transitions in channel planform. Anastomosing reaches have a relatively high bed slope (0.86‰) and coarser sediment bed material (d50 = 3.5 mm). In contrast, meandering reaches have a low slope (0.30‰) and fine sediment bed material (d50 = 0.036 mm). The transition from a meandering to braided pattern is characterized by an increase in channel width-depth ratio, indicating the important role of bank strength (i.e. cohesive versus non-cohesive versus channel boundaries). Interestingly, the braided-meandering and meandering-braided transitions are coincident with variable flow inputs from tributary rivers (Baihe and Heihe rivers respectively). Theoretical analysis of the meandering-braided transition highlights the key control of channel width-depth ratio as a determinant of channel planform.

Key words: Yellow River Source, river pattern diversity, river pattern transition, anastomosing river, anabranching river, meandering river, braided river