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Mechanism of Sudden Channel Change of Mountainous Rivers due to Hydraulic Jump in Channel Bifurcations.

Research Project

Project/Area Number 04650447
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Hydraulic engineering
Research InstitutionHokkaido University, Faculty of Engineering

Principal Investigator

HASEGAWA Kazuyoshi  Hokkaido Univ., Fac.of Eng., Instructor, 工学部, 助手 (70001328)

Co-Investigator(Kenkyū-buntansha) UCHIJIMA Kunihide  Kitami Inst. of Tech., Associate Prof., 助教授 (40003181)
FUJITA Mutsuhiro  Hokkaido Univ., Fac.of Eng., Professor, 工学部, 教授 (80001139)
Project Period (FY) 1992 – 1993
Project Status Completed (Fiscal Year 1993)
Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1993: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
KeywordsMountainous River / Bifurcated Channel / Supercritical Flow / Hydraulic Jump / Channel Blocking / Sediment Deposition / Momentum Equation / Divided Discharge Ratio / 河道閉塞 / 流砂量配分比 / 流速分布 / 水面形 / MaCormack法 / 高解像スキーム計算
Research Abstract

The purpose of this study is to make clear the origin of channel blocking phenomena sometimes observed in a bifurcated channel in mountain rivers. The followings were found through field observations, model experiments and theoretical analysis for origin of channel blocking :
1.Three kinds of bifurcation patterns of channels are found in mountain rivers : Those are inner, outer and straight branching. Large scale of blocking takes place in outer branching channel.
2.A large amount of sediment deposition to block the entrance of one bifurcated channel are brought on by a hydraulic jump which takes place in the front of bifurcation wall (i.e. island). This was verified through the experiments.
3.The momentum equations for the flowing direction and for the normal direction to it, applied to two control volume sections enclosing the bifurcation of channel, have four kinds of solutions with respect to the divided discharge ratio and water depths at the two entrances of bifurcated channel : They are corresponding to any state that two channels are in supercritical flow, or one is in supercritical and the other is in ordinal flow, or both are in ordinal flow.
4.It was confirmed in the experimental channel that the divided discharge ratio shifts from one solution to others when total discharge was reduced in steps ; the channel blocking was advanced with the change of discharge.
5.From the above, it will be concluded that origin of a blocking of bifurcated channel is a large amount of sediment deposition in a hydraulic jump which takes place near the bifurcation of channel and the sudden discharge change due to the shift of flowing state.

Report

(3 results)
  • 1993 Annual Research Report   Final Research Report Summary
  • 1992 Annual Research Report
  • Research Products

    (17 results)

All Other

All Publications (17 results)

  • [Publications] 長谷川和義: "分岐反力が働く射流分岐水路における流れと土砂堆積" 土木学会北海道支部論文報告集. 49. 409-414 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 長谷川和義: "2次元Macormack法を用いた射流分岐水路の流れの解析" 土木学会北海道支部論文報告集. 49. 397-402 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Hasegawa: "Changes of Bifurcated Channe48l in Mountainous Rivers." Proc.of Workshop on Hydraulics and Hydrology in cold Regions.205-216 (1993)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] 長谷川和義: "移動床急勾配分岐流路における流れと河床の堆積" 土木学会北海道支部論文報告集. 50. 504-507 (1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Hasegawa: "Analysis of Blocking Phenomena in Bifurcated Channels Found in Mountainous Rivers." Proc.of 1994 National Conf.on Hydraulic Eng.,ASCE.(1994)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Hasegawa: "Flow and Sediment Deposition in a Steep Bifurcated Channel with Reaction from the Bifurcation Wall" Proceedings of Hokkaido Branch of JSCE. Vol.49 (in Japanese). 409-414 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Hasegawa: "Numerical Analysis of Supercritical Flow in a Bifurcated Channel Using the 2-Dimensional MaCormack Method" Proceedings of Hokkaido Branch of JSCE. VOl.49 (in Japanese). 397-402 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Hasegawa: "Changes of Bifurcated Channels in Mountainous Rivers" Proceedings of Workshop on Hydraulic and Hydrology in Cold Regions. 205-216 (1993)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Hasegawa: "Flow and Sediment Deposition in a Steep Bifurcated Channel with Movable Bed" Proceedings of Hokkaido Branch of JSCE. Vol.50 (in Japanese). 504-507 (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Hasegawa: "Analysis of Blocking Phenomena in Bifurcated Channels Found in Mountainous Rivers" Proceedings of 1994 National Conference on Hydraulic Engineering, ASCE. (1994)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1993 Final Research Report Summary
  • [Publications] K.Hasegawa,T.Mizugaki: "Changes of Bifurcated Channels in Mountainous Rivers" Workshop on Hydraulics and Hydrology in Cold Region,Proceedings.205-216 (1993)

    • Related Report
      1993 Annual Research Report
  • [Publications] K.Hasegawa,T.Mizugaki: "Analysis of Blocking Phenomena in Bifurcated Channels Found in Mountainous Rivers" Proceedings of ASCE National Conference on Hydraulic Engineering.1-5 (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] 長谷川和義・水柿俊直: "移動床急勾配分岐流路における流れと河床の洗掘・堆積" 土木学会北海道支部論文報告集. 50. 504-507 (1994)

    • Related Report
      1993 Annual Research Report
  • [Publications] 長谷川 和義: "分岐部反力が働く射流分岐水路における流れと土砂堆積" 土木学会北海道支部論文報告集. 49. 409-414 (1993)

    • Related Report
      1992 Annual Research Report
  • [Publications] 長谷川 和義: "2次元MaCormack法を用いた射流分岐水路の流れの解析" 土木学会北海道支部論文報告集. 49. 397-403 (1993)

    • Related Report
      1992 Annual Research Report
  • [Publications] 長谷川 和義: "射流分岐水路における跳水の発生条件" 水工学論文集. 36. 361-366 (1992)

    • Related Report
      1992 Annual Research Report
  • [Publications] 長谷川 和義: "急勾配分岐水路における跳水の発生と土砂堆積" 土木学会北海道支部論文報告集. 48. 439-444 (1992)

    • Related Report
      1992 Annual Research Report

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Published: 1992-04-01   Modified: 2016-04-21  

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