EFFECTS OF TREE DESTRUCTION AND DEBRIS DAM FORMATION AT THE GRAVEL-BED BARS IN KUMAGAYA IN THE ARAKAWA RIVER ON THE MAXIMUM WATER DEPTH AND FLOOD HYDROGRAPH DURING THE FLOOD EVENT CAUSED BY TYPHOON HAGIBIS

• TANAKA Norio

  Graduate School of Science and Engineering, Saitama University

• IGARASHI Yoshiya

  Graduate School of Science and Engineering, Saitama University

• SUENAGA Hiroshi

  Graduate School of Science and Engineering, Saitama University

抄録

 During the flood event caused by Typhoon Hagibis, a large number of trees on the forested gravel bars were destructed in Kumagaya, on the alluvial fan in the Arakawa River. Parts of the trees were trapped in the downstream bars and formed debris dams. The change in the resistance by a debris dam could affect not only the formation of repelling current, but also the flood propagation downstream. A two-dimensional flood simulation model of the destruction and trapped driftwoods was applied to the site, to clarify the changes in flow pattern due to the destructive flood. The maximum velocity was decreased on the gravel bar where debris dams were formed although the velocity was increased by the destruction in the low channel. The tree destruction situation itself was mitigated in the sheltered area of the forest by the debris dam formation. From the point of the maximum water depth at the embankment, the trapping effect was low in the case of Arakawa River, which has a wide cross-section, but it also reduced the peak discharge by around 10m³/s.

収録刊行物

• Journal of JSCE

  Journal of JSCE 10 (1), 19-29, 2022

  公益社団法人 土木学会

キーワード

• gravel bar
• vegetation resistance
• washout
• trapping
• flood retention

詳細情報

• CRID: 1390853741275714048
• NII論文ID: 130008143336
• DOI: 10.2208/journalofjsce.10.1_19
• ISSN: 21875103
• Web Site: https://www.jstage.jst.go.jp/article/journalofjsce/10/1/10_19/_pdf
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可