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1999 Fiscal Year Final Research Report Summary

TEMPORAL AND SPATIAL CHANGES IN BRAIDING INDEX OF ALLUVIAL RIVERS IN JAPAN AND THEIR REASONS

Research Project

Project/Area Number 09680181
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 自然地理学
Research InstitutionChuo University

Principal Investigator

SUZUKI Takasuke  CHUO UNIVERSITY, FACULTY OF SCIENCE AND ENGINEERING, PROFESSOR, 理工学部, 教授 (60055168)

Project Period (FY) 1997 – 1999
KeywordsRIVER BRAIDING / RIVER SINUOSITY / ALLUVIAL RIVER / CHANNEL DEFORMATION / RIVER IMPROVEMENT / JAPAN
Research Abstract

Channel forms of alluvial rivers in the Meiji Era of Japan, I.e. 1870〜1910's, is assumed to be under the nearly natural condition, because no large dams were constructed before and during the Meiji Era. The temporal and spatial changes in channel braiding and sinuosity of 34 alluvial river during the past about 100 years were examined with morphometry using 1/50,000 topographic maps published repeatedly four or nine times in the different years since 1870's. The results are summarized as follows. 1) in the Meiji Era, the maximum value of braided index of a river tends to appear in the channed span of 1×10ィイD1-3ィエD1 in channel gradient, I.e. at the fan margin where the mean grain size of river sediment decreases from gravel to sand. 2) In the present, as compared with the data for the Meiji Era, the maximum value of braided index has increased markedly in the fan and appears at the mid-fan of 3×10ィイD1-3ィエD1 in channel gradient. Whereas the maximum value has decreased markedly in the large plains composed of fan, meander plains and delta, but it appears at the same area as that in the Meiji Era. 3) After the construction of weirs, the braided index increase in the upstream channel of the weirs in fan, but a little effect of weirs on the braiding appears in the meander plains. 4) The maximum value of sinuosity tends to appear in the channel span of 1×10ィイD1-3ィエD1〜1×10ィイD1-4ィエD1 in channel gradient. This threshold gradient is larger than those in the Mississippi River. These temporal and spatial changes in channel braiding and sinuosity is considered to be resulted from the river improvement and dam construction since the 1960's in particular.

  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] 鈴木隆介: "土木的時間と空間の拡張"土木学会誌. 83・1. 124-127 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 鈴木隆介: "河川網状度の時空的変化"地形. 20・2. 121 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 鈴木隆介: "河川網状度および屈曲度の時空的変化"地形. 20・4. 497-498 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 鈴木隆介: "河床勾配および河床礫円形度に基づく堆積低地の地形種区分"地形. 21・3(発表予定). (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 鈴木隆介: "建設技術者のための地形図読図入門 第2巻 低地"古今書院. 354 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Takasuke Suzuki and Yasuo Takase: "Temporal and spatial changes in braiding index of alluvial rivers in Japan."Transactions, Japanese Geomorphological Union. 20-2. 121 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Takasuke Suzuki and Yasuo Takase: "Temporal and spatial changes in braiding index and sinuosity of rivers during the past 100 years in Japan."Transactions, Japanese Geomorphological Union. 20-4. 497-498 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] KentaroTomura, Koji Suzuki andTakasuke Suzuki: "Demarcation of Geomorphic types forming alluvial plains based on combination of channel gradient and roundness of river sediment."Transactions, Japanese Geomorphological Union. 21-3(in press). (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Takasuke Suzuki: "Introduction to Map Reading for Civll Engineers, Volume 1, Geomorphological Basis for Map Reading. (book)"Kokonshoin, Tokyo. 1-200 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Takasuke Suzuki: "Introduction to Map Reading for Civll Engineers, Volume 2, Plains. (book)"Kokonshoin, Tokyo. 201-554 (1998)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2001-10-23  

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