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Morphological characteristics of Japanese beaches viewed from the number of long shore bars: field investigations, laboratory experiments, and modeling

Research Project

Project/Area Number 11680094
Research Category

Grant-in-Aid for Scientific Research (C)

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

Principal Investigator

SUNAMURA Tsuguo  Osaka University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (00011164)

Co-Investigator(Kenkyū-buntansha) TAKEDA Ichiro  Kyoto Kyoiku University, Department of Education, Professor, 教育学部, 教授 (30197298)
Project Period (FY) 1999 – 2001
Project Status Completed (Fiscal Year 2001)
Budget Amount *help
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1999: ¥900,000 (Direct Cost: ¥900,000)
KeywordsLong shore bars / Multiple bars / Spilling breakers / Surf zone / Breaking waves / Large-scale turbulence / Backshore height / バー(沿岸砂州) / 後浜上限 / 多段バー / 波の遡上限界 / 水路実験 / バーの形成機構 / 海底勾配
Research Abstract

The study aims to examine (1) the influence of the presence of long shore bars upon the subaerial beach morphology in Japan through field investigations, (2) the formative conditions for long shore bars on exposed beaches facing the Sea of Japan or the Pacific Ocean, and (3) the mechanism of the formation of long shore bars through a laboratory wave flume.
The result of the analysis of the field data obtained from 190 beaches showed that the landward limit of the backshore height is not only controlled by the grain size of beach sediment but also by the number of long shore bars: lower backshore is found at a beach with smaller number of bars. Dimensional analysis applied to the data from 25, exposed beaches facing the Sea of Japan or the Pacific Ocean indicated that the number of bars is expressed in terms of the breaker-type index to the 1.5th power. Bars are originated by the action of spilling breakers. The prevalence of wind waves on the Sea of Japan coast is conductive to the presence of multiple bars commonly found on the beach. The presence of one-bar beaches mostly on the Pacific coast is closely associated with the swell-dominated environment. The laboratory experiment showed that bars are formed by the action not only of oblique vortexes that are the already reported, large-scale turbulence induced by spilling breakers, but also of down bursts, a newly found, spilling-breaker induced turbulence, with the latter being stronger than the former. Thus, the down burst is found to be a crucial element in modeling for bar formation.

Report

(4 results)
  • 2001 Annual Research Report   Final Research Report Summary
  • 2000 Annual Research Report
  • 1999 Annual Research Report
  • Research Products

    (15 results)

All Other

All Publications (15 results)

  • [Publications] 武田 一郎: "非外洋性海浜における後浜上限度"地形. 21. 499-512 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Kubo, H., Sunamura, T.: "Large-scale turbulence to facilitate sediment motion under spilling breakers"Proceedings of international Conference on Coastal Dynamics. 212-221 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Takada, I.: "Height of the landward limit of the backshore at Japanese beaches"Jour. Coastal Research. (submitted). (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Sunamura, T.: "Formative conditions for multiple longshore bars"Transaction, Japanese Geomdrphulogical Union. (in preparation).

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Ichirou Takeda: "Height of the upper limit of the backshore on sheltered coasts (in Japanese)"Transactions, Japanese Geomorphological Union. Vol. 21. 499-512 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Hidehito Kubo, Tsuguo Sunamura: "Large- scale turbulence to facilitate sediment motion under spilling breakers"Proceedings of International Conference on Coastal Dynamics '01. 212-221 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Ichirou Takeda: "Height of the landward limit of the backshore at Japanese beaches"Journal of Coastal Research. (submitted). (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Tsuguo Sunamura: "Formative conditions for multiple longshore bars"Transactions, Japanese Geomorphological Union (in preparation).

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2001 Final Research Report Summary
  • [Publications] Kubo, H., Sunamura, T.: "Large-Scale Turbulence to Facilitate sediment Motion under Spilling Breakers"Proc.Conf.coastal Dynamics '01. 212-221 (2001)

    • Related Report
      2001 Annual Research Report
  • [Publications] Takeda, I.: "Height of the Upper Limit of the Backshore on the coasts of Japan"Jour. of Coastal Research. (採用予定). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] Sunamura, T.: "Formation Conditions for Multiple Longshore Bars"Trans.Japanese Geomorphological Union. (採用予定). (2002)

    • Related Report
      2001 Annual Research Report
  • [Publications] 武田一郎: "非外洋性海浜における後浜上限高度"地形. 21. 499-512 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Kubo,H and Sunamura,T: "Large-Scale Turbulence to Facilitate Sediment Motion under Spilling Breakers"Rroc.4th Int.Conf.Coastal Dynatmics. (印刷中). (2001)

    • Related Report
      2000 Annual Research Report
  • [Publications] Takada,I: "Height of the Upper Limit of the Backshore on the Corots of Japan "Jour.Coastal Research. (印刷中).

    • Related Report
      2000 Annual Research Report
  • [Publications] Sunamura T.and Takeda I.: "Barred beaches: Their topographic characteristics"Trans. Japan, Geomorphological Union. 21(in press). (2000)

    • Related Report
      1999 Annual Research Report

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Published: 1999-04-01   Modified: 2016-04-21  

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