2022 Fiscal Year Final Research Report
Development of a sediment transport model integrating the tsunami attenuation effects of forest trees and the dynamics of sand on the forest floor
| Project/Area Number |
20K15564
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 40010:Forest science-related
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| Research Institution | 防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群) (2021-2022)
Forest Research and Management Organization (2020) |
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Principal Investigator |
Yamamoto Ako 防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群), システム工学群, 助教 (40842498)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 植生被覆 / 海岸林床 / 津波 / 土砂移動モデル / 水理実験 |
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| Outline of Final Research Achievements |
To clarify the sediment trapping effect of vegetation on the coastal forest floor, a sediment mobile bed experiment was conducted using silica sand, a vegetation model, sand from an actual coastal forest, and vegetation from the actual forest floor. Waves were generated by bore waves that reproduced the turbulence caused by the tsunami tip, and by steady currents that simulated the passage of a tsunami. Actual samples were collected from Iwaki Beach in Akita Prefecture, Futtsu Beach in Chiba Prefecture, and Komatsu Beach.
Sediment transport decreased exponentially with vegetation cover. The sediment transport rate increased when vegetation cover was small and the vegetation was washed out due to the development of scour, indicating that the sediment trapping effect of vegetation is not only dependent on the amount of cover and leaf trapping, but also on the amount and distribution of rhizomes, which prevent the development of scour.
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| Free Research Field |
森林防災，海岸工学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究で対象とした海岸林を防災・減災機能を最大限発揮する健全な林帯を造成していくには，林床の洗堀防止に加え，土砂を捕捉する場（堆積場）となる環境づくりが望まれる．本研究において植生の土砂捕捉効果を定量化することにより，海岸林周辺の植生をどのように維持管理することが林床の土砂流出を防止し安定した基盤づくりの基礎となる研究である．今回の研究で得られた植生の土砂捕捉効果をより多様な植生および砂粒径（土質）に適用することでより詳細かつローカルな条件に対応した被害想定や防災・減災効果を発揮する海岸防災林帯の維持・管理の指針を示すことが可能となる．
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