2019 Fiscal Year Final Research Report
Verification and prediction of the damping effect of coastal forests on tsunamis over 20 m height
| Project/Area Number |
17K01348
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Natural disaster / Disaster prevention science
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| Research Institution | Forest Research and Management Organization |
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Principal Investigator |
Hoshino Daisuke 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (60391182)
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| Co-Investigator(Kenkyū-buntansha) |
野口 宏典 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (80353803)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | 空中写真 / 立体視 / 数値実験 / 津波線流量 / 流体力指標 / 最大水位 / 林分構造 / マツ |
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| Outline of Final Research Achievements |
In the Tochinaihama cove, Miyako City, Iwate Prefecture, where the Tohoku Pacific Coast Earthquake Tsunami higher than 20 m is recorded, one-dimensional numerical simulation of the tsunami inundation was performed depend on the presence or absence of a coastal pine forest. Firstly, stand structure of the coastal forest was restored by stereoscopic analysis of aerial photographs before and after tsunami disaster on the center line. The presence of coastal forest contributed the reduction of inundation height and fluid force index than them of the absence of forest. As the result, the tsunami inundation distance was reduced and run-up time delayed. For further accurate evaluation of the tsunami inundation and depressing effect of coastal forest, the aerial photograph analysis was performed to biomass and destroyed part before and after tsunami disaster over a wide area. As the result, both biomass and destroyed part of coastal forest non-homogeneously distributed in the inundation area.
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| Free Research Field |
造林学
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| Academic Significance and Societal Importance of the Research Achievements |
東北地方太平洋沖地震津波の研究成果の多くは、人口の多い海岸平野において、汀線での津波の浸水高や遡上高が5－10 mの事例に限られてきた。日本列島の沿岸には、ほかに多くの隆起海岸やリアス式沈水海岸が存在し、そうした地形を多く擁する三陸沿岸では、津波がＶ字型沿岸地形の最奥へ波高を増やしながら襲来し、汀線での波高はゆうに20 mを超えた。過去の研究では林帯幅が20 m以上ある海岸林であれば津波の流勢緩和が期待できると論じられたが、20 mを超えるような巨大な津波は想定外であった。今後のリアス式沈水海岸等における津波減災のためには、こうした巨大津波に対する海岸林の減勢効果の評価と予測が必要であった。
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