Evaluation of tsunami resistance of coastal forest by combining mechanistic and growth model.

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K01254
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Natural disaster / Disaster prevention science
• Research Institution: Hokkaido Research Organization
• Principal Investigator: Torita Hiroyuki 地方独立行政法人北海道立総合研究機構, 森林研究本部林業試験場, 部長 (50414264)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 津波 / 海岸防災林 / 限界流速 / 被害形態 / 森林管理

Outline of Final Research Achievements

In order to construct the strong coastal forests against tsunamis, we evaluated the influence of forest management on the tsunami resistance of Pinus thunbergii Parlat. forests using a mechanistic model. We set up three forest management types, which were sparse (sparse type: ST), middle (middle type: MT), and dense (dense type: DT) stand. As an indicator expressing resistance to tsunami, critical velocity required to overturn or break the trunk of trees was calculated. The critical velocity increased with increasing tree growth and the value of critical velocity differed among management types. ST was the most resistant to tsunami of the three forest management types. However, our results showed that when water depth exceeds 8 m, forests were completely destroyed and the limitation existed on improving its resistance. Moreover, the forest management was found to have a possibility to control damage phenomena (overturning or trunk breakage) of trees by tsunamis in coastal forests.

Free Research Field

防災科学、森林科学、雪氷学

Academic Significance and Societal Importance of the Research Achievements

東北地方太平洋沖地震津波による人的被害および経済的被害は甚大である。今後、津波発生の危険性が高まりつつある中、海岸林が果たす防災機能を効果的に発揮することが求められている。本研究では、海岸林の津波抵抗性を定量的に評価し、適切な森林管理によりその抵抗性を向上させる事が可能であることを示した。これらの成果は、海岸林が防潮機能を発揮し、減災効果を発揮するための基礎的知見の一つとなる。