Estimation of Historical Typhoons from the Distribution of Large Coastal Boulders in Subtropical Coastal Areas

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K18878
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 22:Civil engineering and related fields
• Research Institution: Kyoto University
• Principal Investigator: Mori Nobuhito 京都大学, 防災研究所, 教授 (90371476)
• Co-Investigator(Kenkyū-buntansha): 渡部 靖憲 北海道大学, 工学研究院, 教授 (20292055) ; 中條 壮大 大阪市立大学, 大学院工学研究科, 准教授 (20590871) ; 安田 誠宏 関西大学, 環境都市工学部, 准教授 (60378916)
• Project Period (FY): 2018-06-29 – 2021-03-31
• Keywords: 巨礫 / 波浪 / 台風

Outline of Final Research Achievements

In recent years, there are many researches on the distribution of large coastal boulders that have moved from the sea and run-up on land. We attempted to estimate the wave forces and related typhoon intensity from the observed distribution of typhoon boulders. In order to estimate the boulder movement by numerical models, we conducted hydraulic model experiments of boulder movement for solitary waves simulating tsunami and irregular waves simulating typhoon waves. In the case of solitary waves, the distance traveled by boulders was larger when the horizontal bed was dried out, and in the case of irregular waves, when the bed was submerged. In addition, a numerical model of the boulder movement phenomenon was developed, and its range of application and model optimization were carried out using the results of hydraulic experiments. Good results were obtained for the distance of boulder movement by solitary wave and irregular wave.

Free Research Field

水工水理学

Academic Significance and Societal Importance of the Research Achievements

沿岸巨礫の研究は，沖（古台風）から陸上（観測結果）までの巨礫移動過程の時間軸をいかに逆に戻ることができるのかという点に学術的挑戦性がある．本研究で開発された巨礫分布を説明可能な巨礫移動の数値モデルをもとに，数百年スケールの過去巨大津波および巨大台風強度の両者を推定な道筋が得られた．これを発展させることにより，古台風災害評価学という新しい分野の開拓につながることが期待される．