Development of tsunami sediment transport and urban area inundation model for improving tsunami vulnerability evaluation

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K15259
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 25030:Disaster prevention engineering-related
• Research Institution: Tohoku University
• Principal Investigator: Yamashita Kei 東北大学, 災害科学国際研究所, 准教授 (00772633)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 津波 / 土砂移動 / 市街地氾濫 / 東日本大震災 / 気仙沼湾

Outline of Final Research Achievements

This study aims to improve a numerical simulation of tsunami hazard which has strong local characteristics due to tsunami-induced sediment transport and urban area inundation, and to deepen the understanding of tsunami damage mechanism. First, we conducted a field survey on the distribution of basement rocks and the geology of the seafloor in Kesennuma Bay, Miyagi Prefecture, where was largely eroded by the giant tsunami during the Great East Japan Earthquake. A tsunami sediment transport model using the field survey data was validated. An effective technique for numerical simulation of tsunami inundation that considers the destruction process of buildings was proposed, and the tsunami sediment transport model was improved by considering the effect of mixed fluid with density change due to sediment transport.

Free Research Field

海岸工学、津波工学

Academic Significance and Societal Importance of the Research Achievements

気仙沼湾狭窄部の地形や底質環境の実態と海底基盤岩分布を現地調査で把握し，調査結果を踏まえた検証計算より，基盤岩分布の考慮が津波土砂移動モデリングの精度向上に重要な役割を果たすことを示した．また，建物群とそれらの倒壊過程を考慮した津波氾濫解析モデルを提案し，局所的な津波挙動や建物倒壊に伴う流況変化に対して合理的な解析結果を得た．さらに，土砂移動を伴う混合流体の影響を考慮した津波土砂移動モデルを開発し，気仙沼地域における津波被害に及ぼした土砂移動影響の知見を得た．本研究は，津波土砂移動氾濫のハザード評価手法を高度化し，被害メカニズムへの理解を深めて合理的な被害軽減策の立案に貢献すると期待される．