Coupled atmosphere-ocean-river modeling and assessment of vulnerability to compound flooding

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K20447
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0303:Civil engineering, social systems engineering, safety engineering, disaster prevention engineering, and related fields
• Research Institution: Toyohashi University of Technology
• Principal Investigator: Toyoda Masaya 豊橋技術科学大学, 工学(系)研究科(研究院), 助教 (70908558)
• Project Period (FY): 2021-08-30 – 2023-03-31
• Keywords: 複合氾濫 / 高潮 / 洪水 / 台風

Outline of Final Research Achievements

In this study, a new numerical model was developed for compound flooding hazards due to storm surge and high-river discharge, and the model was applied to evaluate the hazard of compound flooding in an urban area. Firstly, a coupled wave and storm surge model was constructed by incorporating the river channel directly into the model and this model can consider the river flow. The model also utilizes the results of a rainfall-runoff model for flood flows from upstream, seamlessly converting ever-changing flow rates into water levels at the model boundaries.
For actual operation, Osaka Bay (Typhoon No. 21 in 2018) and Ise Bay (Typhoon No. 24 in 2018) were selected for evaluation. It was found that small and medium-sized rivers with smaller allowable flows have a very high compound flooding risk due to the short time difference between storm surges and high-river dishcarge.

Free Research Field

海岸工学

Academic Significance and Societal Importance of the Research Achievements

既存の数値モデルでは，「高潮」や「洪水」を個々に取り扱うモデルは存在していたが，これらを一体に取り扱うモデルは開発されていなかった．本研究では，実現象に即した「高潮と洪水の同時生起およびそれによる水位上昇」を高精度に表現可能なモデルを構築している．また気候変動により今後台風強度が増大することが懸念され，複合氾濫リスクも増大すると考えられる．本モデルの運用を，将来気候計算にも発展させることで，将来起こり得る災害リスクの評価や，脆弱な地点・河川の検出に応用できるものと期待される．