[P07] How extreme precipitation complexity affects regional-scaled flood hazard assessment: A case study of Miyagi Prefecture
| Affiliation | IRIDeS, Tohoku University |
|---|---|
| Author | 鄭 安棋 |
| Co-Author | Atsuya Ikemoto（東北大学工学研究科土木工学専攻） Yusuke Hiraga（東北大学工学研究科土木工学専攻） Yushi Miki（東北大学工学研究科土木工学専攻） Anawat Suppasri（東北大学災害科学国際研究所） Tomoya Iwasaki（スイス・リー・インターナショナル・エスイー日本支店） Yugo Shinozuka（スイス・リー・インターナショナル・エスイー日本支店） Takafumi Ogawa（スイス・リー・インターナショナル・エスイー日本支店） Fumihiko Imamura（東北大学災害科学国際研究所） |
Keywords
- Regional-scaled flood hazard assessment
- Extreme precipitation complexity
- Miyagi Prefecture
Outline
Extreme precipitation complexity, especially in the form of time-variation precipitation pattern, significantly affects the flood inundation simulations. However, such an effect is not always considered in any form of flood hazard assessment. Taking precipitation complexity into account significantly increases the computational load, as it may increase the numbers of scenarios. In this study, how the extreme precipitation complexity affects regional-scaled flood hazard assessment was investigated by taking Miyagi Prefecture as an example. To do this, the authors incorporate the best available information of extreme rainfall distribution (i.e., return periods of 50, 100, and 200 years) and extreme discharge coefficient (i.e., of each grid mesh) data of entire Japan to generate the extreme precipitation models inputted for the flood inundation model. Then, four time distribution types of precipitation (i.e., homogeneous, advanced, centered, and delayed patterns) was considered. Following this, the flood inundation model was modified to account time distribution of each extreme precipitation model in flood inundation simulation. Our results show that the commonly used approach based on homogeneous time distribution of precipitation results in bias in flood hazard assessment. Additionally, our sensitivity test of patch size (i.e., in time) suggests that the large patch size cannot adequately resolve the extreme precipitation complexity, affecting the assessment results for flood management and urban area planning.
