Compound simulation of fluvial floods and storm surges in a global coupled river-coast flood model: Model development and its application to 2007 Cyclone Sidr in Bangladesh

Hiroaki Ikeuchi*, Yukiko Hirabayashi, Dai Yamazaki, Sanne Muis, Philip J. Ward, Hessel C. Winsemius, Martin Verlaan, Shinjiro Kanae

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Water-related disasters, such as fluvial floods and cyclonic storm surges, are a major concern in the world's mega-delta regions. Furthermore, the simultaneous occurrence of extreme discharges from rivers and storm surges could exacerbate flood risk, compared to when they occur separately. Hence, it is of great importance to assess the compound risks of fluvial and coastal floods at a large scale, including mega-deltas. However, most studies on compound fluvial and coastal flooding have been limited to relatively small scales, and global-scale or large-scale studies have not yet addressed both of them. The objectives of this study are twofold: to develop a global coupled river-coast flood model; and to conduct a simulation of compound fluvial flooding and storm surges in Asian mega-delta regions. A state-of-the-art global river routing model was modified to represent the influence of dynamic sea surface levels on river discharges and water levels. We conducted the experiments by coupling a river model with a global tide and surge reanalysis data set. Results show that water levels in deltas and estuaries are greatly affected by the interaction between river discharge, ocean tides and storm surges. The effects of storm surges on fluvial flooding are further examined from a regional perspective, focusing on the case of Cyclone Sidr in the Ganges-Brahmaputra-Meghna Delta in 2007. Modeled results demonstrate that a >3 m storm surge propagated more than 200 km inland along rivers. We show that the performance of global river routing models can be improved by including sea level dynamics.

Original languageEnglish
Pages (from-to)1847-1862
Number of pages16
JournalJournal of Advances in Modeling Earth Systems
Volume9
Issue number4
DOIs
Publication statusPublished - 1 Aug 2017

Funding

This paper was financially supported by the Funding Program for the Global Environmental Research Fund (S-10 and S-14) by the Ministry of the Environment, Japan; the Program for Risk Information on Climate Change by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan; JSPS KAKENHI grants 16J07523, 16H06291. PJW received funding from the Netherlands Organisation for Scientific Research through VIDI grant 016.161.324. We thank Shinichiro Kida in Kyushu University, Japan, for his invaluable comments. We are grateful to A. K. M. Saiful Islam in Institute of Water and Flood Management, Bangladesh University of Engineering and Technology, Bangladesh, for providing us with the observed water level data by BIWTA during Cyclone Sidr as part of research collaboration. The CaMa- Flood model is available on the developer’s webpage (http://hydro.iis. u-tokyo.ac.jp/~yamadai/cama-flood/), the 1-in-100-year extreme sea levels of the GTSR data set are freely available online at the archive of the 4TU.Research Data (https://data.4tu.nl/ repository/uuid:aa4a6ad5-e92c-468e- 841b-de07f7133786) and other parts of the GTSR data set may be available upon request to the developer (sanne. muis@vu.nl). Simulation results presented in this work may be available upon request to the corresponding author (ikeuchi@ rainbow.iis.u-tokyo.ac.jp).

FundersFunder number
Funding Program for the Global Environmental Research FundS-14
Japan Society for the Promotion of Science16J07523, 16H06291
Ministry of Education, Culture, Sports, Science and Technology
Nederlandse Organisatie voor Wetenschappelijk Onderzoek016.161.324
Ministry of the Environment, Government of Japan

    Keywords

    • Cyclone Sidr
    • fluvial flooding
    • global model
    • mega-delta
    • storm surge

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