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Lookup NU author(s): Professor Hayley Fowler
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2026 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/ Study Region: Urban area of Haikou, Hainan Province, China. Study focus: Compound flooding in typhoon-prone coastal cities arises from the interaction between coastal water level and rainfall, but the role of their relative timing remains underexplored. This study proposes a framework that captures the relative timing for improved compound flooding assessment. Using the D-Flow FM model, we simulate 49 time-lag scenarios to quantify how timing ((Formula presented) ) between coastal total water level and rainfall modulate inundation. For each scenario, we evaluate inundation volume and compute absolute ((Formula presented) ) and relative ((Formula presented) ) increments relative to the baseline. We delineate compound zones and decompose contributions from water level, rainfall, and their interaction. New hydrological insights for the region: The results indicate that time-lags strongly shape compound flooding and produce nonlinear responses. Inundation is consistently larger when rainfall peaks before the coastal water level peak. A window from −19 h to −4 h yields volumes exceeding the historical event, and the maximum inundation occurs at −13 h with (Formula presented) = 9.44% and ((Formula presented) = 8.53 million m³). Water level is the dominant driver, yet within compound zones, the interaction term exceeds rainfall alone. These findings highlight that taking (Formula presented) = 0 h as the worst-case can underestimate risks, emphasizing that the relative timing of rainfall and coastal water levels is a critical factor for managing compound flooding in coastal cities.
Author(s): Wu G, Xu H, Sun L, Lu C, Fowler HJ, Willems P, Wang J, Liu Q, Sheng Y
Publication type: Article
Publication status: Published
Journal: Journal of Hydrology: Regional Studies
Year: 2026
Volume: 66
Print publication date: 01/08/2026
Online publication date: 13/06/2026
Acceptance date: 08/06/2026
Date deposited: 24/06/2026
ISSN (electronic): 2214-5818
Publisher: Elsevier BV
URL: https://doi.org/10.1016/j.ejrh.2026.103635
DOI: 10.1016/j.ejrh.2026.103635
Data Access Statement: Data will be made available on request.
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