Abstract
Emergency responders in coastal cities are anticipated to provide effective evacuation of at-risk populations during the preparedness and response phases of coastal floods due to land-falling storms or cyclones. However, existing contingency plans primarily focus on the evacuation of the general public rather than special arrangement for elderly populations who constitute a large proportion of flood fatalities. Here we present a system-level methodology to elaborate citywide coastal flood evacuation plans for optimal deployment of shelters and effective transfer of elderly people with special needs. We conduct a comparative analysis between Shanghai and New York City, which are both among the most exposed coastal cities to storm-induced flooding but represent two distinct institutional systems of emergency operation. The results show marked disparities in evacuation patterns for elderly residents in the two cities. Storm flood evacuation is more challenging in Shanghai due to insufficient provision of shelter capacity (~230,000). Implementing risk-informed and strategic planning could not only meet the potentially huge demand of vulnerable elderly (~520,000) but also improve the overall efficiency of evacuee transfer by a factor of 3. Our work provides new insights into operational emergency evacuation decisions and informs flood management policy development for major coastal cities globally.
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Data availability
The traffic network data, demographic data, evacuation centre data and evacuation zone map for NYC are freely available from the United States Census Bureau (https://www.census.gov/) and the NYC Open Data Portal (https://opendata.cityofnewyork.us/). The transport network and POI data in Shanghai are obtained from the AMAP Data Portal under licence. Shelter data in Shanghai are derived from the Shanghai municipal civil defence office (https://mfbwz.mfb.sh.gov.cn/mfbwz/mfb/yjbncs/map.html#). The population census data are provided by the Shanghai Statistics Bureau. The topographic data and seawall/floodwall data are collated from Shanghai Municipal Institute of Surveying and Mapping and Shanghai Water Authority, respectively. Certain datasets of Shanghai are available from the authors upon reasonable request and with permission of the parties that provided the data.
Code availability
Data analysis and results representation were produced by using Origin software (https://www.originlab.com) and ESRI ArcGIS (https://www.esri.com). FloodMap modelling software was used with permission from co-author D.Y.
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Acknowledgements
This work was supported by the National Natural Science Foundation of China (grant no. 42371076), Science and Technology Commission of Shanghai Municipality (grant no. 21230750600), the Engineering and Physical Sciences Research Council of UK (grant no. R034214/1) and Hong Kong Research Grants Council-Early Career Scheme (grant no. 27202419). N.L. has received funding from the National Science Foundation of the United States (grant no. 1652448). D.Y. and R.W. were funded by the UK Natural Environment Research Council (grant no. NE/R009600/1 and NE/S017186/1). J.B. acknowledged financial support from the Netherlands Organization for Scientific Research (NWO) (grant no. ALWSD.2016.007).
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J.Y. conceived the study, prepared the dataset, interpreted the result and drafted the manuscript. J.Y. and D.Y. designed the initial emergency evacuation model. R.W., N.L., N.W., S.L., J.B. and M.G. contributed to the further development of the methods and provided guidance on the optimization of shelter deployment. J.Y. and Y.Y. performed flood inundation modelling and network-based geospatial analysis. B.S. and L.Y. assisted in the questionnaire survey. All authors commented on the manuscript and gave final approval for publication.
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Yin, J., Yang, Y., Yu, D. et al. Strategic storm flood evacuation planning for large coastal cities enables more effective transfer of elderly populations. Nat Water 2, 274–284 (2024). https://doi.org/10.1038/s44221-024-00210-z
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DOI: https://doi.org/10.1038/s44221-024-00210-z