Key points:
- Emergency planners in Shanghai and New York City were encouraged to develop a blueprint for efficient evacuation of the elderly in flood-threatened areas of the cities.
- While travel times for New York City evacuation neighborhoods are less than 20 minutes, each trip of flood evacuations can take up to 3-4 hours in Shanghai since vulnerable neighborhoods are underserved by shelters.
- In the 136 largest coastal cities, the total population exposed to 100-year coastal floods is estimated to grow more than threefold from 38.5 million in 2005 to 150 million by the 2070s.
With climate change worsening and severe weather increasing, emergency planners in cities across the world are facing pressure to ensure their citizens can be safely evacuated if need be.
Emergency planners in Shanghai and New York City were among those who needed a plan. Both cities are highly exposed to storm-induced flooding and analysis showed that—with two distinct systems of emergency operation—there were significant differences between them when it came to evacuating elderly people to safety.
After studying emergency operations in the cities, experts devised a blueprint for efficient evacuation that could be used in similar flood-threatened cities around the globe, such as Mumbai, Bangkok, Jakarta, Ho Chi Minh City, Miami and Tokyo.
The new study in Nature Water by experts recommends that emergency planners build more neighborhood shelters, reducing the time needed to get vulnerable people in flood threatened areas to safety. They note that travel times for New York City evacuation neighborhoods are markedly less than 20 minutes, whereas each trip of flood evacuations can take up to 3-4 hours in Shanghai, since vulnerable neighborhoods are underserved by shelters.
“Differences in evacuation patterns for elderly residents in Shanghai and New York City, demonstrate the value of risk-informed, strategic evacuation planning for storm flooding. Our work provides new insights into operational emergency evacuation decisions and could provide a blueprint for flood management policy development in major coastal cities globally,” said study author Nigel Wright from the University of Birmingham (UK).
Recent coastal flood catastrophes in Shanghai (1997), New Orleans (2005), New York City (2012) and Macau (2017) illustrate that coastal cities in both developing and developed countries are particularly vulnerable to storm surge flooding.
In the 136 largest coastal cities, the total population exposed to 100-year coastal floods is estimated to grow more than threefold from 38.5 million in 2005 to 150 million by the 2070s, with economic damage likely to increase to more than 10 times the current levels ($6 billion in 2005) by 2050.
In Europe, if no action is taken, the expected number of people exposed to coastal flooding annually is set to increase from 10,200 up to 3.65 million by 2100. This would occur mostly in major cities, due to rising extreme sea level and continued socioeconomic development.