AsianScientist (Aug. 22, 2012) – A new study of nine major coastal cities around the world has revealed that Shanghai is most vulnerable to serious flooding.
European cities such as Marseille in France and Rotterdam in the Netherlands, in contrast, are the most resilient.
These findings, published recently the journal Natural Hazards, are based on a new method to calculate the flood vulnerability of cities, developed by researchers from the Netherlands and the University of Leeds.
The researchers used their index to analyze the vulnerability to coastal flooding of nine cities built on river deltas: Casablanca (Morocco), Calcutta (India), Dhaka (Bangladesh), Buenos Aires (Argentina), Osaka (Japan), Shanghai (China), Manila (Philippines), Marseille (France), and Rotterdam (the Netherlands).
Measures of the level of economic activity in a city, and social issues such as the number of flood shelters, the awareness of people about flood risks, and the number of disabled people in the population, were some of the 19 components used to measure the vulnerability of a city to flooding.
Surprisingly, the analysis revealed that the highly prosperous megapolis of Shanghai, in China, is more vulnerable than much poorer cities such as Dhaka in Bangladesh.
“Vulnerability is a complex issue,” explained Professor Nigel Wright, who led the team from the University of Leeds.
“It is not just about your exposure to flooding, but the effect it actually has on communities and business and how much a major flood disrupts economic activity. Our index looks at how cities are prepared for the worst – for example, do they have flood defenses, do they have buildings that are easy to clean up and repair after the flood?” he said.
According to Wright, Shanghai is particularly vulnerable because it is exposed to powerful storm surges and the land is subsiding as sea levels rise.
Moreover, although a large population lives along the coast in flood-prone areas, but the city is poorly prepared, with little resilience to a major flood and insufficient flood shelters for victims, he said.
“A 1-in-100 year flood in Shanghai would lead to widespread damage, with serious consequences for the city, across China and, through wider economic links, for the whole world,” he said.
The vulnerability index also revealed that Dhaka, which sits just meters above current sea levels, is regularly hit by tropical cyclones and floods, yet it has few defenses in place and little resilience.
Manila in the Philippines and Calcutta in India are also highly vulnerable largely because of their large populations and degree of expose to storms.
The European cities of Marseille and Rotterdam, while also exposed to flood risks, are least vulnerable with good flood management infrastructure and tight building regulations for flood-prone areas. These cities will “bounce back quickly,” Write said.
The researchers also used their vulnerability index to assess how climate change would affect the vulnerability of these cities in the future.
With sea levels predicted to rise over the next 100 years, the study found that Shanghai and Dhaka will remain the most vulnerable cities in 2100, although the vulnerability of all the cities will increase. The risks may even double in the case of Manila.
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Source: University of Leeds; Photo: Lowcola/Flickr.
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