Of the world's cities, Shanghai is the most vulnerable to serious flooding, a study by European researchers suggests.

Researchers from the Netherlands and the University of Leeds in England studied nine coastal cities around the world and used that information to devise a new method to calculate the flood vulnerability of cities.

The method includes measuring the level of economic activity in a city, its speed of recovery, 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, a Leeds release said Tuesday.

The study analyzed 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).

The highly prosperous Shanghai is more vulnerable than much poorer cities such as Dhaka, the study found.

"Vulnerability is a complex issue," Leeds researcher Nigel Wright said. "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? It is important to know how quickly a city can recover from a major flood."

Shanghai's is particularly vulnerable because it is exposed to powerful storm surges and the land is subsiding as sea levels rise, the researchers 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," Wright said.

The study was published in the journal Natural Hazards.