Kolkata among cities MOST vulnerable to floods

Shanghai, Dhaka and Kolkata are the cities most vulnerable to flooding, according to a new study, reports Syed Tashfin Chowdhury

A recent study has found that Kolkata is the one of the cities most vulnerable to flooding. Kolkata trails behind Shanghai and Dhaka, the two cities most vulnerable to flooding, according to the Coastal City Flood Vulnerability Index.

The study was published in the Natural Hazards journal and conducted by scientists from the United Kingdom and Netherlands. The research uses a new technique to estimate the vulnerability of nine cities of the world to flooding by taking into account 19 indicators including weather patterns, environmental factors, the city's speed of recovery, level of economic activity and the population's awareness of flood shelters.

Marcos Brindicci, Osaka and Casablanca were some of the other cities on the index.

The study looks at the physical exposure of a city to rivers as well as "economic and social ones," Nigel Wright, co-author of the study from the University of Leeds' School of Civil Engineering told the BBC.

Wright went on to explain that the study tried to also take into account certain issues "such as how much attention is given by local or national governments to protect citizens and citizens' property through investing in various forms of resilience".

The study had different observations about each of the nine cities.

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The study consulted the most number of sources for data on Kolkata. Besides the Department of Natural Resources, the Weather Underground India and the World FactBook, other sources included the World Bank, UNICEF India and the AsianDevelopment Bank, GIS Development of India, ministry of water resources and more.

The study underlined Kolkata as the most vulnerable city, right after Dhaka, due to storm surge, coastal line length and river discharge. Kolkata is also vulnerable to coastal floods due to a growing population, thus becoming the second most economically vulnerable city to such disasters after Manila.

In political administrative vulnerability in a post-flood situation, Kolkata comes third after Dhaka.

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With data received from the Yazhi River Committee and United Nations Economic and Social Commission for Asia and the Pacific, the study observed that Shanghai is most exposed to coastal floods "due to its high length of coastline and the high value of river discharge and also due to the high-number of its population living near flood-prone coastal areas with fewer shelters".

According to the study, although Shanghai ranks fourth in the economic vulnerability component of the index, which takes into account factors like growing coastal population, recovery time after flood event and kilometers of drainage canal, it has the most vulnerable politico-administrative resilience in case of such flood occurrences.

As soon as the study's findings were reported, Chinese authorities tried to downplay the findings. Hu Xin, deputy director of the Shanghai Flood Control Headquarters, was quoted as saying, "We should see that Shanghai has defensive measures in place, such as flood control walls and a city drainage system. I feel that these can basically protect the safety of Shanghai."

Land subsidence is a major challenge for Shanghai and has been one of the points of discussion in the research. The city has sunk as much as 2.5 meters over the past century amidst massive urbanisation as there has been persistent demand for high-rise buildings and underground excavation projects.

To keep that in check, the Shanghai city government is planning to issue new regulations while all excavation projects will soon be legally required to go through a risk assessment before these can proceed.

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Dhaka is the second most vulnerable city to coastal flooding among the nine coastal cities built on river deltas, says the study.  With data from the World Bank, HighBeam research and World FactBook, the study underlines that climate change has impacted Bangladesh in "various and diverse ways" with increased chances that Dhaka's "social vulnerability to floods will double by 2100".

Of the nine cities examined by the CCFVI, Dhaka is regularly affected by tropical cyclones and flooding and has very little resilience.

In terms of susceptibility, Dhaka is the second most vulnerable, considering the high number of people living in coastal flood-prone areas with very few shelters.

In terms of resilience to coastal flooding, Dhaka remains the third most vulnerable due to growing coastal population, recovery time after flood and kilometers of drainage canal. Dhaka is the fourth most vulnerable in terms of exposure to and geological positioning of water bodies, due to storm surge, coastal line length and river discharge.

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Although Manila ranks fourth in the CCFVI, it is the second most vulnerable city under the hydro-geological exposure category, due to tropical cyclones and floods.

The report mentioned, "Typhoon Ketsana in 2009 illustrates this exposure of Manila and the surrounding areas to environmental threats. With flood waters reaching nearly 7 meters in some city areas (WWF 2009) and hundreds of deaths during this one storm, Manila is highly vulnerable."

Manila is the fourth most vulnerable city to coastal floods. However, its economic vulnerability is greater than Shanghai and the other seven cities in the study.

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Casablanca is the fifth most flood-prone city, according to the study, which used information from the websites of the environmental ministry of France, the government of Morocco and the International Federation of Red Cross for floods in Morocco.

Although Casablanca experienced the least number of cyclones during the past decade among all the nine cities and has the least social vulnerability to coastal floods alongside Marseille in France, it is still economically vulnerable to coastal floods.

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Other cities which are precariously vulnerable to floods are Rotterdam (the Netherlands), Buenos Aires (Argentina), Marseille (France) and Osaka (Japan).

The study pointed out that Buenos Aires has very low resilience and fewer institutional organisations to deal with floods.

Marseille in France and Rotterdam in the Netherlands have equally low vulnerability, mostly because both have slightly more resilience than the other cities, even though thir hydro-geological indicators are still significant.

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Finally, Osaka is the least vulnerable city out of the nine, with the least shortcomings in terms of hydro-geological and politico-administrative factors.

The study recommended "an urgent need for action towards adaptation measures by raising the anticipatory mentality of local population" in most of these cities as "the population close to the coastline and the number of cultural heritages exposed to floods will increase by 2100."

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