Insights and Analysis

Flooding in Asia’s Megacities

January 4, 2012

By Kourtnii S. Brown

My colleagues in The Asia Foundation’s Environment Program recently returned from Bangkok, where the Asia-Pacific Climate Change Adaptation Forum they were scheduled to attend was canceled due to the worst flooding in Thailand in 60 years.

Thailand floods

Bangkok residents evacuate flooded neighborhoods during Thailand's worst flooding in over half a century. Experts predict that massive floods will hit Asia’s coastal megacities even harder due to stronger storms and sea level rise. Photo: Voice of America.

The disaster resulted in over 600 deaths, approximately 10 million lives affected, $21 billion in lost revenues from major industries, and an estimated $24 billion dollars in damage to property, according to the World Bank. Technical specialists blame the disaster in part on an unusually wet monsoon period coupled with the bad timing of a seasonal high tide in the Gulf of Thailand, but also on the government’s inefficient watershed management and infrastructure for draining high floodwaters on the Chao Phraya river.

In October, the Foundation’s country representative in Thailand, Kim McQuay, blogged about the poor readiness of the recently elected Puea Thai government and the Bangkok Metropolitan Authority to protect communities and businesses and to coordinate recovery for flood victims. In November, In Asia interviewed McQuay about the lack of foresight and responsibility on behalf of a succession of Thai governments and other stakeholders to undertake necessary preventive and mitigation plans that build resiliency to natural disasters.

So it’s sadly fitting that a flood prevented a network of adaptation practitioners from meeting to discuss solutions on how to make watershed management, among other challenges for strengthening disaster preparedness, more resilient to climate change. In fact, it was in the script. According to a 2009 World Wildlife Fund report, massive floods – predicted to be even harder on Asia’s coastal megacities due to stronger storms and sea level rise – are bound to disrupt business-as-usual more frequently by 2050 as a result of missed investments in crucial urban infrastructure over the past few decades.

The floods in Thailand are just a glimpse of what’s to come. The UN Population Fund (UNFPA) forecasts that urban population will rise from the present 3.2 billion to nearly 5 billion by 2030 and that three out of every five people will live in cities. Asia will be home to at least 10 megacities (cities with populations over 10 million), many of which are located in tropical areas or floodplains, and where climate scientists predict rainfall intensity and temperature are likely to increase the most. Many other Asian megacities, including Dhaka, Manila, Ho Chi Minh City, Jakarta, and Mumbai, are particularly vulnerable to climate change flood risks as a result of their low-lying coastal location, total area prone to flooding, and expected population growth.

To compound this risk, each of these urban centers also has densely growing populations of urban slum dwellers and squatter settlements located in high-risk, flood-prone areas. In many cases, these areas do not benefit from a city’s watershed management infrastructure that handles potable water access, water runoff flows, water pollutants, or solid waste. As a result, inhabitants of slums and squatter settlements are far more susceptible to vector-borne and water-borne illnesses (such as malaria and dengue) even under normal conditions, and more so immediately after flooding occurs.

Yet socioeconomic factors in Asia’s megacities, such as weak economies, inadequate health care, corruption, and poor governance, continue to overshadow efforts to position climate change adaptation as a top priority in today’s urban planning. A recent Maplecroft Climate Change and Environmental Risk Atlas predicts that infrastructure, already inadequate in many Asian cities, will struggle to cope as urban populations grow, “making disaster responses less effective at a time when disasters might become more frequent.” The World Bank states that the total costs of damage from floods to buildings and land subsidence are likely to be significant under the most severe climate change scenario (A1F1), ranging from 2 to 6 percent of Southeast Asia’s regional GDP over the next 30 years.

As we plan development goals in Asia for 2012, urban environmental issues should increasingly be on the development agenda given the predicted additional high costs associated with threats from climate change. Urban planners throughout Asia need to prioritize disaster preparedness and infrastructure that builds resilience to potential impacts from heavier rains, stronger storms, and sea-level rise. Bangkok, Beijing, Delhi, Dhaka, Hanoi, Hong Kong, Jakarta, Karachi, Mumbai, Seoul, Shanghai, and Tokyo are already participating in the C40 Cities Climate Leadership Group, a network of major global cities that are sharing knowledge and tactics for responding to climate change. The C40 Group urges governments and heads of state to empower and provide resources to city leaders in order for them to be well equipped to take action within their cities.

A broad, low-cost place to start for climate action planning should include implementing sustainable water management approaches that work to imitate the way nature handles high water flows and water runoff, such as through increased use of green roofs, urban gardens, and greening urban landscapes. More long-term, nuanced responses must be city-specific strategies that include a combination of coordinated zoning guidelines, flood monitoring stations, a system of levees and retaining walls, waste water treatment systems, and communicating flood warnings to residents.

A new year offers a new opportunity for city leaders in the areas at greatest risk in Asia to set solid climate action plans and begin ramping up investments in climate change adaptation to become resilient to more frequent natural disasters. Anything less will be met with more of the same.

Note: The Asia-Pacific Climate Change Adaptation Forum has been rescheduled for March 2012 in Bangkok.

Kourtnii S. Brown is a program associate for The Asia Foundation’s Environment Programs in San Francisco. She can be reached at [email protected]. The views and opinions expressed here are those of the individual author and not those of The Asia Foundation.


  1. I agree with your view about the growing risk of Asian Mega city located near costal areas : Kolkata, Bangkok or Chinese cities are disaster in term of environmental friendly urban area and their situation is getting to worsen markedly by 2050 with the coming global warming! Additionally there are already high level of pollution in costal areas with large destruction of ecosystem as we can see in South China sea . But maybe is it the concept itself of mega city that should be revisited. I think it might be necessary to assess the advantage-risk trade off of high density settlement versus smaller city settlement with low rise building? I am been living in Dubai and Abu Dhabi and am now living in Penang Malaysia. I feel much better and safer in Penang!

  2. Yes, I agree. Some solutions to disaster risk reduction could be less dense urban/semi-urban settlements in areas less vulnerable to the risks of floods and strong storms, and designed with the proper infrastructure to build resiliency to natural disasters. However, from a sustainable development point of view, high population densities can also make the process of supplying essential municipal services (such as energy, transport, and water) far more efficient and cost-effective. But your concerns are valid; if urban development is not sustainably managed, then the growth of cities can instead be a catalyst for sharp rises in air pollution, slum dwellings, widening economic and social inequalities, energy waste, and environmental degradation, and actually make them more vulnerable to natural disasters in the long-term. Therefore, “greening” cities no matter how dense the population can be a very efficient and impactful way to reduce resource use, help the environment, and continue to build resiliency to threats from climate change.

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