Flood hazard for developing world’s urban dwellers

Pink/red denotes land within ten metres above sea level in Bangladesh Copyright: CIESIN

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[DHAKA] One in five people living in urban areas in developing countries are within ten metres above sea level, putting them at risk from flooding and cyclone-induced storm surges that are likely to increase due to climate change.

A study to be published in the journal Environment and Urbanization next month found that populations are most vulnerable to flooding in Asia, where many people live on the flood plains of major rivers and in cyclone-prone coastal regions.

Scientists used geographical data about population density combined with maps of areas’ elevation above sea level to calculate the populations within the low elevation coastal band.

Although this band accounts for only 2 per cent of the world’s land area, about ten per cent of the world’s population and 13 per cent of the world’s urban population live in these vulnerable zones — rising to 21 per cent for developing countries. 

Asia accounts for three-quarters of the total world population living within ten metres above sea-level.

“People are running towards risk, particularly in China but also in other parts of the world such as Bangladesh, where more than 40 per cent of the land area is within ten metres above sea level,” said lead author Gordon McGranahan of the UK-based International Institute for Environment and Development.

The study calls for action to limit the effects of climate change, to help people migrate away from risk areas and to modify urban settlements to reduce their vulnerability.

But it warns that this will require enforceable regulations and economic incentives, both of which depend on political will, funding and human capital.

“It is too late to rely solely on a reduction in greenhouse gas emissions to mitigate climate change, although this is clearly an imperative,” says McGranahan.

“Climate change is not a natural disaster but has largely been caused by wealthy countries emitting greenhouse gases during their industrialisation. It is therefore incumbent on rich nations to help poorer ones to adapt to the changes ahead,” he added.

“Migration away from the zones at risk will be necessary but costly and hard to implement, so coastal settlements will also need to be modified to protect residents,” adds Bridget Anderson, co-author and research associate at US-based Columbia University’s Center for International Earth Science Information Network.