Heavy rains and land mismanagement have led to deadly floods
Storms and floods ravaging Asia this summer have claimed the lives of more than 1,500 people and left tens of millions facing food shortages and water-borne diseases. While relief agencies are busy sending aid, scientists are working out how to prevent such disasters from happening again.
Several factors have conspired to make the floods in the northeastern region of Bangladesh the worst in recorded history, says Atiq Rahman, head of the Bangladesh Centre for Advanced Studies in Dhaka. Four flash floods came in quick succession, he says, and unusually high tides have slowed the water's discharge into the sea. Little can be done about such conditions, but we can act to lessen their impact, he says.
The Dhaka-based Flood Forecasting and Warning Center, for example, can give three to seven days' notice of floods. This time could be used to focus relief efforts, says Rahman, allowing emergency supplies to get to the right areas of the country. “We knew which areas would be affected most. There was enough warning,” he says, adding that better political organization was all that was needed.
Changes to land use could also have a big effect, says Vaidyanatha Subramanian, a hydrogeochemist at Jawaharlal Nehru University in New Delhi. Canals in Bangladesh have been squeezed by land development, he says, increasing the chance that they will burst from their confines. River banks have been eroded by unregulated mining for sand and by bathing at religious festivals. Subramanian is now collecting data about the timing, strength and duration of rains and the resulting river flow, to work out how much of the flooding is caused by nature rather than humans.
In Taiwan, where typhoon Mindulle caused particularly bad floods in early July, scientific experts have visited disaster sites to work out what went wrong. They note that much of the problem was beyond the government's control: the rains were particularly heavy and the 1999 Chi-Chi earthquake left loose soil that was easily swept away. But they also identified the farming of tea and betelnuts on steep slopes as a factor in excessive soil erosion. The government's subsequent decision to shut down three farming areas has provoked tension with local people.
Bangladesh must also cope with social tension over its land use. Some of the richer areas near hard-hit Dhaka were kept dry by massive embankments. Reports say police used rubber bullets to break up protests where angry citizens tried to break open sluice gates in attempts to open natural drainage routes for the water.
Some of Bangladesh's woes are being addressed by a National Water Management Plan, approved by the National Water Research Council this March. The plan aims to decentralize decision-making about flood management, and create a central organization for sharing information. But the projects, to be implemented over 25 years, have had little time to take effect, says Rahman.
As of 2 August, water levels had dropped to normal throughout most of Bangladesh. But that is little comfort, says Rahman. More rain, expected in mid-August, will create havoc in the saturated area. “The next round will be worse,” he says.
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Cyranoski, D. Reform of land use urged as floodwaters rise across Asia. Nature 430, 596 (2004). https://doi.org/10.1038/430596b