Flooded by misery

Global warming will wreck Bangladesh

By Neelam Singh
Published: Sunday 15 June 2003

while thinking about Bangladesh, our minds conjure up images of jutting lungs, clammy brows, famished stomachs and overflowing rivers. The situation is about to become even sadder. Bangladesh's existing vulnerability to floods (due to its location at the confluence of three great rivers) will increase with temperatures soaring high, indicates a new study. At present, on an average, about one-fifth of the country -- 3.03 million hectares -- is submerged under water every year. In 1988 and 1998, about 70 per cent of the nation had been inundated. With temperature rising by 6c, the flooding in central and northeastern parts may increase by up to 40 per cent in this century, states the study. Since the last century, an overall warming of about 0.5c has been noted in the nation.

Past studies have focussed on how monsoon would become stronger in the region with the wrath of global warming escalating. No one went a step further and looked at the changes in the severity of floods (magnitude, depth and extent). The study, by Canada-based University of Toronto and New Zealand-based University of Waikato, investigated variations in the water levels of the country's three major rivers -- Ganga, Brahmaputra and Meghna.

The researchers used four models to predict changes in flooding patterns. A software programme developed by Denmark-based Danish Hydraulic Institute (dhi) was used to simulate present and future depth and spread of floods in the country. The Surface Water Modelling Centre in Dhaka calibrated the dhi model as per the conditions of Bangladesh.

Most of the results indicate that the average peak water flow of the rivers would increase. There will be a steep increase in deeply flooded land, which is covered by more than 1.8 metres of water for nine months of the year (see table below: Water everywhere). A shift in the onset or withdrawal of monsoons may also affect the time of occurrence and duration of the floods. The rivers may get flooded simultaneously. This would have grave consequences for monsoon and rabi crops, especially rice.

Loss of flood-free and shallow-flooded land will also reduce area under wheat and winter vegetables. "With an increasing number of people living in the floodplains, there is an urgent need to strengthen flood management policies and adaptation measures," opines M Monirul Qader Mirza, the lead author of the study.


  Percentage of mean flooded area in Bangladesh under different land categories for a 6C rise in temperature
Current situation 25 33 42
Results of model 1 20 35 45
Results of model 2 14 31 55
Results of model 3 15 32 53
Results of model 4 19.5 35 45.5

Source: M Monirul Qader Mirza et al 2003, The implications of climate change on floods of the Ganges, Brahmaputra and Meghna rivers in Bangladesh, in Climatic Change 57, Kluwer Academic Publishers

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