DAMS have had their day and underground water reserves are running dry. The only way to water and feed a growing population is to catch more rain.
This is the preliminary conclusion of a five-year international project aimed at solving the world鈥檚 water crisis.
鈥淲e need individual farmers to catch the rain,鈥� David Molden, head of the Comprehensive Assessment of Water Management in Agriculture (CAWMA), told the conference. And to do that, he said, the world鈥檚 2 billion poor farmers must be given access to low-cost technologies designed to capture rainwater.
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The statistics are startling. More than 90 per cent of the fresh water people consume is used to grow food. Molden鈥檚 team calculates that every year food crops use 7000 cubic kilometres of water. Conquering hunger and coping with an estimated 3 billion extra people would push that figure to 12,600 cubic kilometres by 2050, an 80 per cent increase.
Some politicians at the conference supported the building of more dams and irrigation infrastructure. 鈥淭he only way to prevent famine is to collect the water in our rivers for use during drought,鈥� said Kenya鈥檚 water minister, Martha Karua. But the most optimistic engineering assessment predicts that extra dams would supply only an extra 800 cubic kilometres of water per year, says Johan Rockstrom, a Swedish hydrologist working with CAWMA. Most rivers in farming regions are running dry, and good sites for dams are running out.
Since formal irrigation will fail to fill the gap, the future of the world鈥檚 food depends on agriculture鈥檚 forgotten group, the poor farmers of Africa and Asia who rely on rainfall to grow their meagre crops.
Many of them are already leading the way by investing in cheap new technologies to capture more water. Across Africa, farmers are boosting yields by reviving half-forgotten technologies to capture rain in ponds, on terraces and in underground cisterns. And a million women in Bangladesh have each spent $25 to buy simple treadle pumps that tap rainwater in the surface soils of the Ganges delta, said Paul Polak of the Colorado-based International Development Enterprises.
If Africa is to feed itself in 2050, it will have to increase rain-fed farming fivefold, Rockstrom said. And that means Africa鈥檚 leaders need to think beyond dams, says Frank Rijsberman, director of the Sri Lanka-based International Water Management Institute. 鈥淲e are trying to change their minds, but I can鈥檛 say we鈥檝e convinced them all,鈥� he says.
