Friday, March 02, 2007

Conserve, Rethink Use

Two-fifths of the world's people already face serious water shortages, and water-borne diseases fill half its hospital beds. The present is dire but the future looks grim. Cut it how you will, the picture that emerges from today's data and tomorrow's forecasts is so complex and appalling it can leave you feeling powerless. The world cannot increase its supply of fresh water: all it can do is change the way it uses it.

Climate change has had a profound effect on water - just what effect, though, nobody can really say. Some regions will become drier, some wetter. Deserts may well spread and rivers shrink, but floods will also become more frequent. Most of the world's water is already inaccessible, or comes in the form of storms and hurricanes to the wrong places at the wrong times. But there is certainly room for better management of water in agriculture - which currently takes ups 70% of the water we use. Drip irrigation, for example, minimises waste, as do low-pressure sprinklers and even simple earth walls to trap rainfall instead of letting it drain away too fast to be used. Desalination may play a part, but it is energy-hungry and leaves a brine mountain for disposal. Dams will impound more water, but bring other horrifying environmental problems in their train.

One of the disappointments of the World Water Forum in Japan in March 2002 was its focus on mega-engineering solutions like dams and pipelines, rather than using natural systems like forests and wetlands to conserve water. Because the world's water suppy is finite, most of life's other necessities are finite as well. If we do not learn to live within our aqueous means, we shall go hungry as well as thirsty. A world where consumption is a means to survival, not an economic end in itself, will have enough water to go round.

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