Farming and water

Posted: 13 December 2007

Over two-thirds of the freshwater used by humans each year is used for irrigating crops. In Africa, the river Nile loses 90 per cent of its water to irrigation and other uses before it reaches the Mediterranean. In Asia, which has two-thirds of the world's irrigated land, 85 per cent of water goes for irrigation. The river Jordan is so heavily used by farmers that only a third of its water makes it as far as the Dead Sea.

Credit: AAAS Atlas of Population & EnvironmentPerhaps the most infamous example of irrigation concerns the Aral Sea, in central Asia. Half a century ago two rivers, the Ama Darya and the Syr Darya, delivered 55 billion cubic metres of water to the Aral Sea each year. Then in the 1960s a vast Soviet cotton scheme began to tap the rivers for irrigation water. By the 1980s a mere seven billion cubic metres reached the Aral Sea. Fisheries which once supported 60,000 people collapsed; two dozen native fish species became extinct. See: Requiem for a dying sea.