Unleash the Rivers

(4 of 5)
In ways direct and indirect, playing God with water has had a tendency to bite us back. In the 1970s and '80s, Brazil went mad for Amazonian dams, which don't so much electrify the countryside as feed industrial power into chaotic human hives like Sao Paulo. And although irrigation has helped countries with high birthrates avert hunger, it has reintroduced the hoary nemesis that played a big role in the downfall of Mesopotamia and Babylon: the salting out of the soil.

River water is much more mineralized than rainfall, and long desert rivers like the Tigris and Colorado are especially salty. Irrigating a hectare of cropland for one year can leave several tons of salts dispersed in the soil. In her recent book Pillar of Sand, Sandra Postel, a senior fellow with the Worldwatch Institute, cites astonishing figures concerning salt-burdened land: 7 million acres (3 million hectares) damaged in India, more than 6 million in China, more than 4 million in Pakistan. Moscow University's Victor Kovda, an authority on desert agriculture, calculated that more land has recently gone out of production because of salt and associated problems than has come into production through irrigation.

If the Age of Dams has been little more than ephemeral rescue, a denial of nature's limits--a cure in many cases worse than the disease--then what's the alternative on an overcrowded planet?

Water conservation is the only hope--and every person in the industrialized world wastes plenty of it. Even on the usually rain-drenched East Coast of the U.S., reservoirs get alarmingly low from time to time. People can help by using low-flow toilets, taking shorter showers with water-saving nozzles, washing cars less often and not soaking their lawns. But much more water is squandered by agriculture, and that's where the largest saving will have to come from.

Fortunately, progress is possible. Israel pioneered drip-irrigation systems, which deliver water to individual plants instead of spraying it in plumes over fields. Postel points out that small-scale water development can pose fewer and less vexing problems than megaprojects like China's Three Gorges. In some poor nations like Bangladesh, human-powered irrigation devices, such as treadle pumps, are becoming commonplace.

But even if conservation ends the need for new dams, what can we do about the destructive legacy that the Age of Dams has left behind?

One disarmingly simple answer--the U.S. has already done this with public housing--is to dismantle some of what was built. Grand Coulee Dam won't be demolished in any living person's lifetime, but removing a number of small dams--especially on salmon rivers--seems to make good sense, even in economic terms. In the coming age of alternative energy produced by wind turbines and solar cells, we can cut back on hydroelectric power.