Global Policy Forum

By Lester R. Brown and Brian Halweil

Washington - As the world's population reaches 6 billion, water in many places is being used more quickly than it is replenished. If that trend continues, it will have a profound adverse impact on food production and living standards. Water tables are falling in China, India and the United States, which together produce half the world's food. Historically, irrigated farming has been plagued with waterlogging, salting and silting. Now, with the advent of powerful diesel and electrically powered pumps, it is also threatened by aquifer depletion.

Under the North China Plain, the country's breadbasket, water tables are falling by 1.5 meters a year. In India, the pumping of underground water is now estimated to be double the rate of aquifer recharge from rainfall. The International Water Management Institute, the world's premier water research group, estimates that India's grain harvest could be reduced by up to one-fourth as a result of aquifer depletion. In the southern Great Plains of the United States, depletion of the Ogallala aquifer has already led to irrigation cutbacks. Texas, Oklahoma, Kansas and Colorado have been losing irrigated land in the last two decades.

The Yellow River, the cradle of Chinese civilization, first ran dry in 1972. Since 1985 it has run dry for part of each year. In 1997 it failed to reach the sea during 226 days of the year. During the dry season, the Ganges has little water left when it reaches the Bay of Bengal. India's people take the lion's share of the water, leaving too little for the farmers of Bangladesh during the dry season.

In Central Asia, the Amu Darya, one of two rivers that once fed the Aral Sea, is now drained dry by farmers in Turkmenistan and Uzbekistan. As the sea has shrunk to scarcely half its original size, the rising salt concentration has destroyed all fish, eliminating a rich fishery that once landed 45 million kilograms of fish each year. The Colorado, the major river in the southwestern United States, rarely ever makes it to the Gulf of California. The fishery at its mouth that once supported several thousand Cocopa Indians has disappeared. The Nile has little water left when it reaches the sea. Even though virtually all the water in the river is now claimed, the population of the three principal Nile basin countries - Egypt, Sudan and Ethiopia, where most of the water originates - is projected to increase from 153 million at present to 343 million in 2050. This will generate intense competition for water.

Hydrologists estimate that when the amount of fresh water per person in a country drops below 1,700 cubic meters per year, the country is facing water stress. The number of people living in countries experiencing such stress will increase from 467 million in 1995 to more than 3 billion by 2025, as population grows. In effect, these people will not have enough water to produce food and satisfy domestic and other needs. Excessive grain supplies that have depressed world grain prices in 1999 are partly the result of overpumping. If falling water tables were stabilized by a cutback in pumping, the decline in grain production would probably drive prices off the top of the chart.

As water becomes scarce, competition between cities and countryside intensifies. Farmers almost always lose. In North Africa and the Middle East, virtually every country is experiencing water shortages. As cities expand, they take water from agriculture. The countries concerned then import grain to offset the water losses. It is often said that competition for water may take the form of military conflict. But it now seems more likely that the competition for water will take place in world grain markets. It is the countries that are financially strongest, not those that are militarily the strongest, that are likely to win.

United Nations demographers are concerned that by 2050 the world's population could approach 9 billion. If the number could be held below 7 billion by better population control measures, water stresses would be greatly alleviated. If the world stays on the current population trajectory, a growing share of humanity may simply lack the water needed for a decent life.

Mr. Brown is president and Mr. Halweil a staff researcher at Worldwatch Institute, a nonprofit research organization in Washington.

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