Commentary: World's Water Resources in Swift Decline

by Carmen Revenga

The United Nations General Assembly agreed in 2003 to proclaim the years 2005 to 2015 as the International Decade for Action, "Water for Life," beginning with World Water Day on March 22, 2005.

As Kofi Annan said, "Water is essential for life. Yet many millions of people around the world face water shortages. Many millions of children die every year from water-borne diseases. And drought regularly afflicts some of the world's poorest countries. The world needs to respond much better."

Water policies in most nations are failing to protect life's most vital resource. This fact is reflected in growing water scarcity and alarming declines in the health of aquatic ecosystems worldwide. More precious than oil, yet routinely wasted, water is arguably the world's most pressing resource issue.

Human development depends on adequate water - a fact that has driven the location of communities, the extent of agriculture, and the shape of industry and transportation for centuries. Because of its central place in our activities, water is also the focus of much engineering activity and investment in the form of dams, canals, pipelines, and irrigation systems.

Global water consumption rose six-fold between 1900 and 1995 - more than double the rate of population growth - and continues to grow rapidly as agricultural, industrial, and domestic demand increases.

As population increases and freshwater systems are modified to a point where many of their basic functions are affected, it becomes increasingly difficult to ensure that there is enough water for both people and nature. Water supplies are unevenly distributed around the globe, with some areas containing abundant water and others a much more limited supply.

Estimates of water scarcity calculated by the World Resources Institute in collaboration with the University of New Hampshire show that some 41 percent of the world's population, or 2.3 billion people, live in river basins under "water stress," meaning they are subject to frequent water shortages. Some 1.7 billion of these people live in "highly stressed" water basins where problems with local food production and economic development abound.

Global food production must increase in the years ahead to accommodate population growth, which means the world's farmers will need more water for irrigation. Growth in food production in the last 50 years has been roughly matched by a proportional increase in water use. Agriculture is society's major user of water, withdrawing some 70 percent of all water.

Unfortunately, most irrigation systems are relatively inefficient and result in massive water waste. Global estimates of irrigation efficiency show that around 60 percent of irrigation water never reaches the crop and is lost to evaporation and runoff.

Water pollution adds enormously to existing problems of local and regional water scarcity by removing large volumes of water from the available supply. In many parts of the world, rivers and lakes have become so polluted that their water is unfit even for industrial uses

Global concerns about water scarcity include not only surface water sources but groundwater sources. More than 1 billion people in Asian cities and 150 million in Latin American cities rely on groundwater from wells or springs.

Overdrafting of groundwater sources can rob streams and rivers of a significant fraction of their flow. In the same way, pollution of aquifers by nitrates, pesticides, and industrial chemicals often affects water quality in adjacent freshwater ecosystems.

Better management of water resources is the key to mitigating water scarcities in the future and avoiding further damage to aquatic ecosystems. In the short term, more efficient use of water could dramatically expand available resources.

This is particularly true in the agricultural sector, where experience shows that drip irrigation systems routinely cut water use 30-70 percent, while simultaneously increasing crop yields 20-90 percent.

More efficient water technology alone will not be sufficient to fully address the looming water crisis. It will also require difficult policy choices that reallocate water to the most economically and socially beneficial use.

This may mean diverting water from agriculture to commercial or household uses. In China, for example, planners estimate that a given amount of water used in industry generates more than 70 times more economic value than the same water used in agriculture.

To a certain extent, the transfer of water from low-value uses to higher-value uses is already well under way, especially where individuals hold legal water rights that they can sell to others. Farmers outside the city of Tirupur in southern India, for example, have begun to abandon farming so that they can sell their groundwater at a premium to water-hungry industries and urban users. Such "water markets" are becoming more common in arid regions of the western United States and Australia.

An important key to using and allocating water more efficiently is phasing out subsidies and allowing water prices to reflect the true cost of supply. Price reforms in Chile reduced irrigation water use 22-26 percent and saved $400 million in costs for developing new water supplies.

As the UN has noted, the policy and social decisions made over the next decade will be crucial to stopping freshwater shortages. Better governance and more effective policies are essential to outpacing the growing demand for our most important natural resource. (WRI Features, 863 words).