More than half of the world's major rivers have become seriously depleted and polluted, degrading and poisoning the surrounding ecosystems, according to the World Commission on Water for the 21st Century. This continual damage threatens the health and livelihood of people who depend upon the rivers for irrigation, drinking and industrial water, says the commission, which is sponsored by the United Nations and the World Bank.
Rivers are in trouble because of excessive dam construction or river diversions for farming, excessive water withdrawal and the draining of wetlands as well as pollution. The commission offers a few examples of the virtual destruction of some rivers.
More than 400 million people depend on the Yellow River, which ran dry in its lower reaches 226 days in 1997. Farmers are depleting aquifers, and the Yellow River and its tributaries are severely polluted.
More than 90 percent of the natural flow is used by irrigation or is lost through evaporation. What reaches the Mediterranean is heavily polluted by fertilizer and industrial and municipal waste.
Amu Darya and Syr Darya
The two rivers' flow has been cut by three-quarters, causing a drop of the Aral Sea's water level by 53 feet. The exposed salt flats pose health hazards to the population.
Just 3 percent of the water is considered an environmentally safe source of drinking water. Some 42 million tons of toxic waste pile up each year in the basin, causing huge health problems.
The world's population derives 40 percent of its food from irrigated lands.
SOURCE: World Commission on Water for the 21st Century