Water : rethinking management in an age of scarcity

Like energy, fresh water is essential to virtually every human endeavor its availability is vital to feeding the world's grow ing population, producing the material goods that raise living standards, and preserving the integrity of natural systems upon which life itself depends. The scarcity of anything so fun damental is bound to disrupt economic and social activity. Not sur prisingly, after the sudden hardships wrought by oil price increases the "energy crisis"-of the seventies, many people wonder if there might next be a crisis in water.

Numbers alone fail to tell water's true story. Enough rain and snow fall over the continents each year to fill Lake Huron 30 times, to magnify the flow of the Amazon sixteenfold, or to cover the earth's total land area to a depth of 83 centimeters. The volume of fresh water annually renewed by the water cycle could meet the material needs of 5 to 10 times the existing world population. Yet lack of water to grow crops periodically threatens millions with famine. Water tables in southern India, northern China, the Valley of Mexico, and the US. Southwest are falling precipitously, causing wells to go dry. Rivers that once ran year-round now fade with the end of the rainy season. Inland lakes and seas are shrinking.