Saturday, August 08, 2009


World Watch - The Stockholm International Water Institute calculated in 2008 that 1.4 billion people live in "closed basins"-regions where existing water cannot meet the agricultural, industrial, municipal, and environmental needs of all. Their estimate is consistent with a 2007 Food and Agriculture Organization calculation that 1.2 billion people live in countries and regions that are water-scarce. And the situation is projected to worsen rapidly: FAO estimates that the number of water-scarce will rise to 1.8 billion by 2025. . .

"Water scarcity" has several meanings. Physical water scarcity exists wherever available water is insufficient to meet demand: parts of the southwestern United States, northern Mexico, North Africa, the Middle East, Central Asia, northern China, and southeastern Australia are characterized by physical water scarcity. Economic water scarcity occurs when water is available but inaccessible because of a lack of investment in water provision or poor management and regulation of water resources. Much of the water scarcity of sub-Saharan Africa falls into this category.

Signs of scarcity are plentiful. Several major rivers, including the Indus, Rio Grande, Colorado, Murray-Darling, and Yellow, no longer reach the sea year-round as a growing share of their waters are claimed for various uses. Water tables are falling as groundwater is overpumped in South Asia, northern China, the Middle East, North Africa, and the southwestern United States, often propping up food production unsustainably. The World Bank estimates that some 15 percent of India's food, for example, is produced using water from nonrenewable aquifers. Another sign of scarcity is that desalination, a limited and expensive water supply solution, is on the rise.

Water scarcity has many causes. Population growth is a major driver at the regional and global levels, but other factors play a large role locally. Pollution reduces the amount of usable water available to farmers, industry, and cities. The World Bank and the government of China have estimated, for instance, that 54 percent of the water in seven main rivers in China is unusable because of pollution. In addition, urbanization tends to increase domestic and industrial demand for water, as does rising incomes-two trends prominent in rapidly developing countries such as China, India, and Brazil.

A looming new threat to water supplies is climate change, which is causing rainfall patterns to shift, ice stocks to melt, and soil moisture content and runoff to change. According to the Intergovernmental Panel on Climate Change, the area of our planet classified as "very dry" has more than doubled since the 1970s, and the volume of glaciers in many regions and snow pack in northern hemisphere mountains-two important freshwater sources-has decreased significantly. . .