Water scarcity looms.

AuthorGardner, Gary

Water scarcity is growing in urgency in many regions as population growth, climate change, pollution, lack of investment, and management failures restrict the amount of water available relative to demand. 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. In 2007 the UN Food and Agriculture Organization (FAO) calculated that 1.2 billion people live in countries and regions that are water-scarce. FAO estimates that the number of water-scarce will rise to 1.8 billion by 2025.

Water scarcity can be physical or economic. Physical water scarcity exists wherever available water is insufficient to meet demand. 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.

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 is 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.

Population growth is a major driver of scarcity at the regional and global levels. 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 and rising incomes tend to increase domestic and industrial demand for water.

In some cases, water scarcity leads to greater dependence on foreign sources of water as shown by countries' "water footprints"--the volume of water used to produce the goods and services, including imports, that people consume. The ratio between the water footprint of a country's imports and its total water footprint yields its water import dependence (see table).

Water Import Dependence, Selected...

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