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Chapter 2. Signs of Stress: Climate & Water: Falling Water Tables
Even as major rivers are running dry, water tables are falling on every continent as the demand for water outruns the sustainable yield of aquifers. Overpumping is a new phenomenon, largely confined to the last half-century. Only since the development of powerful diesel and electric pumps have we had the capacity to pull water out of aquifers faster than it is replaced by precipitation.
Overpumping is now widespread in China, India, and the United States—three countries that together account for nearly half of the world grain harvest. Water tables are falling under the North China Plain, which produces 25 percent of China's grain harvest; under the Indian Punjab, the breadbasket of India; and under the southern Great Plains of the United States.54
Hydrologically, there are two Chinas—the humid south, which includes the Yangtze River basin and everything south of it, and the arid north, which includes the Yellow River basin and everything to the north. The south, with 700 million people, has one third of the nation's cropland and four fifths of its water. The north, with 550 million people, has two thirds of the cropland and one fifth of the water. The water per hectare of cropland in the north is one eighth that of the south.55
Northern China is drying out as the demand for water outruns the supply, depleting aquifers. In 1999 the water table under Beijing fell by 1.5 meters (5 feet). Since 1965, the shallow water table under the city has fallen by some 59 meters or nearly 200 feet. The deep aquifer that some wells draw from may have fallen even more. A 2001 World Bank report says, "Anecdotal evidence suggests that deep wells around Beijing now have to reach 1,000 meters (more than half a mile) to tap fresh water, adding dramatically to the cost of supply." Falling water tables under the capital remind China's leaders of the shortages that lie ahead as the country's aquifers are depleted.56
The North China Plain, a region that stretches from just north of Shanghai to well north of Beijing, embraces five provinces: Hebei, Henan, and Shandong, and the city provinces of Beijing and Tianjin. At the end of 1997, official data show that these five provinces had 2.6 million wells, the bulk of them for irrigation. During that year, 99,900 wells were abandoned, apparently because they ran dry as the water table fell. Some 221,900 new wells were drilled. In the two major cities, Beijing and Tianjin, the number of wells abandoned exceeded the number of new wells drilled. This wholesale abandonment of wells has no precedent. The drilling of so many new wells reflects the desperate quest for water as the water table falls.57
Although earlier data showed the water table dropping by an average of 1.5 meters (5 feet) a year under the North China Plain, these recent data on well abandonment and new well drilling suggest that it now could be falling much faster in some places. Overpumping is greatest in the Hai River basin, immediately to the north of the Yellow River basin. This area, which includes Beijing and Tianjin, both large industrial cities, is home to over 100 million people.58
Water use in the basin currently totals 55 billion cubic meters annually, while the sustainable supply totals only 34 billion cubic meters, leaving an annual deficit of 21 billion cubic meters to be satisfied by groundwater mining. When this aquifer is depleted, water pumping will necessarily drop to the sustainable yield, cutting the basin's water supply by nearly 40 percent. Given rapid urban and industrial growth in the area, and agriculture's relegation to third place in the line for water, irrigated agriculture in the basin could largely disappear by 2010—forcing a shift to less productive rain-fed agriculture. The 2001 World Bank report concluded that north China's fast deteriorating water situation could have "catastrophic consequences for future generations unless water use and supply could quickly be brought back into balance."59
In addition to losses of irrigation water from aquifer depletion, farmers are faced with a diversion of irrigation water to cities and industry. Between now and 2010, when China's population is projected to grow by 126 million, the World Bank projects that the nation's urban water demand will increase from 50 billion cubic meters to 80 billion, a growth of 60 percent. Industrial water demand, meanwhile, is projected to increase from 127 billion cubic meters to 206 billion, an expansion of 62 percent. In much of northern China, this growing demand for water is being satisfied either by investing in water efficiency or by taking irrigation water from agriculture.60
Under India's Punjab, where the double cropping of high-yielding winter wheat and summer rice produces a grain surplus for shipment to other states, the water table is falling. Dropping by an estimated 0.6 meters per year, it is forcing farmers with shallow wells to drill deeper.61
In the southern Great Plains of the United States, irrigated agriculture is based largely on water pumped from the Ogallala aquifer, which is essentially a fossil aquifer with little recharge. As the water table falls and the aquifer is depleted, farmers are forced to abandon irrigated agriculture, returning to dryland farming. In several states that dominate U.S. food production, including Colorado, Kansas, Oklahoma, and Texas, the irrigated area is slowly shrinking as the Ogallala is depleted.62
An economic analysis of the water situation in the high plains of Texas, where much of the state's irrigated cropland is located, concluded that crop production in the region will decline steadily as water supplies shrink. The big losers between 2000 and 2025 will be irrigated feedgrains, including both corn and sorghum. The area in wheat, a dryland crop, will expand slightly. Overall, grain production is projected to decline 17 percent. A similarly detailed analysis for nearby states, such as Oklahoma and Kansas, would likely also show production declines for the more water-dependent crops.63
In southern Texas, El Paso and its sister city across the border in Mexico, Juarez, both draw their water from the same aquifer. As population in the two fast-growing cities has climbed, demand has outstripped the sustainable yield of the aquifer. David Hurlbut, analyst with the Public Utility Commission of Texas, believes that because of their failure to address the water supply issue effectively, the two cities are moving toward hydrological bankruptcy.64
With continuing population growth, the world water situation can only get worse. Even with today's 6.1 billion people, the world has a huge water deficit. Using data on overpumping for China, India, Saudi Arabia, North Africa, and the United States, Sandra Postel, author of Pillar of Sand, calculates the annual overpumping of aquifers at 160 billion cubic meters or 160 billion tons. Using the rule of thumb that it takes 1,000 tons of water to produce 1 ton of grain, this 160-billion-ton water deficit is equal to 160 million tons of grain—or half the U.S. grain harvest.65
At average world grain consumption of just over 300 kilograms or one third of a ton per person a year, 160 million tons of grain would feed 480 million people. In other words, 480 million of the world's 6.1 billion people are being fed with grain produced with the unsustainable use of water. We are feeding ourselves with water that belongs to our children.66
54. Share of China's grain harvest from the North China Plain based on Hong Yang and Alexander Zehnder, "China's Regional Water Scarcity and Implications for Grain Supply and Trade," Environment and Planning A, vol. 33 (2001), and on USDA, op. cit. note 12; India in Postel, op. cit. note 3, p. 170; United States from Postel, op. cit. note 15, pp. 56-57, 252.
55. Brown and Halweil, op. cit. note 44; water resource distribution in China also discussed in Fred W. Crook and Xinshen Diao, "Water Pressure in China: Growth Strains Resources," Agricultural Outlook (USDA, Economic Research Service), January/February 2000, pp. 25-29.
56. James Kynge, "China Approves Controversial Plan to Shift Water to Drought-Hit Beijing," Financial Times, 7 January 2000; World Bank, China: Agenda for Water Sector Strategy for North China (Washington, DC: April 2001), pp. vii, xi.
57. Hong and Zehnder, op. cit. note 54, p. 85.
58. Kynge, op. cit. note 56; Dennis Engi, China Infrastructure Initiative, Sandia National Laboratory, www.cmc.sandia.gov/iGAIA/china/ciihome.html .
59. Engi, op. cit. note 58; World Bank, op. cit. note 56.
60. Population projection from United Nations, op. cit. note 4; Albert Nyberg and Scott Rozelle, Accelerating China's Rural Transformation (Washington, DC: World Bank, 1999).
61. Postel, op. cit. note 15, p. 73.
62. Ibid., p. 77.
63. Bonnie Terrell and Phillip N. Johnson, "Economic Impact of the Depletion of the Ogallala Aquifer: A Case Study of the Southern High Plains of Texas," presented at the American Agricultural Economics Association annual meeting in Nashville, TN, 8-11 August 1999.
64. David Hurlbut, "The Good, the Bad, and the Arid," Forum (Tennessee Valley Authority and Energy Environment and Resources Center, University of Tennessee), spring 2001, p. 11.
65. Postel, op. cit. note 15, p. 255; rule of thumb from FAO, Yield Response to Water (Rome: 1979); USDA, op. cit. note 12.
66. USDA, op. cit. note 12.
Copyright © 2001 Earth Policy Institute