"Eliminating water shortages depends on a global attempt to raise water productivity similar to the effort launched a half-century ago to raise land productivity, an initiative that has nearly tripled the world grain yield per hectare." –Lester R. Brown, World Facing Huge New Challenge on Food Front in Plan B 3.0: Mobilizing to Save Civilization
Chapter 2. Emerging Water Shortages: A Food Bubble Economy
As noted earlier, overpumping is a way of satisfying growing food demand that virtually guarantees a future drop in food production when aquifers are depleted. Many countries are in essence creating a "food bubble economy"—one in which food production is artificially inflated by the unsustainable use of water. When a stock bubble bursts, the stocks eventually regain their value. But when a food bubble bursts, production may not regain earlier levels. With aquifer depletion, either the rate of pumping is reduced to the level of recharge, if it is a replenishable aquifer, or pumping ceases entirely, if it is a fossil aquifer.
This consequence of excessive reliance on underground water was not obvious when farmers began pumping on a large scale a few decades ago. The great advantage of pumping groundwater is that farmers can apply the water to crops precisely when it is needed, whereas surface water is released for everyone at once, whether or not that is the best time for individual farmers. Groundwater, in contrast, is also available throughout the year, including during the dry season, enabling farmers to double crop their land.
The superior productivity of pump irrigation water over surface water is evident from data collected from farms in India. Yields of foodgrains in Punjab for land irrigated from wells was 5.5 tons per hectare, while yields on land irrigated with water from canals averaged 3.2 tons per hectare. Similar data for the southern state of Andhra Pradesh also showed a strong advantage going to pumped irrigation, with foodgrain yields averaging 5.7 tons per hectare compared with 3.4 tons on land irrigated with canal water.53
The high productivity of irrigation based on groundwater means that the food production losses will be that much greater when the groundwater runs out. For India, where roughly half the irrigated land is watered with underground water, production losses could be steep. In the Pakistani Punjab, overpumping may be less damaging than in India partly because Pakistan depends so heavily on surface water from the Indus River.54
In the United States, 37 percent of all irrigation water comes from underground; 63 percent comes from surface sources. Yet three of the top grain-producing states—Texas, Kansas, and Nebraska—each get 70-90 percent of their irrigation water from the Ogallala aquifer, which is essentially a fossil aquifer with little recharge.55
At what point does water scarcity translate into food scarcity? In which countries will the loss of irrigation water from aquifer depletion translate into an absolute decline in grain production? David Seckler and his colleagues at the International Water Management Institute summarize this issue well: "Many of the most populous countries of the world—China, India, Pakistan, Mexico, and nearly all the countries of the Middle East and North Africa—have literally been having a free ride over the past two or three decades by depleting their groundwater resources. The penalty of mismanagement of this valuable resource is now coming due and it is no exaggeration to say that the results could be catastrophic for these countries and, given their importance, for the world as a whole."56
Since irrigation water played such a central role in the tripling of the world grain harvest from 1950 to 2000, it comes as no surprise that water losses will shrink harvests. Outstanding among the countries that are living in a food bubble economy are China and India, which together contain 38 percent of the world's people. Less populous countries in a similar position are Pakistan, Mexico, and Saudi Arabia. The question for each of these countries, and for the entire world, is not whether the bubble will burst, but when.57
53. Andrew Keller, R. Sakthivadivel, and David Seckler, Water Scarcity and the Role of Storage in Development, Research Report 39 (Colombo, Sri Lanka: International Water Management Institute, 2000), p. 5.
54. "Pakistan: Focus on Water Crisis," op. cit. note 21.
55. USDA, op. cit. note 1, Chapter 2.1, p. 5.
56. Seckler, Molden, and Barker, op. cit. note 17.
57. Population from United Nations, op. cit. note 8.
Copyright © 2003 Earth Policy Institute