If groundwater resources are overexploited, aquifers will be unable to recharge fast enough to keep pace with water withdrawals (Worldwatch Institute)

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Global Irrigated Area at Record Levels, But Expansion Slowing

In 2009, the most recent year for which global data are available from the United Nations Food and Agriculture Organization (FAO), 311 million hectares in the world was equipped for irrigation but only 84 percent of that area was actually being irrigated, according to new research conducted by the Worldwatch Institute for its Vital Signs Online service (www.worldwatch.org). As of 2010, the countries with the largest irrigated areas were India (39 million hectares), China (19 million), and the United States (17 million), writes report author Judith Renner.

The irrigation sector claims about 70 percent of the freshwater withdrawals worldwide. Irrigation can offer crop yields that are two to four times greater than is possible with rainfed farming, and it currently provides 40 percent of the world’s food from approximately 20 percent of all agricultural land.

Since the late 1970s, irrigation expansion has experienced a marked slowdown. The FAO attributes the decline in investment to the unsatisfactory performances of formal large canal systems, corruption in the construction process, and acknowledgement of the environmental impact of irrigation projects.

The increasing availability of inexpensive individual pumps and well construction methods has led to a shift from public to private investment in irrigation, and from larger to smaller-scale systems. The takeoff in individual groundwater irrigation has been concentrated in India, China, and much of Southeast Asia. The idea of affordable and effective irrigation is attractive to poor farmers worldwide, with rewards of higher outputs and incomes and better diets.

“The option is often made even more appealing with offers of government subsidies for energy costs of running groundwater pumps and support prices of irrigated products,” said Renner, a senior at Fordham University in New York. “In India’s Gujarat state, for example, energy subsidies are structured so that farmers pay a flat rate, no matter how much electricity they use. But with rising numbers of farmers tapping groundwater resources, more and more aquifers are in danger of overuse.”

If groundwater resources are overexploited, aquifers will be unable to recharge fast enough to keep pace with water withdrawals. It should be noted that not all aquifers are being pumped at unsustainable levels—in fact, 80 percent of aquifers worldwide could handle additional water withdrawals. One troubling aspect of groundwater withdrawals is that the world’s major agricultural producers (particularly India, China, and the United States) are also the ones responsible for the highest levels of depletion.

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