Study: Efficient Irrigation Methods Increase Water Usage

LOS ANGELES (CN) – Irrigation techniques promoted to farmers around the world as water-saving are actually increasing water usage, according to a new study.

The Paradox of Irrigation Efficiency,” published Thursday by the American Association for the Advancement of Science, found that efforts to increase water savings increased overall water usage and decreased groundwater levels.

The goal of efficient irrigation methods is to save water to be re-routed to cities, industry or back into natural aquifers.

Because water is a finite resource, governments try to balance increasing demand for it from farms and growing cities – especially in arid regions – by supporting policies designed to increase irrigation efficiency, the study said.

Quentin Grafton, public policy professor at The Australian National University and one of the study’s authors, told Courthouse News that the methods aren’t working and are actually increasing both on-farm water usage and groundwater extraction.

“Key decision-makers are arguing for increases in irrigation efficiency to increase fresh water availability,” Grafton said. “And it’s just not gonna work.”

Governments give incentives to install technologies that improve the “crop per drop” ratio in global food production. Currently, those operations consume huge amounts of water – up to 70 percent of what’s available in some parts of the world – to produce 40 percent of the global food supply.

In India, the largest backer of efficiency methods, irrigators have received at least $7.5 billion in subsidies for installing water-efficient technology, while Australian irrigators have received $3 billion, Grafton said.

But these methods are disrupting the natural flow of the water cycle.

According to the study, in lower-efficiency irrigation systems – such as traditional farming – any water not used directly in irrigation flows back into surface water systems or aquifers.

Under efficient methods, less water is “lost,” meaning less re-enters natural water systems, which leads to a decline in available water overall, according to researchers.

The study said farmers will also typically use more water if efficient irrigation methods, and government incentives, mislead them into believing they are saving money while using less water.

“Irrigation is not a foe – it’s our friend,” Grafton said. “But [water usage] must be managed because it is making our water more scarce.”

Grafton said lawmakers are largely unaware of the long-term, public costs of continuing to subsidize efficient irrigation because they are “captured” by industries who regularly advise them, lobby them and contribute to their political efforts.

“I’m not talking about corruption,” Grafton said. “But [lawmakers] meet with those industries all the time and they start to think like the industry…and you can bet your bottom dollar [those industries] will lobby for any available funds.”

The study proposes a set of policy solutions for staving the global water crisis while continuing to improve and advance efficient irrigation systems.

Governments will need to implement comprehensive water measurements – identifying who is using water and how much of it – and regulate the extraction process, according to the researchers.

Lawmakers will also have to reevaluate the impact of incentives for irrigators and determine the value of trade-offs between competing uses of available water.

Assessing the risk of installing efficient irrigation systems must also take into account climate change and other factors.

The team of researchers based in Europe, China, Australia and the U.S couldn’t point to any place currently implementing all of the suggested policy changes.

Grafton said California’s groundwater management plan could become the “model for rest of the world.”

California’s plan calls for regular measuring and monitoring of groundwater levels to determine movement of return flows and outflows from natural aquifers.

Stephanie Pincetl, professor at the University of California, Los Angeles’ Institute of the Environment, said efficiency methods aren’t only to blame.

California’s flood control policies have also decreased groundwater levels because they “essentially eliminate” winter flooding that used to recharge ground water, according to Pincetl.

“So one can point the finger at ‘efficiency’ methods as reducing groundwater recharge, but there are confounding factors, and efficient farming is one piece of the problem,” Pincetl said.

In the state’s Central Valley – an area that produces more than 25 percent of U.S. agriculture – the aquifer system is ranked as one of the most stressed on the planet.

Groundwater levels there dipped more than 32 inches between 2007 and 2010, a decrease that should normally take decades, according to the National Science Foundation.

The Central Valley aquifer system supplies about 20 percent of the overall U.S. groundwater demand.

“This is an unfolding global water tragedy – I’m not giving hyperbole,” Grafton said. “You’re not gonna end poverty and hunger if you don’t address this. This is big-time stuff.”

The paradox of irrigation efficiency and the water inflows and outflows can be seen in a watershed example. Ranges of crop transpiration, evaporation, runoff and recharge are authors’ judgment of possible values. These values depend on crop and soil types, weather, and other factors. (N. Desai/Science)
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