Increased irrigation efficiency actually reduces available water

  Last updated December 3, 2018 at 4:09 pm


We are heading for a global water tragedy, researcher warns.

Credit: iStock

it’s a mantra that’s all too familiar in the dry, hot climate of Australia.

Using technology to improve irrigation efficiency seems like a simple, common sense way to reduce water usage.

However, in a Policy Forum piece in the journal Science, Australian and international experts argue increasing efficiency simply results in more water being used on farms, and less being returned to the environment.

The paper’s lead author, Professor Quentin Grafton of Australian National University told the AusSMC: “When irrigation efficiency increases, such that a greater share of the water extracted for irrigation is used to grow crops, this frequently reduces the volume of water that previously flowed back to streams and to replenish groundwater.”

Governments around the world are working on policies to balance higher freshwater demands with finite resources by increasing irrigation efficiency and providing subsidies to irrigators, but Professor Grafton argues this won’t work.

“Contrary to common wisdom, increasing irrigation efficiency frequently reduces the water available for reallocation yet governments around the globe are pouring billions of dollars into making irrigation more efficient, with disastrous consequences for fresh water availability,” he said.

The University of Adelaide’s Professor Wayne Meyer wrote a similar paper in 2000 entitled, “Will improved water use efficiency deliver everyone’s aspirations?”

He told the AusSMC that failing to address this issue results from a “chronic lack of understanding of regional connected water processes and a lack of understanding of irrigators and their businesses.”

“Improved water use efficiency actually increases ‘demand’ for water by irrigators as they strive to capture the benefits of increased production capacity,” he said.

“Unless there is an accompanying mechanism of offsetting irrigator response, little or no ‘saved’ water will be available for environmental use. The simplistic notion that improved water use efficiency will free water for environmental purposes will not deliver.”

The Policy Forum piece offers five steps to respond to the global water challenge, including physical water accounts to see “who gets what and where,” and limits on irrigated areas.

The Policy Forum piece’s second author, John Williams of ANU, told the AusSMC: “The other three steps to avoid a global water tragedy include: valuing water (including in-stream flows) to ensure that the public benefits of irrigation efficiency subsidies exceed the costs; risk assessments of the effects of increases in irrigation efficiency, including uncertainties over inflows and outflows; and a much better understanding of how irrigators’ actions change as their irrigation efficiency increases.”

Professor Meyer agrees valuing water, especially in Australia, is important.

“When water extraction was capped in the Murray Darling Basin, its value increased, more effort was made to control and use it, irrigation area and intensity increased and hence demand increased.

The previously “sloppy” system was not stretched to its limit, now it is. There is no easy fix for this, although the establishment of tradeable water markets certainly helps.”

With drought crippling New South Wales and Australia’s agricultural industry reliant on irrigation farming, the paper urges policymakers to act before it’s too late.

Professor Snow Barlow at the University of Melbourne told the AusSMC this research is “an important and timely ‘call to arms’”.

“Irrigation to produce food is overwhelmingly the largest global use of fresh water, our scarcest natural resource. It is responsible for producing 40 per cent of the globe’s food,” he said.

“As we endeavour to implement the historic Murray Darling Plan this paper illustrates that incentive and compliance measures that use irrigation efficiency as a sole measure are not sufficient or adequate measures of catchment sustainability.

If the plan is to be implemented sustainably for future generations we need to ensure that the compliance measures utilise the technology that is now available to adequately monitor water recharge as well as extraction and water use efficiency.”

You can read the full AusSMC Expert Reaction here

Education Resource:

Increased irrigation efficiency actually reduces available water

About the Author

Olivia Henry
Olivia Henry is Media Officer at the Australian Science Media Centre. She spends her days nerding out about the latest research in the hopes that journalists will nerd out too. Olivia has Bachelor’s degrees in Biomedical Science and Media (Journalism), and has studied in Japan and Spain. Before joining the AusSMC in 2018, Olivia worked at Fairfax Media, SciWorld, Channel 44 Adelaide and interned at Australia's Science Channel. If you like this super-funky-science-machine, you can catch her talking science on 2CC Canberra or hosting the Night Shift on Radio Adelaide.

Published By

The Australian Science Media Centre (AusSMC) is an independent, not-for-profit service for the news media, giving journalists direct access to evidence-based science and expertise. We aim to better inform public debate on the major issues of the day by improving links between the media and the scientific community. The Centre works with journalists to help them cover science as well as identify the science angles in everyday news stories and works with the scientific community to help them interact more effectively with the media and ensure that their voices are heard on issues of national importance.

Featured Videos

Experts React to Alcohol Industry Concealing Cancer Links