Governments are pouring billions of dollars into making irrigation more efficient, with disastrous consequences for freshwater availability. Quentin Grafton and John Williams look at how to reverse the tide of bad policy.
While the World Economic Forum recognises this crisis, one of the key solutions proposed by many governments is to increase irrigation efficiency and then reallocate water to industry, households or the environment.
Contrary to common wisdom, however, increasing irrigation efficiency will, typically, reduce the water available for reallocation.
Today, as part of an international collaboration with nine other scientists and economists from eight countries and seven universities, we have published a lead paper in Science entitled ‘The Paradox of Irrigation Efficiency’. Our research responds to the unfolding global water tragedy by demonstrating that increases in irrigation efficiency, in general, reduce surface run-off and groundwater recharge to the detriment of people, the environment, and our future.
What happens to irrigation efficiency really matters. This is because irrigation is responsible for about 70 per cent of the world’s freshwater extractions.
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. Because this water is not consumed by irrigated crops, and therefore does not increase crop yields, it is treated as a ‘loss’ by irrigators.
The tragedy is that these so-called unconsumed water losses to farmers are actually return flows – water that is frequently recovered and reused elsewhere in a watershed or basin. They have value. The key point, and the paradox, is this: advanced irrigation technologies that increase irrigation efficiency frequently increase on-farm water consumption and groundwater extractions while also reducing return flows.
Irrigation technologies allow farmers to increase water used by existing crops, substitute to more water-intensive crops, or expand the irrigated area. These activities, in turn, reduce return flows – and therefore the water available for reallocation and the environment.
The paradox has been overlooked or ignored for far too long, principally because it provides an inconvenient truth. Indeed, why would anyone be against increased efficiency?
A failure to understand this paradox means that the United Nations High-Level Panel on Water, comprising 11 sitting heads of state (including Australian Prime Minister Malcom Turnbull), recommended in May 2018 “…incentives for water users, including irrigators, to use water efficiently”. Yet, the Panel failed to recognise that these policies may increase, rather than decrease, water consumption in the absence of the five steps outlined in our paper in Science.
Subsidies that increase irrigation efficiency, without limits on water extractions, are bringing some countries to disaster.
In India, irrigation is responsible for more than 80 per cent of freshwater extractions. The Indian federal government has allocated some US $7.5 billion to increase irrigation efficiency and Indian states have their own subsidies for irrigation efficiency. Yet, in the Indian state of Rajasthan, subsidies for drip irrigation are responsible for an increase in the irrigated area and the total volume of water applied by farmers. In a country which has already had riots over water access, and where groundwater extractions in some key food-producing regions are unsustainable, subsidies to increase irrigation efficiency are exacerbating, not resolving, its water crisis.
In Morocco, the adoption of drip irrigation, supported by multi-billion dollar subsidies, has reduced recoverable return flows, principally to overexploited aquifers. This has led to increased water consumption and exacerbated groundwater overexploitation.
A similar story is repeated in other countries. Indeed, in a landmark study in 2017, the Food and Agriculture Organisation of the United Nations observed, based on data from 13 countries, that “…reductions in water consumption by irrigated agriculture will not come from the technology itself.”
This is not just a poor country problem.
Along the Snake River in the US state of Idaho, farmers have increased their irrigation efficiency over decades. This has been responsible for reduced groundwater recharge to the connected Eastern Snake Plain Aquifer by about 30 per cent since the mid-1970s, despite increased rainfall.
In Australia’s Murray-Darling Basin, billions have been spent increasing on and off-farm irrigation efficiency. Yet despite the cost to taxpayers, there has been no comprehensive water accounting of the impact of irrigation on return flows or even a cost-benefit analysis of the dollars spent. This is bad policy from any viewpoint. These subsidies were supposed to be paid to increase stream flows, but may have actually reduced net stream flows in the Basin by as much as all the water in Sydney Harbour – perhaps more.
So why do governments continue to subsidise increased irrigation efficiency? And why is there so little robust, comprehensive water accounting that measures water inflows and outflows in irrigation at the farm and basin scale? Why don’t we measure what happens to return flows when irrigation efficiency increases?
One reason is that subsidies for irrigation efficiency promote rent-seeking behaviour by beneficiaries who lobby to maintain the status quo. There is also a phenomenon called ‘regulatory capture’ identified by the Nobel Laureate in Economics, George Stigler. This involves public servants who are charged with regulating an industry being ‘captured’ by it instead, and end up serving the industry they regulate rather than the public good.
Our Science paper provides five key steps to resolve this global challenge. To deliver a more water-secure future, these actions demand that policymakers who fail to act for the public good in terms of water policy ultimately pay a political cost.
First and foremost, physical water accounts are needed from the farm scale to the basin scale to make transparent “who gets what and where”. Second, reductions in irrigated water consumption require decreases in water extractions and limits on the irrigated area.
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.
We provide clear pathways that will allow the world to mitigate global water insecurity while ensuring we have enough food and fibre. Countries that claim to have the world’s best water practice – like Australia – need to stop wasting money by subsidising increases in irrigation efficiency that are reducing, not increasing stream flows.
Governments around the world also need to start doing comprehensive and basin-scale water accounting, as is starting to happen in California. In 2018, with all the remote sensing technologies available, and at low cost, it is simply inexcusable and irresponsible not to do comprehensive water accounting.
It’s time to do the right thing in terms of irrigation efficiency and to implement our five key steps. It’s time to stop this unfolding global water tragedy.