As if California’s current drought wasn’t bad enough, it could be just a foretaste of what’s to come. Many of the U.S.’s major watersheds are “stressed” , and, across the world, several important regions are set to run low on water.
With growing populations and deepening climate change, we’re going to need to find new ways to conserve and make better use of supplies. The days of using water casually, as if there’s always more to come, will be over for a good proportion of the planet, including much of the southwest and western United States.
How can we overcome our shortages? A new paper from researchers at McGill and Utrecht Universities identifies six strategies–or “wedges”–that could make a significant difference. Each could provide a reduction in water-stressed population of at least 2% by 2050.
“We have calculated that if four of these strategies are applied at the same time we could actually stabilize the number of people in the world who are facing water stress rather than continue to allow their numbers to grow, which is what will happen if we continue with business as usual,” says Tom Gleeson, a professor at McGill.
Below is a summary of the six ideas, which are outlined in more detail in the latest edition of Nature Geoscience:
Farming accounts for about 70% of all water use, so the sector presents the greatest opportunity for saving. The paper says a 0.5% increase in productivity per year (producing the same amount of food with less water) would produce a 20% saving by 2050, and a 2% improvement in the population affected by water stress. “New cultivars of important crops, such as wheat or rice, can be used to optimize water irrigation efficiency,” Gleeson wrote in an email.
A lot of water is wasted during crop irrigation, because instead of actually watering crops, water is sent every which way. Shifting away from flood irrigation and sprinklers to drip and precision systems could improve efficiency 1% a year until 2050, though heavy investment would be needed.
Plugging leaks in domestic and industrial systems would provide another wedge–enough to produce a 20% stress reduction by 2050. As with the first two options, this may not be that difficult. “Because all three uses of water are currently inefficient in many water-stressed regions, significant gains in these three wedges are plausible,” the authors write.
The fourth option isn’t directly about water but could have an important impact: tempering population increases. “A full wedge of water-stress relief would require keeping the population in 2050 below 8.5 billion, for example, through help with family planning and tax incentives,” the paper says.
As well as what the researchers call “soft measures,” they also propose “hard measures” involving upgrades to essential infrastructure. These include making reservoirs larger, so they can hold more water. To supply a full wedge, they say 600 cubic kilometers of water storage would be needed, which is a lot.
Another costly option: investing in desalination plants. “A 50-fold increase would be required for one wedge, which would imply significant capital and energy costs,” the paper says.
The authors mention other options, including rainwater harvesting for agriculture and reducing meat production, which is a big drain on supplies. But they don’t quantify their impact.
“My personal favorite is improving agricultural water productivity,” says Gleeson. “As we write in the article both of the hard path measures of increasing water storage in reservoirs and desalination of sea water may be less plausible for economic and practical reasons.”