Simulating the impact of groundwater overuse

Many assume freshwater is an unlimited resource, thanks to its constant renewal through the natural water cycle. However, growing reliance on groundwater extraction from natural underground aquifers is causing rapid depletion.

Mohamad Hejazi, executive director for the Climate and Sustainability Department at KAPSARC, working with an international team, sought to determine likely future scenarios for groundwater use. Their study highlights the limits to groundwater extraction in different regions across the world, and suggests that groundwater must be treated like any other depletable resource. 

“There is a myth that water scarcity can be dealt with by simply pumping groundwater to meet demand,” says Hejazi. “We wanted to demonstrate that many places have already witnessed their peak and decline in terms of groundwater supply.” 

Around one-fifth of the world’s food is grown using groundwater irrigation. These agricultural uses comprise 43% of groundwater consumption, and are particularly important in arid regions. However, many underground aquifers are not refilled within a human lifetime, and some are ‘fossilized,’ or cut off entirely from the surface water cycle. The costs of extracting from certain aquifers, and the associated damage to the environment, often outweigh the value of the water extracted.

“As groundwater levels fall and extraction costs increase, the practice becomes increasingly precarious,” says Hejazi. “We are not saying that groundwater resources will run out, but the costs associated with extraction make it a finite resource.”

To examine groundwater extraction futures, Hejazi and co-authors fed data related to 235 water basins worldwide into the Global Change Analysis Model. The model simulated 900 possible future scenarios, accounting for the dynamic interactions between regional factors such as the economy and land use, and wider global factors including socioeconomic, climate, and sustainability strategies. 

In one-third of the basins, the majority of the 900 scenarios resulted in peak and decline patterns. These basins included many regions currently serving as the breadbaskets of the world, and potentially expose around 44% of the world’s population to groundwater stress. 

In the water-scarce Middle East, populations are already highly dependent on groundwater and non-traditional water sources such as desalinated water. Hejazi and his team are confident their findings can instigate planning to safeguard populations against severe groundwater depletion.

“There will be food price implications alongside other emerging vulnerabilities,” he says. “We need to plan for these scenarios now, as part of our wider commitments to net zero and sustainable living goals.”