Global water resources are stretched by climate change and human population growth, and farms and cities are increasingly turning to groundwater to fill their needs. Unfortunately, the pumping of groundwater can cause the ground surface above to sink, as the aquifers below are drained and the architecture of the ground collapses. For the first time, a new study maps this loss of groundwater storage capacity around the world.
In the study, published October in the journal Nature Communications, researchers from DRI, Colorado State University, and the Missouri University of Science and Technology examined how groundwater extraction is driving land subsidence and aquifer collapse. “Our study puts land subsidence happening from excessive groundwater pumping to a global context,” said Fahim Hasan, a Ph.D. candidate at Colorado State University and the study’s lead author.
By combining publicly available data with the predictive capabilities of computer modeling, they found global aquifer storage capacity is disappearing at a rate of approximately 17 km3 per year (about the size of 7,000 Great Pyramids of Giza). This loss of groundwater storage is permanent, forever reducing the amount of water that can be captured and stored.
To identify and quantify how much land is subsiding due to groundwater pumping in regions where no data is available, the team utilized advanced machine learning techniques. They first compiled all the publicly available information they could find from federal and state agencies and scientific studies. Then, they used this data to build a computer model that can use risk factors for land subsidence, like land use and climate data, to produce statistical predictions for ground subsidence in other regions.
They tested the accuracy of the model’s predictive capacity by assessing how well it predicted subsidence in regions where subsidence has been verified. In this way, they could expand the study to include rural and little-studied regions around the world.
The study found that the United States, China, and Iran account for most of the global groundwater storage loss, with some regions experiencing more than 5cm/year of land subsidence.
