The world’s largest aquifers are under stress, according to a decade of data from the GRACE satellites.
Key groundwater basins on every inhabited continent are being drained, particularly in the planet’s dry midsection, according to an analysis of NASA satellite data by researchers at the University of California, Irvine.
From northern China to the Middle East, from North Africa to the Central Valley of California, a common and unsettling story is unfolding: the effort to produce massive grain and food surpluses that will feed billions and to supply drinking water to the largest knots of humanity on the planet is taxing aquifers beyond their capacity.
The infographic below illustrates two findings from the study. The top map shows the rise or fall in groundwater levels in the world’s 37 largest aquifers. Shades of red mean that water levels dropped between 2003 and 2013, the years covered by the data. Blue means that water levels rose.
The second map categorizes the type of stress for each aquifer. The four categories are based on the rate at which water soaks into an aquifer compared with the rate at which it is removed. Unstressed aquifers are displayed in the lightest shad of pink, while the next shade of coral depicts aquifers that are classified as experiencing human-dominated stress, meaning that without man-made recharge — such as water applied to land for irrigation — aquifer levels would not rise. Variable stress is depicted in the next shade of reddish-pink, and overstressed aquifers are in the darkest shade of wine red, signifying that they do not experience any replenishment.
Brett Walton contributed to this infographic, which was made to accompany Walton’s article Groundwater Depletion Stresses Majority of World’s Largest Aquifers. Contact Brett Walton or send a tweet to @WaltonWater.
is both a scientist and a journalist, helping to drive Circle of Blue’s reporting with data and research. She holds an MS in Environmental Engineering from Michigan Technological University, and she brings proficiency in ESRI’s ArcGIS mapping software.