NASA Satellites Show Disturbing Trends in Water Supply
NASA launched a satellite mission in 2002 that has been transmitting data to us over a decade now. The mission is called GRACE, which stands for Gravity Recovery and Climate Experiment, and it measures the amount of water held underground in aquifers.
Aquifers are underground layers of water-bearing permeable rock from which groundwater can be extracted with water wells. About 30% of all of the world’s freshwater resources are located in aquifers.
Data from NASA’s program was revealed in a recent study, which concluded that 21 of the 37 largest aquifers (57%) are running out too fast to be replenished. Even more concerning: an additional 13 are declining at a rate that puts them in a category NASA calls the “most troubled”.
This is putting us closer to peak water territory.
In the below map, red shades show negative changes in the water supply in the world’s biggest aquifers.
Trends in Groundwater Storage, 2003-2013
The biggest water sources exert strong gravitational pulls on the satellites, and NASA can use this data to spot trends in water supply while monitoring the world’s largest sources of groundwater.
The below map shows the type of stress exhibited on each water source. Overstressed aquifers do not experience any replenishment, while variable stress means that an aquifer is in decline but still experiences some sort of replenishment. Lastly, human-dominated stress means that aquifer levels will not increase unless humans help recharge the wells through irrigation or other methods.
Changes in Storage vs. Aquifer Stress
Keep in mind that these are all of the world’s best aquifers, and that changes in smaller groundwater sources are not well reflected in the study. In the United States, it is expected that 40 of 50 states have at least one region that will see some kind of a water shortage in the next 10 years.
California, which is struck by a historical drought, currently relies on 60% of its water from aquifers. For more information on the water challenges faced in the United States, don’t forget to take a look at America’s Water Crisis.