Researchers from Princeton, the University of Arizona, and the Geological Survey of Denmark and Greenland combined 1 million data points of groundwater levels with machine learning to map estimates of groundwater depth across the continental United States with a resolution of about 100 feet — a higher resolution than ever before.
This estimate includes all groundwater above a depth of 392 m, the deepest depth with reliable porosity data and roughly the limit of active circulation in the hydrologic cycle. The researchers estimate that a total of 306,000 cubic kilometers of water, or more than 13 times the volume of all the Great Lakes combined, underlies the continental United States.
Reed Maxwell, Ph.D., pictured to the right, is a past Groundwater Foundation Darcy lecturer (2020) and one of the researchers, hopes the map can be a resource for a variety of users, including regional water management decisionmakers, as well as for farmers making decisions about irrigation.
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