How much fresh water is in the United States? It’s a tough question, since most of the water is underground, accessible at varying depths. In previous decades, it’s been answered indirectly from data on rainfall and evaporation. Knowing how much groundwater is available at specific locations is critical to meeting the challenges of water scarcity and contamination. Now, researchers at Princeton University and the University of Arizona have answered this question in unprecedented breadth and detail. Combining direct measurements with artificial intelligence methods, their new map estimates groundwater depth across the continental United States at a resolution of around 30 meters (98 feet).

Other groundwater news:

• Nature Communications: High resolution US water table depth estimates reveal quantity of accessible groundwater
• Virginia Tech: Major river deltas are sinking faster than sea-level rise