New Study Finds Limited and Uneven Water Reserves Near Earth’s Surface

Roughly 5.5 million cubic miles of groundwater are stored in the earth’s crust, according to new research published in the journal Nature Geoscience, but the resource is distributed unevenly across the globe, as shown in this map. Combining data with models on the permeability and porosity of rocks and soils, and on water table gradients, researchers illustrated the depth of groundwater around the world. If earth’s groundwater were to cover the planet’s surface evenly, the scientists predicted that the pool would be approximately 600 feet deep. However, only six percent of this groundwater is usable for most purposes. This water, which is closer to the surface, is also more sensitive to climate change and human contamination. The research highlights how unevenly this resource is distributed across the globe, scientists say, as well as the need to manage water reserves in a sustainable way.