Global volume and distribution of modern groundwater: groundwater age transport modeling results (data)

We find that the total groundwater volume in the upper 2 km of continental crust is approximately 22.6 million km3, of which 0.1–5.0 million km3 is less than 50 years old. Although modern groundwater represents a small percentage of the total groundwater on Earth, the volume of modern groundwater is equivalent to a body of water with a depth of about 3 m spread over the continents.

This water resource dwarfs all other components of the active hydrologic cycle. For each continent, we present the geomatic assignment of hydrologic parameters and the resulting simulation-based modern groundwater equivalent (D_eq50) for the purely geomatic assignment of parameters, an estimate pairing models to watersheds using groundwater recharge and strict lithology control, and an estimate using recharge and strict water table gradient control.