Water in a changing world: the renewable freshwater cycle
The renewable freshwater cycle in units of thousands of km3/yr, respectively, for pools (white numbers) and fluxes (black numbers). Total precipitation over land is ~110,000 km3/yr. Approximately two-thirds of this precipitation is water recycled from plants and the soil (evapotranspiration is 70,000 km3/yr), whereas one-third is water evaporated from the oceans that is transported over land (40,000 km3/yr). Total evaporation from the oceans is ~10 times larger than the flux pictured here (~425,000 km3/yr). Groundwater holds ~15,000,000 km3 of fresh water, much of which is not in active exchange with the earth's surface.
Image and text from Jackson et al. 2001.