Hydrosphere—The Water Realm Which Supports Human Life

Abstract

The Earth is sometimes called as an aqua planet, even though the total amount of water is only 0.02% of the planet, because the existence of water substantially controls the energy budget and the environment of its surface. The roles of storages and flows under the context of global hydrological cycles and Earth system science, and interactions among them are discussed, and estimated volumes and fluxes are quantitatively illustrated. Terrestrial, atmospheric, and combined water balance concepts are described and applications of them are presented. Representative estimates of global water balance consist of global mean precipitation, evapotranspiration, and runoff by various researchers are introduced and compared.