Hydrological cycle

Water covers 70% of the Earth’s surface and is present in the atmosphere; it also comprises a large percentage of all living matter.

Water is renewable; it exists in an endless cycle, moving between its gaseous, liquid and solid forms. This “hydrological cycle” constitutes nature’s way of replenishing, redistributing and purifying the world's natural water resources.

Hydrological cycle

Source: Environmental Education for Kids

The magnitude of each component of the hydrological cycle in a region or country is determined by a number of factors, including the amount of water received from precipitation, inflow and outflow in rivers and aquifers (this factor is particularly important in transnational water bodies) and the amount lost through evaporation and

evapo-transpiration. Human activities also greatly affect the individual components of the hydrological cycle, through actions such as water abstraction from ground and surface waters. 

Precipitation levels in Europe

Source: EEA 2003/EEA data service