Background to rivers
Background information for the study of rivers.
The hydrological cycle is also known as the water cycle.
Seas and oceans contain 97 per cent of the world's water, and ice holds 2 per cent. That leaves just 1 per cent of the world's water as fresh water on land or in the air. This water is recycled again and again through the process of evaporationevaporation: The process in which a liquid turns into a gas, condensationcondensation: Condensation is a change of state in which gas becomes liquid by cooling. and water transfers such as surface run-off.