The hydrologic, or water, cycle describes the storage and movement of all water on Earth. This lesson will cover the different reservoirs where water can be stored and how it moves between them.
Definition of the Hydrologic Cycle
The water cycle, also known as the hydrologic cycle, defines the movement and storage of water through Earth. Water on Earth is constantly moving and changing states.
Water can be found all around the globe and is constantly on the move.
This chart shows how the water is distributed across the planet. As shown by the first bar graph, almost all the water on Earth is contained in the oceans. Only 3% of water is fresh water available for drinking, and of that 3%, almost 69% is trapped in glaciers or underground.A reservoir stores water for a period of time.
Not all reservoirs hold water for the same amount of time. Glaciers, for example, can keep water trapped as ice for thousands of years. The atmosphere, on the other hand, keeps water for an average of nine days before it releases it down as rain or snow.
Some different reservoirs that can store water include:
Movement of Water
In order for water to move from one reservoir to another, it needs a method of transportation. A common example is water moving from the atmospheric reservoir by method of precipitation, or more commonly known as rain. Water is constantly moving from one reservoir to another, and this occurs by a number of different methods. The largest movement of water in the water cycle is the evaporation of water from the oceans.