5.1B: Importance and Size of Stores and Fluxes
The relative importance and size (percentage contribution) of the water stores (oceans, atmosphere, biosphere, cryosphere, groundwater and surface water) and annual fluxes between the ocean, atmosphere and land.
Stores and flows (a.k.a. transfers)
Flows and Fluxes
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- Stores are reservoirs where water is held. There are four main stores:
- the oceans (largest by far)
- glaciers and ice sheets (cryosphere, second largest)
- surface runoff
- The umbrella terms for a number of land-based stores, including rivers, lakes, groundwater and the moisture held in soils and vegetation.
- the atmosphere
- Of the freshwater stores:
- The cryosphere is the largest, holding 69% of global freshwater
- Groundwater holds 30%
- Less than 1% is stored in the biosphere (vegetation and soil moisture)
Flows and Fluxes
- Flows are the transfers of water from one store to another. (all in km cubed per year)
- Oceans and atmosphere
- Evaporation 400,000
- Precipitation 370,000
- Atmosphere and landmasses
- Evaporation 60,000
- Precipitation 90,000
- Landmasses and oceans
- Surface runoff 30,000
- Oceans and atmosphere
- Fluxes are the rates of flow between stores. The greatest fluxes occur over the oceans.
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