5.3A Water Budgets
Water budgets show the annual balance between inputs (precipitation) and outputs (evapotranspiration) and their impact on soil water availability and are influenced by climate type (tropical, temperate or polar examples)
The water budget is the annual balance between precipitation, evapotranspiration and runoff. The annual balance between the inputs and outputs.
It is calculated from the formula:
P = E + R +/- S
(Where P is precipitation, E is evapotranspiration, R is runoff and S represents changes in storage over a period of time, usually one year)
The balance can be calculated at various scales, from global to local. Water budgets at a national or regional scale provide a useful indication of the amount of water that is available for human use (for agriculture, domestic consumption etc.). At a local scale, water budgets can inform about available soil water.
Available soil water is the amount of water that can be stored in the soil and is available for growing crops. This is valuable to users, such as farmers, who can use it to identify when irrigation might be required, and how much.
Influenced by climate type!
THEN THERE IS ALSO A WEIRD DIAGRAM THING