Rivers 1 continued

Inputs into the drainage basin include:

Energy from sun for evaporation
Precipitation ( Rain, snow)

Outputs move moisture out of the drainage basin and include:

Evaporation and transpiration from plants
Runoff into the sea
Water percolating deep into underground stores where it can be effectively lost from the system

Stores of water:

Glaciers
Rivers
Lakes
Soil
Plants/Vegetation
Rocks

Transfers and flows move water through the system and enable inputs of water to be processed from one store to another.

Within the drainage basin the balance between inputs and outputs is known as the water balance.

When precipiatation is greater than evapotranspiration, the soil is refilled with water, when the soil becomes saturated excess water has difficulty infiltrating into the ground and cause surface runoff.

The water budget shows the relationship between temperature, precipitation and evaporation rates over the year.

During the months of the year when precipitation exceeds evapotranspiration, once soil has been recharged there will be a water surplus.