Drainage Basins

Drainage basin

Area that supplies a river with its supply of water, this includes water found below the water table as well as soil water and any surface flow.

Evapotranspiration

The total output of water from the drainage basin directly back into the atmosphere from evaporation and transpiration

Evaporation

The process by which liquid water changes to a gas. This requires energy, provided by the sun and aided by wind.

Groundwater flow

The slow movement of water through underlying rocks

Infiltration

The downward movement of water from the surface into the soil

Overland flow

The tendency of water to flow horizontally across land surfaces when rainfall has exceeded the infiltration capacity of the soil and all surface stores are full

Interception storage

The precipitation that falls on the vegetation surfaces or human-made cover and is temporarily stored on these surfaces

Throughflow

The movement of water down slope through the subsoil under the influence of gravity

Run-off

All of the water that enters a river channel and eventually flows out of the drainage basin

Percolation

The downward movement of water within the rock under the soil surface. Rates vary depending on rock.

Water balance

The balance between inputs and outputs in a drainage basin

Stemflow

The proportion of precipitation intercepted by the canopy that reaches the ground by flowing down stems, stalks or tree bole.

Soil storage

The amount of water stored in the soil.

Vegetation storage

Most plants remove water from the soil and store it in the structure of a plant

Infiltration capacity

Is exceeded when rainfall intensity is greater than the infiltration rate

Channel Flow

Transfers of water within a river or stream