KEY TERMS:

Drainage basin The area that is drained by a river and its tributaries.

Watershed The boundary between two separate basins.

Precipitation All the ways moisture comes out of the atmosphere (usually rain).

Confluence Where two tributaries meet.

Channel flow The flow of water within the river channel.

Surface runoff (overland flow) the flow of water over the land.

Infiltration Water seeping from the surface into the soil.

Throughflow A horizontal movement of water through the soil driven by gravity from soil moisture storage to the river channel storage.

Percolation Water seeping deeper underground within the soil and rock to enter the groundwater storage.

Interflow Water flowing downhill through permeable rock above the water table.

Groundwater flow A very slow horizontal movement of water below the water table through permeable rock.

Baseflow The groundwater flow that feeds into rivers through its banks and beds.

Throughfall Precipitation falling through spaces in the vegetation canopy to the ground.

Stemflow Precipitation flowing slowly down the branches and stems of vegetation to the ground.

Interception Precipitation temporarily collected and stored by vegetation and or buildings in urban areas.

Vegetation storage Water taken up and stored by plants.

Surface storage Water stored on the surface of the land in puddles, lakes or manmade ditches and reservoirs.

Groundwater storage Water stored, longterm, deep underground in rocks or the joints and cracks of rocks.

Channel storage Water stored in the river channel as it moves through the drainage basin system.

Evaporation Water changing from liquid to gas due to energy from the sun.

Transpiration Water vapour leaving the stomata in the underside of plant leaves.

Evapotranspiration A combination of evaporation and transpiration. Water is lost from the drainage basin system to the atmosphere as water vapour.