Geography Hydrological Cycle in a Drainage Basin

Drainage Basin The area from which a single stream or river and its tributaries drains all of the water.

Watershed Separates one drainage basin from another.

Source The start of a river.

Channel Where the water within a river is held.

Tributary A stream or river that flows into a larger river.

Confluence The meeting of two tributaries in a river.

Mouth The end of the river - where it reaches the sea.

Discharge Volume of water in a river at a given time.

Precipitation Any form of water that falls from clouds and reaches Earth's surface.

Evapouration The transformation of water liquid to vapour by energy from heat or air movements.

Condensation The change of state of water from a gas to a liquid.

Sublimation A change directly from the solid to the gaseous state without becoming liquid.

Vegetation storage Any moisture taken up by vegetation and held within plants.

Interception Water is prevented from reaching the surface by trees or grass.

Artificial interception Water is prevented from reaching the surface by man-made constructions such as roofs/cars.

Infiltration The process by which water on the ground surface enters the soil below.

Soil moisture storage Water that is stored below the surface in unsaturated ground.

Transpiration Evaporation of water from the leaves of a plant (through pores called Stomata).

Stomata Small openings on the underside of a leaf through which water, oxygen and carbon dioxide can move.

Channel flow The movement of water within the river channel.

River discharge The volume of water flowing through a river channel. This is the total volume of water flowing through a channel at any given point and is measured in cubic metres per second (cumecs).

Percolation The process by which water moves downward from layers of soil into layers of rock.

Groundwater storage The storage of water underground in layers of porous rock (rock that contains.

Groundwater flow Water flowing through the rock layer parallel to the surface.

Surface runoff (overland flow) when water travels across the surface of the earth e.g. down a hill.

Throughflow Water flowing through the soil layer parallel to the surface.

Channel storage Water held in a river or stream channel.

Erosion The breakdown of soil and rock by external agents such as wind, water and ice.

River transport The movement of sediment of all sizes in a river.

Hydraulic action The force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away.

Abrasion - The collision of rocks with the banks and bed of the river - causing them to be eroded.

Attrition The collision of sediments resulting in smaller and more rounded rocks.

Solution Dissolving rocks such as limestone through acidic water in the river - this is a process of both erosion and transport.

Saltation The movement of sand or other sediments by short jumps and bounces that is caused by wind or water.

Traction The rolling of pebbles or boulders along the bed of the river - they are heavy and remain along the bottom.

Suspension A mixture in which particles can be seen and floating within the river because they are light, such as clay/silt.

Angular A description used for rocks that are jagged and not smooth.

Cumecs An abbreviation of cubic metres per second - which is a measure of the discharge of a river.

Turbulence A type of movement of water in which, rather than moving downstream, the water moves in different directions and at different speeds.