Water cycle - Edexel EQ1

Closed system

A sequence of linked processes with a transfer of energy but not matter between the parts of the system (the inputs and outputs happen within the system). An example is the global hydrological cycle.

Evapotranspiration

The combined effect of evaporation and transpiration.

Green water

Water stored in the soil and vegetation (the invisible part of the hydrological cycle).

Blue water

Water stored in rivers, streams, lakes and groundwater in liquid form (the visible part of the hydrological cycle).

Aquifer

A permeable or porous rock which stores water.

Infiltration

The movement of water from the ground surface into the soil.

Systems approach

Systems approaches study hydrological phenomena by looking at the balance of inputs and outputs, and how water is moved between stores and flows.

Watershed

The highland which divides and separates waters flowing into different rivers.

Catchment

The area of land drained by a river and its tributaries.

Surface run-off

The movement of water that is unconfined by a channel across the surface of the ground. Also known as overland flow.

Water budget

The annual balance between inputs (precipitation) and outputs (evapotranspiration and channel flow) at a place.

Percolation

The transfer of water from the surface or from the soil into the bedrock beneath.

Cryosphere

Areas of the Earth where water is frozen into snow or ice.

River regime

The annual variation in discharge or flow of a river at a particular point or gauging station, usually measured in cumecs.

Throughflow

Water moving sideways through the soil, downslope under the influence of gravity.

Precipitation

The movement of water in any form from the atmosphere to the ground.

Stores

Reservoirs where water is held, such as the oceans.

Processes

The physical mechanisms that drive the flux of material between stores.

Precipitation

The movement of water in any form from the atmosphere to the ground.

Storm hydrograph

Shows changes in a river's discharge at a given point on a river over a short period of time (usually before, during and after a storm).

Drainage basin

The catchment area from which a river system obtains its supply of water.

Frontal rainfall

Occurs frequently in mid-latitudes when a warm tropical air mass meets a cooler polar air mass. The warmer air is less dense and rises over the colder air, which causes the warm air to cool, leading to condensation of water vapour, clouds of different types and precipitation.

Convectional rainfall

Often associated with intense thunderstorms, which occur widely in areas with ground heating such as the tropics and continental interiors.

Orographic rainfall

Concentrated on the windward slopes and summits of mountains.