Water Cycle (Enquiry Question 1)

Afforestation

The planting of trees in an area that has not been forested in recent times

Albedo

A measure of the proportion of the incoming solar radiation that is reflected by the surface back into the atmosphere and space

Blue water

Water is stored in rivers

Catchment

The area of land drained by a river and its tributaries

Channel flow

The flow of water in streams or rivers

Condensation

The change from a gas to a liquid

Convectional rainfall

Often associated with intense thunderstorms

Cryosphere

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

Cyclonic rainfall

A period of sustained moderately intensive rain; it is associated with the passage of depressions

Deforestation

The cutting down and removal of all or most of the trees in a forested area

Evaporation

The change in state of water from a liquid to a gas

Evapotranspiration

The combined effect of evaporation and transpiration

Falling (recessional) limb

The part of a storm hydrograph in which the discharge starts to decrease

Fluxes

The rate of flow between the stores

Fossil Water

deep groundwater from former pluvial (wetter) periods

Green water

Water stored in the soil and vegetation

Groundwater flow

The slow transfer of percolated water underground through pervious or porous rocks

Groundwater storage

Water held within permeable rocks (also known as an aquifer)

Infiltration

The movement of water from the ground surface into the soil

Infiltration capacity

The maximum rate at which rain can be absorbed by a soil

Interception

Where water is captured by vegetation

Interception loss

Water retained by plant surfaces and later evaporated or absorbed by the vegetation and transpired

Lag time

The time between peak rainfall and peak discharge

Orographic rainfall

Concentrated on the windward slopes and summits of mountains

Peak discharge

The time when the river reaches its highest flow

Percolation

The transfer of water from the soil into the bedrock beneath

Potential Evapotranspiration

The water loss that would occur if there was an unlimited supply of water in the soil for use by vegetation

Precipitation

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

Precipitation

Moisture in any form

Processes

The physical mechanisms that drive the fluxes of water between the stores

Reforestation

Planting trees in places with recent tree cover

Residence time

The average time a water molecule will spend in a reservoir or store

Rising limb

The part of a storm hydrograph in which the discharge starts to rise

River regime

The annual variation in discharge or flow of a river at a particular point or gauging station

Saturated

overland flow The upward movement of the water table into the evaporation zone

Soil moisture

storage Water held within the soil

Stem flow

This is when water trickles along twigs and branches and then down the trunk

Storm hydrograph

The variation of discharge within a short period of time

Surface run-off

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

Systems approach These approaches study the hydrological phenomena by looking at the balance of inputs and outputs

and how water is moved by stores and flows

Throughfall

When the rainfall persists or is relatively intense and the water drops from the leaves

Transpiration

The diffusion of water from vegetation into the atmosphere

Vegetation

storage Any moisture taken up by vegetation and held within plants

Water budget

The balance between precipitation

Watershed

The high land which divides and separates waters flowing to different rivers