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Water in the UK

S278_17 Glossary

S278_17 Glossary
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The combined effects of evaporation and transpiration.
Permalink: Evapotranspiration



A measure of how close air is to saturation with water vapour.

Permalink: Humidity

Hydraulic conductivity

A measure of the volume of water that will flow through a unit cross-sectional area of rock per unit time, under a unit hydraulic gradient and at a specified temperature: K in the

Darcy’s law equation.

Permalink: Hydraulic conductivity

Hydraulic gradient

The slope of a water table.

Permalink: Hydraulic gradient

Hydrological cycle

Another name for the water cycle.


Permalink: Hydrological cycle

Hydrologically effective precipitation

The quantity of water available from underground or from rivers in an area, given by the excess of precipitation over actual evapotranspiration.

Permalink: Hydrologically effective precipitation


The study of water movement on and beneath the ground, and the physics and chemistry of water.

Permalink: Hydrology


The parts of the Earth that are mainly composed of water.

Permalink: Hydrosphere



The managed watering of crops so they can be grown in areas where they could otherwise not be grown, or to improve the yield.


Permalink: Irrigation


Meteoric water

Fresh water derived by condensation from the atmosphere and which accumulates as surface water or underground water.

Permalink: Meteoric water

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