water cycle

Anticyclone

A system of high pressure, causing high temperatures and unseasonably high evaporation rates.

Aquifer

A permeable or porous rock which stores water

Channel Flow

Water flowing in a rivulet, stream or river

Convectional Precipitation

Solar radiation heats the air above the ground, causing it to rise, cool & condense forming precipitation (often as thunderstorms)

Cryosphere

The global water volume locked up within a frozen state (i.e. snow and ice)

Depression

A system of low pressure, with fronts of precipitation where low and high pressure air masses meet.

Desalination Plant

The conversion of seawater to freshwater, suitable for human consumption.

Desublimation

The change of state of water from gas to solid, without being a liquid (the opposite process to sublimation)

Drainage Basin

The area of land drained by a river and its tributaries

Drainage Density

The total length of all rivers & streams divided by the area of the drainage basin

Drought

An extended period of deficient rainfall relative to the statistical average for the region (UN)

Economic Water Scarcity

When water resources are available but insufficient economic wealth limits access to it

ENSO Cycles

El Nino Southern Oscillations - naturally occurring phenomena that involves the movement of warm water in the Equatorial Pacific

Evapotranspiration

The combined total moisture transferred from the Earth to the atmosphere, through evaporation and transpiration

Frontal Precipitation

Where air masses of different temperatures meet at a front, one mass will be forced over another, causing precipitation beneath the front.

Global Hydrological Cycle

The continuous transfer of water between land, atmosphere and oceans.The Earth is a closed system

Groundwater Flow

Water moving horizontally through permeable or porous rock due to Gravity

Hydrological Drought

Insufficient soil moisture to meet the needs of vegetation at a particular time

Infiltration

The movement of water vertically through the pores in soil.

Integrated Drainage Basin Management

Establishing a frame of coordinated efforts between administrations (e.g. local government) and stakeholders (e.g businesses) to achieve balanced management of a basin (World Bank)

Interception

Raindrops are prevented from falling directly onto the ground, instead hitting the leaves of a tree.

Meteorological Drought

When long-term precipitation trends are below average

Monsoon

The drastic variation between wet and dry seasons for sub-tropical areas, caused by a changed prevailing wind. Can lead to annual flooding.

Open System

A system affected by external flows and inputs (such as a drainage basin, or a sediment cell)

Percolation

Water moving vertically from soil into permeable rock

Physical Water Scarcity

A physical lack of available freshwater which cannot meet demand

Relief Precipitation

Precipitation caused when air masses are forced to rise over high land, determined by the relief/ morphology of the land

River Regime

The pattern of river discharge over a year

Runoff

Water flowing over the surface of the ground eg. after precipitation or snowmelt

Salinisation

Where salt water contaminates freshwater stores or soils, creating saline conditions and reducing human use/ consumption.

Saltwater Encroachment

The movement of saltwater into freshwater aquifers or soils. This may be caused by sea level rise, storm surges or over-extraction

Smart Irrigation

Providing crops with a water supply less than optimal, to make crops resistant to water shortages

Storm Hydrograph

Variation of river discharge over a short period of time (days)

Sublimation

The change of state of water from solid to a gas, without being a liquid

Throughflow

Water moving horizontally through the soil, due to gravity

Transpiration

The process through which water evaporates through the stomata in plants' leaves

Water Budget

The annual balance between inputs and outputs within a system

Water Conservation

Strategies to reduce water usage and demand

Water Recycling

The treatment and purification of waste water, to increase supply

Water Scarcity

There are limited renewable water sources (between 500 and 1000 cubic metres per capita per year)

Water Security

The ability to protect and access a sustainable source to adequately meet demand

Water Sharing Treaty

International agreements for transboundary sources

Water Transfer

Hard engineering projects, such as pipelines or aqueducts, that divert water between basins to meet demand

Watershed

The boundary between neighbouring drainage basins