Geography

Glossary of key-terms for Paper 1 IGCSE

Closed system

A system unconnected to an other entity - No inputs nor outputs from or to

Hydrological cycle

The movement of water between air, land and sea

Stores

Bodies of water that receive, hold and release volumes of water

Transfers

The movement of water between stores in the hydrological cycle

Transpiration

The loss of moisture from vegetation into the atmosphere

Overland flow

Water flowing over the surface under the influence of gravity. It occurs when the soil is saturated

Infiltration

The initial movement of water from the surface into the upper level of soil

Percolation

The downward vertical movement of water within soil or rock

Through-flow

the flow of water through the soil under gravity

Groundwater flow

The flow of water through permeable rock

Evaporation

The process in which liquid water is changed into water vapour

Condensation

The process by which water vapour changes into water droplets

Precipitation

Occurs when water in any form (Rain, Snow, Sleet, Hail), falls from the atmosphere to the Earth’s surface

Evapotranspiration

The combined losses of water from the ground, water bodies and vegetation

Interception

Precipitation caught and stored by plant leaves

Drainage basin

The area of land drained by a river system

Watershed

A ridge (imaginary line drawn) of high land that forms the boundary between two drainage basins

Source

The origin or starting point of a river

Mouth

The point at which the river flows into a much larger body of water. Ocean, lake or sea

Confluence

The point at which a tributary joins a larger river

Tributary

A smaller river or stream that flows into a larger river through a confluence

Channel network (River system)

The pattern of a main river and its tributaries within the drainage basin/system

River regime

The variation in the discharge of a river over the course of a year

Base flow

Normal discharge of a river, which is altered by a storm event

Rising limb

The rising flood water in the river

Falling/Recession limb

The flood water falling

Lag time

The time difference between the peak rainfall and the peak discharge

Peak flow

Maximum discharge in the river

Water abstraction

The removal of water from the water bodies from the surface or underground source for human use and consumption

Storm hydro-graphs

A graph showing how the discharge of a river is affected by a storm

Storm flow

The additional discharge of the river as a result of the rainstorm

Fluvial

Of or relating to a river or stream

Weathering

The breakdown of rock in a not involving movement site

Mass movement

The large-scale movement of weathered material under the influence of gravity

Friction

The resistance encountered when one body moves relative to another body with which it is in contact

Erosion

Wearing away of the Earth’s surface by a moving agent such as a river

Hydraulic action

The sheer force of a river water removing loose material from the bed and banks of the river

Abrasion

The wearing away of the bed and banks by the river’s load

Attrition

The collision of rocks and stones against each other and with the bed and banks. Over time the original sharp edges become smooth and round and smaller

Solution

The dissolving of some rocks slowly in the river water by chemicals

Transportation

The movement of the river’s load by 4 different processes

Traction

The rolling of large boulders that are too heavy to carry along the river bed

Saltation

The bouncing of small boulders along the river bed

Suspension

Lighter material which is carried along by the river’s flow

Solution

Material dissolved in the water by chemicals.

Load

The particles of sediment and dissolved matter carried along by a river

Discharge

The amount of eater passing a specific point at a given time

Deposition

The laying down of material carried by rivers or the sea because of a reduction of velocity or discharge, lose of energy

Gorge

A narrow, steep-sided valley often formed when a waterfall retreats upstream

River cliff

A steep slope forming the outer bank of a meander. It is formed by the undercutting of the river current

Slip-off slope

The inside bank of a meander where deposition occurs due to slow river flow

Meander neck

A strip of land between two meanders which gradually narrow due to erosion of the outside banks (where it is the fastest) of these meanders

Irrigation

Supplying dry land with water by systems of ditches and also by more advanced means

Water supply

The provision of water by public utilities, commercial organisations or by community endeavours

Portable water

Water that is free from impurities, pollution and bacteria, and is thus safe to drink

Water stress

When water supply is below 1700 cubic metres per person per year

Water scarcity

When water supply falls below 1000 cubic metres per person per year

Water surplus

Occurs when the demand for water is less than the supply

Pollution

Contamination of the environment

Cloud seeding

Releasing particles of dry ice or silver iodide into cold clouds to encourage precipitation

Rainwater harvesting

The accumulation of rainwater for reuse on-site rather than allowing it to run off

Reservoir

A natural or artificial lake used as a source of water supply

Dam

A barrier that holds back water

Wells and boreholes

A means of tapping into aquifers, gaining access to groundwater

Aquifer

A rock that allows water to move through it, such as a layer of sandstone

Water treatment

Improving water quality to make it acceptable for a particular end-use such as human consumption or irrigation

Flood

A high flow of water that overtops the bank of a river

Monsoon

The season of heavy rainfall during the summer in hot Asian countries