IGCSE Geography RIVERS

Tributary

A stream or river that flows into a larger river

Distributary

a branch of a river that flows away from the main stream

Source

the place where a river begins

Confluence

a meeting or gathering together of more than one river channel

Erosion

Processes by which rock is broken down in the river channel and and carried away by the flow

Transportation

the movement of sediment downstream by the river

Deposition

the process in which material is laid down as the river loses its energy

Water cycle

The continuous process by which water moves from Earth's surface to the atmosphere and back

River channel

The main path/course of the river.

Precipitation

All forms of water that falls to the ground eg. rain, snow, sleet, or hail

Watershed

An area or ridge of land that separates waters flowing to different rivers, basins, or seas.

Source

The place where a river begins

Mouth

The end of a river where it empties into a larger body of water (usually the ocean)

Upper course

This is the name given to the start of a river's journey, here it is small, youthful and full of energy.

Middle course

The section of the river between the mountains and the lowland, where transport of eroded material is important and the river begins to cut sideways due to the reducing gradient.

Lower course

The section of the river near the sea, where deposition is the most important process and the valley becomes wider and flatter.

Cross sectional area

The width of the river multiplied by the depth of the river

Drainage basin

The area from which a single stream or river and its tributaries drains all of the water

Flooding

When a river bursts its banks and water temporarily covers the land beside the river

Levée

The raised banks beside the river, created when sediment is left behind in a flood

Meander

A bend in a river

Oxbow lake

A crescent-shaped lake that is formed when a meander of a river is cut off from the main channel

Velocity

The speed of water flowing down the stream

Wetted perimeter

The total distance in a linear cross-section of a stream that is in contact with water.

Infiltration

the process by which water on the ground surface enters the soil

Throughflow

When water in the soil flows downhill

Groundwater store

Water stored underground in permeable and porous rocks

Percolation

The downward movement of water through soil and rock due to gravity.

Evapotranspiration

The combined amount of evaporation and transpiration

Groundwater flow

Water moving within rocks below the ground

Channel flow

The movement of water within the river channel.

Overland or surface flow

Water moving across the surface of the ground which occurs when rain cannot soak quickly enough into the ground due to tarmac surfaces or hard-baked soil

Condensation

The change of state from a gas to a liquid

Depression storage

Storage of water in hollows and holes in the ground

Interception

As precipitation approaches the surface, some of the rainfall will strike plant leaves, branches and other objects that protrude from the ground surface.

Evaporation

The change of state from a liquid to a gas

Bankfull width

The width of the stream when the river water is at it's highest possible level

Channel bed roughness

The lumpiness of the river bed, caused by rocks on the bottom of the river. Reduces downstream due to erosion smoothing the bedload

Dam

a structure built across a river to control the river's flow

Delta

A landform made of sediment that is deposited where a river flows into an ocean or lake

Discharge

the quantity of water in a stream that passes a given point in a period of time

Gradient

Angle of a slope

Hydraulic radius

A description of the channel shape/cross profile.

Hydraulic Radius = Cross-Sectional Area/Wetted Perimeter

So... A High Hydraulic Radius means the river is MORE EFFICIENT, since the moving water loses LESS energy as less of it is in contact with the water.

Load

the amount of sediment that a river or stream carries

Pothole

A depression formed in a stream channel by the abrasive action of the water's sediment load.

Rapids

A fast-flowing and turbulent part of the course of a river

Surface runoff (overland flow)

when water travels across the surface of the earth e.g. down a hill

V-shaped valley

The characteristic upland shape of a valley eroded by a stream or river

Water depth

How deep the river channel is

Waterfall

A stream of water that falls when the layers of rock in an area are eroded at different rates by the river, causing a nick in the long profile

Long profile of a river

shows gradient changes of river over different courses

Hydraulic action

The force of the river against the banks can cause air to be trapped in cracks and crevices. The pressure weakens the banks and gradually wears it away.