GCSE AQA Rivers

Source

The place where a river starts, usually in an area of highland.

Mouth

The place where the river ends, where it meets the sea.

Watershed

An area of highland which separates 2 drainage basins, it marks the boundary between them.

Tributary

A smaller river which joins a larger river.

Confluence

The point at which 2 rivers meet.

Catchment

The area where water drains into a drainage basin.

Drainage basin

The area of land drained by a river.

Surface run-off

When water flows over a hard surface (e.g. a river)

Condensation

When a gas cools and turns into a liquid. This forms clouds at high altitudes.

Transpiration

When plants release water vapour from their bodies (or more specifically the stomata in their leaves).

Precipitation

The fancy word for rain, sleet, snow, hail etc

Evaporation

When a liquid turns to a gas and rises.

The Hydrological (Water) Cycle

This cycle shows how water moves between the land, seas and atmosphere via precipitation, evaporation etc

Discharge

The volume of water in the river, measured in cumecs (m3/sec).

Upper course

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

V-Shaped valleys

These are features formed in the upper course of a river due to downwards erosion. The characteristic shape of these features gives the name.

Interlocking spurs

These are features formed in the upper course of the river as it flows downhill and winds its way between more and less resistant rock.

High Force, River Tees

This is the name of the largest waterfall in the UK and the river which creates it.

Waterfalls

These are features formed in the upper course of a river when it flows over two types of rock with different resistances. The less resistant rock is cut back more quickly than the more resistant rock and a plunge pool is formed. These retreat upstream when the soft rock is eroded away, creating overhangs which collapse due to gravity.

Plunge pool

This is a feature formed at the bottom of a waterfall, it is created by the force of the water hitting the riverbed. It is deepened by corrasion between the boulders.

Steep-sided gorge

This is a feature left behind when a waterfall retreats upstream.

Vertical erosion

This is the type of erosion that occurs mostly in the upper course of a river, after it has used most of its energy to overcome the force of friction.

Lateral erosion

This is the type of erosion that occurs mainly in the lower course of a river, it is erosion in a sideways direction.

Middle course

This is the middle section of the river's journey.

Meanders

Bends in the river that occur in the middle course.

River beach/slip-off slope

This is a feature formed on the inside bend of a meander due to deposition (due to low velocity and high friction).

River cliff

This is a feature formed on the outside of a meander where the thalweg erodes the banks through hydraulic action and corrasion.

Meander migration

This is the name of the process in which a meander moves and becomes more exaggerated due to constant erosion and deposition.

Erosion

This is the destructive action of the water in the river which wears away land.

Ox bow lakes

This is a feature formed when the neck of a meander narrows so much that the river simply cuts through in times of flood (as it is a more direct route out to sea).

Lower course

This is the last section of a river's journey, here it is large and fast.

Levees

These are natural barriers formed by the continuous flooding of a river on to the flood plain. The river deposits heavier materials such as clays and the front and lighter materials like silt at the back. Over time, these features form.

Floodplain

This is a feature formed when the river floods and deposits sediment. These are usually very fertile.

Deltas

These are features formed by huge quantities of sediment being deposited at the mouth of a major river such as the Nile. For these to form you need a small tidal range, low wave energy and large amounts of sediment.

River capacity

How much water the river can hold.

Deforestation

This is a human cause of flooding, when people remove trees and reduce interception.

Dams

These are a device used to store water, if they burst it can cause a catastrophic flood. They are also a type of hard engineering technique which holds back water in times of flood.

Impermeable rock

This is a physical cause of flooding; it is a type of rock that does not allow percolation so increases surface run off.

Saturated ground

This is a physical cause of flooding; this is when the ground becomes so soaked with water that it cannot hold any more and increases surface run off.

Hard engineering

A type of technique that interrupts and works against nature e.g. channelisation.

Soft engineering

A type of technique that uses nature against itself e.g. afforestation.

Flood relief channels

This is a type of hard engineering technique which alters the course of a river to divert flood water away from settlements. Is expensive but very effective.

Embankments

This is a type of hard engineering technique, they are raised banks along the side of a river which increase channel capacity and prevent bank erosion. These can be used as walkways by pedestrians but can be ugly.

Channelisation

This is a type of hard engineering technique in which the river channel is straightened or deepened to allow it to carry more water out to sea faster. This is very long lasting and effective but can lead to a greater risk of flooding downstream.

Flood defences

These are techniques and devices installed to protect against floods.

Flood walls

This is a type of hard engineering technique in which a wall is constructed to form a barrier against the flood water.

Floodplain zoning

This is a type of soft engineering technique. The local council examine the flood risks in different areas and prevent buildings in theses areas (e.g. on a flood plain). This can aggravate the problem of housing shortage but lessens surface run off.

Washlands

This is a type of soft engineering technique in which certain areas of land are allowed to flood naturally to prevent flooding in other areas. These can become fertile farmland but cannot be used as they flood too often.

Warning systems

This is a type of soft engineering technique which warns residents of an imminent flood. This is a very cheap flood defence but can be vandalised.

Afforestation

This is a type of soft engineering technique. Trees are planted in the catchment area to increase interception. This is a cheap method of reducing flooding but can increase fire risk.

Gabions

These are a type of hard engineering technique. Wire cages are filled with rocks resistant to erosion and are placed along the banks of the river. They also reduce erosion but are ugly.