GCSE Geography - Rivers

Drainage basin

Area of land drained by a main river and its tributaries.

Watershed

The edge of the drainage basin.

Confluence

Where two rivers meet.

River mouth

Where the river meets the sea.

River source

Where the river starts.

Tributaries

Smaller feeder rivers going into the main channel.

River velocity

Speed of river in m/s.

River discharge

The amount of water in the river in cumecs (cubic m/s).

Bedload

Material carried by the river.

Erosion

The wearing down of material by water, wind or ice.

Abrasion

When pebbles, rocks and sand are dragged along the river bed wearing it away.

Hydraulic action

Fast flowing water is forced into cracks and breaks it up.

Solution

When alkaline rocks (e.g. limestone) are dissolved by acidic rainwater.

Attrition

When rocks are worn away by knocking into each other.

Vertical erosion

Downward erosion to make a valley deeper.

Lateral erosion

Sideways erosion of a river on the outside bend of a meander channel.

Eddy

Downward spiral of water, drilling effect.

Helicoidal flow

Smooth, natural, swinging side-to-side, corkscrewing flow of a river.

Suspension

Fine, light material is held up and carried along by the river.

Solution

Minerals are dissolved in the water by chemicals.

Traction

Large boulders (too heavy to be suspended) are rolled along the river bed in times of peak flow.

Saltation

Small rocks that are just light enough to be picked up and carried short distances before being dropped due to lack of energy in the water. Creates an effect of bouncing along the river bed.

Transportation

The movement of material by water, wind or ice.

Deposition

The process where material being transported by a river can no longer be carried and is dropped because the river doesn’t have enough energy to move it any longer.

Sediment

Material dropped by a river.

Cross profile

The imaginary slice across a river channel and its valley at a specific point.

Long profile

The gradient (steepness) of a river as it moves downstream from source to mouth.

Upper course

The point of the river near the source, up in the hills

Middle course

Section of the river between the upper and lower course.

Lower course

The final section of a river which flows into another body of water.

Interlocking spur

Ridges of highland that appear to project across a river valley when the river winds around areas of hard rock.

Oxbow lake

Horseshoe shaped lake adjacent to a straighter stretch of river formed by a cut off meander.

Estuary

Tidal part of the river where fresh river water and salt water from the sea merge.

Floodplain

Large area of flat land either side of the river that is prone to flooding.

Levee

Naturally raised river banks found at the edge of the river channel on rivers prone to flooding.

Gorge

Narrow very steep sided valley almost always downstream of a waterfall.

Meander

A bend in the river.

Waterfall

Where water falls down a vertical drop in the river channel.

Meander scar

A dried up oxbow lake

Sinuous

Bendy.

Thalwag

Fastest flow of a river.

River cliff

Steep sided cliff created by erosion in the outside of a meander bend.

Slip off slope or river beach

A shallow area where load like pebbles and sand have been deposited. Found on the inside of a meander bend.

Meander neck

The bit of land in between two outside bends of meanders.

Floodplain

The area of flat land around the river covered by water in times of flood and left with a fine layer of fertile silt that builds up with every flood event.

Hydrograph

A graph showing discharge of a river at a given point over a period of time.