River Processes

Types of erosion /Types of transportation/ deposition/ river profiles/ Drainage basins

Abrasion (erosion)

Rocks carried along a river wear down the riverbed and banks

Vertical erosion (erosion)

Downward erosion of a river that deepens its bed

Corrosion (erosion)

Where rocks such as limestone are dissolved by the acid in the water in a river

Lateral erosion (erosion)

Sideways erosion by a river on the outside of a meander channel

Hydraulic action (erosion)

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.

Which physical landforms in the lower course of a river?

-Floodplains
-levees

-estuaries

Attrition (erosion)

Small rocks being carried by the river smash together and break into smaller

Solution (erosion)

Soluble rocks are dissolved int the water

Saltation (transportation)

Where small sand and gravel particles bounce along the river bed or sea bed. They will travel in the direction of the flow of water.

Traction (transportation)

where large rocks or large particles are dragged along the river bed or sea bed by the current.

Deposition

Process in which sediment (alluvium) is laid down in new locations.

Flocculation

The process where sediment is attracted to salt particles. Think 'flock' like sheep.

At which parts of the river does deposition occur?

The middle and lower course

Cross profile and Long profile of upper course

The long profile is steep and shallow
The cross profile is narrow and v shaped.

Cross profile and Long profile of Middle course

The long profile is flatter
The cross profile is deeper and U shaped

Cross profile nd Long profile of Lower course

The long profile has a very gentle (lower) gradient and is almost flat.
The cross profile is very wide and deep.

Which physical landforms form in the upper course of the river?

-Water falls and plunge pools
- V-Shaped valleys
- Interlocking spurs

Catchment area

The area within the drainage basin

Confluence

The point at which two rivers or streams join

Which physical landforms form in the middle course of the river?

-meanders
-oxbow lakes

Drainage Basin

The area of land drained by a river

Everything that’s inside a drainage basin

• Drainage basin

• Catchment area

• Confluence

• Tributaries

• Watershed

• Estuary/mouth

• Source

Name 3 reasons why deposition occurs

1. Because sediments get too heavy
2. They lose energy
3. As the velocity decreases

Suspension (transportation)

where silt (sand

Solution (transportation)

where rocks that are soluble are dissolved by water (limestone and chalk in particular). They are then transported within the water.

Tributaries

A stream or smaller river that flows into a larger stream or river. A branch of a river.

Watershed

An area or ridge of land that separates waters flowing to different rivers

Estuary (mouth of river)

The point where the river comes to an end

Source

The beginning or start of a river