7Works of river

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River erosion

River erosion

The process of wearing away of the rocks on the bed and banks of the river by the energy of the river flow.

•River erosion also happens by the load carries on the river channel itself.

•The erosion rate varies with different volume and velocity.

Processes involved in river erosion.

Corrasion (abrasion)

Attrition

Solution (corrosion)

Hydraulic action

Types of river erosion

Vertical erosion

Headward erosion

Lateral erosion

Vertical erosionRiver removes

material from river bed

By corrosion/abrasion process

Result:Deepen a river channel and create narrow V-shaped valley.

Headward erosion

River cut its source

Results: lengthening of the river in the upstream direction

Lateral erosion

The wearing away of river bank

By corrosion and solution process.

Result: widen the river and form a U shaped valley.

River transportation

Objectives:•Understand river transportation•Understand processes of river transportation (suspension, saltation, traction and solution)

River transportation

When a river transport its load downstream.

The loads are the eroded materials

The volume and velocity of the river affects the river transportation rate

4 ways of river transportation

Traction

Saltation

Suspension

Traction

Material: Big rocks

How? Rolling and Dragged on the river bed

Why? They are heavy

saltation

Material: small stones

How? Hopping and Bouncing on the river bed

Why? Caused by swirling water

suspension

Material: fine (very small) rocks.

How? Carried along the river surface

Why? They are very light

Solution

Material: dissolved materials

How? Carried along the water

Cant see by naked eyes

Mnemonics:

Teacher (Traction)

SAya (SAltation)

SUka (SUspension)

SOtong (SOlution)

Summary:

River trasportation Definition:

4 ways of river transportation: