EROSION

Bed, banks and load can be worn down (eroded) in a number of ways.

Attrition

(When the particles collide and break each other into smaller fragments)

• Occurs at all levels, ie large loads and small particles.
• Turbulent flow will increase the amount of erosion by attrition, due to higher likely hood of collision.

Hydraulic Aciton

(When the water wears away the bank, leading to undercutting and collapse)

• Often on the outside of bends where velocity is highest.
• Higher velocity leads to higher rate of erosion.
• Turbulant flow will increase erosion from hydraulic action.
• Air forced into cracks of banks, exapand and explode, leading to further break down.

Abbrasion

(When particles are ground along the bed and banks, gradually wearing them away.)

• Usually occurs at highest levels in storms.
• Abbrasion is high if river contains high sediment load, and travels at high velocity.

Corrosion

(Acidic content of the water wears away the channel, similar to Chemical weathering.)

• Acid from pollutants or humic acid.
• Unaffected by velocity or sediment load, as this is caused by the soluble load, which can be transported with almost zero energy.
• High concentration of acid will increase rate of erosion.

{ Main Page | Weathering |Riffles and Pools| Transport }