River Processes

Erosion

As the river moves through the river basin, it alters the landscape due to the wearing away and removal of land caused by the following processes:

• Attrition occurs when particles of load collide and knock pieces off each other.

• Abrasion occurs when smaller material rubs against the bed and the banks of the river.

• Corrosion occurs when acid in the water dissolves particles of rocks from the bed and banks of the river.

• Hydraulic action is the sheer force of the water and air forcing itself into the soil and moving away parts of the bed and banks of the river.

Transportation

Once the material (known as load) has been eroded, it is then carried along the river by the following processes:

• Traction is the rolling of stones along the river bed.

• Saltation is the movement of particles 'leap-frogging' along the river bed.

• Suspension is the movement of material that is carried within the water flow.

• Solution is the movement of material that is dissolved in the water.

• Sometimes the process of carrying material, such as twigs, on the top of the water is called flotation.

Deposition

When the river slows down, the load is 'dumped'. This is known as deposition. Large boulders are deposited first and fine sediment last.