River erosion involves four interacting processes, which are:
1. Corrosion or Abrasion: This is the wearing away of sides and floor of a river by the boulders, pebbles, sand and salt which are being transported.
2. Hydraulic Action: This involves the mechanical loosening and movement of materials by the force of moving water.
3. Corrosion or Solution: This is the solvent action of water on materials it comes in contact with while flowing.
4. Attrition: This is the wearing down of the transported materials as they roll and collide with one another.