1. Hydraulic action: The force of the flowing water can break down and transport sediment.
2. Abrasion: The riverbed material carried by the flowing water acts as an abrasive and scours the riverbed and banks as it moves downstream. This process involves both friction and impact. Friction occurs as the moving water slides across the riverbed and banks, while impact occurs as the sediment carried by the water collides with the riverbed and banks
3. Attrition: Sediment particles also collide with each other, fracturing into smaller grains, leading to further erosion; this process is called attrition.
In addition to these three main erosion processes, rivers can also cause erosion through:
Bank caving: As the river meanders, sections of the bank are undercut by the river's current, eventually collapsing into the river channel.
Mass wasting: Landslides and other forms of mass wasting can contribute to river erosion if they occur along the riverbanks.
