Abrasion- is the scrapping, scouring and rubbing action of materials carried along the river. Rivers carry rock fragments in the flow of the water or grag them along the bed, and in doing so wear away the banks and bed of the river channel.
Hydraulic power- is caused by the sheer power of the moving water. It is the movement of loose unconsolidated material due to the frictional drag of the moving water on the sediment or lying on the channel bed.
Corrosion- is most active on rocks that contain carbonates. The materials in the rock are dissolved by weak acids in the river water and is carried away as a solution.
Attrition- is the reduction in the size of fragments and particles within a river due to the processes described above. Fragments strike each other as well as the riverbed, making it smoother, smaller, and more rounded as they move along the river channel.
Traction-Large stones and boulders are rolled along the river bed by water moving downstream. Tends to only happen at times of high discharge.
Saltation- small stones bounce or leap-frog along the channel bed. This process is associated with relatively high energy conditions. small particles may be thrust up from the bed of the river only to fall back to the bottom further down the river.
Suspenion- very small particles of sand and silt are carried along by the flow of the river. Such material is not only carried but is picked up, mainly through turbulence that exists within the water.
Solution- is the dissolved minerals are transported within the mass of the moving water.
Happens when ;
- a decrease in its level of energy
- there is a reduction in the gradient of the river
- the discharge is reduced, such as during changes in weather
- shallow water
- there is an increase in the size of the load
- the river floods and overtops its banks