Channel Processes - Erosion

Channel Processes - Erosion

Erosion ( a general definition) - The break up of rocks by the action of rock particles being moved over the earths surface by water, wind and ice.

The four main processes of river erosion...

• Abrasion - Also known as corrosion. It is the scraping, scouring and rubbing action of the river's load. Rivers carry rock fragments in the flow, or drag them along the bed. In doing this they wear away the banks and bed of the river channel. Abrasion is the most effective/significant in short, turbulent periods when the river is at bankfull level or in flood. During times when river levels are low, the load consists of smaller particles (as the river has less energy to carry large ones). These include sand grains, and tend to smooth the surface of a river channel.
• Hydraulic Action - Caused by the sheer power of moving water. It is the movement of the loose unconsolidated material due to the frictional force of the water on the sediment lying on the channel bed. As velocity increases, the turbulent flow lifts a larger number of grains…