Channel Processes Flashcards
What are the 4 main river processes
- Erosion
- Transportation
- Deposition
- Sedimentation
State 5 erosional processes that occur in a river
- Abrasion
- Attrition
- Solution (corrosion)
- Cavitation
- Hydraulic action
State 4 transportation processes in a river
- Traction
- Saltation
- Suspension
- Solution
What is abrasion?
Where the sediment carried by a river scours the bed and banks.
What is corrosion (solution)?
Where carbon dioxide dissolves in the river to form a weak acid, which dissolved rock by chemical processes.
What is cavitation?
Where air bubbles trapped in the water become compressed into small spaces like cracks in the river bank.
These bubbles eventually implode which creates a small shockwave - weakening the rock.
Where is cavitation most common?
At the base of waterfalls and rapids
What is attrition?
Where eroded rocks collide and break into smaller fragments, making pieces of sediment smaller and more rounded as they move downstream.
What is hydraulic action?
When the pressure of water hits river banks and forces water into cracks. If air is present, it may become compressed and cavitation may occur.
What is solution?
Process by which dissolved material is carried in a river
What is suspension?
Occurs when material made up of very fine particles such as clay and silt are lifted as the result of turbulence and transported by the river.
What is saltation?
The process by which material, such as pebbles and gravel that are too heavy to be lifted, are bounced along the river by the force of the water.
What is traction?
The process by which large materials, such a boulders, are rolled along the river bed by the force of the water.
What is deposition?
The process of eroded material being dropped, and occurs when a river loses energy.
What causes a river to lose energy?
When discharge or velocity decreases, usually close to river banks and shallow areas.
