Rivers are a crucial component of the water cycle, primarily characterized by the downward flow of water due to gravity.
They play a significant role in shaping the landscape through processes such as erosion, transportation, and deposition, resulting in various landforms.
River Processes
Erosion
The process of removing material from the riverbed and banks. Types include:
Attrition: Rocks collide and break into smaller pieces.
Abrasion: Rocks scrape the bed and banks, loosening material.
Solution: Particles dissolve in the river water.
Hydraulic Action: Force of water compresses air in cracks, weakening the banks.
Transportation
Movement of material downstream. Types include:
Suspension: Light materials carried along by the river.
Traction: Large rocks roll along the riverbed during high energy.
Solution: Dissolved materials carried even in low energy.
Saltation: Rocks and pebbles bounce along the riverbed.
Deposition
Occurs when the river loses energy and drops material. Typically happens in the lower course where the river meets the sea.
The Long Profile of a River
Upper Course: Features vertical erosion leading to waterfalls and v-shaped valleys.
Middle Course: Lateral erosion shapes features like meander bends.
Lower Course: Characterized by wide, deep rivers forming oxbow lakes and deltas.
River Landforms
Upper Course: Waterfalls and rapids form due to vertical erosion of softer rock beneath harder rock.
Key Questions
Where does vertical erosion take place? Answer: In the upper course of a river.
What process moves the largest rocks in a river? Answer: Traction.
Name one landform found in the upper course of a river. Answer: Waterfalls.