Rivers undergo three main processes: erosion, transportation, and deposition. They erode most in their upper reaches where the channel is narrow and flow is fast. In their middle reaches, transportation dominates as the channel widens and sediment of varying sizes is moved downstream. Deposition occurs most in lower reaches where the channel is wide and flow slows, causing sediment to drop out of the river system. These fluvial processes shape the landforms left behind, such as deltas, valleys, and floodplains.

1. Fluvial Processes II
A revision of Fluvial Processes,
Landforms and Characteristics

2. Fluvial Processes
• Rivers are driven by Gravity
and the water cycle
• They have elements, processes
and create landforms as
outputs.

3. Fluvial Processes
• Rivers Erode
• Rivers Transport
• Rivers Deposit

4. The Elements of the Process
• The Elements of fluvial
Processes are
• Gravity
• Water
• Sediment
• Topography

5. The Outputs of the Process
• The outputs of the processes
are landforms such as deltas,
V-shaped valleys, islands and
oxbow lakes.

6. How Rivers erode
• When a river is flowing fast it
has a lot of energy to erode the
bed and banks of its channel.
• This occurs in the upper
portions of the river.

7. How Rivers transport
• Rivers transport larger material
where they have the most
energy.
• Large sediment (rocks) require
a lot of energy to be moved.
Small sediment (ash) requires
little energy to be moved.

8. How Rivers Transport
• Sediment is moved…
• In Suspension (dissolved)
• By Saltating (bouncing)
• By Traction (rolling)

9. How Rivers Transport
• Rivers mainly transport in the
mid section of the river

10. At the base the river is wide
and slow

11. How Rivers Deposit
• Rivers deposit their load
(sediment) when they lose
energy.
• Where rivers flow slowly they
drop their sediment.

12. Where Rivers Deposit
• Rivers flow slowly at their
mouth in the lower section of
the river.
• Rivers flow slowly on the inside
of bends.

13. Characteristics of the River
• Text
Upper course
Narrow channel, fast
flowing
Mid Course
Medium channel, medium
speed
Lower Course
Wide Channel, Slow Velocity

14. Processes on the River
• Text
Erosion Dominates
Transport Dominates
Deposition Dominates

15. Erosion and Deposition
Fast = Erosion Slow = Deposition

16. Why the Channel Moves
• Text Channel moves this way
Outside of Bend
= Fast flow Inside of Bend
and Erosion = Slow Flow
And Deposition

17. Rivers at the mouth are wide
• Text

18. Rivers at the source are
narrow and fast

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