Fluvial Processes II

A revision of Fluvial Processes, Landforms and

Characteristics

Fluvial Processes

•Rivers are driven by Gravity and the water cycle

•They have elements, processes and create landforms as outputs.

Fluvial Processes

•Rivers Erode•Rivers Transport•Rivers Deposit

The Elements of the Process

•The Elements of fluvial Processes are

•Gravity•Water•Sediment•Topography

The Outputs of the Process

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

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.

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.

How Rivers Transport

•Sediment is moved…•In Suspension (dissolved)•By Saltating (bouncing)•By Traction (rolling)

How Rivers Transport

•Rivers mainly transport in the mid section of the river

At the base the river is wide and slow

How Rivers Deposit

•Rivers deposit their load (sediment) when they lose energy.

•Where rivers flow slowly they drop their sediment.

Where Rivers Deposit

•Rivers flow slowly at their mouth in the lower section of the river.

•Rivers flow slowly on the inside of bends.

Characteristics of the River

•TextUpper course

Narrow channel, fast flowing

Mid CourseMedium channel, medium speed

Lower CourseWide Channel, Slow Velocity

Processes on the River

•TextErosion Dominates

Transport Dominates

Deposition Dominates

Erosion and Deposition

Slow = DepositionFast = Erosion

Why the Channel Moves

•Text

Outside of Bend= Fast flow and Erosion

Inside of Bend= Slow FlowAnd Deposition

Channel moves this way

Rivers at the mouth are wide

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Rivers at the source are narrow and fast

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