Fluvial Erosion Flashcards Preview

Geog Revision River Landforms > Fluvial Erosion > Flashcards

Flashcards in Fluvial Erosion Deck (12)
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1

What does a rivers total energy depend on

The weight of water, the height of the river above its base level, the steepness of the channel (controls speed and kinetic energy)

2

How is energy in a river lost

Internally (turbulence within the flow) or externally (contact with the bed and banks) + friction

3

What are the 4 erosional processes

Abrasion (corrasion), hydraulic action, corrosion, attrition

4

What is abrasion (corrasion)

The scraping, scouring and rubbing action of materials carried along by a river (the load).

5

When is abrasion most effective

In short turbulent periods when the river is at bankfull or flood

6

What is hydraulic action

Caused by the sheer power of moving water. The movement of loose unconsolidated material due to the frictional drag of the moving water on sediment lying on the channel bed.

7

When is hydraulic action most effective

At meanders- which leads to undercutting and collapse

8

What is corrosion

The minerals in a rock are dissolved by weak acids in the river water and carried away in solution

9

When is corrosion most effective

On rocks that contain carbonates eg limestone and chalk

10

What is attrition

The reduction in size of fragments and particles within a river due to the processes described above

11

What kind of pebbles are found upstream

Larger and more angular (whereas smaller and round pebbles downstream)

12

Why do rivers erode

Because they possess energy