Geography - Water on the Land

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Describe the upper course of a river
Steep, Narrow, Shallow channel, V-shaped valley
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Describe the middle course of a river
Medium gradient, gently sloping valley sides, wide, fairly deep channel
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Describe the upper course of a river
Very wide, almost flat valley, Very wide, deep channel
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What are the differences between vertical and lateral erosion?
Vertical erosion deepens the river channel, making it V-shaped. It is dominant in the upper course. Whereas lateral erosion widens the river valley, and is dominant in the middle and lower courses.
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What are the four processes of erosion?
Hydraulic action, Abrasion, Attrition, and Solution
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Describe Hydraulic action
The force of the water breaks rock particles away from the river channel
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Describe Abrasion
Eroded rocks picked up by the river scrape and rub against the channel, wearing it away
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Describe Attrition
Eroded rocks picked up by the river smash together and break into smaller fragments
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Describe Solution
River water dissolves some types of rock
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What are the four processes of Transportation?
Traction, Saltation, Suspension, and Solution
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What is Transportation?
The movement of eroded material
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Describe Traction
Large particles like boulders are pushed along the river bed by the force of the water
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Describe Saltation
Pebble-sized particles are bounced along the river bed by the force of the water
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Describe Suspension
Small particles like silt are carried along by the water
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Describe Solution
Soluble materials dissolve in the water and are carried along
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What is deposition and why does it occur?
It is when a river drops the eroded material it's transporting. It happens when a river loses velocity.
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Why does a river slow down?
The volume of water in the river falls, the amount of eroded material in the water increases, the water is shallower, or the river reaches its mouth
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Explain the formation of a meander
Meanders form when the current is faster on the outside of the bend because the river channel is depper (less friction). More erosion occurs on the outside, and as inside bend is slower (more friction) desposition occurs, forming slip-off slopes
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Explain the formation of an ox-bow lake
Formed when a meander's outside bends get close together and the neck narrows. The river breaks through this land, and the river flows along the shortest course. This cuts the meander off from the main river, leaving an ox-bow lake
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Explain the formation of a Waterfall
Waterfalls form where a river flows over an area of ahrd rock followed by soft rock. The softer rock is eroded more, creating a 'step' in the river. This eventually creates a steep drop, called a waterfall.
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Explain the formation of a Gorge
After a waterfall is formed, the hard rock is undercut by erosion and collapses. The collapsed rocks erode soft rock by abrasion at the, creating a plunge pool. This occurs many times, so the waterfall will retreat, forming a gorge
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What is a flood plain?
A wide valley floor that is occasionally flooded. It is formed by deposition, from the water slowing down during a flood. Also, the deposition that happens on slip-off slopes of meanders builds up the flood plain
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What is a levee?
Natural embankments along the edges of a river channel. Formed by deposition, as the heaviest material is deposited closest to the river channel and this builds up.
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What are the physical factors of flooding?
Prolonged rainfall, Heavy rainfall, Snowmelt, and Relief.
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What are the human factors of flooding?
Deforestation (less water is intercepted) and Building construction (often impermeable, and impermeable surfaces increase surface run off)
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Other cards in this set

Card 2

Front

Describe the middle course of a river

Back

Medium gradient, gently sloping valley sides, wide, fairly deep channel

Card 3

Front

Describe the upper course of a river

Back

Preview of the front of card 3

Card 4

Front

What are the differences between vertical and lateral erosion?

Back

Preview of the front of card 4

Card 5

Front

What are the four processes of erosion?

Back

Preview of the front of card 5
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