Water

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  • Created by: gidmt
  • Created on: 27-04-16 19:54
What is hydraulic action?
The force of flowing water that washes away loose material on the bed/banks
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What is abrasion?
When stones are carried into the river and wear the bed/banks away
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What is corrosion?
The slightly acidic river water that dissolves rocks made of calcium carbonate
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What is attrition?
When stones collide together and break down to become smaller
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Describe a drainage basin
An area of land drained by a river. The river has its source in the mountains. Precipitation fell within the boundary of the watershed drains into river. Small tributary streams join river as it travels to the mouth
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How are v-shaped river valleys formed?
In the mountains, the river cuts into the land as it flows down steep slopes. This vertical erosion, and movement of weathered material, creates the v-shaped valley. The river winds around hard rock creating interlocking spurs
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How is a waterfall formed?
When a layer of hard rock lies over a layer of softer rock. The hard rock is less easily eroded. Eventually a drop develops over which the water falls.
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How is an oxbow lake formed?
As the meander continues to erode it becomes closer until the loop is completely cut off from the main channel
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How is a meander formed?
By lateral erosion. On the outside of the meander, the water flows fast so erosion occurs. On the inside of the meander, the water flows slower so has less energy to carry material and so deposits it. This causes the meander to change shape
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How is a floodplain formed?
Every time the river floods, silt is deposited on the flood plain to create fertile soils
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How is a delta formed?
When a river deposits its material at the mouth at a faster rate then what the sea can remove it
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Case Study - Boscastle 2004: what are the causes?
1) waterlogged ground. 2) impermeable rocks. 3) storms brought 200mm of rainfall in 4 hours. 4) steep slopes and narrow valleys meant precipitation drained quickly. 5) bridges became blocked due to fallen trees
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Case Study - Boscastle 2004: what are the impacts?
1) 100 people had to be airlifted to safety. 2) 80 cars were washed out to sea and properties flooded. 3) £300 million of damage
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How should rivers be managed using hard engineering?
1) building a dam. 2) straightening and deepening of channels. 3) walls
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How should rivers be managed using soft engineering?
1) afforestation. 2) restriction of building. 3) ecological flooding
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Other cards in this set

Card 2

Front

What is abrasion?

Back

When stones are carried into the river and wear the bed/banks away

Card 3

Front

What is corrosion?

Back

Preview of the front of card 3

Card 4

Front

What is attrition?

Back

Preview of the front of card 4

Card 5

Front

Describe a drainage basin

Back

Preview of the front of card 5
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