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Rivers - Coggle Diagram
Rivers
Types of erosion (CAASH)
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Attrition
Eroded material constantly hit into each other, causing them to become smaller, smoother and rounder
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Hydraulic action
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Gas can get stuck in the rocks, this can lead to an increase of pressure, this leading to the erosion
Transportation types
Traction
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Like a tractor, it is moving something large and taking a lot of effort and energy to do so
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Solution
Mineral and small particles get dissolved in the water, helped by its acidity
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Long/cross profile
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Cross profile
Upper course
Erosion dominates deposition, this means the valley has steep sides and is shaped like a V. Narrow, shallow channel
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Middle course
Neither erosion or deposition is dominant, this means that the valley is gently sloped and the channel is wider and deeper than the upper course
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Lower course
Deposition dominates over erosion, this means the valley is wide and flat, meaning the channel is wide and deep also.
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River management
Hard engineering
Involves building artificial structures to try and control the river, however, they tend to be more expensive
Dams and reservoirs
A wall used to trap and control the amount of discharge, the walls hold back the water and release it in a controlled manner
Positives:
- Can be used to create renewable hydroelectric energy
- Good for flooding control
Negatives:
- Expensive
- Can ruin the natural beauty of a place
- Reservoirs can flood agriculture and farms
Embankments and levees
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Positives:
- Cheap
- Floodwater stays in the river
- Easier to build on floodplains
- Protects high cost areas
Negatives:
- Can ruin the natural beauty of a river
- Reduces access to the river
- Water speeds up, this can lead to floods further downstream
River straightening
The river is made straighter and deeper, allowing more river discharge.
Positives:
- More water is held downstream
- Improve shipping route
Negatives:
- Long process to achieve
- More flooding risks downstream
Flood relief channels
Flood water flows into a channel, then getting redirected into an area where it can be reabsorbed or reentered later down stream
Positives:
- Remove excess water
- Reduce flood risks
- Doesn't affect the ecosystems
Negatives:
- Expensive
- Relief channel can flood
Soft engineering
Doesn't involve building artificial structures to try and control the river, they tend to be less expensive
Afforestation
Planting trees in the river valley to absorb excess water and intercept rain water to reduce surface runoff
Positives:
- Creates socio-economic benefits
- Creates a small carbon sink
- Ecological habitats
Negatives:
- Reduces farmland
- Reduces space to build on
- Lost revenue from agriculture
Preparation and planning
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Positives:
- People can protect their possessions
- People can mentally prepare
- Less insurance claims
Negatives:
- Not everyone has access/acknowledges the warnings
- Flash floods may happen too quickly for people act upon these warnings
- Doesn't stop/minimise the flood
Floodplain zoning
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Positives:
- Less damage
- Less insurance claims
- Can make locals feel safer
Negatives:
- Not always possible to change the use of the land
- Planners have to approve the use of the land
- Can be more expensive to build on lower risk areas
River restoration
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Positives:
- Discharge in the river is reduced
- Reduces flooding risks downstream
- Low cost
- Biodiversity is kept
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