Coasts Flashcards
What is positive feedback
Something that causes a system to go out of control
What is negative feedback
Something that brings the system back to normality
What happened in Hallsands
- Houses were close to the beach and ocean
- Company dredged/moved the shingle from the beach.
- Shingle protected the beach from erosion.
- Erosion caused the houses to get destroyed.
How many high and low tides are there every 24 hours
2 high, 2 low
How are tides formed
Tides are formed by equal attraction of the earth and the moon creates a high tide on the right side of the moon.
What 3 things does energy acquired by waves depend upon
- ) Strength of the wind.
- ) The length of time it is blowing.
- ) Distance over which it blows (fetch.)
What happens when waves approach irregular coastline
They refract
What is lithology
How vulnerable a rock is against water due to its chemical composition
What is plant succession
The sequence of vegetation changes which occur as plants establish themselves in an environment
What is Zonation
The geographical expression of plant succession, with older and more diverse plant communities located at increasing distance from the shore .
What is eustatic change
rising sea level
What is isostatic change
uplift of landmass
What are the 3 A01 parts of SEE-SAW for 20 mark question
- Scale
- Explanation
- Examples
What are the 3 A02 parts of SEE-SAW for 20 mark question
- Seeing Links
- Analysis and evaluation
- Weighted conclusion
How many marks is A01 worth
10
How many marks is A02 worth
10
What are the 4 options of coastal management
- )Hold the line
- ) Advance the line
- ) Retreat the line
- )Do nothing
What does hold the line mean
Maintain existing coastal defences
What does retreat the line mean
build no coastal defences, move people away from the coast
What does advance the line mean
Build new coastal defences further out to sea than the existing line of defence
Wat does do nothing mean
Build no coastal defences at all, deal with erosion and flooding as it happens
What is the aim of coastal management
To protect homes, businesses and the environment from erosion and flooding.
How can we choose which places are protected
cost - benefit analysis
What places are normally more favoured to protect
The larger settlements and important industrial sites rather than smaller isolated settlements
What is hard engineering
Where the sea is built out of concrete or rocks providing permanent defence. they have a specific purpose.
Why are sea walls recurved
So they can throw back the wave, preventing erosion of the coast
Why does the facing on a sea wall have to be continuous
As if it wasn’t it would be eroded quickly by Hydraulic action
What do sea walls create and why is it bad
a strong backwash, bad as it erodes under the wall.
Are sea walls expensive
yes
How much can sea walls be per metre
£800 to £5000 per metre.
What is a recurved sea wall made up of
steel pile and concrete
What is rock armour / rip-rap made up of
large boulders piled up along the beach
What does rock armour do
the boulders absorb wave energy and so reduce erosion.
Is rock armour / rip-rap expensive or cheap and how much per metre
fairly cheap, £300 per metre
What are 2 limitations of rock amour
- ) can shift in storms
2. ) Not always visually attractive
What are 2 positives of rock armour
- ) Fairly cheap
2. ) Can look relatively natural depending on location
What are gabions
rock - filled cages
where are gabions usually placed
A wall of gabions is usually placed and built at the foot of cliffs
What do Gabions do
- they absorb wave energy and so reduce erosion
- They allow waves to percolate
Are Gabions expensive or inexpensive and how much per square metre
cheap, £11 per square metre
3 limitations of Gabions
- ) Fail relatively quickly, spilling contents if stacked
- ) move in strong waves
- ) look ugly
What are revetments
slanted structures built at the foot of cliffs
What materials are revetments made from
concrete, wood or rocks
what is the job of revetments
Waves break against the revetments, which absorb the wave energy and so prevent cliff erosion
are revetments expensive or inexpensive to build and how much per metre. are they cheap or expensive to maintain
expensive to build, cost £100 per metre, cheap to maintain
3 limitations of revetments
- ) expensive to build
- ) they damage foreshore ecosystems
- )They create a strong backwash which can erode