Coasts Flashcards
What are the costs and benefits of managed retreat?
- allows natural erosion to occur
- allows build up of the beach
- expensive - building loss and compensation for people
Give an example of managed retreat
Tollesbury, Essex
What are the costs and benefits of rip rap/rock armour?
- absorbs wave energy and so protects cliffs/buildings form erosion
- unaesthetic
- cheaper - £1000-3000
Give an example of rip rap/rock armour
Slapton, Devon
What are the costs and benefits of a groyne?
- stops longshore drift - so builds up the beach and encourages tourism
- cheaper - £2000 /m
- unaesthetic
- may expose other areas of the coast
Give an example of a groyne
Bournemouth, Dorset
What are the costs and benefits of a sea wall?
- protects buildings/cliffs from erosion successfully
- durable - last 80 years
- expensive £6000 /m
- curved seawalls reflect wave energy back into the sea so they remain powerful
Give an example of a seawall
Torcross, Devon
What are the costs and benefits of beach replenishment?
- sand absorbs wave energy so protect the coast
- builds up the beach and natural looking so encourages tourism
- cheaper £2000 /m
- doesnt last long and transportation is time consuming
Give an example of beach replenishment
Bournemouth, Dorset
What is the difference between hard and soft engineering?
Hard engineering options are more expensive and have a high impact on the landscape, they are more effective but have a shorter term impact (vice versa for soft engineering)
What are the characteristics of destructive waves?
have strong backwash and weak swash - material dragged into the sea
high energy, develop in stormy conditions
usually 6-8 per minute
What are the characteristics of constructive waves?
have strong swash and weak backwash - sediment is deposited and builds up the beach
low energy, develop in calm conditions
10-15 per minute
What is the fetch?
the distance of water over which the wind travels, transferring energy
What is the amplitude of a wave?
the height
How are cave arch stack stumps formed?
- waves erode a joint and open it up (hydraulic action)
- joint/fault grows into cave which continues to grow
- cave erodes back until it meets the other side of a headland
- the arch continues to erode until the headland can no longer support itself and collapses
- this leaves a tall rock stack which is subject to erosion until the base is separated from the top and a stump is formed
Give an example of a cave arch stack stump
The Old Harry Rocks, Swanage, Dorset
What are joints and faults?
joints are smaller cracks in rock
faults are larger cracks in rock
- they both make rock more prone to erosion
Which human activities have affected the coastline?
- urbanisation
- agriculture
- industry