Hard Engineering

Question 1

Revetments
Draw a diagram.
How does it work?
Advantages?
Disadvantages?

Answer 1

See notes
Open structure of planks which absorbs the waves energy but allows water and sediment to build up beyond , the ramp shape spreads the wave energy.can be wooden or concrete
Advantages:
Protects high risk property or densely populated areas
Still allows build up of the beach
Cheaper than a sea wall: £1,000 per 10 meters
Disadvantages:
Doesn’t cope well with strong waves (weaker than sea walls)
Vulnerable to rotting

Question 2

Coastal Barrages
Draw a diagram.
How does it work?
Advantages?
Disadvantages?

Answer 2

See notes
Building a partially submerged wall, 
Sluce gates open and close to allow some water through and controls water flow
Advantages:
Generate hydroelectric power
Control water level
Disadvantage:
Change sedimentation
Ugly

Question 3

Rock armour/rip rap
Draw a diagram.
How does it work?
Advantages?
Disadvantages?

Answer 3

See Notes
Large rocks are places to dissipate and absorb wave energy, as the water percolates 
Advantages:
Stops cliffs from being undercut 
Good for fishing/crabbing
Disadvantages:
Very expensive, £14,000 per square meter 
Transport costs 
May not match local geology

Question 4

Gabions 
Draw a diagram.
How does it work?
Advantages?
Disadvantages?

Answer 4

See notes
Artificially reinforce a cliff face by driving metal bars into the cliff to stabilise it
Advantages:
Cheap
Easy to fix
Disadvantages:
Unstable- hazard to those working above
Not a long time solution

Question 5

Offshore reefs
Draw a diagram.
How does it work?
Advantages?
Disadvantages?

Answer 5

See notes
Away from the coast, bars which dissipate the wave energy and encourages waves to break offshore
Advantages:
Can be built using waste material e.g. Tyres
Encourages deposition

Question 6

Groynes
Draw a diagram.
How does it work?
Advantages?
Disadvantages?

Answer 6

See notes
Maintain beaches by blocking the path of longshore drift through fence like structures built at right angles to the coast
Advantages:
Cheap-£10,000 per groyne
Maintains an even spread of sediment across the beach
Disadvantages:
-wooden = vulnerable to rotting
Stop delivery of sediment further down the coast causing an insufficient supply to spits

Question 7

(Recurved) sea walls
Draw a diagram.
How does it work?
Advantages?
Disadvantages?

Answer 7

See notes
Large concrete (curved) wall absorbs and redirects waves energy back out to sea as it dissipates 
Advantages: 
able to withstand strong waves
Provides a walkway
Protects valuable resources or densely populated areas from erosion
Disadvantages:
Very costly £30,000 per 10 meters
Aesthetically displeasing