hard engineering

Question 1

what is hard engineering?

Answer 1

using artificial structures to defend land against natural erosion processes.

Question 2

describe sea walls:

Answer 2

• barrier placed at the back of beach, or foot of cliffs
• recurved sea walls are more expensive than flat ones, but are more effective at reflecting wave energy
• reflected wave energy obstructs incoming wave, reduces erosion overall
• made out of materials that block waves (e.g. hard rock/concrete makes them resilient for longer).

Question 3

what are advantages and disadvantages of sea walls?

Answer 3

a:
- top of sea wall can provide promenade, protects it from flooding, too
- effective
- good to protect high value assets

d:
- extremely expensive
- unnatural and obtrusive structure
- needs a lot of maintenance to prevent cracks (would be exploited by hydraulic action and would fall apart)

Question 4

describe groynes (wood/stone):

Answer 4

• built on the foreshore
• extend from the beach to the sea at 90 degree angle
• trap sediment being transported by longshore drift
• builds up a wider beach, absorbing wave energy and reducing erosion

Question 5

what are advantages and disadvantages of groynes?

Answer 5

a:
- cheaper than other methods
- creates a larger beach: enhances tourist value of beach

d:
- considered an unattractive ‘eyesore’
- traps sediment being moved down, so beaches further along are starved of sediment and are more susceptible to erosion

Question 6

what are gabions?

Answer 6

• wire cages filled with pebbles/rocks
• placed at the back of the beach, create a low, wall-like structure, act as a buffer against the sea
• water enters cage and disperses wave energy, reducing erosion
• backwash can’t remove the rocks, giving the place stability
• can support a cliff

Question 7

what are advantages and disadvantages of gabions?

Answer 7

a:
- relatively cheap
- protects more expensive structures behind and increases their life span
- flexible
- improve drainage around the cliff, as water can cause weathering and erosion in it
- will become vegetated and merge into the landscape

d:
- rubbish can be trapped inside the mesh
- can be easily broken up/rust and don’t have a long lifespan (wire in the cages eroded over time)
- unnatural and unattractive

Question 8

describe rock armour:

Answer 8

• huge piles of large rock/boulders (e.g. granite)
• act as a barrier between the sea and land
• can’t be moved by storm waves
• on a downward slope to deflect wave energy
• gaps in the boulders disperse wave energy and break waves
• usually transported by a barge

Question 9

what are the advantages and disadvantages of rock armour?

Answer 9

a:
- easy to maintain once in place
- relatively long-lasting
- habitat for crustaceans
- used for fishing and provides interest to the coast, provides shelter for fish, boosts food industry
- relatively cheap

d:
- rocks are brought in from other countries which is expensive to transport, don’t fit with the local geology which can disturb the natural ecosystem balance
- large, obtrusive structure