Hard engineering strategies - advantages and disadvantages
Erosion is a natural process which shapes cliffs. Over time, erosion can cause cliff collapse - therefore the coastline needs to be managed. The use of man-made structures to control the coast. involves building artificial structures which try to control natural processes. Each engineering strategy has its advantages and disadvantages.
Sea walls
A sea wall
Concrete walls that are placed at the foot of a cliff to prevent erosion. They are curved to reflect the energy back into the sea.
Advantages
- Effective at protecting the base of the cliff.
- Sea walls usually have promenades so people can walk along them.
Disadvantages
- Waves are still powerful and can break down and erode the sea wall.
- Expensive - approximately £2,000 per metre.
Rock armour/rip rap
Rock armour on a beach
Large boulders placed at the foot of a cliff. They break the waves and absorb their energy.
Advantages
- Cheaper than a sea wall and easy to maintain.
- Can be used for fishing.
Disadvantages
- They look different to the local geology, as the rock has been imported from other areas.
- The rocks are expensive to transport.
Gabions
Gabions
Rocks are held in mesh cages and placed in areas affected by erosion.
Advantages
- Cheap - approximately £100 per metre.
- Absorb wave energy.
Disadvantages
- Not very strong.
- Look unnatural.
Groynes
Wooden groynes on a beach in Sussex
Wooden or rock structures built out at right angles into the sea.
Advantages
- Builds a beach - which encourages tourism.
- They trap sediment being carried by longshore drift.
Disadvantages
- By trapping sediment it starves beaches further down the coastline, increasing rates of erosion elsewhere.
- They look unattractive.