UNIT 1C - COASTAL MANAGEMENT (Managed retreat - Managed retreat is the…
UNIT 1C - COASTAL MANAGEMENT
- Managed retreat is the controlled flooding of low-lying coastal areas. If an area is at high risk of erosion, managed retreat could be an option. It usually occurs where the land is of low value, for example farm land.
Landowners need to be compensated - this can cost between £5,000 - £10,000 per hectare.
Land is lost as it is reclaimed by the sea.
Salt marshes are diverse ecosystems supporting many species.
Creates a salt marsh which can provide habitats for wildlife and a natural defence against erosion and flooding.
This is a cheap option compared to paying for sea defences.
- Soft engineering does not involve building artificial structures, but takes a more sustainable and natural approach to managing the coast. Each strategy has its advantages and disadvantages for use.
t - Marram grass planted on sand dunes stabilises the dunes and helps to trap sand to build them up.
Areas have to be zoned off from the public, which is unpopular.
Can be damaged by storm waves.
Maintains a natural-looking coastline.
- The sediment is redistributed from the lower part of the beach to the upper part of the beach.
Needs to be repeated continuously.
Only works when wave energy is low.
Reduces the energy of the waves.
Cheap and simple.
- Sand is pumped onto an existing beach to build it up.
The sand has to be brought in from elsewhere.
Needs to be constantly replaced.
Larger beaches appeal to tourists.
Blends in with the existing beach.
- Erosion is a natural process which shapes cliffs. Over time, erosion can cause cliff collapse - therefore the coastline needs to be managed. Hard engineering involves building artificial structures which try to control natural processes. Each engineering strategy has its advantages and disadvantages.
s - Wooden or rock structures built out at right angles into the sea.
They look unattractive.
By trapping sediment it starves beaches further down the coastline, increasing rates of erosion elsewhere.
They trap sediment being carried by longshore drift.
Builds a beach - which encourages tourism.
- Rocks are held in mesh cages and placed in areas affected by erosion.
Not very strong.
Absorbs wave energy.
Cheap - approximately £100 per metre.
- Large boulders placed at the foot of a cliff. They break the waves and absorb their energy.
The rocks are expensive to transport.
They look different to the local geology, as the rock has been imported from other areas.
Can be used for fishing.
Cheaper than a sea wall and easy to maintain.
- 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.
Expensive - approximately £2,000 per metre.
Waves are still powerful and can break down and erode the sea wall.
Sea walls usually have promenades so people can walk along them.
Effective at protecting the base of the cliff.