Engineering Management Approaches
Geography: Edexcel A Level, topic 3.4.2
Coastal Defences - Hard Engineering
Hard engineering strategies aim to reduce the effects of flooding and erosion by building man-made structures that control the sea's flow.
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Sea walls
- Sea walls are made out of hard concrete that deflects waves. They are often curved to dissipate the wave’s energy and refract it back towards the sea.
- They are a good long-term solution because of the resistance of concrete, leading to less maintenance.
- But they create a strong backwash that can undercut the wall and they are expensive to build and maintain.
Rip-rap
- Rip-rap is simply a pile of boulders. They are often placed in front of sea walls to dissipate the wave’s energy and support unstable rock structures.
- They are long-lasting and relatively cheap.
- But they provide a hazard for people accessing the beach and have gaps between the rocks allowing erosion and weathering to continue.
Revetments
- Revetments are angled walls placed just offshore to assist in breaking down the force of the waves to reduce their ability to erode the coastline.
- They are a more cost-effective technique to a sea wall and reduce the rate of erosion.
- But they often require regular maintenance and can create access problems to the beach.
Groynes
- Groynes are stone or wooden fences that stick out at 90o to the coast. They stop material being transported long distances by longshore drift.
- They create wider beaches, which slows down waves and so reduces erosion and flooding. They are also relatively cheap.
- But beaches further down the coast get narrower, which means waves are not slowed down and erosion and flooding are more likely.
Offshore breakwaters
- Offshore breakwaters are made up of rocks placed in a line parallel to the shore.
- They provide calmer conditions behind the breakwater, allowing the beach to be used safely for recreational sports.
- But they can cause wave patterns to change and are expensive to install.
Coastal Defences - Soft Engineering
Soft engineering strategies aim to reduce the effects of flooding and erosion using our understanding of the sea and working sustainably.
Beach nourishment and reprofiling
- Beach nourishment and reprofiling involves moving material to the upper sections of beaches from elsewhere.
- It slows down waves by widening beaches and so reduces the risk of erosion and flooding.
- It maintains the beach for tourist use, supporting the local economy.
- But removing sand and shingle from the seabed threatens certain organisms (e.g. corals). It is also expensive and must be repeated.
Dune stabilisation
- Dune stabilisation involves the creation or restoration of sand dunes to maintain their protective position. This can be achieved through nourishment or planting vegetation.
- This provides a natural barrier to coastal flooding and can support wildlife habitats.
- But only a small area is protected and it is ineffective in preventing wave action during powerful storms.
Cliff re-grading
- Cliff re-grading and drainage involves restructuring and supporting the cliff to prevent further collapse from weathering and mass movement processes.
- This maintains the cliff and provides a natural environment for plant and wildlife to continue to flourish.
- But there are risks associated with altering cliff profiles which can lead to further collapsing and unintended changes to the profile.
Test yourself on Engineering Management Approaches
What are the disadvantages of sea walls?
Which of the following is a soft engineering coastal defence strategy?