Coastal Defences (Edexcel GCSE Geography A)
Revision Note
Author
Bridgette BarrettExpertise
Geography Lead
Coasts - Hard Engineering
Shoreline management plans
The UK coastline is divided into sections
The management of coastal recession and flooding is the responsibility of:
The Environment Agency
Local Authorities
Shoreline management plans are developed to:
Reduce the threat of flooding and erosion
Benefit the local communities, economy and environment
There are four possible options:
No intervention - nothing is done to prevent flooding or recession
Hold the line - defences ensure that the existing shoreline remains where it is
Managed realignment - natural change is allowed to occur but in a managed way
Advance the line - new defences are built to advance the coastline
Decisions about which option to use in different areas are complex
The decisions depend on:
The economic value of the land and resources that are protected, such as businesses and homes
Whether possible solutions will work
Cultural value of the land
Community pressure
Hard engineering methods
Hard engineering involves the construction of structures to alter natural coastal processes
Hard engineering defences work against the power of the waves
Each type of defence has its strengths and weaknesses
Hard engineering is often used when settlements and expensive installations (power stations, etc) are at risk
The economic benefit is greater than the costs of building the defences
Hard Engineering Projects
Strategy | Description | Advantages | Disadvantages |
|---|---|---|---|
Sea Wall | A wall, usually concrete, is curved outwards to reflect the power of the waves out to sea | Most effective at preventing both erosion and flooding (if the wall is high enough) | It is very expensive to build and maintain It can be damaged if the material is not maintained in front of the wall Restricts access to the beach Unsightly to look at |
Groynes | Wood, rock or steel piling built at right angles to the shore, which traps beach material being moved by longshore drift | Slows down beach erosion Creates wider beaches, which may increase tourism Can be constructed rapidly | Stops material moving down the coast where it may have been building up and protects the base of a cliff elsewhere Starves other beaches down the coast of sand, leading to increased erosion. Wood groynes need maintenance to prevent wood rot Makes walking along the shoreline difficult |
Rip-rap | Large boulders are piled up to protect a stretch of coast | Cheaper method of construction Works to absorb wave energy from the base of cliffs and sea walls Can be put in place quickly | Boulders can be eroded or dislodged during heavy storms Boulders are often transported from overseas, which is expensive Restricts access to the beach |
Gabions | A wall of wire cages filled with stone, concrete, sand, etc built at the foot of cliffs | The cheapest form of coastal defence Cages absorb wave energy Can be stacked at the base of a sea wall or cliffs | Wire cages can break, and they need to be securely tied down Not as efficient as other coastal defences |
Coasts - Soft Engineering
Soft engineering works with natural processes rather than against them. It is:
Cheaper and does not damage the appearance of the coast
A more sustainable approach to coastal protection
Soft engineering methods are not as effective as hard engineering methods
Soft Engineering Projects
Strategy | Description | Advantages | Disadvantages |
|---|---|---|---|
Beach nourishment | Pumping or dumping sand and shingle back onto a beach to replace eroded material | Beaches absorb more wave energy Widens beach front Easy and cheap to maintain May increase tourism | Has be repeated regularly which is expensive Can impact sediment transportation down the coast Removing material from the seabed damages fragile ecosystems such as corals and sponges |
Dune regeneration | Planting vegetation helps to create or stabilise sand dunes and beaches Reduces wind erosion | Sand dunes act as a barrier between the sea and land The wave energy is absorbed, preventing erosion and flooding Cheap method of stabilising dunes | Hard to protect larger areas of coastline cliffs with this method Restricts access to some areas of the beach whilst the dunes establish |
Managed retreat | Existing coastal defences are abandoned or removed, allowing the sea to flood inland until it reaches higher land or a new line of defences | No expensive construction costs Creates new habitats such as salt marshes | Disruptive to people where land and homes are lost Saltwater damages existing ecosystems The cost of relocation can be expensive Compensation to people and businesses may not be paid |
Worked Example
Rip-rap is an example of hard engineering
Explain one way that rip-rap helps protect coastal landscapes
(2 marks)
One mark will be awarded for demonstrating knowledge of what rip-rap is
A second mark will be awarded for explaining how this helps to protect the coastline
Answer:
Large boulders are placed at the foot of the cliff (1) this dissipates the energy of the waves protecting the base of the cliff (1)
Exam Tip
Make sure that you are able to explain the advantages and disadvantages of the different coastal defence strategies. This is a question which regularly appears in the exam paper.
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