Coastal management (WJEC Eduqas GCSE Geography B): Revision Note

Specification links

The notes on this page cover part of 2.1.2 of the WJEC Eduqas B specification – How are coastlines managed?

• Contemporary management options to reduce the risk of coastal floods/erosion. Coverage must include:

  • costs/benefits of hard engineering options such as sea walls, groynes, gabions and rock armour.

  • costs/benefits of soft engineering options to include beach nourishment, beach stabilisation, managed retreat and wetland creation.

Coastal management – hard engineering

• Coastal management aims to protect the environment and people from erosion and flooding

• Some coastal areas cannot get protection or management because of economic constraints

• The cost-benefit analysis (CBA) is used to help decide if defending a coastline from erosion and/or flooding is worthwhile

  • The cost of a defence is measured against the value of the land (and properties) that it protects, along with the number of years needed

  • If an area has no value, then the cost is considered to be too great

Hard engineering methods

• Hard engineering builds sea defences using materials like concrete, wood, or rock

• Construction is expensive, and they need regular maintenance

• Defences protect against the waves' power

• Every type of defence has strengths and weaknesses, such as:

  • Protecting one area can affect other regions along the coast, leading to increased erosion and flooding

• Hard engineering is used when settlements and expensive installations, like power stations, are at risk because the economic benefit exceeds the costs of construction

Hard-engineered defences

Seawall

• These are usually built from concrete and curved outward to reflect the waves' power out to sea

Advantages

• Most effective at preventing both erosion and flooding (if the wall is high enough)

Disadvantages

• Very expensive to build and maintain

• It can be damaged if the material in front of the wall is not maintained

• It can restrict 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

Advantages

• Slows down beach erosion

• Creates wider beaches

Disadvantages

• Beaches along the coast are deprived of sand

• Wooden groynes need to be maintained to prevent wood rot

• Walking along the shoreline is difficult

Rip-rap or rock armour

• Large boulders are piled up to protect a stretch of coast

Advantages

• Cheaper method of construction

• Works to absorb wave energy from the base of cliffs and sea walls

Disadvantages

• Boulders can be eroded or dislodged during heavy storms

Gabions

• A wall of wire cages filled with stone, concrete, sand, etc., built at the foot of cliffs

Advantages

• Cheapest form of coastal defence

• Cages absorb wave energy

• Can be stacked at the base of a seawall or cliffs

Disadvantages

• Wire cages can break, and they need to be securely tied down

• Not as efficient as other coastal defences

Revetments

• Sloping wooden or concrete fence with an open plank structure

Advantages

• Work to break the force of the waves

• Traps the beach material behind them

• Set at the base of cliffs or in front of the seawall

• Cheaper than seawalls but not as effective

Disadvantages

• Not effective in stormy conditions

• They can make the beach inaccessible to people

• Regular maintenance is necessary

• Visually unattractive

Coastal management - soft engineering

Soft engineering methods

• Soft engineering works with natural processes rather than against them

• Usually cheaper and does not damage the appearance of the coast

• Considered to be a more sustainable approach to coastal protection

• However, they are not as effective as hard engineering methods

Soft-engineered defences

Beach nourishment

• Adding sand and shingle to a beach to replace eroded material, therefore, making it wider and higher

• The added material is sourced from elsewhere, often placed by barges and moved with trucks and bulldozers

Advantages

• Beaches absorb wave energy 

• Widens the beachfront

• Increases the beach's recreational value

Disadvantages

• Has to be repeated regularly, which is expensive

• Can affect sediment movement along the coast

• Removing material from the seabed harms fragile ecosystems like corals and sponges.

Beach stabilisation

• This involves building fences, planting vegetation or using natural materials such as straw to trap sand

• The aim is to protect against erosion by deflecting or absorbing wind and wave energy

Advantages

• Cheap method to protect against flooding and erosion

Disadvantages

• Hard to protect larger areas of coastal cliffs

Beach reprofiling

• The angle of a beach is reduced to better absorb wave energy

• Sediment is moved from the lower part of a beach to the upper part

Advantages

• Cheap and simple

• Increasing the beach's profile creates a wider beach

• Wave energy is reduced, which reduces erosion

• Has a natural appearance and can protect coastal habitats

Disadvantages

• It only works in areas with low wave energy

• Dredging sand from the seabed damages marine ecosystems

• Taking sand and shingle from offshore areas can lead to more erosion in other areas

• Must be repeated often and increases long-term costs

• Public access is limited during the process

Wetland creation

• Restoring or building wetland habitats like salt marshes and tidal flats helps reduce coastal flooding and erosion

Advantages

• Wetlands act as a barrier between the sea and land

• Keeps the coastline looking natural

• Wetlands absorb the wave energy, reducing erosion and flooding

• Wetlands enhance biodiversity and act as carbon sequestration

Disadvantages

• High initial costs for land and infrastructure

• Can cause conflict with existing land uses

• It can take a long time to establish

Managed retreat

• The existing coastal defences are abandoned, allowing the sea to flood inland until it reaches higher land or a new line of defences

• Advantages

  • There are no expensive construction costs

  • Creates new habitats such as salt marshes

• Disadvantages

  • Disruptive to people, where land and homes are lost

  • The cost of relocation can be expensive

  • Full compensation to people and businesses may not be paid