Coastal Management (AQA GCSE Geography): Revision Note

Specification links

The notes on this page cover part of 3.1.3.2 Coastal landscapes in the UK on the AQA GCSE specification. (opens in a new tab)

3.1.3.2 - Key idea: Different management strategies can be used to protect coastlines from the effects of physical processes.

• The costs and benefits of the following management strategies:

  • Hard engineering – sea walls, rock armour, gabions and groynes.

  • Soft engineering – beach nourishment and reprofiling, dune regeneration.

  • Managed retreat – coastal realignment.

• An example of a coastal management scheme in the UK to show:

  • The reasons for management.

  • The management strategy.

  • The resulting effects and conflicts.

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

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

Sea wall

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

Off-shore barriers

• Large concrete blocks, rocks and boulders are sunk offshore to alter wave direction and dissipate wave energy

Advantages

• Effective at breaking wave energy before reaching the shore

• Beach material is built up

• Low maintenance

• Maintains natural beach appearance

Disadvantages

• Expensive to build

• Can be removed in heavy storms

• Can be unattractive

• Prevents surfing and sailing

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 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

• Can make beach inaccessible for people

• Regular maintenance is necessary

• Visually unattractive

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 replenishment

• Putting sand and shingle back onto a beach to replace eroded material

Advantages

• Beaches absorb wave energy 

• Widens beach front

Disadvantages

• Has 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.

Dune regeneration

• Planting vegetation creates or stabilises sand dunes and beaches

• It reduces wind erosion

Advantages

• Dunes act as a barrier between the sea and land

• Keeps the coastline looking natural

• Dunes absorb the wave energy, reducing erosion and flooding

• Cheap method to stabilise dunes

Disadvantages

• Hard to protect larger areas of coastline cliffs with this method

• Areas have to be zoned off from the public, which is unpopular

• Storm waves can damage the dunes

Beach reprofiling

• The angle of a beach is reduced to reduce 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

Managed retreat

• Managed retreat is the planned relocation of populations and infrastructure away from eroding or flooding coastlines

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

Advantages

• No expensive construction costs

• Creates new habitats and increases biodiversity

• Salt marshes which act as a natural buffer to erosion and flooding

• Reduces the pressure on other areas inland or along the coast

Disadvantages

• People lose their land and homes

• Saltwater damages current ecosystems.

• Relocation can be costly

• People and businesses might not get compensation.

• Managed retreat can create controversy, especially when it concerns high-value land, leading to pushback from landowners and developers

Cliff regrading and drainage

• The angle of a cliff face is reduced to slow mass movement

• Drainage tubes remove water from the cliff

• Particularly useful on cliffs of clay and limestone (these erode easily and slip when wet)

Advantages

• Low cost and sustainable

• Stops sudden loss of large cliff sections

• Regrading can slow down wave-cut notching at the base of cliffs because it reduces wave energy

• Drainage lowers water saturation in the cliff

Disadvantages

• It does not stop cliff erosion

• Efficient drainage can dry out the cliff face, causing it to collapse

• Regrading takes away part of the cliff, causing the cliff to retreat

Managing coastal retreat

• There are conflicting views about using a particular type of engineering for coastal defence

• Most coastal managers aim to use a range of methods depending on the value of what is being protected

• This method is known as Integrated Coastal Zone Management (ICZM)

• ICMZ aims to use a combination of methods to best reflect all stakeholder's needs

Coastal strategies

• Management of coastal regions is done through identifying coastal cells

• This breaks a long coastline into manageable sections and helps identify two related risks:

  • The risk of erosion and land retreat 

  • The risk of flooding

• Identification allows resources to be allocated effectively to reduce the impacts of these risks

• The 'cost to benefit' is easier to calculate using coastal cells

Shoreline management plans

• Shoreline Management Plans (SMP) set out an approach to managing a coastline from flooding and erosional risk

• The plans aim to reduce the risk to people, settlements, agricultural land and natural environments (salt marshes etc.)

• There are four approaches available for coastal management, with differing costs and consequences:

Hold the line

• Long-term approach and the most costly

• Build and maintain coastal defences so the current position of the shoreline remains the same

• Hard engineering is the most dominant method used, with soft engineering used to support

Advance the line

• Build new defences to extend the existing shoreline

• Involves land reclamation

• Hard and soft engineering is used

Managed realignment or retreat

• Removing some or all coastal defences lets the coastline move naturally.

• The land gradually turns into flooded marshes, which protect the area behind. 

• The natural approach to coastal defence requires no maintenance and creates new habitats for animals and plants.

• The sea takes the land, causing conflict, loss of livelihood, and saltwater damage to ecosystems.

• Primarily soft engineering with some hard engineering for support.

Do nothing

• It's the least expensive option, but it stirs up the most debate.

• The coast erodes and retreats landward.

• No investment protects the coastline or defends against flooding, despite any past efforts.

How do we choose an approach?

• Deciding on an approach is complex and depends on:

  • Decisions about which approach to apply are complex and depend on:

    • The economic value of the resources that would be protected, e.g., land, homes, etc.

    • Engineering solutions: It might not be possible to 'hold the line' for moving landforms such as spits or unstable cliffs 

    • Cultural and ecological value of land: Historic sites and areas of unusual diversity

    • Community pressure: Local campaigns to protect the region

    • Social value of communities: Long-standing, historic communities

Case study: The Holderness Coast

• The Holderness Coastline is located on the East Coast of Yorkshire and runs for 61 km Flamborough Head in the north down to Spurn Head, where it meets the Humber Estuary in the south

• It is the fastest-eroding coastline in Europe at 2 m per year

• It is made of soft boulder clay and chalk

• The coastline has naturally narrow beaches, which give less protection as wave power is not reduced

• Longshore drift is the dominant process due to North Sea waves

• Waves along the coastline have a long fetch (travel long distances), which increases wave energy

• The biggest issue of the Holderness coastline is that it is retreating too quickly

Management

• Bridlington is protected by a 4.7 km long sea wall

• Gabions have been built at Skipsea

• Hornsea's cliffs are formed from soft boulder clay and as a popular tourist destination, its management is aimed at protecting hotels and arcades, and creating a sandy beach. Hornsea has spent money on repairing its wooden groynes at a cost of £5.2 m; it also has a concrete seawall. Recently a stone and steel gabion along with a concrete revetment have been built south of Hornsea, helping to protect the caravan park

• Riprap at a cost of £2 m, groynes and beach nourishment at Mappleton have produced a sandy beach and protects the town 

• Withernsea has a seawall, groynes, riprap and beach nourishment in an effort to widen the beach and so reduce wave energy

• 2.25% of all UK gas comes through the gas terminal at Easington and £4.5 m was spent on riprap, but the scheme protects the terminal and not the village

• Spurn Head is protected with groynes and rock armour

Conflicts

• Careful management of coastal regions is necessary to ensure sustainability

• Conflict arises when coastal development is seen to be given a higher priority than overall coastal conservation

• The management along the Holderness Coast has been successful in part, with the village of Mappleton and the B1242 road no longer at risk from erosion

• Due to the use of groynes at Mappleton, sediment has been prevented from moving south, which has increased erosion at Great Cowden 

• Erosion has destroyed farms along with the loss of 100 chalets at the Golden Sands Holiday Park

• Locals have disagreed about where sea defences are located, especially if community land is not protected

• Some sea defences negatively impact tourism and reduce the amount of money coming into the area

• Spurn Head is at risk of losing habitats due to a lack of sediment to maintain the spit

• Overall, maintaining coastal defences is expensive and the cost may be too great to continue defending an area that is eroding quickly and will continue to erode