Coastal Management (Edexcel IGCSE Geography)
Revision Note
Written by: Jacque Cartwright
Reviewed by: Bridgette Barrett
Coastal Strategies
Management of coastal regions is performed by 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-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
Coastline is allowed to move naturally
Processes are monitored and directed when and where necessary
Most natural approach to coastal defence
Mostly soft engineering with some hard engineering to support
Do nothing
Cheapest method, but most controversial of the options
The coast is allowed to erode and retreat landward
No investment is made in protecting the coastline or defending against flooding, regardless of any previous intervention
Decisions about which approach to apply are complex and depend on:
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
Hard Engineering Methods
Hard engineering involves building some form of sea defence, usually from concrete, wood or rock
Structures are expensive to build and need to be maintained
Defences work against the power of the waves
Each type of defence has its strengths and weaknesses
Protecting one area can impact regions further along the coast, which results in faster erosion and flooding
Hard engineering is used when settlements and expensive installations (power stations etc) are at risk - the economic benefit is greater than the costs of building structures
Hard Engineered Defences
Strategy | Description | Advantages | Disadvantages |
|---|---|---|---|
Sea Wall | A wall, usually concrete, and curved outwards to deflect the power of the waves | Most effective at preventing both erosion and flooding (if the wall is high enough) | 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 | Stops material moving down the coast where the material may have been building up and protecting the base of a cliff elsewhere Starves other beaches of sand. 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 | Boulders can be eroded or dislodged during heavy storms |
Gabions | Wire cages filled with stone, concrete, sand etc | 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 |
Revetments | Sloping wooden or concrete fence with an open plank structure | Work to break the force of the waves Traps beach material behind them Set at the base of cliffs or in front of the sea wall Cheaper than sea walls but not as effective | Not effective in stormy conditions Can make beach inaccessible for people Regular maintenance is necessary Visually unattractive |
Off-shore barriers | Large concrete blocks, rocks and boulders are sunk offshore to alter wave direction and dissipate wave energy | Effective at breaking wave energy before reaching the shore Beach material is built up Low maintenance Maintains natural beach appearance | Expensive to build Can be removed in heavy storms Can be unattractive Prevents surfing and sailing |
Soft Engineering Methods
Soft engineering works with natural processes rather than against them
Usually cheaper and do 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
Strategy | Description | Advantages | Disadvantages |
|---|---|---|---|
Beach replenishment | Pumping or dumping sand and shingle back onto a beach to replace eroded material | Beaches absorb wave energy Widens beachfront | Has to be repeated regularly which is expensive Can impact sediment transportation down the coast |
Fencing, hedging, and replacing vegetation | Helps to stabilise sand dunes or beaches Reduces wind erosion | Cheap method to protect against flooding and erosion | Hard to protect larger areas of coastline cliffs |
Cliff regrading | The angle of a cliff is reduced to reduce mass movement | Prevents sudden loss of large sections of cliff Regrading can also slow down wave cut notching at the base of cliffs as wave energy is slowed | Does not stop cliff erosion |
Managed retreat | Existing coastal defences are abandoned 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 The cost of relocation can be expensive Compensation to people and businesses may not be paid |
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 needs
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, management is aimed at protecting hotels, arcades and creating a sandy beach
Hornsea has spent money on repairing its wooden groynes at a cost of £5.2 million
It also has a concrete sea wall
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 million, and groynes and beach nourishment at Mappleton have produced a sandy beach and protects the town
Withernsea has a sea wall, groynes, riprap and beach nourishment in an effort to widen the beach and reduce wave energy
2.25% of all UK gas comes through the gas terminal at Easington and £4.5 million 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 as being 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
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