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Coastal management is about deciding how (or whether) to protect the coast from erosion and flooding. This lesson covers the different approaches to coastal management, the engineering techniques used, and the arguments for and against each strategy.
The coast needs management because:
However, coastal management is expensive, and it is not always economically viable to protect every stretch of coastline. Difficult decisions must be made about where to invest limited resources.
In England and Wales, the coast is managed through Shoreline Management Plans. These divide the coastline into sections and assign each section one of four policies:
| Policy | Meaning | When used |
|---|---|---|
| Hold the line | Maintain the current line of defence (protect the coast in its current position) | Where valuable property or infrastructure is at risk |
| Advance the line | Build new defences seaward of the existing line | Rare; used where land reclamation is planned |
| Managed retreat (managed realignment) | Allow the sea to flood inland in a controlled way, often creating new salt marshes | Where the cost of defence outweighs the value of the land |
| No active intervention | Do nothing — let natural processes take their course | Where the coast has low economic value or few properties |
Exam Tip: Managed retreat is increasingly favoured by the Environment Agency because it is cheaper than hard engineering and creates new wildlife habitats (salt marshes). However, it is deeply unpopular with communities who lose their homes and land.
Hard engineering uses man-made structures to protect the coast. These are typically expensive, have a significant visual impact, and may cause problems further along the coast.
| Defence | Description | Advantages | Disadvantages | Approximate Cost |
|---|---|---|---|---|
| Sea wall | A concrete or stone wall built along the coast, often curved to deflect wave energy | Very effective at preventing erosion and flooding; long-lasting (30-50+ years) | Very expensive (£5,000-£10,000 per metre); can be ugly; creates a strong backwash that scours the beach | High |
| Groynes | Wooden or rock barriers built perpendicular to the coast to trap sediment moved by longshore drift | Effective at building up the beach; relatively cheap (£5,000-£10,000 each) | Starve beaches further along the coast of sediment (terminal groyne syndrome); need regular maintenance | Medium |
| Rock armour (rip-rap) | Large boulders placed at the base of the cliff to absorb wave energy | Effective at reducing erosion; relatively cheap; look natural | Can be dangerous for walkers; may be out of keeping with local geology; can shift in storms | Medium |
| Gabions | Wire cages filled with rocks, placed at the base of the cliff | Cheap (about £100 per metre); quick to install | Ugly; wire cages rust and break after 5-10 years | Low |
| Revetments | Slatted wooden or concrete structures built along the cliff base to absorb wave energy | Less expensive than sea walls; effective; allow water to drain through | Can be damaged by storms; limited lifespan | Medium |
| Offshore breakwaters | Rock or concrete barriers built in the sea, parallel to the coast, to break waves before they reach the shore | Reduce wave energy reaching the beach; encourage deposition behind them | Expensive; can be a hazard to navigation; may disrupt sediment movement | High |
Soft engineering works with natural processes rather than against them. Soft engineering techniques are generally cheaper, more sustainable, and more environmentally friendly than hard engineering.
| Defence | Description | Advantages | Disadvantages |
|---|---|---|---|
| Beach nourishment | Adding sand or shingle to a beach to make it wider. Material is often dredged from the seabed or brought from elsewhere. | Looks natural; wider beach absorbs wave energy and protects the cliff; good for tourism | Expensive (must be repeated every few years as material is washed away); dredging can damage seabed ecosystems |
| Beach re-profiling | Reshaping the beach using bulldozers to create a steeper profile that absorbs wave energy more effectively | Relatively cheap; uses existing material | Must be repeated regularly, especially after storms |
| Dune stabilisation | Planting marram grass and other vegetation on sand dunes to bind the sand and prevent erosion. Fences may be used to trap wind-blown sand. | Cheap; natural-looking; creates wildlife habitat; encourages dune growth | Takes time to establish; dunes can be damaged by storms or trampling |
| Managed retreat (managed realignment) | Allowing the sea to flood low-lying land behind existing defences, creating new salt marshes that absorb wave energy | Cheap; creates valuable wildlife habitat; salt marshes absorb wave energy and act as a natural defence | Loss of farmland and homes; compensation must be paid; deeply unpopular with affected communities |
Exam Tip: AQA often asks you to evaluate hard and soft engineering. A top-level answer will compare the two approaches and conclude that a combination is usually the most effective strategy — hard engineering to protect high-value areas and soft engineering to complement it and manage lower-value areas sustainably.
The Holderness coast in East Yorkshire is the fastest eroding coastline in Europe, retreating at an average rate of 1-2 metres per year (and up to 10 metres in some places during storms).
| Factor | Detail |
|---|---|
| Rock type | The cliffs are made of boulder clay (glacial till), a soft, unconsolidated material that is easily eroded by waves and weakened by rain. |
| Fetch | Waves have a long fetch across the North Sea from Scandinavia, making them powerful. |
| Narrow beaches | The beaches are narrow and do not absorb much wave energy. |
| Longshore drift | Material eroded from the cliffs is transported southward by longshore drift, so it is not deposited locally to protect the cliffs. |
Different sections of the Holderness coast are managed differently:
| Location | Strategy | Reasoning |
|---|---|---|
| Bridlington | Hard engineering (sea wall, groynes) | Large town with significant economic value; tourism is important |
| Hornsea | Hard engineering (sea wall, groynes, rock armour) | Town with homes and businesses to protect |
| Mappleton | Hard engineering (rock armour, two rock groynes — built 1991, cost £2 million) | Village was at risk of losing the main road |
| Between towns | No active intervention | Farmland and isolated properties; cost of protection exceeds the value of the land |
| Spurn Head | Managed retreat / no active intervention | The spit is allowed to evolve naturally; it has breached and reformed several times |
The construction of groynes at Mappleton in 1991 successfully protected the village. However, the groynes interrupted longshore drift, starving beaches to the south of sediment. Erosion rates south of Mappleton increased significantly, and several farms were lost to the sea. This demonstrates the principle that coastal management in one place can cause problems elsewhere — a concept known as terminal groyne syndrome.
Exam Tip: The Holderness coast is the most commonly used AQA case study for coastal management. Make sure you can explain why it erodes so fast, describe at least two management strategies used, and evaluate their effectiveness including unintended consequences.
Lyme Regis is a historic coastal town on the Dorset coast (part of the Jurassic Coast World Heritage Site) that has suffered from both cliff erosion and landslides.
A major coastal protection scheme was carried out in phases (2005-2015), costing approximately £22 million:
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