Hard and soft engineering approaches to coastal management; sediment-cell management and shoreline management plans; managed realignment and do-nothing; and the costs, benefits and sustainability of coastal protection.

What this dot point is asking

AQA section 3.1.3 wants you to compare approaches to coastal management: hard and soft engineering, managed realignment and do-nothing, the sediment-cell approach and Shoreline Management Plans, and the costs, benefits and sustainability of protecting the coast. The strongest answers reason at the sediment-cell scale and reach a supported judgement.

Why the coast is managed

The coast is managed to protect people, property, infrastructure and economic activity from erosion and flooding. But the coast is a connected system: because longshore drift moves sediment along the coast within a sediment cell, an intervention in one place changes the sediment budget elsewhere. Good management therefore weighs the value of what is protected against the cost and the knock-on effects downdrift.

Hard engineering

Hard engineering builds structures to resist the sea:

• Sea walls reflect wave energy and protect the cliff foot; effective but costly and can intensify scour.
• Groynes trap longshore drift to build a wide, protective beach, but starve the coast downdrift.
• Rip-rap (rock armour) and gabions absorb wave energy at the cliff base.
• Revetments are sloping structures that dissipate wave energy.
• Offshore breakwaters break waves before they reach the shore.

It gives immediate, reliable protection of high-value assets but is expensive, can be visually intrusive, disrupts natural processes and fails catastrophically if overtopped.

Soft engineering

Soft engineering works with natural processes:

• Beach nourishment: adding sand or shingle to widen the beach so it absorbs wave energy.
• Dune regeneration and stabilisation: planting marram grass to fix dunes as a natural buffer.
• Cliff regrading and drainage: reducing the slope angle and removing water to limit slumping.

It is usually cheaper, restores habitats and avoids downdrift starvation, but needs repeated maintenance (nourishment washes away) and offers less certain protection in a severe storm.

Managed realignment and Shoreline Management Plans

Decisions are coordinated through a Shoreline Management Plan (SMP) for each sediment cell, choosing one of four options for each stretch:

• Hold the line (maintain existing defences).
• Advance the line (build new defences seaward).
• Managed retreat / realignment (move the defence landward).
• No active intervention (do nothing and let nature take its course).

The cell scale matters because defending one stretch affects others; the SMP lets planners weigh the whole budget.

Try this

Q1. Define managed realignment. [2 marks]

• Cue. Deliberately allowing the sea to flood low-value land behind the old defence line to create salt marsh that absorbs wave energy.

Q2. Explain one disadvantage of using groynes. [3 marks]

• Cue. Groynes trap longshore drift to build a local beach but starve the coast downdrift of sediment, which then erodes faster.

Q3. Name the four Shoreline Management Plan options. [4 marks]

• Cue. Hold the line, advance the line, managed retreat (realignment) and no active intervention.