geography coasts- hard engineering

What are sea walls

Concrete or rock barriers at the foot of cliffs or top of beach. Curved to reflect waves out to sea

How much do sea walls cost

£5000-£10000 per metre

Advantages of sea walls

• effective at stopping the sea

• Often creates a walkway

Disadvantages of sea walls

• can look obstructive and unatural

• Very expensive with high maintenance costs

What are groynes

Rock or timber structures built at right angles to beach

They trap sediment move by longshore drift and enlarge the beach

Wider beach reduces wave damage

How much do groynes cost

Timber groynes are £150000 each (every 200 metres)

Advantages of groynes

• create a wider beach - good for tourism

• Not too expensive

Disadvantages of groynes

• interrupting longshore drift can lead to increased erosion elsewhere

• Unnatural and rock groynes are unattractive

What is rock armour

Piles of large boulders at foot of cliffs

Rock absorbs wave energy to protect cliffs

How much does rock armour cost

£200000 per 100 metres

Advantages of rock armour

• relatively cheap

• Easy to maintain

• Can add interest to the coast

Disadvantages of rock armour

• rocks are often from elsewhere and don’t fit in with local geology

• Expensive to transport rock

• Can be obstructive

What are gabions

Rock-filled wire cages the support cliff and provide a buffer against the sea

How much do gabions cost

Up to 50,000 per 100 metres

Advantages of gabions

• cheap to produce

• Can improve cliff drainage

• Eventually become vegetated and merge in landscape

Disadvantages of gabions

Unattractive initially

Cages rust within 5-10 years