Methods Of Protection- Erosion

Recurved Sea Wall- HARD ENGINEERING

• Concrete, curved under the side to deflect the power of the waves
• Usually built infront of cliffs to protect settlements/infrastructure
• Life span of approximately 30-50 years
• Cost- £200,000-£500,000/ 100m length

Advantages

• Reflects wave energy
• Most effective means of preventing erosion
• Can prevent coastal flooding
• Socially reassuring
• Low maintenance

Disadvantages

• Expensive
• Deflected waves often scour the base, undermining the wall which can cause it to collapse
• Cost of maintenance is high
• Good medium term protection but continued erosion can cause long term failure
• Disruption of natural Beach Processes

Rock Armour/Rip-Rap- HARD ENGINEERING

• Large boulders on the beach lessen the force of the waves by absorbing wave energy within the gaps between the rocks
• Large boulders of 10 tonnes or more
• Cost £100,000-£300,000/ 100m length

Advantages

• Relatively Cheap
• Natural materials
• Allows build up of a beach
• Permeable face absorbs wave energy and encourages upper beach stability
  

Disadvantages

• Environmentally ugly
• Can be undermined and removed by waves due to washing away
• Expensive to obtain and transport the boulders
• Unattractive, dangerous access to beach

Gabions (Rock Filled Cage)-HARD ENGINEERING

• Cages of boulders built into cliff face, small rocks help absorb wave energy
• Life span of 5-10 years as the steel will rust
• Cost £5000-£50,000/ 100m of frontage

Advantages

• Effective where severe erosion occurs
• Cheaper than sea walls
• They absorb energy from the waves
• Permeable face absorbs wave energy and encourages upper beach stability

Disadvantages

• Environmentally ugly
• Shorter life span than sea wall
• Visually unattractive
• Limited life leading to unsightly and hazardous…