Method of Protection How does it work? Advantages Disadvantages Sea walls reflect rather than absorb wave energy Most expensive (up to £2.5 Most effective means of Concrete Wall, million /km) preventing erosion curved under the Reflected often scour A promenade can be built side to deflect the the base, undermining the behind the sea wall for power of the waves. wall (may eventually tourists to walk along. collapse) More tourists means more money for local people. Large boulders on the beach - lesson Environmentally ugly the force of the Relatively Can be undermined and waves by absorbing Uses natural materials / removed by due to the wave energy rocks washing away of sand and within the gaps shingle beneath. between the rocks. Engineering Cages of boulders Environmentally ugly built into the cliff face Effective where severe (usually used in Hard - small rocks help to erosion and cheaper than numbers) absorb the wave sea walls. Cost: approx £350 per energy. metre Less durable than a sea wall may need replacing – Wooden structures Much cheaper than a sea quicker. break the force of the wall Don't give total protection waves and trap Effective at breaking the to base of cliff beach material force of the waves Environmentally ugly behind them. Cost: approx £1,000 per metre
Method of Protection How does it work? Advantages Disadvantages Hard Engineering Concrete Wall, curved under the side to deflect the power of the waves. Sea walls reflect rather than absorb wave energy Most effective means of preventing erosion A promenade can be built behind the sea wall for tourists to walk along. More tourists means more money for local people. Most expensive (up to £2.5 million /km) Reflected often scour the base, undermining the wall (may eventually collapse) Large boulders on the beach - lesson the force of the waves by absorbing the wave energy within the gaps between the rocks. Relatively Uses natural materials / rocks Environmentally ugly Can be undermined and removed by due to washing away of sand and shingle beneath. Cages of boulders built into the cliff face - small rocks help to absorb the wave energy. Effective where severe erosion and cheaper than sea walls. Environmentally ugly (usually used in numbers) Cost: approx £350 per metre Wooden structures break the force of the waves and trap beach material behind them. Much cheaper than a sea wall Effective at breaking the force of the waves Less durable than a sea wall – may need replacing quicker. Don't give total protection to base of cliff Environmentally ugly Cost: approx £1,000 per metre
Coasts%20Revision%20Session%20Handout%20DGr.docx