L11 - Hard coastal engineering

• sea walls

  provide a barrier between the waves and the land. it is placed along the back of a beach and can double up as a promenade. Recurved sea walls are more expensive than flat ones but are more effective as they deflect the waves back out to sea
• gabions

  Steel wire mesh cages filled with pebbles or rocks. they are placed at the back of a sandy beach to create a low wall-like structure. water enters the cages and this absorbs and dissipates the waves energy, thus reducing rate of erosison. they can also be put at the base of a cliff to reduce the chance of landslides
• groynes

  wooden or stone structures built into the foreshore, extending from the beach to the sea. they are built at right angles and spaced at regular intervals, around 50 metres apart. they trap sediment and prevent longshore drift and the now built up beach slows down the wave energy because the waves have further to go before hitting the cliff
• rock armour

  made up of huge boulders of hard rock eg granite to create a barrier between land and sea. they are big enough to not be moved by large waves and it helps dissipate the waves energy
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  a sea wall

  
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  a gabion

  
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  groynes

  
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  rock armour