Coastal defences

• Rock armour are large boulders of resistant rock, like basalt as an example. These large boulders are placed in front of the land to protect the land and the road directly behind the land from the force of the destructive waves. It is the destructive waves that are causing undercutting, leading to an overhang and collapse. Eventually the coastline begins to retreat, which is what is happening here. When rock armour is put in place, a destructive wave crashes into the boulders it then loses its force and hydraulic action is reduced and so the coastline is protected from erosion.
• Rock armour is a quick and cheap way to protect our coastline. This has worked in other places around Ireland such as Lahinch in County Clare.
• Rock armour

  
• Groynes are concrete or wooden walls or fences that

  are built out into the sea at right angles to the coast.

  They work to reduce longshore drift by trapping

  the sediment carried by waves. They trap the sand,

  which then builds up the level of the beach.

  An example can be seen at Rosslare, Co. Wexford.

  
• Sea walls are built to break the power of the

  incoming waves. They are curved at the top to push

  the waves back out to sea.

  An example can be seen at Bray, Co. Wicklow.

  
• Gabions are steel wire cages filled with stones. They

  are then stacked on top of each other where they

  act like a sea wall. They are used to slow down or

  prevent erosion by breaking the power of the waves.

  An example can be seen at Lahinch, Co. Clare.