Coastal defence

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  • Created on: 04-02-09 18:22
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Costal Defence
When managing the coastline there are two main options:
1. Hard Engineering, where manmade structures are used to reflect large amounts of
wave energy and thus protect the coastline
2. Soft Engineering, where beaches and other natural material are used to control or
redirect erosion processes. See: Erosion Processes
Hard Engineering Techniques
Recurved sea wall
Deflects the power of the waves
Very expensive, up to £12 million/kilometre
Very effective
Can be undermined as deflected waves can scour
material at the base of the wall
Wall itself is eroded
Protect against flooding
Deflected waves may wash beach material
Rip Rap
Also known as rock armour
Absorb wave energy and break the power of waves
Comparatively cheap
Can be ugly, changing the appearance of the coastline
Can be undermined as sand underneath is washed away
or moved
Stops longshore drift to anchor beach material
protecting the base of cliffs
Effective at reducing erosion in the area they are placed
May starve areas further down the coast increasing
erosion in these areas
Protection from flooding
Cages built into the cliff face to protect cliff from the force
of the waves
Cheaper than sea walls and can be effective in areas of
severe erosion
Visually intrusive

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Breaks the force of waves and beach material builds up
behind them
More effective than sea walls
Visually intrusive
Need to be replaced fairly often
Soft Engineering
Beach nourishment
Beach material is added to provide a `natural solution'
Maintains beauty of landscape
Expensive to maintain and longshore drift moves
material down the coast
May cause environmental damage to obtain material
Sand dunes
Natural barriers to the waves
Marram grass planted reduces erosion
As does footpath control
Supports the local ecosystem
Salt marshes
Plants…read more


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