coastal defences

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  • Created by: harryc1
  • Created on: 16-09-16 11:44
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  • Types of Hard and Soft engineering used on the coastline of the UK
    • Revetments-slated wooden structures built at the base of a cliff
      • Positives
        • Effective for many years
        • Absorb wave energy through the slats
        • Can be cheap compared to other techniques
      • Negatives
        • Not effective in storm ciondition
        • Regular maintenance is required
        • Can make the beach inaccessible for tourists
    • Rip Rap-Large rocks placed in front of the cliff
      • Positive
        • Can be very cheap
        • Dissipates wave energy
        • Effective for many years
      • Negative
        • unattractive
        • Not effective in storm conditions
        • Can make the beach inaccesable for tourists
    • Re-curved seawalls- walls usually made of concrete; modern ones have a re-curved face
      • Positive
        • Reflect and absorb wave energy
        • Very visible- make residents feel safe
        • Effective for many years
      • Negative
        • Expensive to build
        • Ugly- puts tourists off
        • Can cause wave scouring if not positioned correctly
    • Groynes- usually made of wood; stretch from the coastline into the sea
      • Positive
        • Effective for many years
        • Keep beach in place for tourist industry
        • Prevents longshore drift- sand builds up on one side of the groyne
      • Negative
        • Disrupt the natural processes working on the beach such as longshore drift
        • Unatractive-ndifficult to walk along the beach
    • Gabions- wire cages filled with stone used to reduce erosion
      • Possitives
        • Cheaper than other coastal defence
        • Rock cages absorb wave energy
      • Negatives
        • Wire cages can break-need to be ties down securely
        • Not as efficient as other form of coastal defence
    • Offshore reefs- large concrete blocks and natural boulders are sunk offshore to altar wave direction and to dissipate wasve energy and tides.
      • Positives
        • Allows the build up of sand due to the reduction of wave energy
        • Waves break further oiffshore and therefore reduce their erosive power
      • Negatives
        • May be removed by heavy storms
        • Difficult to install

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