Coastlines 3

Coastlines 3

DEFENDING THE COASTS
1. HARD ENGINEERING - using structures or machinery to control coastal processes (usually expensive)
  1. Sea wall - A concrete wall which is curved on the underside to deflect the power of the waves
    1. Advantages: Very effective and stops erosion
    2. Disadvantages: Expensive 1km=£1-2 million. Looks ugly and only lasts 75 years. However, compared to others it's quite a long time
  2. Groynes - Structures either wood or steel to stop longshore drift, anchors the beach material protecting the base of cliffs
    1. Advantages: Effective and traps sand. Cheaper as it is made of wood. £5,000 per metre
    2. Disadvantages: Don't last very long; 25 years. Visual impact not the best. Because they don't trap the sand, the next beach has less sand
  3. Rip Rap - Large bolders on the beach that absorb wave energy so they prevent erosion further up
    1. Advantages: Very effective of reflecting the waves. The boulders are very cheap, however the transport costs more
    2. Disadvantages: The sea could move them over time as they get eroded and become lighter in weight
  4. Gabions - Metal cage filled with stones. Placed in front of coast
    1. Advantages: They are cheap and are effective as they stop erosion. About £20 for 1 box
    2. Disadvantages: An eyesore. Metal looks unnatural on a beach. Only lasts 20 years as metal erodes.
2. SOFT ENGINEERING - when you work with nature. The most sustainable options which has less impact on the environment (cheaper)
  1. Beach Nourishment - Putting the sand back on the beach as it could of moved due to longshore drift
    1. Advantages: Looks natural. Continue to attract tourists and economy goes up
    2. Disadvantages: Have to keep repeating it due to longshore drift. Lorries, tippers and flatteners needed. Increase in CO2 emissions
  2. Manage Retreat - Letting the sea flood the land, farmland and areas of low value
    1. Advantages: Very cheap, effective and is natural
    2. Disadvantages: Doesn't stop anything from happening and doesn't solve anything. Becomes marshland. Debris deposited by sea
How should coastal environments be managed in the future?
1. Why are sea levels changing?
  1. Climate change causes water to expand as it gets warmer therefore the ocean sea level rises. Also ice sheets that cover parts of Antarctica and Greenland are melting and therefore flowing into the sea.
2. Why are some coastlines more at risk?
  1. Some coasts are sinking or subsiding. This is caused by river estuaries and deltas sinking under their own weight. As more sediment is deposited and becomes more compact, the land will start to subside. **NEW ORLEANS IS SUBSIDING 28MM PER YEAR!**. In some parts of England, the crust has been sinking ever since the ice melted 10,000 years ago at the end of the Ice Age. The parts that were covered in ice were under pressure but when the ice melted they began to rise as a result other areas subsided. This is called post-glacial rebound. The area in the UK that is subsiding is the South-East because of the Northern parts of UK were covered in layers of ice.
3. How will these changes to our coastline affect people?
  1. 1. Drainage problems 2.Land Subsidence 3. Increased coastal erosion 4. Higher river discharge 5. Tourism/economy decline
4. Counties will be affected by the rising sea level:
  1. Camarthenshire. Gloucestershire. Merseyside. Lincolnshire. Essex.
Its the council's responsibility to do these. Government has no legal duty. Each council has to come up with a shoreline management plan (SMP)

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