Coast

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  • Created by: lauuren
  • Created on: 22-03-14 20:17

Coastlines

Waves

 Constuctive waves have a stong swash and weak backwash, whereas, Destructive waves have a stong backwash and weak swash   

The formations of Caves, Arches, Stacks & Stumps

  • Sea erodes cliff (Hydraulic Power) and creates cracks
  • Water gets into cracks, making them longer and they form into small caves(Corrosion)
  • Air trapped in cave increase pressure and can lead to cave breakthrough (Arch)
  • Under-cutting cause arch to collape, leaving part of the cliff detached, called a Stack
  • Futher under-cutting causes the stack to erode, forming a stump, which may be covered in high tides

Headlands and Bays are Erosional Landforms

Resistant hard rock is eroded slower by waves than less resistant soft rock, leaving the hard rock jutting out. These are called headlands. The eroded soft rock leaves bays carved into the cliff.

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Hard Engineering - Man-Made

Sea Wall

  • Concrete or rock wall barrierat foot of cliff or top of beach
  • Curved face to reflect waves, usually 3-5m high (£6million/km)

Advantages:           Stops the sea and has a walk way                                                     Disadvantages:      Obtrusive and unnatural. Expensive and high maintainance cost.

Groynes

  • Timber or rock structure build out to sea on the coast (£10,000 each)
  • Acts as a buffer, reduces wave attacks and stops LSD
  • Results in bigger beachs, enhancing tourist potential

Advantages:          Not too expensive and useful for fishing                                                 Disadvantages:     Timber groynes erode quickly. Starves south beaches (shifts problem)

Rock Armour (Norwegian Granite)

  • Large boulders at foot of cliff, forces waves to break
  • Absorbs energy and protects the cliff (£1,000 - £4,000/meter)

Advantages:         Cheap and easy to maintain. Provides interest to the coast                        Disadvantages:     Expensive to transport and very obtrusive (don't fit in with the local geology)

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Soft Engineering - Natural

Beach Replenishment (Addition of Sand or Shingle)

  • Making the beach higher and/or broader                                                                              Advantages:     Obtained locally (blends in with existing beach material) Bigger beaches                            increase tourist potential. Cheap and easy to maintain (£3,000/metre)

Dune Regeneration

  • Effective buffers damaged and destriyed by trampling
  • Marram grass planted to stabalise dunes and help them to develop (Areas fenced off)   Advantages:      Relatively cheap (£2,000/100 metres) Natural coastal environment and                                popular with people and wildlife                                                               Disadvantages:   People not happy to be prohibited and easily damaged by storms.                                      Time consuming to plant grass and fance off areas

 Marsh Creation (Managed Retreat) 

  • Allowing low-lying coastal areas to be flooded (Salt Marsh = effective barrier to the sea)  Advantages:       Creates needed wildlife habitats, cheap (£5,000-£10,000/hectare)  Disadvantages:  Land will be lost (Landowners need compensating)
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Long Shore Drift

  • Waves follow the direction of the prevailling (most common) wind
  • They usually hit the coast at an oblique angle (not 90*)
  • The swash carries material up the beach in the same direction at the waves
  • The backwash then carries the material back towards the sea
  • The backwash is always pulled back down the beach at a right-angle, due to gravity
  • Over time, the material zig-zags along the beach in the direction of Sediment Movement

Beach                                         Sediment Movement

                      Swash                                                              Backwash

Sea

                                                  Direction of                                                                                                                                        prevailling wind

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