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Unit 1 Dynamic Planet Revision

Unit 1 Dynamic Planet Revision. Topic 5: Coastal Change. What you need to know. Impact of geology on the shape of coasts and types of landforms Marine processes such as erosion, deposition and transport plus sub aerial processes, mass movement and rising sea levels

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Unit 1 Dynamic Planet Revision

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  1. Unit 1 Dynamic Planet Revision Topic 5: Coastal Change

  2. What you need to know • Impact of geology on the shape of coasts and types of landforms • Marine processes such as erosion, deposition and transport plus sub aerial processes, mass movement and rising sea levels • A case study of a rapidly eroding coast - Barton on Sea - Dorset • Costs and benefits of hard and soft engineering • A holistic approach to management of coasts

  3. Geological structure and coasts • What features can you identify on this photograph?

  4. Unscramble the following coastal processes • onutsilo sponsenius • talasniot • tintocar • nolutios • inobaras • dilcuahyr cation • natitorit

  5. Practice Question (2 mins): Explain why the coast in the picture erodes rapidly (2 marks)

  6. Possible answers (For 2 marks you need 2 correct statements) • The rocks in the area are very soft and so the sea will easily erode the bottom of the cliff and then the cliff will slump due to mass movement.

  7. Comparing concordant and discordant coasts Map to show the geology of the Dorset coast True or false The south coast of Dorset is a concordant coast Swanage Bay is an example of a concordant coast

  8. Types of waves Typical question 2 marks How does a constructive wave differ from a destructive wave?

  9. Typical answer - 2 points = 2 marks • Destructive waves have a shorter wave length than a constructive wave • Destructive waves have a bigger wave height than a constructive wave • In a destructive wave the swash is smaller than the backwash while in a constructive wave the swash is bigger than the backwash 9

  10. Hurst Castle Spit N In what direction is the longshore drift? You have 2 minutes to draw a diagram to explain longshore drift

  11. For a quick animation have a look at this link http://www.learnnc.org/lp/multimedia/14706

  12. Managing coastal erosion Hard v soft engineering Hard engineering attempts to stop the sea examples include - sea walls, gabions, rip rap (rock armour), groynes. Examples along the Dorset coast include Bournemouth - sea wall and groynes Highcliffe - sea wall and groynes hurst Spit - rock armour at the start of the spit

  13. Holiday cabins at Barton on Sea are removed or moved further inland as the cliff erodes Beach material trapped behind the groynes Direction of Longshore Drift No coastal protection at Barton – and no beach as material is trapped by the groynes – therefore cliffs slump

  14. Longshore Drift Groyne traps material on the up drift side leaving less beach down drift

  15. Hurst Castle Spit Yacht marina at Key haven sheltered by the spit Hold the Line – by putting rip rap at the start of the spit and move shingle from the end back to the start. Salt Marsh LSD Groynes on the end of the spit

  16. Advantages and Disadvantages of Hard engineering

  17. Soft Engineering Soft Engineering works with the sea to protect the coast. 1. Beach replenishment where beach is added to help protect the coast eg at Bournemouth 2. Cliff regrading - used in areas with soft rocks, the cliff face is made less steep and may be then covered in netting to help stabilise it and allow plants and vegetation to grow through. 3. Drainage pipes to drain the water out of the cliff to help prevent it slumping.

  18. Netting covers the lower part of the cliff which has been bulldozed to make it less steep. Plants grow through the netting and stabilise the cliff Drainage pipes take the water out of the sand so that it doesn’t become too heavy and slump

  19. Integrated Coastal management Zone along Christchurch Bay

  20. Strategic Retreat Hold the Line Coastal Management along the Christchurch Bay coast

  21. Typical Question relating to coastal management • Using examples describe how hard engineering along coasts can cause more problems than they solve (4 marks)

  22. Hard engineering is where the defences try to stop the sea. This is not always good for example sea walls are very costly and need constant repair. Groynes may trap material in one place but it means the beaches further down the coast are starved of new material and the beach can disappear as at Barton in Christchurch Bay meaning the coastline is badly eroded. Rip rap can trap litter and sea weed which is a problem if the beach is a tourist attraction.

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