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

5. 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.
Rotational slumping caused by heavy rainfall and gravity causes the land to slip downwards and the coastline to retreat.

6. Comparing concordant and discordant coasts

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

8. 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

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

10. Managing coastal erosion

11. Beach material trapped behind the groynes
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

12. Longshore Drift
Groyne traps material on the up drift side leaving less beach down drift
This is a picture of one of the groynes – material is trapped behind the groyne stopping beach forming further along the coast

13. Advantages and Disadvantages of Hard engineering
type of defence
Advantages
Disadvantages
Sea Wall
Strong defence against the sea
Expensive - so only worth building where land is valuable and
costly to maintain
Gabions
Cheaper option
good defence on loose rock faces
ugly until vegetation starts to grow on them need replacing as the stones in the cages get eroded and metal corrodes
Rip rap
Good option as they take the energy out of the wave and can move. Very effective at cliff foot. Cheaper than a sea wall
Traps sea weed and litter between the rocks which can smell.
Unsightly and not good for swimmers at high tide.
Groynes
Traps the beach moved by longshore drift and protects the coast.Good for resorts which rely on beaches for tourists
Cause more problems downdrift (terminal groyne syndrome as at Barton (Highcliffe has groynes and so no sediment gets to Barton)

14. 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.

15. 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
This picture shows how they are stabilising the cliff

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

17. Hard engineering is where the defences try to stop the sea
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 seen on the Holderness Coast 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.