3.1.3.2 Coastal Landscapes in the UK - Medmerry Case Study - Coastal Management Strategies (Managed Retreat)

Question 1

Managed retreat:

Answer 1

form of soft engineering where low-lying and low value land is allowed to naturally flood so defences can be improved further inland

Question 2

How is managed retreat a natural defence for the coastline?

Answer 2

• managed retreat allows floodwater to encroach on the land up to where the land is naturally higher
• this gives more space for wave energy to be absorbed
• as salt marsh and vegetation develops it provides natural defences against storms
• an earth bank is also built
• this is a natural looking feature that provides protecting in the even of a severe storm

Question 3

How is managed retreat a sustainable option?

Answer 3

• in long-term, allowing managed retreat is more sustainable option than spending large sums of money trying to protect the coast with sea walls or groynes
• long-term option that recognises how the benefits of protecting low-lying land are outweighed by the costs
• salt marshes often develop from flooding associated with managed retreat
• this can become a natural form of coastal protection as mud is deposited and forms barriers against the waves
• it can also create new and valuable wildlife habitats
• as sea levels continue to rise, managed retreat seems likely to become an increasingly popular choice for managing the coastline

Question 4

Why might managed retreat not be feasible for some parts of the coast?

Answer 4

• The value of the land e.g. high value agricultural land which is fertile and high yielding and contributes to food production is unlikely to be flooded - however, low-value grazing land could be
• Physical and human geographical features need to be considered
• Unique or high biodiversity or an important ecosystem would not be considered a feasible location to flood
• Topography – only low lying land would allow the sea to flood a large enough area

Question 5

Aims of managed retreat:

Answer 5

1. Improve coastal stability
2. Protect areas of land further inland rather than those near to the coast
3. Create natural defences to absorb and reduce the force of the waves e.g. salt marshes

Question 6

SMP’s:

Answer 6

• Shoreline Management Plans
• identify most sustainable approach to managing flood and coastal erosion risk in the short term (1-20yrs), medium term (50yrs) and long term (50-100yrs)

Question 7

4 approaches to coastal management:

Answer 7

• no active intervention - sometimes known as ‘do nothing’, this is where there are no current plans to build defences
• hold the line - maintain current defences
• advance the line - increase coastal defences to extend the coastline out to sea
• managed retreat (realignment) - allow the coastline to achieve a new position further inland

Question 8

What do SMP’s take into account?

Answer 8

take into account of the likely changes associated with climate change e.g. rising sea levels

Question 9

What is coastal management being driven by?

Answer 9

• increasingly coastal management driven by costs and benefits, with only those areas of high-value lends protected by costly engineering schemes
• elsewhere, where he lands is relatively low value e.g. farmland or moorland, the ‘do nothing’ approach most likely to be adopted
• here it is more appropriate for people to adapt by relocating further inland
• this may involve moving mobile homes on a holiday park, relocating a coastal path or altering a golf course
• however, homes may be permanently lost in some locations

Question 10

Where is Medmerry located?

Answer 10

stretch of coastline on the south coast of England near Chichester, West Sussex

Question 11

How big is the realignment scheme in Medmerry?

Answer 11

Medmerry is largest managed coastal realignment scheme in Europe

Question 12

What was the coast at Medmerry previously used for?

Answer 12

flat, low-lying coast use for farming and caravn parks

Question 13

Why is the managed retreat scheme taking place at Medmerry?

Answer 13

• for many years, the land was protected by low sea wall, but now in need of repair - building a new sea wall to protect area against future sea level rise very expensive option so managed retreat scheme chosen
• given relatively low value of land, it was decided to allow Sea to breach the current sea defences and flood some of the farmland that was previously protected

Question 14

How much does the Medmerry scheme cost?

Answer 14

costs £28mn

Question 15

What will the Medmerry scheme do?

Answer 15

• create a large natural salt marsh to form a natural buffer to the sea
• help to protect the surrounding farmland and caravan parks from flooding
• establish a valuable wildlife habitat and encourage visitors to the area

Question 16

What has been done so far at Medmerry?

Answer 16

• embankments have been constructed inland to give protection to farmland, roads and settlements
• alteration of the coastline is called coastal realignment

Question 17

Advantages of Medmerry managed retreat scheme:

Answer 17

• Social:
  
  • It may help take the pressure off areas further along the coast and reduce their risk of flooding
• Economic:
  
  • It is often cheaper in the long term to use managed realignment than to continue to maintain hard engineering defences
• Environmental:
  
  • Managed realignment is designed to conserve or enhance the natural environment
  • It creates new intertidal habitats that compensate for those lost through coastal squeeze

Question 18

Disadvantages of Medmerry managed retreat scheme:

Answer 18

• Social:
  
  • Relocation of people to new homes causes disruption and distress
  • If the long-term plan for the realignment of 40 sq km of North Norfolk coast goes ahead, this will destroy 6 villages
• Economic:
  
  • Short-term costs may be high. As relocation costs have to be paid
  • The recent Medmerry realignment scheme, in West Sussex cost £28 million, when it only cost £0.2 million a year to realign the shingle beach
• Environmental:
  
  • Large areas of agricultural land are lost
  • Habitats of coastal birds such as bitterns, cranes and marsh harriers would be affected, so bird numbers would initially decline
  • It may take a long time for them to reach their previous numbers