Managed Retreat Case Study Uk Abroad

Activate Your Learning


Explore the pros and cons, including cost-benefits of managed retreat case-studies and consider examples of communities facing retreat as an option and the factors leading to these decisions.

While this activity is not for credit. You will be expected to know the material in quizzes and midterms.


Below are some text fields in which you will make a list of pros and cons of managed retreat vs. traditional “hold the line” methods of coastal management.

Mandatory Reading

The link below provides further information, including a discussion of costs and benefits. Use this information to help you answer the questions below.
Managed Realignment

Managed Retreat

Question 1: List the pros of managed retreat.

Click for answer.

  • Creates natural coastal habitat that provides protective functions
  • Initial costs are high but long term savings are likely
  • Provides a more sustainable long term solution
  • Returns land that floods regularly to natural habitat and reduces damage to property
  • Eliminates "coastal squeeze"

Question 2: List the cons of managed retreat.

Click for answer.

  • Causes controversy due to lack of understanding
  • Requires large initial financial investment
  • Requires long term planning
  • Requires community buy-in and cooperation of multiple agencies

Hold the Line - Traditional Engineering Methods

Question 3: List the pros of hold the line traditional engineering methods.

Click for answer.

  • Each project may be less expensive than managed retreat
  • Public tend to trust hard engineering
  • Less disruptive
  • Requires less long-term planning and cooperation among agencies

Question 4: List the cons of hold the line traditional engineering methods.

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  • Projects often need to be rebuilt often (especially sand re-nourishment and dune building etc.)
  • Overall long-term costs can be higher than managed retreat due to repeated rebuilding needs
  • Hard structures such as sea walls, breakwaters, groins, etc., can cause increased erosion rates down drift of the project, creating problems elsewhere and for other communities.

Main Factors

What are the essential elements that allow for managed retreat? Look back at the examples in the U.K. and the U.S. What are the main factors that lead to success in the examples?

Question 5: List the main factors that lead to success in the US Examples (California Coast)

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  • Community buy-in with multiple user groups reaching consensus.
  • Scale - relatively small
  • Available funding
  • Long term sustainability planning was feasible

Question 6: List the main factors that lead to success in the UK Examples.

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  • Community buy-in and overcoming disagreement.
  • Tourism from creation of bird preserve
  • Reduction of flood risk
  • There may be others.

Your Conclusion

Write a concluding paragraph based on the facts you have gathered in the above questions.

Question 7: Explain which method of coastal management – traditional use of structures to "hold the line", or managed retreat, you think will prevail fifty years from now.

Click for answer.

There is not a right or wrong answer to this question, what you wrote will depend on your opinion. Generally, you may conclude from the material covered that there is a trend away from hard engineering as the solution to coastal erosion etc. and towards a more managed approach, with soft engineering and examples of managed retreat. More sustainable coastal management practices will likely prevail in 50 years than today. More communities will accept the necessity to practice some form of retreat, including long term planned and managed retreat as in the examples. Other communities may be abandoned or partially abandoned.

Case Study - Medmerry, West Sussex

Project Synopsis

Medmerry is the largest managed realignment of the open coast in Europe, on the stretch of coast that was most threatened by coastal flooding in South East England. The Environment Agency (EA) has built 7km of new flood embankment on higher ground and has breached the existing defence, creating intertidal habitat to compensate for Natura 2000 (N2K) loss elsewhere around the Solent. The scheme mitigated for the loss of freshwater SSSI and the impact on important populations of protected species, and created an accessible landscape-scale nature reserve in collaboration with the RSPB and the local community. The Medmerry scheme had 3 key objectives: 

1) Sustainable flood risk management: It will provide a higher standard of protection to 348 properties in Selsey, as well as key infrastructure such as the main road and waste water treatment works. 

2) Creation of compensatory intertidal habitat: Delivering 183ha of intertidal habitat, including mudflat, saltmarsh and transitional grassland. 

3) Involvement of local communities: Creating new access routes and viewpoints for walkers, cyclists and horse riders, and linking Selsey to Bracklesham. 

ASE was commissioned by the Environment Agency to undertake archaeological mitigation works during the Medmerry Managed Realignment, Europe's largest managed realignment scheme.  The works involved the archaeological mitigation of over 40 hectares of relief channel, borrow pit, access road and service trenching across the c. 450 hectare site from August 2011 to November 2013.  Site conditions were challenging and the persistent wet weather from mid 2012 to early 2013 eventually forced a pause in works from January-March 2013.  Further information about the project can be found at Environment Agency website.

Descriptions of Works

ASE managed the archaeological fieldwork and advised the Medmerry Project team on the risks posed to the project by archaeology and how they could be mitigated.  These risks were a result of; the scale of the ground works, the increasing significance and extent of finds being recovered and the inability to fully evaluate areas ahead of mitigation. ASE employed different methodological approaches to reduce the risk of delay to the construction programme as a result of archaeological works.  ASE also offered advice on the management of the archaeological costs of the project and how archaeological mitigation could most effectively be programmed.  ASE contributed to what became a close working relationship between the various contractors, designers and client, that successfully delivered a complex and time constrained programme of works. 

The Results

Extensive Bronze Age remains dating to c. 1,000BC were recorded across the site including houses, wells, industrial sites and funerary remains.  These finds suggest a level of population and structure within the Bronze Age landscape not previously observed in Sussex.  

A c. 200m long medieval timber structure constructed of wattle 'sails' was uncovered, preserved in silts at the base of a wide channel.  The structure has provisionally been interpreted as a fish weir and is the first discovered in Sussex.   

The works also highlighted the role the site played during WWII with pill boxes and plane crash sites dating from 1940-41 and an air to ground attack training ground from 1943, which continued in use until the early 1960s.  

Palaeoenvironmental sampling is proving to be key in relating change observed within the archaeological record with contemporary environmental and climatic conditions.   This work has already identified and dated a number of ancient storm surge events and ongoing post-excavation work is expected  to establish how environmental conditions altered over the last c. 6,000 years.  This work will contribute to our understanding of how climatic and environmental change affects human populations, a pertinent issue relating directly to this site and the local population.  

Page last modified on 14 aug 14 12:39



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