Coastal risk, resilience and management

• Hard Engineering: Sea Wall

  How it works: they protect the inland area against wave action and prevent coastal erosion by reflecting wave energy

  Cost: £5000 to £10 000 at 200m intervals

  Advantages: effective erosion prevention, promenade has tourism benefits,

  Disadvantages: visually unappealing, expensive to construct and maintain, wave energy is reflected so erosion with happen elsewhere at higher rates

  Material: concrete, stone, sheet piles
• Hard Engineering: Gabions

  How it works: Metal cages that contain rock, usually constructed at the base of cliffs to absorb wave energy and reduce erosion

  Cost: less than £250 per metre

  Advantages: relatively cheap, absorbs wave energy, local rocks used

  Disadvantages: not very strong, if mesh breaks there a risk of injury

  Material: metal and rock
• Hard Engineering: Offshore breakwater

  How it works: rock barrier which forces waves to break before reaching the shore, usually parallel or close to the coast ->fixed or floating

  Cost: depends on the material but similar to rock armour

  Advantages: reduces incoming wave energy, provides sheltered beach area, shelters vessels from waves and currents

  Disadvantages: semi-permenant structure, relatively costly, floating not as effective, potential navigation hazard

  Material: stones and rocks from local geology
• Hard Engineering: Cliff Drainage

  How it works: eliminating surface run off and infiltration on the slope, done by pumping water out of the cliff by digging ditches and using pipes

  Cost:

  Advantages: prevents landslides/mass movements, no build upon impermable and saturated clays

  Disadvantages: cliff is still open to erosion

  Material:
• Hard Engineering: rock armour

  How it works: large rocks placed at the foot of a cliff or at the top of beaches, forms a permeable barrier and this breaks the waves energy

  Cost: £1000 to £3000 m

  Advantages: relatively cheap and easy to construct and maintain, often used for recreation

  Disadvantages: intrustive, rocks not from usually geology, dangerous

  Material: rocks
• Hard Engineering: embankments

  How it works: earthfilled structures to contain high river levels

  Cost:

  Advantages: safer from flooding, provides habitat

  Disadvantages: big visual impact, beaches may become inaccessible, disrupt the dune process

  Material:
• Hard Engineering: revetments

  How it works: sloping structure placed at the foot or toP of cliff/beach to break the waves energy

  Cost: £4500/m at its highest

  Advantages: relatively cheap

  Disadvantages: unnatural and high levels of maintenance

  Material: wood, concrete or rock
• Soft Engineering: beach nourishment

  How it works: addition of sand or pebbles to an existing beach to make it higher or wider with the sediment usually being dredged

  Cost: £300/ m

  Advantages: relatively cheap, easy to maintain, looks natural, increases tourist potential

  Disadvantages: needs constant maintenance

  Material:
• Soft Engineering: cliff regrading and drainage

  How it works: cliff regrading reduces the angle of the cliff to help stabilise it, drainage removes the water through piping in the cliff to prevent landslides and slumping

  Cost: it varies

  Advantages: can be effective on clay or loose rock where other methods wouldn't, drainage is cost effective

  Disadvantages: regrading causes the cliff to retreat, drained cliffs can dry out and lead to collapse

  Material:
• Soft Engineering: dune stabilisation

  How it works: marram grass can be planted to stabilise dunes. Areas can be fenced in to keep people off newly planted dunes.

  Cost: £2 -£20 metres

  Advantages: maintains a natural coastal environment, provides wildlife habitats, cheap and sustainable

  Disadvantages: time consuming to plant, people may walk over it

  Material:
• Soft Engineering: marsh creation

  How it works: form of managed retreat, by allowing low-lying coastal areas to be flooded by the sea. The land then becomes a salt march

  Cost: cost varies over how big the land is

  Advantages: relatively cheap, creates a natural buffer to powerful waves, creates an important wildlife habitat

  Disadvantages: agricultural land is lost, farmers/landowners need to be compensated

  Material:
• Cost Benefit Analysis:

  • carried out before a coastal management project is given the go ahead
  • costs are forecast and then compared with the expected benefits. Costs and benefits are 2 types:

  > tangible = where costs and benefits are known and can be given a monetary value

  > intangible = where costs may be difficult to assess but are important

  A project where costs exceed benefits is unlikely to be given permission to go ahead
• Traditional Approaches:

  • coastal approaches can be prevented up to a point but it is expensive to do
  • it is often controversial
  • hard engineering until the 1990s was tackled by local councils but it was expensive
  • soft engineering is now more popular
• Sustainable integrated approaches:

  • soft-engineering schemes often adopt sustainable principles but only when protecting a small stretch of coastline and the environment
  • government and non-government agencies are looking more holistic
  • holistic ---> parts of something are interconnected and can be explained only by reference to the whole.
• Sustainable integrated approaches: Shoreline Management Plans (SMP)

  • End of 20th century, integrated plans for coastal management in England and Wales were given a structure around the sediment cell systems.
  • E.A., local councils, DEFRA, Natural England and National Trust are all involved in collecting data, consulting planning and agreeing policies.
  • Aim: Identify the most sustainable approaches to managing flood and coastal erosion risks to the coastline over: Short term – 0 to 20 years, Medium term – 20 to 50 years, Long term – 50 to 100 years
• SMP’s must be flexible, adapting to changes in areas such as legislation, politics and social attitudes towards funding coastal defence.

  In essence, do not commit future generals to inflexible and expensive defence of coasts.

  22 larger SMP’s, smaller-scale management units have been identified and implements called Strategic Coastal Defence Options (SCDO’s)
• SMP'S: SCDO'S

  1. Hold the line -Maintain and/or strengthen existing defences to prevent any flooding or erosion; rebuild
  2. Advance the line - Construct additional defences seaward of the current coastline;
  3. Managed retreat/strategic realignment - Let natural processes operate to allow the development of landforms such as salt marsh which can then act as defences
  4. Do nothing/ no active intervention - Natural processes are not prevented from operating so that the coastal zone system functions with no interference
• Sustainable integrated approaches: Integrated Coastal Zone Management (ICZM)

  • Rio de Janeiro summit encouraged all types of environmental management to be holistic.
  • This required both natural and human factors be taken into consideration as well as sustainability.
  • Aim – Establish sustainable levels of economic and social activity; resolve environmental, social & economic conflicts while protecting the coastal environment.
  • This means that complete sections of coastline are managed as a whole rather than individual towns/villages
• ICZM: Integration in several ways:

  Among all elements in the physical environment

  Among sectors of human activity e.g. fisheries, tourism, settlement, transport

  Among level of government – local, regional and national

  Among countries – sediment transport does not stop at international border

  Among perspectives such as scientific, cultural, political and economic.
• Why we needed change:

  • traditional methods of hard and soft engineering was often done locally and in a piecemeal manner
  • often this lead to further issues down south
  • e.g. building a sea wall -> further down coast == reduce but the output would stay the same, leading to many negative impacts e.g. cliff recession increase, spit shrinkage, salt marsh erosion etc.
• risks and opportunities of inhabiting the coastal regions of the world:

  • Risks -> flooding, loss of life, property damage, coastal erosion, loss of property, sea level rise
  • Opportunities -> fishing, salt extraction, industry, trade, energy generation, recreation, tourism
• The threat of cliff retreat:

  • soft rock is eroded at a quicker rate when compared to hard rock
  • amount of material which is eroded exceeds that which is deposited. Stabilisation techniques are used to limit the amount of erosion and the potential for landslides, collapse and falling rocks.
  • rates of cliff retreat will increase by up to an order of magnitude by 2100 according to current predictions of sea-level rise: an increase much greater than previously predicted
  • Climate change is accelerating sea-level rise (SLR) and, with coastal urbanisation increasing worldwide
• SMPs were developed by coastal groups between 2006 and 2012.

  Coastal groups include:

  the Environment Agency

  local authorities

  others with an interest in coastal management
•  Shoreline Management Plan Explorer is an online tool that makes shoreline management plans easier to access and use.

  It is available for:

  • coastal managers
  • local authority planners
  • the public, including communities living on the coast
• You can use the Shoreline Management Plan Explorer to view:

  SMP management approaches and actions for each section of coast

  where changes to management approaches have been made and why

  areas protected for their environmental, historic or landscape importance which must be considered when deciding the approach to managing flood and erosion risk

  guidance on how shoreline management plans are developed and updated
• Human Intervention at the coast:

  • United Nations Environment Programme (UNEP) -> over half the worlds population lives within 60 KM of the coast and 3/4 of all major cities
  • coasts are under immense pressure
  • habitat destruction
  • large number at risk of erosion
  • human intervention to address these coastal issues can take many forms