ICMZ

• why are somerset levels particularly at risk of sea level rising

  - being close to the sea means more risk

  - planet is warming

  - sea levels move up and down by 14m
• December 1981


  - low pressure winds created a storm surge of 1.7m on top of the high tide

  - 1,072 homes flooded

  - 6 million pounds of damage

  - 12,500 acres of land has sea water
• shoreline management approaches


  1) hold the line

  2) managed retreat

  3) advance the line

  4) no active intervention
• hold the line


  intervene against coastal erosion with hard or soft engineering to prevent any further shoreline retreat.
• managed retreat


  realignment of the coast to a pre-determined line some distance further inland from the current position of the coast (see above)
• advance the line


  - : extend the coast into what is currently the sea. (Very few examples around Britain, but the basis of Dutch polder reclamation and construction of man-made islands in Tokyo Bay).
• no active intervention


  - permit natural systems to modify the coastline as they are currently operating. It usually means allowing erosion and cliff retreat to continue.
• sea walls (hard engineering)

  - large concrete curved wall reflects wave energy

  + effective, easily made

  - expensive, not permanent

  eg swanage beach , dorset
• revetments (hard engineering)


  - porous design to absorb wave energy

  + easily made, cheaper than seawalls

  - lifespan limited

  eg holderness coast UK

  
• gabions (hard engineering)


  - rocks in cage absorb wave energy

  - cheap

  - hard to lift , small scale

  - seaton beach, devon,uk
• groynes (hard engineering)


  - prevent longshore dirft, perpendicular wooden platforms, trap material

  + cheap, good for fishing

  - interuupt sediment flow, unattractice

  eg New timber groynes installed in Swanage beach in 2005-6 reducing the loss of beach material
• rock armour (hard eingeering)

  - large rocks at base of cliff abosrb cliff energy

  +cheap

  - hard to transport

  eg Lyme regis
• offshore reefs (Soft engineering)

  - waste materials eg old tyre weighted down to reduce speed of incoming wave

  + low technology, cost effective

  - damage marine

  eg sea palling, norfolk
• beach nourishment (soft engineering)

  - sand pumped from seabed to replace eroded sand

  + looks natural

  - expensive, shot term solution

  eg skegness, lincolshore
• managed retreat (soft engineering)

  - relocation of residents and removal of structures and infrastructure

  - costs money to relocate people

  + reduces risk of flooding
• lyme regis (location)


  - small town on south coast of UK, makes up jurrasic coast

  - south west Dorset
• opportunities at lyme regis

  - tourism is biggest industry

  - eg boat trips, water sports

  - 37,500 employed in tourism sector 65% in coastal area
• hazards of Lyme regis

  - rapid rates of coastal erosion and landslides

  - built on limestone so is solid on top of it are clays and sands which slide over limestone to form landslides

  - beach is eroding as sea erodes bottom of land causing unstable land

  - houses damaged due to landslide, black venn is most active coastal landslide
• management


  - management plan divided into 4 zones and phases, east cliff, monmouth beach, the cobb and the harbour to cobb gate

  - £35 million spent since 1994 to prevent coastal erosion to protect homes, roads and infrastructure

  - 480 homes saved from damage

  - cables have been protected
• porblems with management


  - expensive for small community

  - protection only lasts 50 years meaning more money will need to be spent
• startegies for management phase 1

  - built a new sea wall and promenade with rock armour east of the mouth of the river finished in 1995
• phase 2


  -work from 2005- 7 cost £17 million- removal of old wooden groynes repalced by big stone groynes- beach was replenished with sand and shingle to absorb wave energy and protect sea wall from erosion- rock armour added to the end of the cobb harbour
• phase 3


  -built a 390m stretch of sea wall in the eastern part of lyme regis- slopes at christ church and east cliff stabilised- £!9.5 million spent on this phase
• benefits


  -long term protection for erosion- more sand and shingle for beach so better erosion- calmer conditions for boards in harbour and bay