8.4 Sustainable management of coasts Flashcards
issues of sustainability
- complex, difficult to achieve
- cannot achieve all aspects of sustainability simultaneously:
1. in order to protect environment, have to sacrifice economic aspects, e.g natural scenery means infrastructure unable to be built
2. to achieve social sustainability, sea defenses cannot damage human lives/homes: - spatial and temporal problems: varies in location: LICs have less funding for management strategies/rely more on coasts for large proportion of income so prioritise economic sustainability. Sustainable management in one area may result in further sea erosion further down the coastline, due to reduced erosion in one place leading to deterioration in another place
3. over time climate change = strategies may no longer be sustainable in long term
4. is all coastal management futile: only because of people we have this problem?
different methods of coastal management
- do nothing
- managed retreat: soft engineering
- hold the line: hard engineering
- advance the line
shoreline management plans and how are they decided
- drawn up for every coastline, operate separately but with consideration of others
- usually done on economic basis as easiest to measure
- ratio of 1:5 (every 1 pound spent, 5 point worth saved)
- vulnerability of people - **>45,000 people = hold the line, >9,000 **vulnerable people = hold the line
- other factors: special scientific place, historical/culturally significant
costs and benefits of management
Costs:
Soc:
- reduced recreation/accessibility of beach
- visually unattractive
Ec:
- land prices will rise (home buyers, rent for restaurant owners up)
- maintenance and cost of repair
Ev:
- increased erosion down drift as LSD prevented/slower
- disruption of ecosystems
Benefits:
Soc:
- peace of mind for residents
Ec:
- employment in defence work (but not if employing from elsewhere)
- land prices will rise (land/home owners)
Sustainability:
- economically for some: rise in land prices benefit home owners but not restaurant owners
- peace of mind for residents, but may offset with spoil in natural beauty
- employment may not help if workers not local as need specialist skills
different kinds of hard engineering
-
vertical sea wall:
- maintains the line, socially reassuring
- high cost (over US $4500 per metre), reduced access to beach -
recurved sea wall:
- waves reflected back so dont cause basal scour
- very expensive and concrete not pleasing to eye -
groynes:
-cheap and encourages deposition widening beach so absorbing wave energy
- encourage tourists
- only last 20 years, so maintenance cost high, visually unappealing, and can cause problems downdrift where beaches depleted of sediment/erosion increases -
Breakwater:
- sheltered harbour for small boats/reduced erosion
- very expensive and problems of basal scour and downdrift starvation can increase erosion rates further along -
Gabions:
-cheap to build - 20 gabions = US$1500
- very short lifespan, often no more than 5 years so maintenance costs high, unsightly and wire can be dangerous once it rusts -
Revetment:
- sloping wall parallel to coast
- relatively cheap, very little wave reflection and no basal scour
- over-topping by waves problem at high tide, if damaged erodes very quickly = maintenance -
Rip-rap:
- dissipate wave energy effectively, quite cheap, natural look
- transport costs significant, dangerous if people walk on them (kids?)
soft engineering strategies
-
beach nourishment:
- low initial costs, build beach = bigger buffer, attracts tourist/aesthetically pleasing
- requires constant maintenance (longshore drift removes sediment) considerable local disruption during construction phase -
Sand dune conservation:
- well managed systems allow access to dunes/beach without excessive trampling
- high initial costs, maintenance required -
Managed retreat:
- much cheaper than strengthening existing sea wall, saltmarsh provides feeding ground for migrating birds
- initial works costly/disruptive, compensation for lost productive farmland -
cliff regrading:
- cliff becomes more stable/less prone to unexpected movements
- not unsightly once naturalised
- often expensive, disruptive, unsightly during construction phase
- removes natural cliff line = major ecological impact (nesting birds) -
cliff drainage:
- very little environmental impact apart from construction phases
- expensive -
planning controls:
- cheap, ensures future problems do not arise
- appeals against planning decisions can be long/costly
- does not solve current problems related to building already taking place
sustainability of hard engineering
Sustainable features:
- encourage tourists through widening of beach/features e.g sea wall provide pathway/fishing spots
- construction/maintenance of feature = job opportunities (less sustainable if not local workers) = higher consumption as higher disposable income = economic growth
- socially reassuring = boost tourism?
- prevents displacement of locals/homes
- maintains land value
- prevent destruction of fragile ecosystems
Unsustainable:
- can deter tourists if visibly unattractive/long time to build
- increase erosion further down coastline = shifting problem not solving?
- high costs/need for further investment over time for management reducing available money for other services = social impact?
- encourage more tourists = further issues = trampling?
- sea level rise = sea wall may not protect against waves that go over it
sustainability of soft engineering
Sustainable:
- low costs - suitable for LICs
- visually attractive - bring more tourists
- maintains access for people
- salt marsh able to cope with climate change - long term
Unsustainable:
- increased erosion elsewhere if sand removed for beach renourishment elsewhere
- issue of invasive species/disease from movement of different sand
- maintenance cost - replenishment repeatedly for beach renourishment as sand eroded away
soft engineering last longer because hard engineering have physical limit?
reasons for erosion/defences in North Norfolk coast
- Geology of cliffs: uncosolidated and made of boulder clay, soft sand, silt and gravel
- Sinking land: sea levels rising
- High level of groundwater in cliffs:
- vulnerable to slips/landslides due to unstable
1953 storm surge:
- 1000 lives in norfolk alone, communities devastated
different strategies in north norfolk coast
- managed realignment - pathfinder scheme: Happisburgh
- hold the line: eccles on sea
- advance the line: off shore reef: sea palling
managed realignment - Happisburgh
location:
- 1400 people
- village has 14th century listed stone church and only independent run lighthouse in UK
Details of strategy:
- the pathfinder scheme: introduced by the UK government in 2009, was an £11 million fund distributed to 15 local councils to explore innovative ways of managing coastal change, happisbrugh received 3 million of this
Key actions taken:
1. Property Acquisition and Compensation
2. Community Relocation
3. Demolition of at-risk structures
4. Public Engagement
5. Creation of Green Spaces
comment on sustainability of managed realignment in happisburgh
Social:
- loss of number of local heritage sites: upset locals/loss of community from damaged housing/moving
- limited funding = small number who qualify for compensation, so those who live bit further away get nothing: issue in future?
- elderly unable to move?
+preparing community for future (giving warning/compensation), reduces homelessness in future
Economic:
+loss of infrastructure not sufficient to economically justify building new defences
+access to beach = tourism continues = businesses may still benefit
Environment:
+land-use can work with coastal erosion so does have longevity
- if were to build up beach to defend = starved beach elsewhere - avoided
- cleaning up debris through removal = protect the environment
hold the line strategy in north norfolk coast
Location:
- Eccles on Sea
- 200 homes, 400 people
Details:
- seawall: £500 per metre: sea wall protected coast for many years but in last 15 has begun to undercut
= groynes/revetments (£1500 per meter)
Sustainability of hold the line strategy in Eccles on Sea
Environment:
+ short term prevent loss of habitats/land
- increased erosion elsewhere and disrupts sediment transport
Economic:
+ protect high value properties and reduces cost associated with damage/displacement in short term
- long-term costs outweigh benefits if erosion rates accelerate or se defenses require upgrades
Social:
+ peace of mind, preserving community cohesion (reduced displacement risks)
- long term less effective as will reach point when sea is above the wall
advance the line strategy in north norfolk coast
Advance the line: Sea Palling:
location;
- 25 sites of special scientific interest
- population: 6,500 + 7 million visitors a year, brings approx 2.5 billion to local economy each year
- tourism accounts for 14.5% of employment in norfolk
details of the strategy:
- 9 offshore reefs (£9 million total)
- refraction between first 4 reefs led to increased erosion - uneven pattern
- first reef trapped sand behind (act as groyne), further down reefs less effective as less sediment so made other reefs shorter/closer together so less sediment erosion
