EQ4- coastal management Flashcards
(31 cards)
terminal groyne syndrome
-groynes cause sediment buildup on one side of the groyne(in direction of LSD) but starve the opposing side
-EG south of mappleton: used groynes but to the south materials are transported away from the beach but not replineshsed so at low tide its exposed+little sediment. led to ^ erosion+slumping. localised rate of erosion exceed 10m/year
hard
groyne
-stone or timber fences built perpindicular to coast+ spaced along beach
-prevent LSD movement of sediment+encourage deposition to build a higher+wider beach
-cost £150-250 per metre
-EG hornsea, withernsea+ mappleton
hard
sea wall
-concrete w steel reinforcement+deep piled foundatiosn. can have a stepped or bullnose profile, to dissipate wave energy
-physical barrier against erosion+flood barrier
-designed to dissipate not reflect wave energy
-destruction of natural cliff face+foreshore enviroment+can reduce beach volume if reflective+look unappealing
-cost £3000-10,000
-EG: porthcawl, holiday resorts: Hornsea+withernsea
hard
rip rap
(rock armour)
-large igneous/metamorphic rocks in front of sea walls/cliffs to absorb +dissipate waves
-often at base of sea wall to protect them from undercutting + scour
-no longer cheap+may move in severe weather+vegetate overtime
-£1300-6000
-EG withernsea+easington
hard
revetment
-massive stone,timber or interlocking concrete slopping structures which r permable used to reflect rather than resist waves+reduce swash distance by encouraging infiltration
-reduce erosion on dune faces+mud banks, +encourage deposition
-costly+dont cope well w v strong waves, may become vegtated
-EG Easington gas terminal
hard
offshore breakwater
-large igenous or metamorphic rock boulders (offshore riprap)
-reduce power of waves offshore+reduce erosive force
-encourages deposition between breakwater+beach can interfere w LSD
-mimic natural bars+reefs. can be built using waste material
-possible ecological impacts+may not work at large scale
-may not work large scale
scouring
when water erodes the sediments that surround the base or support structures for bridges, sea walls, roads, and other man-made buildings
soft
dune stablizing
-fences used to reduce wind speeds
-dune then replanted w marram +lyme grass to stabilise surface
-reduces erosion by wind+water
-fencing costs £400-2000 per 100m+replanting £1000 per 100m
-replanting can be very cost effective long term
soft
cliff regrading+drainage
-cliff lsope angles reduced to ^stability
-revegetated to reduce surface erosion
-incliff drainage reduces porewater(cost effective) pressure+massmovement risk
-drained cliffs can dry out +lead to collapse/rockfalls
-£1million per 100m
-can be disruptive during construction
EG
CD=small scale at easington
CR=mappleton
soft
beach nourishment
-artifical replenishment of beach sediment to:
-replace sediment lost by erosion, enlarge beach so it dissipates wave energy+reduces erosion n ^ amenity value of beach
-£20 million per km of beach
-ongoing costs r high
-sediment mustnt be sources from elsewhere in sediment cell
soft engineering
-works w natural phsyical systems+processes to reduce coastal erosion+flood threat
-less obvious+intrusive at coast
-may be cheaper in long term
-not suitable for all coasts
-involves accomadation working w natural processes
hard engineering
-involves control. used to overcome natural processes-stop or alter them (eg massmovement+erosion)
-reassuring, more resistant, can be used by tourists, a one off solution that could be used for decades
-requires lots of maintance, costs normally v high, even well designed engineering r prone to failure, coastlines r made unattractive+needs of coastal ecosystem r usually overlooked, defences built in 1 place frequently have adverse consequences further along coast
sustainable management
-involves adjustment working to secure future of coastline
-can lead to local conflicts in many places
-its managing the wider coastal zone: people + their livelihood, social+cultural well-being, safety from coastal hazards, +minimising environmental impacts.
sustainable coastal management
coastal communities r at threat bc
-rising global sea levels, but uncertainity about scale+timing of rise
-^frequency of storms +possibility of ^ erosion+flooding
-eg tuvalu, bangladesh
Sustainable coastal management types:
-Managing natural resources=long-term productivity
-Managing flood + erosion risk where possible, or relocating to safe areas
-Creating alternative livelihoods before existing 1s r lost to the sea
-Adapting to SLR by relocating, alternative building methods + water supplies
-Educating communities to understand why change is needed + how to adapt.
-Monitoring coastal change + adapting to unexpected trends
Adopting sustainable coastal management may lead to conflict because:
-coastal natural resources may have to be used less in order to protect them -some people lose income
-relocation may be needed where engineering solutions are too costly or not technically feasible
-some erosion and/or flooding will always occur, as engineering schemes cannot protect against all threats.
-future trends, eg SLR, may change, creating uncertainty and the need to change plan.
how r coastal management decisions made?
cost benefit analysis
-considers social+economic aspects of a stratergy
-the benefits of a scheem (new businesses/jobs+savings in lives n property) r divided by costs of building+maintaining it
cost benefit analysis: North Norfolk
-policy here=no active intervention
-to defend village would have an impact on wider coastal management plan: happisburgh would end up as promontory(high rock), blockin LSD+cause eorison downdrift
-long term plan= managed realingment, this would involve property being lost
CBA: north norfolk
COSTS
-£160,000 could be available to Manor Caravan Park to assist in relocating to a new site
-Affected residents could get up to £2000 each (a total costs of £40-70,000) in relocation expenses + cost to council of finding plots of land on which to build new houses.
-Grade 1 listed St Mary’s Church and Grade 2 listed Manor House would be lost.
-Social costs as the village is slowly degraded, including health effects and loss of jobs.
CBA: north norfolk
BENEFITS
-By 2105, between 20 and 35 houses would be ‘saved’ from erosion, with a combined value of £4 million - 7 million
-45 hectares of farmland would be saved, with a value of £945,000
-The Manor Caravan Park would be saved, which employs local people.
how r coastal management decisions made?
enviromental impact assesment/bipolar
-try to asses effects any stratergy will have upon an area
-especially important along coastlines as attrractive scneary+ecosytsems r valuable tourists assests
how r coastal management decisions made?
feasibility studies
-look at technical merits of a particular scheme +site
-considers all aspects n determines liklihood of it succeeding
-it may be denied primarly by return investment=so will project may enough profit to justify investment
-is engineering planned suited to local geology or coastal processes?
how r coastal management decisions made?
risk assesment
-involves taking decisions in light of likely recurrence interval+what is at risk
-insurance+legal claims will make this important considerations in future
how r coastal management decisions made?
shoreline management plans
-try to decide most appropriate scheme for each part of litoral cell(11 in england +wales), in discussion w parties
-coastal groups have been established based on litoral cell boundaries
-production= appointment of expert firms of consulting engineers to undertake study of all issues eg land use, enviroment protection, economics+action of coastal processes
-final report establishes management policy for coast defences by dividing into seperate management units+making specific recs for each unit
