Coastal Management Flashcards
(46 cards)
What are the 3 reasons why humans may choose to intervene in natural processes at the coast?
Reduce rates of coastal erosion
Limited likelihood of coastal flooding
Protect coastal habitats and ecosystems
Give evidence that many people are increasingly at risk from effects of coastal flooding, erosion and habitat destruction
Around 50% of the world’s population lives within 60km of a coast and 75% of all large cities are on the coast
Combined with rising sea-levels this puts coastlines under increasing pressure
Give an economic and environmental reason why it is not possible to protect all coastlines at risk
Economic - Unaffordable
Environmental - would have huge consequences for coastal systems, material eroded from one part of the coast provides sediment that protects another area of the coast.
Which body/organisation in UK has responsibility for funding coastal protection?
The Environmental Agency
What criteria does The Environmental Agency use when deciding which sections of coastline to protect?
The number of households at risk
likely impact on agriculture
likely impact on the environment and habitats
whether erosion is affecting local infrastructure and transport
cost of constructing management schemes, including ongoing maintenance.
Define ‘traditional approaches to coastal management’
Traditionally, human intervention at the coast involved taking direct action along short sections of coastline to stop or slow down erosion or reduce risk of coastal flooding.
Strategies include hard and soft engineering.
Define ‘Sustainable approaches to coastal management’
Have become the preferred approach in recent decades as our understanding of coastal systems has increased,
More holistic approach
take long-term view
Focus on sediment cells
What are hard engineering strategies?
Used until 1990s
Strategies for tackling problem of erosion lay with local councils
Typically opted for hard engineering strategies - involved making a physical change to the coastal landscape using resistant materials eg) concrete, wood, boulders
Intended to impede and intercept natural coast processes so they are less likely to produce undesirable consequences
Strategies are generally effective but come at high cost
What is the cost-benefit analysis? (CBA)
Before a project is given the go-ahead a cost-benefit analysis is carried out
When the financial cost of the strategy is compared to expected benefits in terms of savings eg) value of land saved, housing protected, savings in relocating people etc
A project where costs exceed benefits is unlikely to go ahead
What is soft engineering?
In contrast to hard engineering, soft engineering strategies work with, rather than against, natural processes to protect coasts.
Involve manipulating and maintaining natural coastal defences eg) beaches, dunes which can absorb and adjust wave energy.
Often require intervention, distributing costs into the future
What are Groynes and how much do they cost?
Hard engineering strategy
Timber or rock structures built at right angles to the coast
Trap sediment moved along coats by Longshore drift - building up the beach
Cost - £5000 to £10,000 each at 200m intervals
What are the advantages of groynes?
Work with natural processes to build up the beach, so increases tourist potential and protects land behind it.
Not too expensive
What are the disadvantages of groynes?
Starve beaches further along the coast of fresh sediment (as they interrupt Longshore drift).
Often leading to increased erosion elsewhere.
Unnatural and can be unattractive
What are sea walls and how much do they cost?
Hard engineering strategy
Stone / concrete walls at the foot of a cliff or at the top of a beach.
Usually have a curved face to reflect waves back to sea.
Cost - £6000/m
What are the advantages of sea walls?
Effective prevention of erosion
Often have a promenade for people to walk along
What are the disadvantages of sea walls?
Reflect wave energy, rather than absorbing
Can be intrusive and unnatural looking
Very expensive to build and maintain
What are Rip Rap / rock armour and how much do they cost?
Hard engineering strategy
Large rocks placed at foot of a cliff or at the top of a beach.
Forms a permeable barrier to the sea - breaking up the waves but allowing some water to pass through
Cost - £100,000 to £300,000 / 100m
What are the advantages of rip rap / rock armour?
Relatively cheap and easy to construct and maintain
Often used for recreation, fishing, sunbathing
What are the disadvantages of rip rap / rock armour?
Can be very intrusive
Rocks usually not local and can look out of place with local geology
Can be dangerous for people clambering over them
What are revetments and how much do they cost?
Hard engineering strategy
Sloping wooden concrete or rock structures placed at the foot of a cliff or the top of a beach
They break up the waves’ energy
Cost - up to £4500/m
What are the advantages of revetments?
They are relatively inexpensive to build
What are the disadvantages of revetments?
Intrusive and very unnatural looking
They can need high levels of maintenance
What are offshore breakwater’s and how much do they cost?
Hard engineering strategy
A partly subtle barrier, designed to break up the waves before they reach the coast
Cost - similar to rock armour - depending on materials used (£100,000 to £300,000 / 100m)
What are the advantages of offshore breakwater’s?
An effective permeable barrier
