Coastal Management Flashcards
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 groynes?
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
What are the disadvantages of offshore breakwater’s?
Visually uneappealing
Potential navigation hazard
What is beach nourishment and how much does it cost?
Soft engineering strategy
The addition of sand or pebbles to an existing beach to make it higher or wider.
The sediment is usually dredged from the nearby seabed
Cost - £300,000 /100m
What is cliff regrading and drainage and how much does it cost?
Soft engineering strategy
Cliff regrading reduces the angle of the cliff to help stabilise it
Drainage removed water to prevent landslides and slumping
Cost - variable
What are the advantages of cliff regrading and drainage?
Can be effective on clay or loose rock where other methods will not work
Drainage is cost-effective
What are the disadvantages of cliff regrading and drainage?
Regrading effectively causes the cliff to retreat
Drained cliffs can dry out and lead to collapse (rock falls)
What is dune stabilisation and how much does it cost?
Soft engineering strategy
Marram grass can be planted to stabilise dunes
Areas can be fenced in to keep people off newly planted dunes
Cost - £200 to £2000 / 100m
What are the advantages of dune stabilisation?
Maintains an natural coastal environment
Provides important wildlife habitats
Relatively cheap and sustainable
What are the disadvantages of dune stabilisation?
Time consuming to plant marram grass
People may respond negatively to being kept off certain areas
What is marsh creation and how much does it cost?
Soft engineering strategy
A form of managed retreat, by allowing low-lying coastal areas to be flooded by the sea
The land then becomes a salt marsh
Cost - variable depending on the size of the area left to the sea
What are the advantages of marsh creation?
Relatively cheap (land reverts to it’s original state before management)
Creates a natural buffer to powerful waves
Creates an important wildlife habitat
What are the disadvantages of marsh creation?
Agricultural land is lost
Farmers or landowners need to be compensated
How many Shoreline management plans (SMPs) are there?
22 around the coast of England and Wales covering the 11 sediment cells
When were SMPs introduced?
In 1995 introduced to move away from a piecemeal approach to a more integrated approach to coastal management
What principle are SMPs based on?
That intervention will be largely self-contained within each sediment cell, having little or no knock-on effects elsewhere
What is the timescale of an SMP?
Plan for short term (0-20years)
The medium term (20-50years)
The long term (50-100years)
For each section of coastline within an SMP there are four management options to
choose from. Name and outline the main features of each one
Hold the line - when measures are put in place to stop further coastal retreat due to erosion (often using hard engineering strategies)
Advance the line - involves extending the coastline further from the existing shore out to sea (by encouraging the build-up of a wider beach, using beach nourishment and Groyne construction)
Managed retreat - when coastlines are allowed to retreat in a managed way, eg) when flood banks protecting low value farmland are deliberately breached to create salt-marsh environments
Do nothing/no active intervention - involves putting no management schemes in place and allowing natural processes to take their course
What does ICZM stand for?
Integrated Coastal Zone management
What is the main idea behind ICZM?
To consider the whole coastal zone - landward and seaward as a sophisticated set of systems that meet and become integrated at the coast.
Eg) it takes account of runoff from fertiliser and pesticide residues from farmers fields into waterways that discharge into the sea and affect marine organisms.
An ecosystem based approach.
Aims to co-ordinate policies that affect the coastal zone and all activities that take place there from fishing, agriculture and conservation to industry, off-shore energy and tourism.
What is the intention of ICZM?
To manage all the components to permit the best sustainable future in the short and long term for the natural coast and human users of it.
Involves bringing together all those involved in the development, management and use of the coast
What does ITZM involve and why?
As with SMPs, involves managing complete sections of coastline rather than short sections eg) in front of a town or village.
This avoids the situation where erosion is stopped in one place only to starve another location of sediment, as so increasing erosion there.
