Transcript Slide 1

COASTAL ENVIRONMENTS 3
• human activity – coastal land uses
• coastal management schemes
In the UK, 23% of our total land area lies within 10kms of the coast.
This means that 17 million people live within this coastal zone and this level
of usage puts pressure on our natural coasts leading to a need for coastal
management schemes.
How is the land along the coast used?
32% pasture – grazing animals
25% arable – growing crops
10% woodland and heathland habitat
30% is covered by buildings, roads and recreational facilities
The remaining 3% consists of natural cliffs, beaches and mudflats.
Source of photos: www.geograph.co.uk (creative commons licence)
Coastal management in England and Wales is the responsibility of a wide range
of organisations with no overall integrated approach. This has sometimes led to
delays and conflicts. Organisations include:
Department for Environment, Food and Rural Affairs (defra)
Environment Agency
County, rural and urban local authorities
English Nature
Countryside Commission
National Trust
National Parks Authorities
National Nature Reserves
Each local authority has a statutory duty to provide coastal management plans
which meet the Government’s policy aim:
“To reduce the risk to people and the developed and natural environment from
flooding and coastal erosion by encouraging the provision of technically,
environmentally and economically sound and sustainable defence measures.”
In addition, the local authorities are obliged to “discourage inappropriate
development in areas at risk from flooding and coastal erosion”.
Assistance with funding for coastal management schemes comes from the
government but local authorities may need to borrow money or raise local taxes in
order to pay the full costs which in may cases come to millions of pounds.
Planners have the added complication of taking into account:
1. Predicted sea level rises due to global warming
2. Sea level rises or land level rises due to isostatic readjustment following the
retreat of the glaciers at the end of the last ice age.
A key component in managing the coast has been the development of Shoreline
Management Plans (SMP) which set out a strategy for the coastal management
of a section of the coastline. Each SMP covers an area of coastline known as a
sub-cell within a littoral sediment cell, of which there are eleven on the
England and Wales coastline.
A sediment cell is defined as a length of coastline,
which is relatively self-contained as far as the
movement of sand or shingle is concerned, and
where interruption to such movement should not
have a significant effect on adjacent sediment cells.
Each major littoral cell is divided into a number of
sub-cells, based on the best available knowledge
of large-scale processes.
In order to encourage improved co-operation
between authorities a series of Coastal Groups
have been established based on the littoral cell
boundaries.
The production of each Shoreline Management Plans (SMP) involves the
appointment of expert firms of consulting engineers to undertake a detailed study
of all the issues affecting the coast such as land use, environmental protection,
economics and the action of the coastal processes.
The final report establishes the management policy for the coast defences by
dividing it into separate Management Units and making specific
recommendations for each unit based on four alternative options:
• Do Nothing - Carry out no coastal defence activity except for safety measures
• Hold the Line - By intervention, hold the existing defence where it is
• Advance the Line - By intervention, to move the existing defence seaward
• Retreat the Line (Managed Retreat) - By intervention, to move the existing
defence landward
Example from the North Norfolk SMP:
Management Unit No 3
Cley Coastguards to Stiffkey Marshes
Hold the Existing Line in the short term for Blakeney and Morston Defences.
Do Nothing at Blakeney Point - allowing the shingle ridge to evolve naturally.
Coastal defence construction features generally fall into two categories:
Hard Defences
Static shoreline structures such as those constructed from timber, steel,
concrete, asphalt and rubble.
These involve linear structures such as sea walls and revetments and
control structures such as artificial headlands and groynes.
Soft Defences
Mobile/ responsive defence measures which seek to work with nature
rather than control it.
Such structures may consist of sand or shingle beaches and dunes or
banks which may be natural or constructed, and may include control
structures. These can include the soft solutions of beach nourishment,
cliff/dune stabilisation, bypassing and managed retreat.
Some example of ‘hard’ coastal protection methods:
Rock revetments – these have a high cost of about
£100-300,000 per 100m length, but require relatively
low maintenance. The permeable face absorbs wave
energy and encourages upper beach stability.
Permeable revetments can be built from gabions,
timber or concrete armour units.
Sea walls – these have a very high cost of about
£200 - 500,000 per 100m length. They provide good
medium term protection, but continued erosion will
cause long term failure (30-50 year life expectancy).
Seawalls are near vertical structures of concrete,
masonry or sheet piles, designed to withstand severe
wave attack. Their use was popular in the past but
they are now normally considered to be costly and
detrimental to the stability of beaches.
Some example of ‘soft’ coastal protection
methods:
Beach nourishment – this method has a
moderate to high cost of between £5-200,000
per 100m frontage, and it requires ongoing
maintenance. Allows natural beach processes to
continue but use of inappropriate material may
alter appearance of beach or function of beach
processes.
Sand dune planting – stabilising natural sand
dunes by planting marram grass to anchor the
wind-blown sand has low costs of only £400 £2000 per 100m frontage, but it requires ongoing maintenance.
It has minimal impact on the natural system and
fences can be used to control public access.
Damaged fences and accumulated debris can,
however, be unsightly.
Summary of key points:
• in the UK 23% of our total land area lies within 10kms of the coast and this
means that 17 million people live within this coastal zone.
• in England and Wales a large number of government, local authority and
private organisations are responsible for coastal management
• local authorities have to produce Shoreline Management Plans (SMP)
which set out a strategy for the coastal management of a section of the
coastline
• an SMP can recommend four options: Do Nothing, Hold the Line,
Advance the Line and Retreat the Line (Managed Retreat)
• coastal defence methods fall into two categories: Hard Defences and Soft
Defences
• hard defences try to control the natural coastal processes whilst soft
defences try to work with the natural processes and are less unsightly