COASTAL MANAGEMENT

ISSUES

Coastal erosion can lead to cliff collapse. This creates challenges for people and the environment.

A case study of an area of recent or threatened cliff collapse to show:

• Rates of erosion and change in the area

• Why the area is susceptible to coastal processes and cliff collapse

• How human impacts may worsen the situation

• The impact of rapid cliff recession on people and the environment.

What we’re going to do...

Review why some areas are more susceptible than others

Look at areas of rapid erosion in Eastern England

Fieldwork to Highcliffe to investigate management issues

Why are some areas more susceptible to erosion than others?

Coastal erosion on the Norfolk coast (Happisburgh)

Location

http://www.happisburgh.org.uk/http://www.bgs.ac.uk/landslides/happisburgh.html

Rates of erosion and change in the area

Photo taken 01/03/96

01/01/86

01/01/03

20m

01/01/86

01/01/03

01/01/86

Summary:Historic records indicate that over 250 m of land were lost between 1600 and 1850.

1992-2007 – 125m lost: rate of erosion c. 8m/year (BGS website)

Some areas eroding faster than others – affected by the degree of protection afforded by coastal defences

Why is this area so susceptible to erosion?

The cliffs at Happisburgh are between 6-10m high and are comprised of a series of glacial sands and clays deposited during and at the end of the last Ice Age (2mya – 10,000 ya).

These are easily eroded by the sea and …

.. rainwater easily percolates through the sand and saturates the clays, making them more mobile and more likely to slump.

Although there is some sand in the cliff material, most of it is clay …

…which is carried away in suspension.

The small amount of sand isn’t enough to form a wide beach …

… so there’s little to protect the base of the cliff from further erosion.

How the cliffs erode

Sediment is transported northwards and southwards away from this area of Norfolk – so there is no through movement of sediment to replace that which is removed

This coast also is exposed to storms in the North Sea that can raise tide heights by up to 2m

Happisburgh

Photo taken 01/03/96

Draw an annotated field sketch of this photo. Identify the coastal features, the type of mass movement shown and suggest why is it happening.

How might human impacts may worsen the situation?

Human activity

• Coastal defences along the coast … how/why might these have an impact?

• Rising sea levels and increased frequency of storms?

The impact of rapid cliff recession on people and the environment

Living with coastal erosion at Happisburgh (1)

Living with coastal erosion at Happisburgh (2)

Social impacts:• 27 houses lost to sea since 1986 – c. 60 people directly affected;

• 18 listed buildings will be lost including the only privately operated working lighthouse in the country;

• A thriving community – volunteers run the lifeboat and coastguard team, and they have well-organised campaign to save the village

Economic impacts:• Happisburgh has a shop & post office, pub and school – will these

survive?

• Tourism: caravan park, tea rooms and a number of guest houses – will people still come?

• Without protection, coastal erosion is a certainty, not a risk:

• Inability to insure properties

• house as an investment – can they be sold?

Political issues:• Timber defences built in 1959 but started failing in the '80s

• Construction of a rock groyne was started at the south end of Beach Road in 2001…

• …but it was halted because there were 2 objections to the work (despite 325 letters of support).

• By December 2002 so much erosion had happened that the scheme was scrapped – the erosion had led to properties being lost to the sea and so the financial benefits of building the defences were now less than their cost

Environmental impacts:• Loss of valuable farm land

Coastal management

solutions

Different strategies can be used to reduce the threat of erosion/flooding in coastal areas.

Management strategies include:• Hard engineering – including sea walls, groynes, rock armour.

• Soft engineering – including beach nourishment, dune regeneration and marsh creation.

• Managed retreat – coastal realignment and monitoring

A case study of a coastal management scheme to assess the costs and benefits of the adopted strategy.

What can be done to protect rapidly eroding

coastlines?

Hard engineering Uses artificial structures to control or deflect the forces of

nature

Soft engineering Makes use of natural processes to reduce wave energy,

usually without artificial structures.

Whilst we look at some of the different methods, consider the following:

Which methods are less visually intrusive and therefore less likely to deter visitors?

Which methods might be more effective?

Which are likely to be the most expensive?

Which do you think offer the most sustainable approach?

Hard Engineering

Sea Walls

Blackpool

Groynes

Swanage - old

Swanage - new

Rock Armour(aka rip rap)

Morecambe

Soft Engineering

Soft engineering methods…

…try to fit in with and work with the natural processes

…do not involve large artificial structures

…are often more ‘low-key’

…have low maintenance costs (economically & environmentally

…are usually more sustainable

Beach Replenishment

Beach replenishmentWhat is it?

Costs approximately £3000/m

Advantages: DisadvantagesRelatively cheap & easy to maintain Can be easily damaged by storms

Blends in with existing beach (eventually)

Unless structures are also built to retain the beach it will need regular maintenance/replenishment

Increased beach width may/will attract more tourists

Can be unsightly whilst material is re-worked by the sea.

Dune RegenerationWe’ll do this at the end when we

look at dune systems

Managed Retreat(aka managed re-alignment)

Marsh Creation

Northern coast of the Blackwater estuary, Essex

Class Clips: 3243Porlock, North Somerset

Managed retreat/coastal realignmentWhat is it?

Costs depend on value of land – arable is £5k-£10k per ha

Advantages: DisadvantagesCheap compared to cost of building and maintaining defences to protect low value land

Farmers will need to be compensated

Creates much needed and valuable habitat for wildlife

Land can only be used for a limited range of land uses, e.g. animal rearing

Animals can graze land at low tide

Monitoring

1. Which methods are less visually intrusive and therefore less likely to deter visitors?

2. Which do you think are the more sustainable methods: hard or soft engineering? Explain your choice.

3. Why do you think some schemes include both hard and soft engineering, for instance, beach replenishment and groynes?

• the suitability of the method for that part of the coast, and• the outcome of a Cost-Benefit Analysis:

Which method or combination of methods is chosen (if any) depends on:

Costs Benefits

What will it cost to complete? What are the advantages that justify the cost?

How much will it cost to maintain?

For how long will the benefits last?

Who will be badly affected by it? Who will gain from it?

Which areas will be badly affected by it?

How large an area will gain from it?

How bad will any environmental damage be?

How big an improvement to the environment will there be?

Some of the people likely to have views about coastal protection are:

A Birdwatchers C Holiday camp owners

B Londoners D Council treasurers in resorts

E Farmers with land on cliff-tops

F Economic advisors to the government

G People with coastal retirement homes

H Families who take summer holidays by the sea

a) Draw a line like the one below and put the letters A-H along the line to show the likely feelings of the people above:

b) Explain your choice of position on the line for someone towards each end and someone towards the middle.

Do nothing Total protection