Management Strategies - protecting coaslines

What are sea walls?

A structure which provides a barrier between the waves and land.

Its placed along the back of a beach and can double up as a promenade.

Recurved sea walls are more expensive than flat ones but are more effective as they deflect the waves energy back out to sea.

What are the benefits of sea walls?

Social

-Often have promenades on top which can be a cycling route outside peak walking periods

-Steps at base of wall can be seating areas for beach users

Economic

-Last many years if maintained well

Environmental

-Dont disadvantage any areas further down the coast as don't trap sediment.

What are the costs of sea walls?

Social

-Restrict access to the beach if waves overtop the wall, coastal flooding may occur

Economic

-Around 5,000 pounds per linear metre so are expensive. Repairs are also expensive.

Environmental

-From the beach, a wall of concrete is ugly.

-May destroy habitats.

What are groynes?

Wooden or stone structures built in the foreshore, extending from the beach to the sea.

They are built at right angles to the beach and spaced at regular intervals, around 50metres apart.

They trap sediment and prevent LSD.

This means the now built up beach slows down the wave energy as the waves have further to go before hitting the cliffs.

What are the benefits of groynes?

Social

-Rock groynes at Sandbanks, Poole, have concrete crests for people to walk along to reach a viewing or fishing point.

-Act as windbreaks.

Economic

-Cost 5,000 pounds each and are relatively cheap

-If well maintained, can last up to 40 years.

-A large beach with more space for activities attracts more tourists, boosting the local economy.

What are the costs of groynes?

Social

-Barriers that impede walking on a beach

-Dangerous as they have deep water on one side and shallow on the other

Economic

-By trapping sediment, they restrict the supply of sediment down-drift .

-If effective in stormy conditions and need regular maintaining so they don't rot.

Environemntal

-Considered unattractive

What is rock armour?

Aka rip rap

Made up of huge boulders of hard rock to create a barrier between land and sea.

They are big enough to not be moved by large waves and it helps to dissipate wave energy.

What are the benefits of Rock Armour?

Economic

-Relatively cheap, costing around 1000-3000 a metre

-Structure is quick to build and easy to maintain - Can be built in weeks rather than months.

-Last a long time if well maintained

-Versatile and can be placed in front of a sea wall to strengthen its lifespand or use to stabilise slopes on sand dunes.

What are the costs of Rock Armour?

Social

-Make accessing the beach difficult. People may have accidents when clambouring over as rocks may be unstable. If rocks are regularly covered by the tide, they may collect slippery seaweed which accentuates the hazard.

Economic

-Highly resistant rocks from Norway and Spain are preferred, which inflate the costs considerably.

-Heavy storm waves will move the rocks so need regular maintaining.

Environmental

-Ugly and covers vast areas of a beach

What are gabions?

Steel wire mesh cages filled with pebbles or rocks.

Placed at the back of a sandy beach to create a low wall like structure.

Water enters the cages and this absorbs and dissipates wave energy, thus reducing the rate of eroson.

They can also be put at the base of a cliff to reduce the chances of landslides.

What are the benefits of Gabions?

Economic

-110 pounds a metre so relatively cheap and easy to construct

-Often constructed on site using local pebbles making them a lot cheaper than sea walls, rock armour or groynes.

-Good value for money as can last 20-25 years.

Environmental

-Blend in better than other hard engineering methods, especially when sand is blown in them or when they're covered by vegetation.

What are the costs of Gabions?

Economic

-Restricted only to sandy beaches as shingle hurled at them would quickly degrade them

-Easily destroyed so regular maintenance is needed.

-Repair can be expensive

Social

-When damaged, they can be dangerous - people can't rip on them or cut themselves on the broken steel wire mesh.

Environmental

Damaged gabions are unsightly

What are the hard engineering methods for coastal management?

Sea walls

Groins

Rock Armour

Gabions

What are the soft engineering methods for coastal management?

Sand Dune Regeneration

Beach Nourishment

Beach Reprofiling

Managed Retreat

What is beach Nourishment?

The replacing of lost sediment onto the beach.

A large beach means fewer waves reach the back of the beach, and those who do have less energy as they have further to go.

This means erosion is slowed down.

It can be achieved by taking sand from the seabed and putting it back on the beach (recharge) or transporting it back along the beach.

What are the benefits of Beach Nourishment?

Social

-Wider beach means more room for beach users

-People living along seafront more protected from coastal flooding.

Economic

-Wider nourished beach protects expensive properties

-A broader beach may attract more tourists.

Environmental

-A nourished beach is natural and blends with the environment

What are the costs of Beach Nourishment?

Social

-During re-nourishment, access to the beach is restricted for several weeks.

-Beach recycling may cause resentment from residents living close to the donor area.

Economic

-Cheaper than hard engineering but costs around 300,000 pounds to hire a dredger

What is beach Reprofiling?

The artificial Re-shaping of beach using existing beach sediment

In winter, a beach is lowered by destructive waves taking sediment away.

After winter storms, bulldozers move the shingle back up the beach to act as a buffer between land and sea.

What are the benefits of Beach Reprofiling?

Social

-At Pevensey, the residential area behind the beach is protected so residents feel safe

Economic

-If the shingle ridge at Pevensey is breached, the estimated repair cost would be around 125m, whereas the combined cost for nourishment and frequent Reprofiling is 30m over 25 years.

Environmental

In preventing a breach, the Pevensy Levels has been protected and the beach still looks reasonably natural.

What are the costs of Beach Reprofiling?

Social

-Bulldozers restrict access to Pevensy Beach, especially in winter.

Economic

-Major Reprofiling costs can be expensive. Selsey paid 200,000 a year to realign a beach there on the west coast.

Environmental

-A steep, high crested beach may be unnatural and uninviting for tourists.

What is Sand Dune Regeneration?

The artificial creation of new sand dunes or restoration of existing ones by building a fence to protect the area behind them from collapsing, or marram grass may be planted to hold the dune together.

Sand Dunes act as a physical barrier, absorbing the energy from the wave and thus reducing erosion.

What are the benefits of Sand Dunes?

Social

-Protect land behind them

-Popular as picnic and walking areas once established.

Economic

-Small planting projects often use volunteers so minimal costs

Environmental

-At Studland sand dune, Regeneration helped maintain a habitat for many species, including 6 reptile species like sand lizards.

What are the costs of Sand Dunes?

Social

-While becoming established, regenerated sand dunes are fenced off and signs tell people to keep out, which may deter tourists

Environmental

-Once regenerated, there’s no guarantee they’ll be stable. Grass may soon become damaged by storms . Even in favourable conditions, it can take 2-3 years before grasses begin to spread.

Economic

-Dune Regeneration has to be checked twice a year and have fertilisers applied

What is managed Retreat?

A decision made to no longer ‘hold the lines and protect the coast.

People are moved out from homes and relocated.

Buildings are demolished and a deliberate ‘breach’ in current sea defences is made to create new habitats.

What are the benefits of Managed Retreat?

Social

-Takes pressures off coastal areas to reduce their risk of flooding

Economic

-Cheaper than to keep repairing defences long term

Environmental

-Designed to conserve or enhance the natural environment: creates new habitats.

What are the costs of Managed Retreat?

Social

-Relocation of people causes disruption and stress.

-Communities split when large numbers are involved

Economic

-Short term costs are high as relocation costs have to be paid - these can run into millions.

Environmental

-Large areas of agricultural land lost

What is the best coastal management strategy in your opinion and why?

Sea Walls.

Unlike many strategies, it is applicable to both sandy and pebbly beaches.

It has a long life spand and many positives impacts.

Similar to rock armour but doesn't need regular maintenance which many do.

Are safe - many soft and hard strategies have risks.

Give an example of a coastal management scheme in the UK. (Name)

The holderness coast.

Why was the management scheme at the Holderness Coast introduced?

1. During the last glacial period, boulder clay (sand and clay) was deposited along the coastline, which is easily eroded.

2. There are powerful, destructive waves coming from NE direction with a large fetch.

3. In a stormy year, 7-10m of cliffs can be lost - it is the most rapidly eroding coastline in Europe.

Desribe how the Holderness coast management scheme decided which areas on the coastline to protect.

Cost benefit analysis: an area got sea defences if the economic benefits outweighed the cost.

Areas where this was true include Bridlington, Mappleton and Easington.

Holderness Coast Management Scheme: describe the strategy at Mappleton and why it was needed.

Mappleton had lost 75m in the last 40 years.

Although only 250 residents, the main road (B1242) is only 34 Kms from the edge and it would cost more to rebuild it than defend.

In 1991 they built rock armour using 60,000 tonnes of granite blocks.

They also built groynes.

It cost 1.9 million pounds.

Describe whether the Holderness Coast Management Scheme worked in Mappleton.

Yes

It prevented erosion by creating a substantial beach between the groynes.

The garage had the confidence to expand their businesses.

It has become a popular leisure beach and secured tourism to the area.

New residents have been attracted to the area as they can now get a mortgage, ensuring the village’'s survival.

Describe conflict that resulted due to the Holderness Coast Management Scheme.

One conflict occured in Kilnsea.

Located before Spurn head, defences in the local area including Easington increased erosion at Kinsea.

It has lost 300m of coast over the last 150 years.

The council wont protect the area due to costs and fears of impacting the spit at Spurn Head.

The 80-90 residents feel abandoned as they are susceptible to flooding, which leads to poor property prices.