Coastal Environments Case Studies

North Cornish Coastline, has a headland called Trevose Head.

This headland has been eroded by the sea to form a number of smaller headlands and bays. 

On 21 August 2009, 5 holidaymakers were killed in Albufeira.

Causes of the Cliff collapse:

Physical:

• The sandstone cliff was already severely weathered and cracked and had been weakened
• 4.2 Richter Scale eathquake hit the area a few days before the collpase, this may have weaknede the cliffs and made it more liekely to collapse
• At high tide, the sea actively erodes the foot of this cliff, leading to a wave cut notch etc. This continuous indercutting would increase the likelihood of a cliff collpase
• Recent very high tides might have added to the cliffs erosion prior to the collapse

Human:

• Rockfalls were common at these cliffs. Warning signs had been put up to warn people of the potential danger of cliff collpase, however the vitims seemed to ignore this.

The cliffs have retreated here steadily over the past few years. Several Cottages have already collpased onto the beach.

The Government has decided it is too expensive to build sea defences to protect them

Most buldings in danger are set to be demolished, such as a nearby hotel and cafe.

Physical causes:

• The Chalk Cliffs are broken and shattered in this area, which makes them very vulnerable to freeze thaw. This contributing to the rate of cliff retreat 75 cm a year.
• The lack of a wide beach at Birling Gap means that the sea reaches the cliff foot at high tide and continuously undercuts and weakens it 
• With a long south-westerly fetch, powerful waves frequently pound this vulnerable costline.

The National trust is in favour of allowing the costal erosion to continue as the cost has naturally devloping habitats which sea defences would damage if built.

The also say that with rising global warming, the cost of sea defences would be too high.   

26 February 1990 sea defences in Towyn were breached and thousands of homes were flooded.

Main Causes were:

• A storm surge of 1.5 metres 
• Gale force westerly winds
• Comined with a very high tide

Impacts:

• 4 square miles of seawater flooded impacting 2800 properties
• Areas of the town had to be evacuated
• People were forced to live in temporary accomadation, up to a year after the event
• The main railway line was severely damaged

Preventative measures introduced:

• Rock revetments were built on the cost as part of a £2 million flood defence scheme. 
• £600,000 spent on restroing flood banks on either side of the River Clywd estuary 

Cyclone Nargis happened in May 2008. Little warning was given. Winds of 200 km per hour and the low pressure created a storm surge, measuring 6.3 metres high. 

Impacts of Cyclone Nargis:

Social:

• 140,000 killed
• 2-3 million left homeless 
• Food prices went up due to supply problems 
• Stagnant, filthy water created health Issues (e.g. Cholera, Malaria)

Economic:

• Cost of damage was $10 Billion
• Businesses were closed and peolpe lost their jobs/incomes
• Crops were destroyed 

Environmental: Ecosystems/crops affected by saltwater, rice fields flood with sewage.

The rapid rate of erosion along this stretch of cost is a result of the combination of two factors:

Cliffs are made up of clay overlain by sand and gravel, whic is extremely weak and prone to slumping and collpase.

High energy waves from the North Sea pund this coast during winter storms.

Protecting the Naze Coast: (CLIFFS ERODE AT 1.4 METRES A YEAR)

Soft Engineering:

• The cliffs have been regraded to make them shallower and less vulnerable to collpase 
• Cliffs have been planted with vegetation to anchor the soil and reduce the risk of slumping

Hard Engineering:

• Sea wall built at the foot of the cliffs (elastocoast added, a strong porous material) 
• Wooden groynes constructed to interupt LSD and help buld up the beach
• 1998 a granit rock revetment
• 2010, £1.2 million spent on addfitional defences 

In the late 1990's the sea wall at Abbotts Hall Farm was breached.

The Essex Wildlife Trust decided that this land should be allowed to flood due to its low value agricultural land and with sea levels likely to rise in the future.

The creation of a new area of salt marsh seemed to be the best possible alternative.

Counter walls were created on either side of Abbotts Hall Farm to protect the neighboring farmland.

In 2002 the old sea wall was breached and the sea flooded the area.

In addtion to creating new bird habitats, the new salt marsh here also formed important fish nurseries for bass and many other types of fish.