CASE STUDIES

PHYISICAL

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  • Created on: 12-05-11 20:15

The North Sea Storm Surge, 1953

  • A deep Atlantic depression moved across Scotland, deepening all the time, such a rapid fall of preasure could have been responsilbe for a rise in the sureface of the sea, with an anticyclone lying to the west of the Bristish Isles, a steep pressre gradient developed resulting in strong winds moving across the North Sea, with large fetch from the north, combined with the strong winds, storm waves were produced that were 6 m high.
  • For south-east England. Sea defences were breached in several places, 1000's of low-lying land was flooded. There was huge damage to property, communication systems and agriculture were disrupted with high lose of livestock. 250 died.
  • Netherlands was ever greater, with 1,800 dieing, 10% of the countries agricultural land was flooded. In reponse the goverment planned the Delta Scheme. 
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Holbeck Hall, Scarborough, 1993

  • The hotel was situated on top of the cliff behind South Bay.
  • The cliffs here are made mainly of clay and the hotel was 60-70 m away from the egde.
  • When a period of dry weather cracked much of the clay on the cliff top. This dry period was followed by heavy rainfall that penetrated the cracks and began to lubricate the clay along the certain lines of the slippage.
  • It started with cracks, which developed to the end of the garden begining to slide, by the morning the collapse has effected the main part of the hotel.
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Towyn floods, Wales Feb 1990

  • Waves crashed through the 40 year old sew wall at towyn in the north Wales.
  • The floods were a result of the breaching of the railway embankment that streatches the coastline.
  • A severe storm has already made the sea wall really weak and vulnerable to storm damage.
  • The flooding caused 5,000 people were effected with £30 million needed to rebuild, 2,800 properties were evacuated. 6,000 Carvans damaged. 40% had no insurance. £10.5 million needed to build new defences. 3000 people were in temporary accomadation. 3 months later only 1000.
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Storm Surges in Bangladesh

  • 1070,1085 and 1991. During a storm surge high winds, associated with cyclones forming to the south, push water northwards up the increasingly narrow Bay of Bengal.
  • The country stands at sea level, covering most of the river delta of the river Ganges. Cyclones cause massive sweeps of water causing the water level to rise to 10m
  • Storm surges travel inland, destroying farmland, villages and infrastructure, killing crops, livestock and people.
  • In 1970 the death toll was 300,000, Most building were made from wood so was just swept away. The salt water contaminated the soil causing food shortages issues making people depended on aid.
  • Is in real increase of danger dur to global warming
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A national scheme, Netherlands

  • The delta region, a series of dams that seal off the channels between the large islands to keep out the sea.
  • 2 channels allow ships to reach the ports of Rotterdam and Antwerp and the creation of some fresh water areas.
  • The East Scheldt dam, which is unlike those that has already been built. Pressure from environmentalists has resulted in the building of storm surge barrier with cluice gates that can be lowered in times of need. The area behind the dam has remained as salt water, preserving salt marshes and mud flats for wildlife.
  • The coastal dune area, the dutch dunes occupy an area of 42,00 hectares. currents and waves remove sand in some areas and deposit it elsewhere. 7 million m of sand is washed away.
  • Sand mixed with water is pumped up from the sea bed up to 20 km out at sea. It is then transported to the dutch coast and sprayed on the beaches. (sand replenishment.
  • Grasses and trees are planted to hold the sand and reduce wind speeds, sleeper dykes are placed, some areas are fenced off to prevent trampling.
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Soft engineering: the Sefton coast, northwest, Eng

  • Natural erosion levels are comounded by the effects of dredging, spoil dumping and wall construction associated with the development of the ports of Preston and Liverpool.
  • At the present rate of dune erosion at fromby point is 5 m per year.
  • The area attacts large number of tourists, the frontal dunes suffered greatly as a result of this access. Problem with off-road cars breaking up dunes and vegetation. Sand is also removed by contractors.

The scheme was;

  • close monitering of visiter access with controls in areas, prohibiting the use of off road cars, controlling the level of sand which is extracted, removing of trees and shrubs cover from the existing frontal areas would help to re-establish and maintain a spectrum of habitats.
  • A determination to protect the area for future use, in other words to be sustainable.
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