Coastal Landscapes and Change (Case Studies)

  • Created by: yuhgab
  • Created on: 03-05-19 09:44

The Nile Delta

The delta is a depositional landform formed from sediment brought down the Nile by annual floods. The Aswan High Dam was constructed in the 1960s.

What occurred? 

  • River discharge fell from 35 billion m3 metres per year to around 10 billion m3.
  • Sediment volume fell from 130 million tonnes to about 15 million tonnes.

These changes were caused by:

  • Water withdrawals for industry, cities and farming from the reservoir behind the dam.
  • Sediment being trapped behind the reservoir and dam; sediment is deposited as water moves slowly in the reservoir.

Effects on the Delta:

Erosion rates at the Rosetta jumped from 25 m per year to 200 m  per year as the delta was starved from sediment. Transportation is significant in maintaining the dynamic equilibrium between deposition and erosion at the coast. Interference with the flow of sediment down rivers can lead to dynamic coastal change. 

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Glamorgan Heritage Coast

The Glamorgan Heritage Coast is located in the Northern hemisphere in the south of Wales, stretching 14 miles from Aberthaw to Porthcawl. 

What is the geological structure:

  • Jointing (cracks in layers of rock created by Earth's movements).
  • Dip (the angle at which strata lies).
  • Fault (cracks in rocks caused by tectonic movements).
  • Folding (the crumbling of rock in the strata)

Sund dunes there are home to over 300 flower species, having the largest sand dunes in Europe at Merthyr Mawr Warren.

In Tresillian Bay, limestone and shale have eroded to form caves, such as Reynard's Cave.

Dunraven Park has 56 acres of green hillside.

Erosion rates along the cliffs are 10cm per annum, as a result of toppling and joints. To prevent erosion they have built reventments and natural limestone blocks.

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Kiribati

Kiribati is located in Micronesia in the central Pacific Ocean. It has a population of 114,395 and a GDP per capita of US$1,449. 

Why is it at risk?

  • less than 9.8 feet (3m) above sea level; it is a low lying island.
  • Coral bleaching (as a result of increasing temp.) means the coast is unprotected from waves, storms, and floods. Healthy coral acts as a barrier to protect the shoreline.
  • Rising sea levels from the anthropogenic climate change.

What damage can it cause?

  • By 2050, Kiribati could lose 34% of its GDP (1998) - fishing and tourism make up most of their GDP, this will be affected by the risk of sea level rise.
  • Loss of homes, roads and businesses.
  • Land loss - the island will become much smaller.
  • People will flee the island, reducing the population. 
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Holderness Coastline

Holderness is located along the East coast of Yorkshire. It stretches between Bridlington and Flamborough Head in the North, and Spurn Head in the South. It is predicted that 200 homes will fall into the sea by 2100.

Geology -The Holderness coast consists of fine clays, sands and boulders. Therefore, it is weak and has little resistance to erosion; it's the fastest eroding coastline in Europe (2m lost each year). It produces shallow, sloping cliffs. However, a chalk band surrounds the boulder clay.

Fetch- The coast is exposed to winds and waves from the north-east, with a small fetch of about 500-800km. However, waves attacking the coast are influenced by currents; the waves often powerful and destructive

Sub-aerial processes- Mechanical and biological weathering has meant the clay can become crumbly and caused cracks to form. Slumping is the main form of mass movement.

Defences include a sea wall, Groynes and rock armour at Hornsea. However, at Mappleton, there is a 'do nothing' approach, where the cliffs are exposed to wave attack as they are starved of material. 

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Bangladesh

Bangladesh is located in south-east Asia between India and Myanmar. 

Why is it at risk?

  • densely populated: 196 million in 2016.
  • 46% of the population lives less than 10m above sea level.
  • lies on flood plains of three major rivers; Brahmaputra, Megna and the Ganges. 
  • Himalayan snowmelt adds to the monsoon rains and high tides in the Bay of Bengal.
  • Violent thunderstorms and cyclones.

Human causes:

  • Dredging (removal of sediment from the coast).
  • Deforestation to grow rice means they are less protected; 71% mangroves are deforested.
  • Submerging as a result of heavy embankments.
  • Anthropogenic climate change causing sea level rise and melting of Himalayan ice.

Preparing for the future: Adaption: building sea walls. Mitigation: reducing greenhouse gasses.

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California

California is located on the west coast of the USA. The coastline includes San Fransisco Bay, North Coast, Central Coast, and South Coast. Features include the San Fransisco Estuary, wave-cut notches and lagoons.1/3 of households in coastal California have incomes exceeding $75,000. 

How is it at risk?

  • The combination of weak bedrock geology, a steep landscape and high rainfall can cause high erosion risk.
  • It is also at risk to tropical storms, droughts and landslides.
  • 44% of California residents live along the Southern Californian coast. 
  • Sea level rise.

Management

  • They want to protect the land but preserve its natural beauty. 
  • Hard engineering: sea walls, reventments, riprap, breakwaters and groynes.
  • The San Fransisco Bay area is protected by levees.
  • Soft engineering: San Diego is protected by beach nourishment.
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Tuvalu Islands

Tuvalu is a group of islands located between Hawaii and Australia. Many environmental refugees are fleeing to New Zealand as the average height of land is 2m above sea level and is 150m wide (vulnerable to sea level rise). Their GDP is reliant on agriculture, fishing and trade.

Causes:

  • Climate change is a major cause of environmental refugees as it leads to sea level rise; Climate change is caused by greenhouse gas emissions.
  • Sea levels between 1870 and 2010 have risen by 21cm due to the melting of the polar ice caps and thermal expansion.
  • Global temperatures have risen by 0.85°C  from 1880-2012.

Effects:

  • Saltwater intrusion has made it difficult to grow crops, and contaminated drinking water; water shortages.
  • 1/5 of 12,000 people have left as the islands have been rendered unlivable by global warming. Those who relocate struggle, losing their culture and identity and living in the poorest communities.
  • Destruction of coral reefs.

Management

Investments in freshwater storage systems and makeshift bulwarks to slow erosion. Politicians are reluctant to encourage people to evacuate.

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Maldives

The Maldives is an island located in the Northern hemisphere near the equator. It is in the Indian Ocean near Sri Lanka, India and Somalia. 

Effects:

  • More than 60% of coral reefs in the region experienced bleaching.
  • Risk from sea level rise - loss of land and property.
  • Isolated islands are ignored as money is spent on protecting the capital (Malé) and creating new islands (Hulhumalé).

Management:

  • the organisation 'Mangroves for the future' (MFF) is working with Maldivian communities to educate them on the importance of maintaining coastal mangrove swamps as a natural defence.
  • The Global Environment Facility (GEF) has provided small grants to islanders to help them develop sustainable and organic farming as an alternative food and income source to coral reef fish. 
  • The Japanese government has funded mangrove nurseries on the Maldives so damaged mangrove areas can be replanted.
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Portland Bill to Selsey Bill

Portland Bill to Selsey Bill sediment cell system is located around the UK. A sediment cell is a closed system that undergoes the processes of erosion, transportation and deposition within the coastal margin.

(http://www.alevelgeography.com/wp-content/uploads/2018/04/sediment-cells.gif)

(http://www.alevelgeography.com/wp-content/uploads/2018/04/sediment-cells.gif)

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Happisburgh

Happisburgh is located in the north of Norfolk in England, surrounded by Sea Palling, Bacton and Walcott. Players involved include; homeowners, the local authority, DEFRA, businesses and environmentalists. 

What is the conflict?

  • Between landowners and local authorities; disagree on how the coast should be managed. Whilst Weybourne is being protected, Happisburgh lacks the protection and as a result, a large amount of land will be lost.
  • Environmentalists and landowners/residents; landowners/residents may demand for coastal protection that may damage habitats, environmentalists will disagree.

Winners: Lobbying from CCAG (Coastal Concern Action Group) changed the Shoreline Management Plan (SMP) to be 'managed realignment'

Losers: After the SMP changed, coastal defences may be used in the future that may harm the environment.

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Chittagong

Chittagong, Bangladesh is located in the northern hemisphere on the continent of Asia. Surrounding countries include India, Nepal and Myanmar. Players involved include farmers, locals, the Asian Development Bank and environmentalists. 

What is the conflict?

  • locals may be forced to leave (200 people), mostly the poor as roads are realigned.
  • Environmentalists will disagree with the disturbance of natural habitats and removal of vegetation - government prioritises protection.
  • Homeowners and landowners receive no compensation.

Winners: Businesses are protected, Coastal Climate Infrastructure Project (2012).

Losers: Disturbance of people and natural habitats (locals and environmentalists).

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