Geography Case Studies (Theme 2)

  • Created by: Debbix
  • Created on: 02-05-15 14:45

Volcano - Chile

  • Among the Andes mountains there are more than 2000 ash and lava volcanoes, of which 500 are active
  • On 2 May 2008 the Chaiten volcano (thought to be dormant) erupted for the first time in over 9000 years
  • More than 4000 people had to flee their homes
  • People had to cue to be evacuated by naval ships due to lack of other transport
  • cars, houses and tress were covered with ash of up to 15cm thick
  • Forests set on fire
  • Schools made into makeshift shelters, people provided with bottled water due to contaminated groundwater
  • People advised to wear galsses and long sleeves to avoid contact with ash
  • Ash and lava volcanoes:
  • Form at convergent plate boundaries
  • Subducting plate melts and heat and pressure build u[ due to friction between the plates
  • Explosive eruption. Hot lava flows out and lighter ash clouds settle on the lava in layers
  • Steep sides to volcanoes, lava does not flow far before cooling quickly to form solid rock.
  • A caldera is usually formed when the top of a volcano is blown off, it sometimes contains a crater lake
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Earthquake - China

  • Ten days after the chilean volcano - 12 May 2008, China's most devastating earthquake in 30 years
  • 7.9 magnitude earthquake
  • Epicentre in mountainous region of Sichuan province, Wenchuan county exacty
  • 100km north-west of Chengdu, a bustling city of 10 million people
  • Death toll (estimated): 87, 587
  • Dujiangyan - 900 students feared buried under a collapsed high school building
  • Beichuan country - 10,000 believed injured, 80% of buildings collapsed
  • Chengdu - All trains ordered to stop, airport closed
  • Shifang - Several schools, factories and dor mitories collapsed
  • Chongqing - Five children dead and 100 injured after two primary schools collapsed
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River Erosion - Niagara Falls

  • Niagara falls consists of two waterfalls on the Niagara river which marks the border between New York state (the American falls) and Ontario, Canada (the canadian or Horseshoe Falls)
  • The formation began around 18,000 years ago at the end of the Ice Age in North America
  • Torrents of water were released into the Great lakes as ice melted into what is now the Niagara river.
  • About 12,300 years ago this water plunged over the edge of the north-facing Niagara Escarpment.
  • The force of the water gradually wore away the rock layers and Niagara falls 'retreated' as it move upstream back towards Lake Erie.
  • The falls retreated at a rate of 1 metre per year until the 1950's. Since then flow has been controlled by extraction for hydro-electric power (HEP) and canals.
  • The erosion rate is less today
  • The Horseshoe falls carry 90% of the river's water
  • Tourism, and producing HEP, are both money earners
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River deposition - the Ganges Delta

  • Stage 1: The lower course of the slow-moving Ganges river carries a larger quantity of fine silt as suspension load. The river's energy is used in transporting it. As it enters the Bay of Bengal it's speed reduces and deposition takes place. The heaviest material is dropped first and builds up to form islands.
  • Stage 2: Over time more sediment is deposited as the waves are too weak to remove it quickly. The river channel becomes blocked by the silt. More flooding also takes place. The river finds its way to the sea by winding itsef around the islands. These channels are distributaries. Swamps and brackish waters are found here.
  • Stage 3: The sediment continues to be added to the delta. Islands of dry land emerge and vegetation grows. The delta is continually moved by currents and floods.
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Coastal erosion - The Twelve Apostles

  • The Twelve Apostles and London Arch are famous coastal landforms in the port Campbell National Park, Victoria, Australia which have been carved by the sea from the limstone cliffs
  • Originally the rock layers formed as horizontal beds of sediment on the sea floor over 10 million years to become sedimentary rock
  • 70 metre high steep cliffs, wave-cut platforms, notches, arches and stacks are formed
  • Undercuttig eventually cause cliffs to collapse along vertical joints, keeping the slopes steep
  • The Twelve Apostles is a collection of stacks
  • Tallest is 45 metres high
  • Only nine in 1950s
  • Rate of erosion at base of pillars: 2 cm per year
  • Formed as a result of different rates of erosion along the coast due to alterate bands of hard and soft rocks
  • Headlands formed where rock was more resistant
  • Back-to-back caves originally formed on each side of the headlands
  • Continuous erosion caused these caves to erode backwards and become arches
  • When the arches collapsed the stacks were left
  • London Arch is a natural arch that has not yet collapsed
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Coastal deposition - The Hel spit

  • The Hel peninsula is a long sand spit situated at the western end of Gdansk Bay of the Baltic Sea in northern Poland.
  • Long, narrow, low and relatively falt, with sand dunes in many parts
  • Formed by coastal deposition, as a result of longshore drift from West to East
  • The predominent winds are from the west and north-west and this transports sediments from the west of the spit, where it is subject to erosion, to its eastern end where sediment is bulding up
  • The beach material is sorted by the waves, resulting in large sediments at the top of the beach and smaller ones closer to the sea
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Coral Reefs - The Great Barrier Reef

  • The Great Barrier Reef Marine Park was created a World Heritage Area in 1981.
  • The reef is important to Australia's economy:
    • It employs 6% of the workforce and contributes 12% of all exports
  • Threats:
    • Agriculture causes pollutants to go into the sea
    • Industry and sewage - rivers take pollutants into the sea
    • Over-fishing affects the ecosystems
    • Dredging
    • Housing and shoreline development
    • Tourism
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Natural Hazards - Drought in Australia

  • Australia is so large that it experiences several climate types
  • The daily weather can very enormously between different areas
  • There are monsoon rains in the North near Darwin
  • Desert temperatures up to 50 degrees C in the centre of the Northern temperature
  • Only within 400km of the coast in the south-east is the temperature maritime climate not too hot, nor too cold, and wet enough for people to farm an live in
  • Many Australians live in the two states that cover this area: New South Wales and Victoria
  • Any failure in rainfall or river flow will cause a drought
  • Australia is the World's driest continent and experienced its worst drought in over 100 years in 2002
  • Some people don't see a future for crop and livestock farming
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Use local floods of 2007

  • Opportunities of living on a floodplain:
    • Fertile soils for farming
    • Water for irrigation
    • Can travel by boat along the river
    • Flat land for building roads and railways
    • River is source of fish for food
  • Problems of living on a floodplain:
    • Farmland can be flooded
    • Stores of food can be damaged by floods
    • Foundations of foods are unstable
  • Short term emergency relief aid: Aid from governments, organisations and charities to help people survive straight afer a flood.
  • Long-term development aid: Aid from governments, organisations and charities to enable countries and communities to ensure people have access to basic needs so they can improve their living conditions in the months and years after a flood.
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National Parks - Costa Rica

  • Costa Rica has 29 National Parks
  • They cover 12.5% of the total land area
  • They help to protect the country's 208 species of mammals, 850 species of brid, 220 species of reptiles and 132 species of amphibians, as well as over 9000 species of plants
  • The parks also contain volcanoes, caves, tropical forests and beaches
  • the varied natural environments of the National parks offer many opportunities for tourists, scientists and naturalists who visit them
  • They are carefully managed so that the natural environment is not threatened by human activity, and any developments are sustainable
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