Geography Case Studies

Rivers and Coasts
1. River Clyde, Scotland
  1. Source: Lowther Hills, Daer water and Portail water come together to form the River Clyde. | Mouth: Firth Clyde which becomes the Irish Sea| Length of river: 160km | Direction of flow: North West
  2. Waterfalls: Falls of Clyde = 4 Waterfalls in New Lanark in Scotland: Cora Linn, Bonnington Linn, Dundaff Linn, lower falls: Stonebyres Linn. Gorge of red sandstone.
    1. Water Falls formed when hard rock lies over soft rock and water falls over, making plunge pool as it erodes soft rock and leaves hard rock rock overhang that will eventually fall off. So waterfalll retreats
  3. Interlocking spurs: at Crawford, between 300m and 500m high
    1. Interlocking spurs are created as river winds round obstacles of rock. The V-shaped valleys slope downwards and meet at the bottom like zip
  4. Meanders: around Motherwell and Glasgow
    1. Rivers flow in corkscrew motion called helical flow. This means that on the inside bend of a river, there is deposition creating slip-off slopes because of slower flow. On the outside bend, river flows faster, erding the land and creating river cliffs, this means the river bends round and makes meanders.
  5. Oxbow lake forming near town of Udddington
    1. The fast flow of a meander erodes the land making a rive cliff. The slow flow on the inside bend of a meander deposits sediment onto a slip-off slope. Over time, more erosion and deposition makes meander bigger. Finally, the deposition of either end of the meander meets and the curves is cut-off from the river after water floods over deposited sediment and dries up, leaving dry land. Over time, the oxbow lake dries up.
  6. Floodplain: Glasgow built on floodplain of Clyde. Land either side is 5m above sea level.
    1. In the lower stage, land is much flatter and the river has less energy. The flat land around river is a floodplain, like to flood if river gets full.
  7. Estuary: River Clyde estuary is 34km west of Glasgow, is 3km wide. The river joins the Firth Cyde which eventually becomes the Irish Sea.
    1. Estuaries form just before the mouth of the river. Here, the flow is affected by the seawater coming from the opposite direction. The river slows down, loses energy and drops it's load. The creates mudflats that form either side of the river
2. Boscastle Floods, August 2004 (flash flood)
  1. Boscastle is in UK, SW England. In Cornwall, North from Newquay. Built at Confluence of Valency and Jordan rivers.
  2. Causes
    1. Human:
      1. Removing trees and vegetation from valleys and so decreasing interception
      2. Building on floodplains so ground in is impermeable so decreasing infiltration.
      3. Construction of small bridges along the river that trapped boulders and rocks and created damming effect.
      4. Artificially narrowing river so reducing carrying capacity.
      5. Allowing trees to grow right beside river so they fell in and blocked channels.
    2. Physical (natural)
      1. The catchment is small and includes upland area of Bodmin that isn't very permeable
      2. Steep-sided valleys funnel water towards Boscastle.
      3. Surface run-off reaches river quickly.
      4. Summer of 2004 was unusually wet so by august the ground was saturated.
  3. Effects
    1. Human
      1. Holiday makers/ tourists who came for holidays were affected as Cornwall is a popular holiday destination.
      2. Small businesses set up by residents of Boscastle who couldn't afford to pay for damage.
      3. Owner of vehicles because hundreds of vehicles were swept away
      4. Schools and transport/travelling was affected.
      5. Residents of Boscastle who had to deal with long-term/short-term damage.
      6. No deaths.
    2. Physical
      1. Local wildlife affected as sewage pipes burst and risk of contamination form sewage.
      2. Local ecosystems affected as they were damaged..
      3. Local environment as it spoilt the beautiful image of the time and made it very dirty.
  4. Responses (Boscastle Flood defence scheme, costs £4.6 million)
    1. Making bridge-span wider so it's more difficult to break and be destroyed by force of water.
    2. Retaining old defences for extra security.
    3. Relocating defence wall and making river wider and deeper so it can carry higher flows (more) water and a larger load.
    4. Raise car park so cars are above flood level
    5. Remove trees right next to river so they are less likey to fall in and block channels.
    6. Form a wider channel upstream of car park to create an area of slower flow where larger sediment will be deposited and river can spread out.
    7. Taking away lower bridges to prevent damming effect when boulders and trees fall into river.
3. Bangladesh Floods, July-September 1998
  1. Bangladesh was part of India in British Empire. Bangladesh is now separate, but is surrounded N, E and W by India. Part of Asia. In South, shares coastline with Bay of Bengal.
  2. Causes
    1. Human
      1. Deforestation in the Himalayas, at the sources of Brahmaputra and Ganges rivers so less interception, more surface run-off.
      2. Deforestation for fuel and grazing, so increased surface run-off.
      3. In India, the Ganges has been diverted for irrigation, increasing deposition or silt and reducing channel capacity. In the rainy season water is let through causing floods
      4. Rapid unplanned urban growth has added to the problem of flooding. Urban populations in Bangladesh have increased from 4% in 1951 to 35% in 2009 (estimate). The growth is largely made up of poor migrants who often live in vulnerable areas.
      5. Bangladesh is an LEDC and so doesn't have much money to spend on maintaining flood defences and creating them
    2. Physical
      1. Increased surface run-off leads to soil erosion and more silt, raising river beds. The bed of the Brahmaputra is rising 5cm/year.
      2. Bangladesh is 80% flood plain and delta makes it very susceptible to flooding.
      3. Cyclones at sea create a storm surge.
      4. Silt blocks river channels and creates islands, reducing carrying capacity of rivers.
      5. Meeting of 3 huge rivers increases flood risk.
      6. 70% of total land area is less that 1m above sea level-nowhere for water to drain to
      7. Heavy monsoon rains causes summer flooding.
      8. Melting of snow from Himalayas adds to volume in the warmer mouths
  3. Effects
    1. Human
      1. Over 1300 people died.
      2. Lack of access to medical care.
      3. Roads and railways swept away and so aid and rescue distribution was difficult.
      4. Over 20 million made homeless and many lost everything.
      5. Contamination of water by sewage dead bodies/animals, lack of clean water resulted in spread of disease such as Typhoid and Cholera
      6. 20% decrease in production of exports
      7. 400 clothing factorises forced to close
      8. Overall the floods cost the country over $1 billion
    2. Physical
      1. About 1/2 million poultry and cattle were lost
      2. 668,529ha (hectares) of crops destroyed
      3. Deposition of rich fertile soil onto land
      4. Providing water for crops
      5. 57% of land flooded
      6. ≈2/3 of land was covered by water and Capital Dhaka, was ≈2m underwater
      7. 2 million tonnes of rice destroyed
  4. Responses
    1. Small scale - The Preparedness Programme
      1. Cluster village: village raised 2m above sea level. Village houses 25-30 families.
      2. Raised homestead: individual homes raised 2m above sea level on earth banks. The earth banks are planted with grass to prevent erosion and grass takes up water.
      3. Flood Shelter: ≈2ha of raised land where people can bring livestock. Each shelter has space for 100 families, has toilets and community room.
      4. Rescue boats: located around areas most at risk from flooding, near flood shelters.
      5. Radios: radios given to each preparedness committee: flood warnings can be issued and preparedness plan put into action.
      6. + : Appropriate tech, cheap, easy
      7. - : Short-term, need agencies and flood risk map, affect small no. people
    2. Large scale - Dhaka Integrated Flood Protection Project
      1. Embankments - Earth embankments built to hold back rising water and save lives.
      2. Slope Protection - to reduce erosion of embankments and soil erosion, reduce flood risk.
      3. Drains - Storm drains linked back to rivers so water has somewhere to go.
      4. Sluice Gates - able to close channels when water rises and so create a sort of dam so people on the other side are safe
      5. + : Large no. people, long term
      6. - : Expensive, affordable to make/maintain? Dams damage environment
4. Coastal Area and Landforms: Dorset coast
  1. Swanage Bay and Studland Bay
    1. Formation of Bays: Bays form when there is a discordant coast line. In between each hard rock headland is a layer of soft rock which gets eroded by the sea to form a bay
    2. Formation of Old Harry's rocks: The sea erodes the foot of the arch and the roof becomes heavy and collapses. The isolated rock is a stack. Over time stack is undercut and collapses. A stump remains at Swanage/Studland bay.

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	Criado por Bryony McIvor quase 11 anos atrás