Edexcel IGCSE Geography 复习笔记 2.3.2 Coastal Flooding

• Coastal flooding results from a number of factors:
  • Storm surges - a rapid rise in sea level caused by really low-pressure storms (e.g. tropical storm)
  • Storm tides - occur when there is a combination of high tide and low-pressure storm
  • Tsunamis - large sea waves due to underwater earthquakes. The closer to the coast, the bigger the impact
  • King tides
  • Sea level rise due to global warming
  • High river discharge after a storm - when combined with a spring tide, water in the estuary cannot discharge into the sea causing a backflow of water and flooding
• The worst flooding arises from a combination of any of these
• The biggest impacts are felt by emerging countries, although the biggest economic cost is are to developed countries

Prediction

• Early warning systems allow communities to prepare (evacuate or take shelter) before flooding occurs
• Two methods are used to help forecast coastal flooding:
  • Past records (diaries, newspapers, government/council records etc)
    • These will identify areas that are at high risk of flooding and their frequency
  • Modern technology - GIS, satellite and computer monitoring, weather stations (local and national) etc
    • These allow for forecasting and tracking potential hazard events i.e.
      • Tropical storms - track the storm's path and associated storm surge
      • Earthquakes - size and position if underwater and possible tsunami outcome
• Both these methods of forecasting help officials to say when and where the event will occur
• It indicates the possible strength and scale of the flooding, and the likelihood of damage and death

Prevention

• Prevention is about taking action that reduces or removes the risk of coastal flooding
• Actions include:
  • Flood defences
    • These are built along high-risk stretches of coast
  • Emergency centres
    • Centrally placed on higher ground where people can be safe from flooding
  • Early warning systems
    • Allows for preparation or evacuation of an area
  • Education
    • Informing local people on what to do if and when a flood occurs
  • Planning
    • Planning any new development away from high-risk-areas
    • Designing buildings to cope with low levels of flooding
      • Elevating buildings so that flood waters can pass underneath
      • Flood proof buildings with raised foundations (fixed or mechanical)
      • Reinforced barriers
      • Dry flood proofing - sealing a property so that floodwater cannot enter
      • Wet flood proofing - allows some flooding of the building
  • Buffer zones
    • Areas of land are allowed to flood before reaching settlements
      • This allows the energy in the surge to dissipate slowing down the distance the floodwater will travel
      • It can mean moving people away from the coast which could be controversial

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