2B.9 - Coastal Flooding

• What are the top 5 countries with the highest % of population at risk from coastal flooding?

  1. Netherlands (59%)
  2. Bangladesh (58%)
  3. Vietnam (46%)
  4. Egypt (41%)
  5. Myanmar (40%)
• Reasons why some areas are at risk from coastal flooding

  • Lack of sea defence (especially in developing countries)
  • Low lying territory
  • Coastal erosion
  • Tectonic pressure
  • Glacial tilt/Geology
  • Tropical storms (tectonic hazards)
  • Population size/density
  • Sea level rise (Isostatic/Eustatic/Thermal expansion)
• Reasons why people inhabit areas at risk from coastal flooding

  • Inertia/Family
  • Strong trade links
  • Food sources (Fish)
  • Cheaper (can be more expensive also)
  • Transport
  • Employment opportunity
  • Tourism
  • Coastal defences
  • Industrialisation
  • Education/healthcare
• Storm Surges

  • Changes in sea level resulting from variations in atmospheric pressure and associated winds
  • Occur on top of normal tides and when positive surges are added to high tides or in association with strong winds that can cause extreme water levels and flooding
  • Most commonly produced by the passage of (extra-)tropical depressions
  • Can have devastating impacts, especially when there is poor management of coastal defences
  • e.g. Cyclone Sidr, Bangladesh 2007 - 15,000 people killed, 55,000 injured, 1.6 million homes destroyed.
• Kiribati - The frontline of climate change

  • Sea is rising 1.2cm/year
  • Will disappear by 2050
  • Eustatic change and thermal expansion due to global warming is forcing this to rapidly accelerate
  • Many roads lost
  • Many citizens have to move house frequently
  • Mangroves planted
  • Major risk of cultural erosion
  • Highest point is 4m above current sea level
  • Education on climate is strong
  • Failure of hard engineering
• Bangladesh - factors that increase flood risk

  • 40 million live in coastal districts
  • 5 million affected by floods by 2050
  • 8-23mm sea level rise
  • Most elevations are less than 10m above sea level
  • Subsidence - clearance and drainage of over 50 large islands in the Ganges Delta, which are now sinking due to lack of natural deposition of sediment
  • Removing vegetation - Mangroves in the Sundarbans collect sediment and provide protection against extreme weather events; they absorb and disperse tidal surges
  • 71% of Bangladesh's mangrove-forested coastline is retreating by as much as 200m a year