Coastal Flooding (Edexcel IGCSE Geography)

Causes of 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 & Prevention of Flooding

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

      • Floodproof buildings with raised foundations (fixed or mechanical)

      • Reinforced barriers

      • Dry floodproofing - sealing a property so that floodwater cannot enter

      • Wet floodproofing - 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