geography case study: cyclone

• Cyclone Aila was a severe tropical cyclone that struck Bangladesh on the 25th May 2009
• Cyclone Aila

  • Intense rainfall (120mm of rain in a few hours)
  • Very strong winds (270km/h)
  • Large storm surge
• Cyclone Aila's intense rainfall, strong winds and large storm surge


  Caused widespread flooding and devastation across Bangladesh
• Bangladesh

  • Very low-lying country, with 80% of the land less than 10m above sea level
  • Many large rivers that can overflow onto the floodplains during periods of high rainfall
• Cyclone Aila had devastating socioeconomic impacts on Bangladesh, including 190 deaths, 750,000 made homeless, 3.5 million affected overall, and nearly 60,000 animals killed
• Flooding caused by Cyclone Aila's large storm surge which raised the sea level by 3 metres
• Over half of the flooding embankments in Southern Bangladesh were destroyed
• Bangladesh's response and preparedness


  • Helped to limit the effects of the cyclone
• Weather Forecasting and Satellite Technology

  The Bangladesh Meteorological Department (BMD) uses forecasting technology to predict and track tropical cyclones, allowing communities to prepare for them making landfall
• The BMD has weather radars across the country to track weather patterns, and purchases satellite imagery from the US, China and Japan
• In 2018, Bangladesh's first satellite, Bangabandhu Satellite-1, was sent into the Earth's orbit, making satellite imagery more accessible to Bangladesh and supporting the country's preparedness to future tropical cyclones
• Community Preparedness


  The BMD communicates their forecasts to multiple sectors, including television and radio stations, airports, the prime minister and the air force, so the information is spread across Bangladesh and people can prepare
• Warning and Evacuation Strategies

  • Many communities in Bangladesh have little to no access to television, the internet or radio, leaving them extremely vulnerable to tropical cyclones as they do not receive weather forecasts and warnings
• Bangladesh's government has developed an early warning system which targets vulnerable coastal communities through awareness campaigns
• 45,000 cyclone warning volunteers now work in threatened areas around Bangladesh
• 3,500 cyclone shelters have been constructed in Bangladesh following the devastating Cyclone Bhola in 1970, with many functioning as schools and other public buildings
• Storm Surge Defences


  • Embankments have been built to protect some areas from flooding, though this is usually limited to main roads and areas that need to be protected
• The World Bank provided $400 million to upgrade Bangladesh's embankment defence system
• On the eastern coast of the US, tropical cyclones (called 'hurricanes' in the US) are a very frequent hazard
• Between July and October every year, hurricane season hits, with tropical cyclones traveling over the Atlantic and making landfall in eastern coastal areas surrounding the Gulf of Mexico and the Atlantic Ocean
• States such as Florida, Texas and North Carolina are commonly hit by tropical cyclones, with Florida having a 22% chance of a hurricane making landfall every year
• Preparation and Response in The USA

  • The USA invests a lot into hurricane preparedness and response as the cost of damage is usually so high, especially when hitting cities
• Weather Forecasting and Satellite Technology

  The USA's weather forecasting system is usually very effective at tracking the formation and movement of tropical cyclones, with over 20 weather satellites operating every day over the US and Atlantic Ocean
• Satellite Technology


  Meteorologists in the US can predict wind speeds, storm surge heights and the likely track of the cyclone before it makes landfall, and these predictions are usually accurate
• Hurricanes are closely monitored in the US by organisations like the National Hurricane Center, and regular forecasts are given on the television, the radio and online
• Warning and Evacuation Strategies

  • The US has developed effective warning systems and evacuation strategies to ensure those at risk are prepared for the storm
• Hurricane warnings are widely broadcasted on major news channels, and some areas even have hurricane sirens that sound when there is a high risk of a hurricane
• Local authorities play a major part in the evacuation of civilians from areas of high risk, with evacuation orders issued in areas where it is likely people will be severely affected if they stay at home
• Hurricane evacuation routes are established in areas that are often hit by tropical cyclones
• The National Hurricane Center runs National Hurricane Preparedness Week every year, which aims to spread awareness about people's risks and tell them how they can be best prepared for a hurricane
• The USA manages risk through hazard mapping, which identifies areas that are particularly vulnerable to tropical cyclone hazards
• The National Oceanic and Atmospheric Administration analyses and provides this hazard mapping data, which is free to the public, increasing public awareness about areas of high risk
• Storm Surge Defences


  • The US invests a lot of money into storm surge defences, such as levees (embankments) and storm surge barriers
• The US has been criticised heavily for having poor quality storm surge defences, and these defences have been breached on multiple occasions, with the failure of man-made levees in New Orleans during Hurricane Katrina flooding 80% of the city and causing 1,577 deaths
• Hurricane-proof Homes


  • Some areas that are extremely prone to hurricanes have taken precautions to lower the risk to property from storm surges, such as building homes on stilts and using concrete and reinforced windows/doors to be resistant to strong winds and flying debris
• Meteorological


  The study of the atmosphere and weather phenomena, such as temperature, humidity, precipitation, and wind. Involves observation, measurement, and prediction of weather conditions.