Tropical 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 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
• Weather forecasting technology used by BMD

  • Weather radars across the country
  • Satellite imagery purchased from the US, China and Japan
• In 2018, Bangladesh's first satellite, Bangabandhu Satellite-1, was sent into the Earth's orbit. This $280million project has made satellite imagery more accessible to Bangladesh, which may support the country's preparedness to future tropical cyclones
• How BMD communicates weather forecasts

  1. To television and radio stations

  2. Airports

  3. Prime minister

  4. Air force
• Warning and Evacuation Strategies

  • Many communities in Bangladesh have little to no access to television, the internet or radio
  • 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
• Cyclone shelters in Bangladesh

  Many function as schools and other public buildings so they are not left empty for the majority of the year
• Bangladesh has needed financial aid with some of their flood defences. For example, the World Bank provided $400 million to upgrade Bangladesh's embankment defence system
• Tropical Cyclones in the USA

  • A very frequent hazard on the eastern coast of the US
  • Hurricane season hits between July and October every year
• Florida has a 22% chance of a hurricane making landfall every year
• The USA's weather forecasting system

  • Usually very effective at tracking the formation and movement of tropical cyclones
  • Over 20 weather satellites operate every day over the US and Atlantic Ocean, gathering information about the location and intensity of any potential tropical cyclone activity
• Satellite technology used in the USA

  Meteorologists 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 in the USA

  • 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
• Evacuation process in the USA

  1. Local authorities issue evacuation orders in areas where it is likely people will be severely affected if they stay at home

  2. Law enforcement visit homes spreading this information
• 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 US has been criticised heavily for having poor quality storm surge defences, and these defences have been breached on multiple occasions. After Hurricane Katrina, man-made levees failed and flooded 80% of the city of New Orleans, and 1,577 died in the state of Louisiana
• Hurricane-proof homes in the USA

  • Built on stilts to ensure they are high up and resistant to flooding from storm surges
  • Made out of concrete which is resistant to very strong winds
  • Windows and doors can be reinforced to be resistant to heavy winds and breaking if hit with flying debris
• Tropical Cyclones


  • Hurricane Katrina
  • Cyclone Nargis
• A Cyclone's Impact is Linked to Preparation and Responses
• The impacts of tropical cyclones depend on how a country prepares for and responds to the event
• Countries like the USA tend to be better prepared, so they can respond in a more effective way
• Aspects of Forecasting Tropical Cyclones


  • Monitoring
  • Prediction
  • Warning & Evacuation
• Tropical cyclone in a developed country


  • Hurricane Katrina
  • Category 3 landfall
  • South west USA
  • August 29, 2006
• Despite the preparedness, the impact of Hurricane Katrina was devastating
• 20% of the city of New Orleans was flooded, coastal habitats were damaged, and over 1800 people were killed
• Tropical cyclone in a developing country


  • Cyclone Nargis
  • Category 4 landfall
  • Irrawaddy delta, Myanmar
  • May 2, 2008
• Myanmar did not have a dedicated disaster management system for tropical cyclones
• Myanmar's weather agencies did warn about Cyclone Nargis, but the warnings did not reach many people in remote areas in time