Hurricanes
- Created by: Gabzay
- Created on: 26-04-13 16:49
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- Hurricanes
- HURRICANE KATRINA, AUGUST 2005
- Impacts
- Infrastructure
- Communications infrastructure failed - telephones, mobiles, Internet access and local TV stations did not work
- Most major roads into, and out of, New Orleans were damaged
- Levees and floodwalls protecting New Orleans were breached
- 80% of the city was under water when the levees broke
- 1.7 million people lost electricity across Mississippi and Louisiana
- Extensive damage to buildings
- Economic effects
- Many left unemployed - no one was paid, or spent any money, so government could not collect taxes
- Total economic impact of Hurricane Katrina was $150 billion
- Affected importation and production of oil and natural gas
- Oil and petrol prices rose
- Social effects
- 1464 people died in Louisiana; many bodies not recovered for days
- 80% of population evacuated but 20% did not have the means to leave
- 1 million people were made homeless
- Lack of sanitation led to health concerns
- 600,000 pets were killed or left without shelter
- In the immediate aftermath of the hurricane, looting and civil disturbance became serious problems
- Infrastructure
- Causes
- Global warming
- Hurricanes are becoming more intense because of rising sea temperatures
- Global warming causes sea temperatures to rise
- Wetlands disappearing
- Wetlands provide a barrier which can absorb the energy of storm surges at the rate of 0.3m per 2.7 miles when hurricanes hit the coast
- Provide protection for places inland
- Levees and floodwalls
- Poor design, faulty construction and poor maintenance were all possible causes of the failures
- Widespread building of levees, engineering works along the Mississippi and gas from below the delta has speeded up the removal of the wetlands
- Hurricane activity fluctuates naturally
- It is only since 1970 that observations have been taken of hurricane intensity
- Difficult to separate human-induced climate change from natural variability
- Global warming
- Impacts
- WHAT ARE HURRICANES
- Very similar to typhoons and cyclones
- Intense, destructive, low-pressure weather systems
- Very strong sustained winds of over 120 km/h and torrential rain (250 mm can fall in one day)
- Hurricanes tend to develop...
- ...over warm, tropical oceans, where sea temperatures are at least 27 degrees
- ...in late summer and early autumn when temperatures are at their highest
- ...in the trade wind belt between latitudes 5 degrees and 20 degrees either side of the equator
- ...where there is low atmospheric shear
- Hurricanes are named to improve communication
- Hurricanes are measured by using a Saffir-Simpson scale which rates the intensity of hurricane from 1-5
- How hurricanes form
- A strong upward movement of air draws water vapour up from the ocean
- As the air rises, it spirals, cools and condenses - releasing huge amounts of heat energy, which powers the storm
- Colder air sinks down through the centre of the hurricane to form the eye
- When the hurricane reaches land - and its source of heat energy and moisture disappears - it rapidly decreases in strength
- MANAGING HURRICANES
- Defending New Orleans
- Temporary floodgates and pumps at canal entrances to prevent storm surges from breaking flood defences
- Build a system of weirs to regulate the flow of the Mississippi River Gulf Outlet
- Build a system of 8.5 metre high levees to the east and north of the city
- Managing the risk
- Hurricane watch - announce that specific coastal areas could experience hurricane conditions within 36 hours
- Hurricane warning - warn that certain coastal areas can expect sustained winds of at least 119 km/h within 24 hours
- Making people more aware of how vulnerable they are, and what actions they should take
- National Hurricane Centre run a Hurricane Preparedness Week every year
- Hurricane simulation programme in schools to help students learn how to plan, prepare for and deal with the aftermath of a hurricane
- Evacuation
- Difficult and expensive
- Not everyone can afford to leave
- Notice of a hurricane does not give enough time for proper evacuation measures
- Defending New Orleans
- HURRICANE KATRINA, AUGUST 2005
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