Managing Natural Hazards (2nd Test) Flashcards
Define a cyclone
A powerful tropical storm- an area of intense low pressure that forms over warm water.
What do cyclones bring
They bring strong winds, torrential rains and storm surges
Names of cyclones
Atlantic Ocean- Hurricane
Pacific Ocean- Typhoons
Indian Ocean- Cyclones
Area where tropical cyclones form
- Between 5 & 20 north and south of the equator
- Over warm tropical water (27 c & 60 m deep)
- When powerful convection of warm moist air occurs, this rises, cools, condenses and forms storm clouds. Fueled by ocean temperatures, the storm grows and begins to rotate due to the coriolis effect
Life cycle of a tropical cyclone
- Tropical disturbance- Warm moist air forms thunderstorms
- Tropical depression- Storms combine & spin
- Tropical storms- Spiralling winds churn up the sea, grows into a circular shape w/ rainfall
- Tropical cyclone- Clear rotation around central eye (low pressure in centre creates an area of suction which causes storm surges)
Measure of tropical cyclones
Saffir-Simpson hurricane wind scale
Possible damages from wind & storm surges
- Homes broken
- Trees unrooted
- Power lines destroyed
- Coastal roads flooded
Impacts of storm surge
- Saltwater flooding destroys crops (food supply)
- Fishing fleets destroyed (food supply)
- Contaminated water supplies (water-borne diseases)
Reducing TC risk beforehand
- Tracked by satellites
- Warnings
- Evacuation plans can be drawn
- Houses can be boarded up
- Emergency training drills
- Food supplies stored
- Education
- Cyclone shelters made
- Buildings redesigned
Reducing TC risk during
- Stay inside & wait
Reducing TC risk after
- Social networking to reunite families
- International aid
- Plans to reconstruct buildings
- Provide assistance
Define flooding
When an area of land is covered or submerged with water
Causes of flooding
- Prolonged/heavy rainfall
- Storm surges
- Geology
- Snowmelt
- Tsunamis
- Urbanisation
- Rise in sea level
- Deforestation
How can humans be blamed for flooding?
Humans find it attractive to devlop on ‘floodplains’ (flat area of land next to a river)
Floods in an area with untouched floodplains are unlikely to lead to a disaster
Where does rain go when it reaches the ground
Directly into the river
Infiltrate in the soil
Surface run-off
Intercept in trees
Percolation into surrounding drainage basins
Impacts of flooding
- Death
- Crops
- Mines
- Water
Reducing flood risk before
- Flood risk map
- Monitoring
- Hard engineering (Dams, control gates, flood relief chanels)
- Soft engineering (trees, marshlands, controlled flooding)
- Flood proofing houses
Reducing flood risk during
- Search and rescue
- Shelters
Reducing flood risk after
- Clean up
- Assessments on roads, bridges
- Demolition of buildings
Define drought
A prolonged period of abnormally low rainfall, leading to a shortage of water
Natural causes of drought
- Weather patterns
- Climate change
- ENSO
- Climactic factors
Human causes of drought
- Poor farming practices
- Oversbatraction
- Deforestation
- Conflict
Impacts of drought
- Death
- Soil erosion
- Decline in water supply
- Crops
5.Starvation
6.Decrease in air quality - Risk of wildfires
- Desertification
Reducing the risk of droughts beforehand
- Transferring water
- Desalination
- Exploiting unused groundwater in aquifers
- Education
- Monitoring / Warnings
Reducing the risk of droughts during
- Rationing
- Conserve, Reuse, Harvest
- Migration
- Emergency supplies sent out
Reducing the risk of droughts after
- Developing water supplies
- Drought-resistant crops
- Education
- Combatting desertification
Opportunities in floods
- Fertile ‘Alluvium’ deposited
- Floodplain & Delta used for agriculture supported by river irrigation
Define flood plains
A naturally occurring area of flat, low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding
Define lag time
The amount of time between peak rainfall and peak river discharge
