Hydro-metrological hazards Flashcards
(15 cards)
What are the three types of bushfires?
Ground, crown or surface
Surface fires?
Low to high intensity fires burning the surface litter, grass and shrub layer.
Ground fire?
Underground fire in of which peat, coal or tree roots ignite and burn.
Crown fire?
Very high intensity fire, spreading rapidly through the crown (canopy)of trees, especially if there are strong winds.
What are the two classifications of fires?
Forest fire and grass fire
Forest fire?
Often in mountainous areas. Steep terrain and dense forest = rapid and intense fires
Grass fire?
Most common type of bushfires in Australia. Quick burning (up to 25 km/h)
How does climate affect fires?
Areas with high temperatures and low rainfall e.g. South East Australia
How does wind affect fires?
Dry winds can feed a fire by increasing its speed, dry fuel and spread and carry embers = spot fires.
Also, winds can cause flames to bend over and heat fuel through radiation.
How does topography affect fires?
Steep mountainous areas burn faster as radiation heat can pre heat high fuels on the slope.
How does fuel loading affect fire?
Large amounts of dry, flammable fuel
(high in carbon e.g. leave litter)increase the magnitude
of the fire.
What are the four main factors that affect fires?
Climate, wind, topography and fuel load
What are the human causes of a fire?
Human causes of bushfires include both accidental and deliberate ignition.
Accidental causes include leaving campfires unattended, sparking from machinery or powerlines, and negligent discarding of cigarettes. Deliberate causes include arson and other intentional acts of igniting fires.
What are the natural causes of fire?
The primary natural cause of bushfires is lightning strikes igniting dry vegetation. Droughts and dry spells can also increase the risk by making vegetation highly flammable.
