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Year 9 NSW
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Geography
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Australia's physical environment
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Natural hazards
Topic : Natural hazards
In this topic you will learn...
Chapter 1 :
Drought and drought in Australia
Drought is a very costly environmental disaster that occurs often in Australia
A drought is when rainfall and stored water does not provide enough water for all users
Meteorological drought is a prolonged period of low precipitation
Hydrological drought occurs when water reserves fall below the statistical average
Agricultural drought happens when there is insufficient water for agricultural purposes
Australia is a dry continent, which makes it prone to drought
The El Niņo Southern Oscillation system can cause droughts
Drought impacts the lives of all Australians, both in rural areas and in the cities
Chapter 2 :
Bushfires and bushfires in Australia
Australia encounters frequent bushfires, more than any other country in the world
A bushfire is a wildfire that burns out of control, destroying vast regions of bushland
Bushfires require hot, dry conditions and a large amount of available fuel
Spot fires and crown fires are dangerous phenomena that happen along with bushfires
Bushfires can start due to natural causes, or they can be started accidentally by humans
A large proportion of bushfires are started intentionally by arsonists
Bushfires can destroy property as well as plant and animal life
Many plants and animals have adaptations that allow them to survive bushfires
Fire has some beneficial uses, such as regenerating plant growth
The Aboriginal peoples used fire to maintain their land
Chapter 3 :
Storms and a major storm in Australia
Storms are weather patterns characterised by high winds and sometimes high precipitation
Thunderstorms are the most common type of storm in Australia
Thunderstorms form when there is instability in the atmosphere, moist air and a trigger
Thunderstorm clouds are called cumulonimbus clouds
Hail and lightning are common thunderstorm phenomena
In April of 1999, a severe thunderstorm caused over $1.5 billion in damage in Sydney
Dust storms occur during times of drought when high winds pick up dust particles
In 1902, severe dust storms affected South Australia, Victoria and New South Wales
Chapter 4 :
Tropical cyclones and a major tropical cyclone in Australia
A tropical cyclone is an intense low pressure system that affects parts of northern Australia
Tropical cyclones are called typhoons in the north Pacific and hurricanes in the north Atlantic
Cyclones form over tropical waters with a surface temperature of 26 degrees Celsius or more
Warmer water encourages low pressure and cloud formation, creating a tropical depression
As more clouds amass, cyclones begin to spin and generate high winds and heavy rainfall
Cyclones have a calm eye at their centre
Cyclones can cause destructive storm surges and storm tides
There are five categories of tropical cyclone
Early warning is the best defence system against cyclones
On Christmas Eve of 1974, a severe cyclone called Cyclone Tracy did $3.5 billion in damage
Chapter 5 :
Floods and a flood in Australia
Floods occur when water covers land that is usually dry
Floods in Australia cost $300-$400 million in damage every year
Floods are usually caused by high levels of precipitation
Seawater can flood the coast under certain conditions
Slow-onset, rapid-onset and flash floods occur in Australia
Floods can be prevented through flood mitigation. Early detection is also important
In 1990, flooding covered parts of New South Wales, Queensland and South Australia
Chapter 6 :
Earthquakes and an earthquake in Australia
Earthquakes are a sudden shaking of the ground caused by the movement of tectonic plates
Earthquakes are not as common in Australia as in other parts of the world
Earthquakes originate deep within the Earth
Earthquakes occur at faults within the Earth's crust
Seismic waves cause the shaking that accompanies an earthquake
Earthquake magnitude is measured using the Richter scale. Intensity is measured on the Mercalli scale
There is no way to predict or prevent an earthquake
Building regulations can make buildings more resilient to earthquake damage
The 1989 Newcastle earthquake had a magnitude of 5.6, but it did severe damage
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