Bush Fires Flashcards
What are Bushfires?
Bushfires, also known as wildfires outside of Australia, are uncontrolled fires that burn in natural vegetation such as grasslands, woodlands, and forests. These fires pose significant threats to life, property, and the environment due to their intensity and rapid spread. One of the most devastating examples is the Black Saturday bushfire, which occurred in Victoria, Australia, from 7th to 14th February 2009. This catastrophic event was fueled by extreme heatwaves, low humidity, and strong winds, resulting in widespread destruction, loss of life, and severe environmental and economic impacts. Understanding bushfires and their consequences is crucial for improving management strategies, response measures, and community preparedness to mitigate future risks.
What is Magnitude of the BSB?
Area Affected: Over 450,000 hectares destroyed.
Spread Rate: Fires traveled at an average speed of 12 km/h, with bursts up to 60 km/h.
Number of Fires: Approximately 400 individual fires.
Flame Height: Reached heights of 18 to 20 meters.
What is the duration of the BSB?
Duration: The bushfire began on 7th February 2009 and continued to burn for 26 days. It was declared under control on 13th March 2009.
Contributing Factors:
Severe Heatwave:
• Within the two weeks preceding Black Saturday, a severe heatwave impacted Victoria.
• Melbourne experienced temperatures exceeding 43°C for three consecutive days.
Long-Term Drought:
• Persistent drought conditions contributed to extremely dry vegetation, increasing fire risk.
Extreme Temperature:
•On 7th February, Melbourne recorded a peak temperature of 46°C.
High Wind Gusts:
Wind gusts exceeding 100 km/h changed direction late on 7th February, causing unpredictable fire paths and further complicating containment efforts.
What is the Frequency of the BSB?
Fire Incidence:
• Australia is the most fire-prone country globally.
• Fire services respond to 45,000-60,000 bushfires annually.
Urbanisation Impact:
• Expanding city fringes increase risk due to proximity to bush areas.
• Creates a “frontier zone” with high bushfire potential.
Historical Trend:
• Over 230 years, there has been a rise in large-scale, destructive fires.
• Victoria is Australia’s most bushfire-prone state.
• Major fires in Victoria since 1851 culminated in events like the Black Saturday Bushfire.
Millennium Drought:
• Southeast Australia had experienced a 10+ year drought by Black Saturday.
• Many parts of Victoria saw their lowest rainfall on record over a 12-year period.
• Total rainfall loss during this time equated to two years’ worth of average rainfall.
What is Probability of BSB?
Extreme Heat:
• Victoria experienced a heatwave with temperatures reaching up to 48°C.
• Winds exceeded 100 km/h, intensifying fire risk.
• Little to no rain, contributing to extremely dry conditions.
• Extended Heatwave:
• A heatwave hit southeastern Australia in the weeks before 7th February 2009, following two months of hot, dry weather.
• Melbourne endured three consecutive days above 43°C.
• Temperature peaked at 45.1°C on 30th January, one of the hottest days ever recorded in the city.
Tinder-Dry Conditions:
• Extremely high temperatures and very low humidity created tinder-dry vegetation in the Victorian bush, ideal for ignition.
Conditions for Bushfire:
• The combination of prolonged heat, high winds, and dry vegetation made a bushfire almost inevitable.
• With such a high probability of ignition, any spark or heat source could trigger a fire, which ultimately occurred on Black Saturday.
• The extreme conditions significantly increased the likelihood of a large, uncontrollable bushfire once ignition happened.
What is the Scale of Spatial Impact?
Area Affected:
• More than 450,000 hectares burned.
• Buildings Destroyed:
• 3,500 buildings, including over 2,000 houses, were destroyed.
Fatalities:
• 173 people killed, with 120 in the Kinglake area alone.
• Injuries:
• 414 people were injured in the disaster.
Animal Losses:
• Up to one million wild and domesticated animals estimated to have died (RSPCA).
Smoke and Air Quality:
• The bushfires generated significant smoke, affecting air quality.
• Smoke traveled long distances, impacting cities like Melbourne, located over 100 km away from the fire’s forefront.
Ignition of Black Saturday
The Black Saturday bushfires started with the Kilmore East fire when fallen power lines sparked a blaze in farmland at 11:47 am. This fire quickly spread through a pine plantation and crossed the Hume Freeway by 1:58 pm. By around 3 pm, it had burned through Wandong and reached Mount Disappointment. The extreme conditions on the day, including strong winds and high temperatures, led to multiple fire plumes, which generated pyrocumulonimbus storms—large, intense thunderstorms created by the heat of the fire. Some of these storms reached heights of 15 km and produced significant lightning. Five hours after the initial ignition, lightning strikes were recorded near the fire, which led to further fire development, even 100 km ahead of the main fire front. This lightning, known as pyrogenic lightning, played a significant role in causing further fire outbreaks, helping explain the rapid and unpredictable spread of the fires.
Climate and weather on Black Saturday bushfire
The extreme climate and weather conditions on Black Saturday played a critical role in the rapid spread of the bushfires. With temperatures near 40°C, low humidity levels below 20%, and strong winds gusting at 40-60 km/h, the conditions were perfect for fire to spread uncontrollably. By 5 pm, wind speeds reached 115 km/h at Mt William and Mt Gellibrand, intensifying the fire danger. A southwesterly change further worsened conditions, bringing thunderstorms and lightning by 8 pm, which sparked additional fires. Even though the weather change moved out by 11 pm, temperatures remained high, and winds in Melbourne became light before another southerly surge lowered them. Additionally, the months leading up to Black Saturday saw very low rainfall, which created tinder-dry vegetation, or “cured fuels,” that fueled the fires. The dry salts in the environment further increased the flammability of the bush, making the fires even more extreme and difficult to control. These combined factors of extreme weather, dry vegetation, and lightning strikes led to one of the most devastating bushfires in Australian history.
Vegetation of the BSB
The Black Saturday bushfire had a devastating impact on Victoria’s mountain ash forests, which are known for their high carbon density. Even after severe fires, 86-94% of the carbon remains in the massive trunks and root systems of these trees, showcasing their resilience. However, while these forests can recover after fires, the post-fire conditions make new regeneration highly vulnerable. These forests also provided ample fuel for the fires. The bushfire swept through 78,200 hectares of mountain ash forest in the Central Highlands of Victoria, an area known for its susceptibility to wildfires due to the dominance of eucalypt forests. Eucalyptus trees are particularly prone to wildfires, with their fibrous and ribbon bark providing firebrands that ignite spot fires, helping to spread the flames. The region’s landscape, which also includes temperate grasslands, further contributed to the severity of the bushfire. These grasslands, characterized by tall, densely packed vegetation, provide a high fuel load that can intensify fires. Additionally, the tunnel-like effect of the grasslands can accelerate the fire’s speed and intensity. These areas also serve as important habitats for wildlife, including kangaroos, wallabies, and birds, which were affected by the fires and hence many animals lost their lives in fires.
Topography of The BSB
Fires spread faster uphill than on flat ground or downhill. Dr. Andrew Sullivan, a bushfire behaviour expert at CSIRO, explains that the speed of a fire increases as the slope gets steeper. For every ten-degree incline, the fire spreads twice as fast compared to flat ground. However, extremely steep areas, like cliffs, can slow the fire because vegetation is sparse. Even so, fires can still spread downhill or over breaks in fuel by ‘spotting,’ where embers are carried by the wind and start new fires. The reason fires spread faster uphill is that the flames are closer to the fuel on the uphill side, which heats it up, and the hot air from the fire moves uphill, drying out the fuel. On the other hand, fires spread slower downhill. The steep slopes and dense vegetation of areas like Kinglake, Maryville, and Dandenong Ranges made them particularly vulnerable during the Black Saturday fires.
Compare the physical and human factors that explain why less economically developed countries are more vulnerable to natural hazard than more economically developed countries developed countries.
In comparing the physical and human factors that explain why less economically developed countries (LEDCs) are more vulnerable to natural hazards like fires, we can examine the contrasting examples of the Black Saturday bushfires in Australia and the 2015-2016 fires in Indonesia. Both countries faced severe fires, but their differing levels of development, infrastructure, and preparedness influenced the extent of the damage and the ability to respond.
Physical Factors
The physical environment plays a critical role in fire vulnerability. In Indonesia, the presence of peat in affected areas led to ground fires, which are challenging to extinguish. Peat, formed by the partial decomposition of organic matter, becomes a significant fire risk when it dries out, as it did during the 2015-2016 El Niño event. The prolonged dry conditions caused by El Niño turned peat, which is usually waterlogged, into a perfect fuel source. NASA data indicated that when rainfall levels drop below 4mm per day, severe fire risk increases, which was the case during this period. The large-scale burning, fueled by peat and exacerbated by high temperatures, contributed to a devastating fire season.
In contrast, Australia’s Black Saturday bushfires were driven by extremely high temperatures, low humidity, and strong winds. On February 7, 2009, temperatures soared to 45°C in some areas, coupled with humidity levels below 20%, creating ideal conditions for the rapid spread of fires. The wind speeds reached up to 115 km/h in some regions, further pushing the flames through the dense, fire-prone mountain ash forests. The physical characteristics of Australia’s forests, combined with the prolonged heatwave, made it especially vulnerable to large-scale bushfires.
Human Factors
Human activities are also central to explaining why LEDCs like Indonesia are more vulnerable to fires. In Indonesia, the widespread use of “slash and burn” farming techniques has been a major factor in the fires. This method, used by both small farmers and large industrial plantations, particularly for palm oil cultivation, led to thousands of uncontrolled fires. Indonesia is the world’s largest producer of palm oil, and these illegal agricultural practices contribute significantly to deforestation and fire outbreaks. Poor enforcement of laws regarding illegal land clearing and the corruption that allows these practices to continue further compounds the issue.
Australia, on the other hand, has more regulated land management practices. While bushfires are a natural part of Australia’s environment, the country’s fire management policies, such as prescribed burning, aim to reduce fuel loads and prevent uncontrolled wildfires. Following the Black Saturday fires, Australia introduced stricter regulations and improved its firefighting infrastructure, ensuring better preparedness for future fires.
Economic and Government Factors
Economic development also plays a significant role in vulnerability. Indonesia, with a GDP per capita of just $3,620 in 2020, struggles to fund adequate fire management and prevention systems. Rural areas, where most fires occur, lack the resources for proper firefighting infrastructure and emergency response services. In contrast, Australia’s higher GDP per capita, around $51,000, allows for better-equipped rural fire services and advanced firefighting technologies. Australia has well-funded organizations like the Country Fire Authority (CFA), which is crucial in managing fires during extreme conditions.
Additionally, government factors are key to explaining the difference in vulnerability. In Indonesia, poor enforcement of environmental laws and corruption within the government allow illegal land clearing and burning to continue unchecked. This lack of accountability leaves communities highly vulnerable to fire disasters. In contrast, Australia has stringent environmental regulations and laws that are enforced more effectively, with severe penalties for those responsible for arson and illegal burning.
Conclusion
In conclusion, both physical and human factors contribute to a country’s vulnerability to natural hazards like fires. Indonesia’s vulnerability is amplified by its physical environment, agricultural practices, low economic development, and poor governance, making it more susceptible to large-scale fires. Australia, with its more developed economy, better regulations, and robust fire management systems, is better equipped to respond to and mitigate the impact of fires, even under extreme conditions. Therefore, economic development, infrastructure, and government policies are crucial in determining how vulnerable a country is to natural hazards like fires.
Describe how human activities intensified the impacts of a natural hazard you have studied.
Bushfires, or wildfires as they are known outside Australia, are an example of atmospheric hazards that can have their impacts intensified due to human activities. Bushfires are uncontrolled fires that burn in the ground, grass, or forested areas, and they can negatively affect people, the environment, and the economy. Examples of severe bushfire events include the 2009 Black Saturday fires in Victoria, Australia, and the 2015 peat fires in Indonesia. Human activities, such as deliberate and accidental ignition of fires, farming and land clearance practices, urban development in fire-prone areas, and human contributions to climate change, significantly intensify bushfire events. The Black Saturday fire began due to a fallen power line in Kilmore East, with subsequent fires deliberately ignited. Climate change, which refers to long-term shifts in temperature and weather patterns, has exacerbated the risk and intensity of bushfires. Since the 1800s and the industrial revolution, human activities—primarily the burning of fossil fuels—have contributed to climate change, causing heat-trapping gases that increase the frequency and severity of extreme weather events. Urban sprawl and the construction of homes close to bushlands with high fuel loads have compounded the economic and social impacts of bushfires, as seen in the Black Saturday fires, which destroyed over 2,000 homes and claimed 173 lives.
One of the key ways in which human activities intensified the Black Saturday bushfires was through urban development in fire-prone areas. Many of the affected communities were located in areas with dense vegetation, dry forests, and high fuel loads, all of which made them more susceptible to intense bushfires. Urban sprawl in these fire-prone zones made it increasingly difficult for people to escape when the fires struck. In addition, the construction of homes on the tops of hills or in areas with limited evacuation routes increased the risk of property damage and loss of life. The fire spread quickly in these regions because of the high fuel loads and the potential for crown fires, which are fires that spread rapidly through the treetops. These types of fires are difficult to control once ignited, especially when strong winds help carry the flames across large distances. The lack of fire-safe design in residential areas also contributed to the rapid spread of the fires, amplifying the destruction of homes and infrastructure.
Human activities also exacerbated the Black Saturday fires through poor land management practices, particularly in relation to vegetation control and fuel management. Over time, large areas of land, especially in rural and bushland zones, had accumulated excessive fuel from overgrown vegetation. Without regular controlled burns, which are necessary for reducing fuel loads and maintaining the health of forest ecosystems, the amount of dry vegetation became a major contributor to the rapid spread of the fires. Additionally, the widespread planting of highly flammable vegetation like eucalyptus trees in certain regions increased the potential for large, intense fires. While these trees are a natural part of the landscape, their presence in highly populated or vulnerable areas made the fires harder to control and intensified their impacts.
Another major human factor that intensified the Black Saturday fires was climate change. The increase in global temperatures due to the burning of fossil fuels and deforestation has created more extreme weather conditions, including higher temperatures, lower humidity, and longer droughts. These conditions are ideal for bushfire ignition and rapid spread. On the day of the Black Saturday fires, Victoria experienced extreme heat, with temperatures reaching over 40°C, combined with gusty winds that further fueled the fires. These weather conditions are directly linked to the rise in greenhouse gas emissions from human activities. As global temperatures rise, bushfire seasons in Australia and other parts of the world are becoming longer and more severe, which further increases the vulnerability of communities and ecosystems.
Human-induced climate change also makes bushfires harder to predict and manage. The frequency and intensity of extreme weather events, such as heatwaves and intense storms, are increasing, making it more difficult for authorities to prepare and respond to bushfire threats. In the case of Black Saturday, the rapid onset of extreme weather left little time for effective mitigation or evacuation strategies. Moreover, climate change has led to the drying out of vegetation, which acts as additional fuel for the fires.
Social impacts of BSB
Key Stats:
• 173 people killed (120 from Kinglake, 35 children). • 414 people injured. • 7,000 people left homeless.
Key Effects:
• Increased mental health issues (PTSD, anxiety, depression). • Rise in domestic and family violence. • Higher alcohol consumption and chronic diseases. • Increase in unemployment rates.
Mental Health:
• Deloitte Access Economics (2016) report: Increased mental health problems post-bushfire. • 20% of survivors had mental health issues 5 years after the fires (Murdoch University study). • Trauma and PTSD led to long-term emotional and psychological distress.
Domestic Violence:
• Many women reported violence from partners who were not previously violent. • Link to trauma and PTSD from the disaster.
Economic & Social Disruption:
• Unemployment rates rose due to business closures and economic instability. • Community isolation and loss of social cohesion.
Environmental Impact of BSB
Animal Loss:
• 3 billion animals died due to flames and smoke. • Species affected: • 5 million kangaroos and wallabies. • 51 million frogs. • 180 million birds. • 1.1 million wombats. • 114,000 echidnas. • 64,000 koalas. • 2.46 trillion insects.
Faunal Emblems & Habitat Loss:
• Leadbeater’s possum: Lost 45% of habitat, population halved to 1,000 individuals. • Hollow-bearing trees: Critical loss of habitat for many species, including birds and marsupials.
Back: Environmental Impacts Continued
Carbon Emissions:
• 30 tonnes of CO₂ per hectare of forest burned. • Total estimated CO₂ released: 4 million tonnes.
Erosion & Soil Loss:
• Fires exposed critical topsoil to erosion. • Stripping of nutrients, putting non-endangered plants at risk.
Economic Impacts
Property and Business Loss:
• 2,000 houses and 1,500 buildings/businesses were destroyed. • Cost of the fires: Estimated $4.4 billion (Royal Commission, conservative estimate). • Insurance payout: $1.4 billion covered by the Insurance Council of Australia.
Insurance Breakdown:
• 84% of claims were for property damage. • 16% were for motor vehicle claims.
Back: Economic Impacts Continued
Income Loss:
• Male income dropped 9% on average. • Female income dropped 14% on average. • Low socioeconomic areas: 18% income loss on average. • Higher socioeconomic areas: 11% income loss on average.
Sectoral Impact:
• Agriculture: 31% income loss for businesses in this sector.
