Due to the still-recovering vegetation from the 2019-2020 bushfire season, below-normal fire potentials are expected across parts of the Australian Capital Territory, eastern New South Wales and eastern Victoria.
However, bushfires are expected to occur across Australia for the current bushfire season until at least March 2022, disrupting transportation and business operations on a sporadic and localised basis.
To mitigate risk, as part of the initial steps of any residential, commercial, government or subdivision project, a bushfire consultant must perform an impact assessment. Bushfire assessments can also be conducted on existing developments.
The goal is the practical application of bushfire management plans that also comply with Australian standards.
What Risk Does The 2021 – 2022 Bushfire Season Pose
A bushfire is an unplanned and sometimes uncontrolled vegetation fire. It is a broad term encompassing grassland fires, forest fires and brush fires. Bushfires are a natural, necessary and intricate element of the Australian environment.
Although more than 5 million hectares of land were burnt in the 2019-20 season, vast pockets of unburnt land remain, and these wooded and forested regions remain at a normal level of risk.
Grass fires, in particular, pose a severe threat to the community. Due to the fact that they start suddenly and spread quickly, they carry significant implications for residential and commercial properties. A negative impact on infrastructure has a negative impact on the economy.
Forecast models predict above-average fire danger in northern Western Australia owing to grass growth and dry soil and in Southeastern Queensland and northern New South Wales due to grass and crop growth.
Factors That Impact Bushfire Risk
The presence of fuel, oxygen and an igniting source are the primary conditions that determine whether a bushfire will occur. Factors such as ambient temperature, fuel moisture, wind speed and slope angle all influence the speed and intensity with which a bushfire spreads.
- Season: Wildfires are a common feature of Australia’s early fall and summer seasons, especially following lengthy dry spells or periods of exceptionally high temperatures.
- Ignition Source: A majority of bushfires in Australia are caused by natural occurrences, with lightning accounting for almost half of all ignitions. The remainder is accounted for by accidental or purposeful ignition by humans.
This refers to both arson or intentional fire breaks designed to control vegetation, which turn into raging bushfires due to unforeseen changes in conditions.
Unfortunately, both intentional and unintentional fires are more common near inhabited areas and pose a more significant threat to infrastructure.
- High Temperature And Low Humidity: Vegetation and other fuel sources are much closer to their ignition point at high temperatures. The preheating of surrounding fuel sources means a greater risk of bushfires spreading quickly.
Additionally, drier air promotes fires of greater intensity than does moist air. Vegetation releases its moisture quickly when humidity is low, becoming more combustible and flammable.
As a result, the duration since the last rainfall and the quantity of rain received are important factors in determining bushfire risk. A moisture deficit (Drought factor) is an indication of severe bushfire weather conditions.
- Wind Speed: The role of wind speed in creating dangerous conditions for bushfires is greater than the effect of temperature and humidity. This is because wind drives fire into new fuel sources; it dries vegetation, bringing it to ignition point and providing a constant oxygen supply.
In addition, burning embers are carried through the air in an occurrence known as Spotting. In high wind speeds spotting may occur up to 30 kilometres downwind of the fire front. This causes the rapid spread of bushfires.
- Slope Gradient: Radiation and convection preheat the fuel sources during bushfires. As a consequence, flames accelerate while ascending and decrease when descending.
The steepness of the slope has a significant impact on the speed of bushfires spreading. For every 10-degree gradient increase in a slope, the speed of an advancing fire front is doubled; for a 20-degree slope gradient increase, a fire front will travel four times faster than on flat ground.
What Is A Bushfire Impact Assessment And Why Is It Necessary
The 2019 – 2020 bushfire season resulted in a $20 billion impact on the economy. In addition to this, the loss of life, homes, properties and livestock have a profound effect on communities and individuals. During the Black Summer Fires, recorded losses amounted to 18,983,588 hectares being burned, 3,113 homes and 33 lives lost across 15,344 bushfires.
A Bushfire Assessment Report may range from determining the severity of a structure or planned development’s probable exposure to ember attack, radiant heat and direct flame contact, to more complex Bushfire Management Plans that align with bushfire construction requirements.
Bushfire assessments are needed for the protection of urban, residential and commercial development under the Australian Standard AS 3959-2018 Construction of Buildings in Bushfire Prone Areas.
These assessments are carried out by Bushfire Consultants to ensure the practical application of relevant planning, design and construction, legislative compliance pertaining to the planned and existing developments to mitigate damage and loss within bushfire prone areas.
Need A Bushfire Consultant? Get In touch today.
TreeScience offers Bushfire Assessments for residential, commercial, government and sub-division developments, as well as building recommendations and compliance with Australian standards.
Our bushfire consultants are University of Melbourne accredited Bushfire Risk Assessment Practitioners (AQF Level 8) and Bushfire Planning & Design (BPAD) Level 2 and 3 practitioners.
[REFERENCES]