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Grass fire and bushfire behavior

It is just so useful to hear what Kevin and Justin have to say about any aspect of bushfire risk and mitigation. The whole webinar and both presenters were fantastic. Relevant, up to date, considered, trustworthy and experience-based and research-based advice is always provided by Justin and Kevin. Professionally delivered and in a way that is so engaging and easy to absorb and remember

The majority of houses were lost on and during the south west wind change due to significant additional wind, its erratic nature and the larger fire front

Kevin Tolhurst and Justin Leonard have an excellent understanding of the important issues and explained the science behind the recommendations and how to implement them. Their science is solid and recommendations are credible. Most importantly both were able to explain to house holders how to implement the recommendations

Understanding about spot fires starting up on the leeward side of buildings not just the side the wind is coming from. We'd always presumed the leeward side would be a safer place to shelter

I’m completely new to rural living so, understanding the difference dynamics of grass & bushfires and their behavior was very informative

Thought last night's was the best. Easy to consider if the grass is cut you are safe from a grass fire. Not so! More thinking on my part re preparation and awareness

I learnt that some beliefs I had were wrong i.e. fires generally come from NW; grass fires are not powerful or lethal; green grass was "safe". I learnt about thatch

Excellent diagrammatic information from both Kevin Tolhurst and Justin Leonard

The Q&A was excellent and answers by presenters were very informative

Slashing not as effective as burning or grazing

How trees can provide protection from ember attack

The bushfire behavior myth busters e.g. lee side (down wind) side of house is more vulnerable. Eastern facing properties more affected than north and western facing on Black Saturday 2009.

2023 Webinar 4

7.30-9.00pm AEST Wed 13 September
  • Dr Kevin Tolhurst AM, University of Melbourne
  • Dr Justin Leonard, CSIRO
Webinar Summary

Kevin Tolhurst discussed the seasonal outlook for fire risk, noting areas of concern based on grassland infill and moisture levels. He referenced maps from various agencies to illustrate these points. He emphasized the importance of understanding grass fires, especially considering recent rainfall patterns and soil moisture content across different regions of Australia. The speaker then delved into the behavior of grass fires, explaining the characteristics of grass fuels, including their vertical orientation and rapid drying properties. He emphasized the significance of grass fires and the potential for them to be lethal and destructive. Throughout the presentation, the speaker provided examples, images, and data to support his points, covering topics such as the distinction between grasslands and forests, the role of trees in influencing fire behavior, and the formation of thatch, which can contribute to fire spread. He discussed how grass fires spread, driven by wind and fuel conditions, and highlight the complex interaction between wind patterns and topography, and emphasized the importance of grass fuel structure and dryness in influencing fire behavior. In conclusion, the speaker summarized key points about grass fires - their rapid spread, and their potential dangers, especially when mixed with forested areas.

Justin Leonard delved into the topic from the perspective of the house to understand the impact and differences in experiencing grass and forest fires. He highlighted that weather conditions that prime the landscape for fires also make homes and surrounding elements highly flammable, emphasizing the simultaneous vulnerability of both. The discussion shifted to the various elements around houses that contribute to fire risk, including dry soil, timber elements, debris accumulation, and the potential for ember attack. He stressed the importance of considering all aspects of a house's combustibility, including hidden cavities and nooks. The speaker emphasized the insidious nature of grass fires, where fire spread may not be as intense but can still ignite combustible elements near the ground. He discussed the significance of property siting, vegetation separation, wind directions, and the complexity of fire behavior. Smoke becomes a major concern, with different fuels producing varying levels of toxicity. Urban environments introduce additional sources of toxic smoke. The discussion extended to the design of houses, highlighting the importance of sealed sub-floors, attention to near-ground level attack, and mitigating ember vulnerability. Embers were identified as a persistent threat, capable of igniting houses before and after the main fire front passes. The speaker underscored the need for a shared responsibility between homeowners and regulators to effectively manage fire risk and maintain houses. He concluded by acknowledging the role of fires in shaping landscapes and the importance of understanding and managing their impact.

Key Segments

Presentation 1 - Kevin Tolhurst

Presentation 2 - Justin Leonard

Panel and Q&A Session

Sponsored by
Hurstbridge & Eltham Community Bank Branches
Proudly sponsored by
Hurstbridge & Eltham Community Bank Branches
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