Understand the Index

Understand the Index

 

Benefits and Applications of the Index

The Bushfire Exposure Index is a mitigation tool that combines advanced deep-learning algorithms, high-resolution mapping, and multifaceted data to present a picture of bushfire exposure at a granular level. It offers a measure of the potential exposure of residential buildings and communities to bushfires.

With the availability of precise geospatial information presented by the Bushfire Exposure Index, local governments can prioritise safety measures more effectively and optimise resource allocation for mitigative actions. It allows authorities to develop targeted strategies to safeguard areas where people and assets are most at risk.

Beyond aiding government agencies, the Bushfire Exposure Index also serves as a public resource, enabling individuals and communities to understand their exposure levels to bushfires.

• Strengthened Mitigation Strategies: Improve hazard readiness by enhancing mitigation plans, reducing potential impacts, and optimizing emergency responsiveness.

• Community Engagement & Communication: Promote risk awareness and collective action at community levels to ensure consistent and informed communication and engagement.

• Sustainable Community Recovery: Inform and guide communities towards long-term recovery strategies, focusing on resilience and sustainable rebuilding.

• New Resident Education: Provide essential education to new homeowners and renters about risks and preventive measures, promoting informed living choices.

• Resource Allocation & Prioritisation: Optimise the deployment of resources by prioritising needs, ensuring efficiency and efficacy in addressing varied risks.

• Refined Risk Assessments: Identify the need for more detailed and precise risk assessments, enhancing accuracy and reliability in hazard evaluations.

• Updated Emergency Operations: Regularly revise emergency operation plans to incorporate the latest data and insights, maintaining optimum preparedness and responsiveness.

 

Constructing the Exposure Framework

In this section, we break down the processes involved in constructing the Bushfire Exposure Index. This includes the synthesis of the Bushfire Hazard Severity Index and the resultant Bushfire Exposure Index.

 

Bushfire Hazard Severity Index

This index is formulated by integrating fuel models, which are generated from ultra-high-resolution satellite data processed through Artificial Intelligence, with topographical data and post-processing steps.

In the context of our Hobart Bushfire Exposure Index, "Bushfire Hazard Severity" describes the potential intensity and behaviour of a bushfire in a specific location, given the local conditions. It is a measure that considers several factors to determine how severe a bushfire might become if it were to ignite in a particular area.

Here is what contributes to it:

• Vegetation (Fuel) Type: Different plants burn at different intensities. For instance, Fires in grasslands might produce shorter flames than dense forests. Fires in forests, especially those with a dense understory or ladder fuels, can produce taller flames, more radiant heat, and a higher volume of ember attack.
• Vegetation Density: The density refers to how much vegetation is packed into a specific area. Denser vegetation can lead to more intense fires.
• Topography (Slope): Fires tend to spread faster uphill because the flames can pre-heat the vegetation above them. Steeper slopes can, therefore, result in quicker and more intense fires.

We have developed a method to map the bushfire hazard severity, building on established standards and scientific practices. Here is a simplified breakdown of our approach:

1. Vegetation Classification
   • Using advanced deep-learning algorithms and satellite data, we produce a detailed vegetation map with a resolution of 50cm. This map categorises vegetation into two main types: high and low.
   • We assign a weight to each class, representing their potential fire risk.
2. Size Matters
   • We filter out small patches of vegetation that cannot create a 100m-long bushfire front. This ensures we are focusing on areas with significant fire potential.
3. Measuring Vegetation Density
   • Think of it like this: If you're standing in one spot, how much dense vegetation is around you within a 100m radius? We calculate this by looking at our weighted vegetation map.
   • For clarity, we have set a consistent window of 100m around each point in our map to measure this density.
4. Factoring in Slope
   • Terrain plays a significant role in fire behaviour. Fires can spread faster uphill due to the pre-heating of vegetation above the fire.
   • We integrate an 'elevation model' to understand the slope of the land.
   • Our slope calculations rely on a formula: Slope factor = exp(0.069*Slope). This equation originates from the Australian BAL standards (AS 3959:2018). When the slope is equal to or greater than 15 degrees, we cap it.
   • For those interested in the nitty-gritty: this formula is based on Appendix B7, p. 97 of AS 3959:2018.
5. Index Classification

• • To make our findings actionable, we split the results into 10 classes. Each class represents a range of hazard severity.
  • How do we determine these classes? We consider the maximum possible hazard severity (an area with the densest high-risk vegetation and the steepest slope) and then divide this into percentage ranges, from 0% (minimal hazard severity) to 100% (maximum hazard severity).

Note: Steps 3 and 4 are repeated for each of the 4 billion pixels of the model.

 

Bushfire Exposure Index

The exposure index is developed by mapping the footprints of buildings from ultra-high-resolution satellite data, leveraging artificial intelligence. Each building is assigned an exposure score derived from its intersection with the hazard severity index, using the highest value from the intersecting index. The scores are then represented per parcel from the cadastre layers, utilising Tasmanian geospatial datasets to delineate the results, focusing exclusively on parcels with residential buildings.

 

Disclaimer

The Bushfire Exposure Index (the Index) serves as a mitigation tool, designed to enable enhanced understanding and planning in relation to bushfire risks. It is grounded in methodologies that have been reviewed and validated by subject matter experts specialising in natural hazard risk research, bushfire analysis, and forestry. The application of advanced processing methods has yielded results like results found in established bushfire exposure analyses from academic and scientific literature.

Users should be aware that the Index does not delve into the intricate physical properties of buildings, such as roofing materials, deck constructions, and other structural elements.

Hazard impacts in surrounding parcels may induce indirect losses in others, regardless of an individual parcel's exposure profile as portrayed by the Index.

By accessing and utilising the Index, users affirm their understanding and acceptance of these inherent limitations and agree to use this tool responsibly.

While the Bushfire Exposure Index, available on this platform, is developed with care and aims to provide reliable information, it is imperative that users understand and acknowledge the following:

• Limitation of Liability: The developers, contributors, and administrators of the Index do not accept any liability for any damage, loss, injury, or inconvenience suffered because of using the Bushfire Exposure Index. Users are encouraged to use this information responsibly and consider it as one of many tools for informed decision-making.
• No Warranty: The information provided through the Bushfire Exposure Index is supplied “as is” and without warranties of any kind, either expressed or implied. We do not warrant the accuracy, completeness, or fitness for a particular purpose of the information available through the index.
• Not a Substitute for Professional Advice: The Bushfire Exposure Index is not a substitute for professional advice and should not be relied upon as the sole basis for significant decisions. Users are advised to consult with relevant professionals or authorities when considering actions relating to bushfire preparedness, mitigation, and response.
• Dynamic Nature of Data: The environmental data used to build the index is subject to change due to natural processes, and as such, the index should be considered a dynamic resource that represents the conditions at the time of data collection. Users should be aware that the actual conditions may vary, and regular updates and consultation of other resources are recommended.
• Data Interpretation: The Bushfire Exposure Index relies on the interpretation of complex data, and different interpretations could lead to different conclusions. Users are urged to consider this variability when using the index.
• Use at Your Own Risk: By using the Bushfire Exposure Index, users agree to assume all risks related to the use of the information provided, acknowledging the limitations and variability inherent in this kind of data analysis.

By proceeding to use the Bushfire Exposure Index contained herein, users acknowledge and agree to the terms outlined in this disclaimer.