TOWARDS THE AUTOMATION OF UNDERSTOREY MAPPING

Melbourne Water Corporation is responsible for the supply of drinking water to the greater Melbourne area and harvests around 90% of this supply from approximately 160,000 hectares of public lands catchment. The assessment of risk to Melbourne Water’s assets from the potential impacts from bushfires is an important part of Melbourne Water’s obligations and responsibilities. A key factor in determining the level of bushfire threat is the assessment of fuel hazard levels over MW owned and managed lands. In particular, this project attempted to determine details relating to the understorey layer on these lands relating to fuel type and characteristics.

Field measurements to calculate bushfire hazard are time consuming, expensive and subjective, and desktop studies are limited by the quality of the data available, resourcing and the scale of capture. Improved fuel hazard classification and stratification prior to field fuel assessments, would allow for more representative fuel plot placement within strata, show the extent and density of a particular fuel type and assist with the extrapolation of fuel hazard information across the landscape.

This determined the feasibility of hazard stratification based on the biometric characteristics of understorey and overstorey vegetation layers using LiDAR (Light Detection and Ranging) technology and analysis. Using a multi-criteria analysis with variables like hazard classes, riparian buffers, vegetation index, forest height classes, and relative presence of understorey/overstorey produced a single layer providing details to create a fuel hazard assessment of the project area. This project represented a significant progression in the practical application of LiDAR data to fuel load assessment at the landscape level. The methodology could be applied across neighbouring tenures, allowing for more comprehensive assessment of bushfire risk and providing information in determining the best treatment options to protect critical infrastructure assets.

Example of understorey mapping.

AFAC Conference Presentation

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