House loss patterns in the Australian 2019–20 fire disaster confirm the reliability of official risk mapping

Background Wildfire house loss risk mapping in the wildland–urban interface (WUI) is critical for community bushfire adaptation and land use planning, and is undertaken in many nations with wildfire prone landscapes. Aims To use WUI mapping for predicting house loss. Methods We tested the reliability of the New South Wales (NSW) Government WUI mapping by analysing the spatial pattern of 2580 houses and 8656 total buildings that were destroyed by the 2019–20 Australian NSW fire disaster. Key results Of the 12,375 buildings within flammable vegetation (as defined by NSW mapping) that was burned by the 2019–20 wildfires, 56% were destroyed. 81% of destroyed houses were within flammable vegetation, 13% were in a 100 m buffer adjacent to flammable vegetation and 6% were beyond 100 m from flammable vegetation. The proportion of house losses beyond the 100 m buffer was highest under more extreme weather. Conclusions The 100 m distance from flammable vegetation gives an accurate prediction for building survival, and houses >200 m from flammable vegetation have minimal risk. Implications Our findings confirm the suitability of the current WUI mapping used by the NSW Government for identifying areas at risk for house loss risk, albeit the reliability of this mapping breaks down under extreme fire weather.