Refernce Documents - RAL25 0001

                 5.1.2       LANDSCAPE SLOPE

                 Landscape slope was created from a 25m resolution digital terrain model (DTM) by
                 calculating the maximum slope (in degrees) from the central pixel in a group of 9 x 9 cells to
                 the eight (8) adjoining cells in that group.

                 Maximum landscape slope within the site assessment area varied from one (1) and eight (8)
                 degrees.

                 5.1.3       FIRE WEATHER SEVERITY

                 In addition to vegetation fuel loads and slope, fire behaviour and intensity is influenced by a
                 range of weather variables such as wind speed, relative humidity, temperature and
                 atmospheric conditions, as well preceding drought conditions 7.

                 These variables are summarised as an index value which can be used by proxy to estimate
                 and predict fire behaviour: Fire Weather Severity (FWS). The McArthur Forest Fire Danger
                 Index (FFDI) (McArthur 1967) is the most widely used proxy of fire weather severity in
                 Australia and is used for both bushfire hazard assessment, emergency management and in
                 regulations such as in AS 3959:2018 Construction of buildings in bushfire-prone areas. Unlike
                 AS 3959:2018, which adopts a single FFDI for all of Queensland (40), fire weather conditions
                 vary spatially according to temperature, wind, relative humidity and precipitation. Although
                 FWS is equivalent to the Forest Fire Danger Index (FFDI) defined in AS 3959:2018; spatially
                 explicit FWS values for Queensland have been calibrated by Leonard et al. (2014) based on a
                 gridded prediction of the FFDI from long term spatial weather products produced by the
                 Australian Bureau of Meteorology. Adopted FWS values reflect a 1:20 year or 5% annual
                 exceedance probability (AEP) weather event.

                 Climate change projections suggest that the likelihood, intensity and extent of bushfires are
                 likely to increase, together with longer, hotter and drier fire seasons (Bureau of Meteorology
                 2019). The gridded fire weather severity values for Queensland have been adjusted to reflect
                 the expected climate in 2050 using the Intergovernmental Panel on Climate Change A1FI
                 climate scenario 8 (Queensland Fire and Emergency Services 2019).

                 The fire weather severity used for the purpose of calculating fireline intensity was based on 1
                 in 20-year weather conditions (i.e. 5% annual exceedance probability) to reflect the severity




                 7
                     Days since last rainfall.

                 8 The SRES A1FI scenario is most similar to the current RCP 8.5 scenario.



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Document Set ID: 23448646
Version: 1, Version Date: 13/01/2025