Estimating the potential bushfire hazard of vegetation patches and corridors

[摘要] The methodology used in Queensland for State-wide mapping of Bushfire Prone Areas (Leonard et al, 2014) involves the application of procedures that combine spatial information on landscape slope, potential fuel load and fire weather severity to estimate and classify the potential fire-line intensity of vegetation across the landscape. This methodology also describes spatial procedures that identify and amend the estimated hazard potential of narrow or small patches of vegetation that are unlikely to support the full potential of a running fire front. Experience in use of this mapping since its release in 2013 has highlighted the opportunity to improve the rigor of this approach to better reflect recent research knowledge about bushfire attack mechanisms (e.g. Newnham et al 2014) and to also take advantage of improvements in vegetation mapping prepared by the Queensland Fire and Emergency Services (QFES).While the disruptive effects of non-flammable surfaces is well documented and adequately reflected in the methodology for State-wide mapping of Bushfire Prone Areas, greater account of the contextual effect of grassland or other continuous vegetation types is warranted in order to give greater certainty to land use planning decisions in the bushfire interface. Improved mapping rules have been integrated into the spatial modelling process in order to better reflect the spatial complexities of bushfire behaviour for small and narrow patches of hazardous vegetation.Patch and corridor mapping rules are applied in four stages. The first stage involves the modification of the Vegetation Hazard Class layer to remove small isolated patches. This temporary Vegetation Hazard Class layer is then used to derive an interim bushfire hazard class layer which is then modified by a second stage of filtering to degrade patches between 0.5 ha and 3 ha (Step 2). Narrow corridors under a minimum width are removed (Step 3), before final merging of spatial fragments lower than the minimum resolution of mapping (Step 4). The fire-line intensity of smaller hazardous vegetation patches using these new rules provides better alignment with the likely intensity of running fires that would occur under conditions assumed by in the methodology used for State-wide mapping of Bushfire Prone Areas (Leonard el. al. 2014). These intensity levels are also more cognisant of the context of vegetation patches, particularly with regard to continuity of adjacent fuel types.

[发布日期] 2017-08-03 [发布机构] CSIRO

[学科分类] 地球科学(综合)