Indexing the vegetated surfaces within WUI by their wildfire ignition and spreading capacity, a comparative case from developing metropolitan areas

The main objective of this study is to push forward a rapid and cost-free method for forest fire proneness assessment within the wildland urban interface (WUI) for developing metropolitan areas. It compares between the forest surfaces within two capital regions from the Western Balkans (WB), namely Sarajevo and Tirana. This study follows a multi-criteria approach and integrates a variety of wildfire ignition or spreading causes relying on anthropogenic, hydro-meteorological, geophysical, and fuel properties of the study area. The indexing method utilizes specific techniques of data clustering and criteria weighting. The relative degree of implication that each criterion has with wildfire ignition and spreading behaviour is weighted via a hierarchical pairwise comparison (AHP) among criteria. The workflow is automated via graphical modeller in QGIS, making the method easily reproducible to other metropolitan areas in the developing regions. Relying on the map of wildfire spreading capacity index (WSCI), the study demonstrates a vulnerability analysis focusing on the exposed buildings. According to the results, Sarajevo has four times more exposed buildings than Tirana. However, the exposed buildings in Tirana record higher risk values than in Sarajevo. The sensitivity of the proposed indexing model is tested via Receiver Operating Characteristic (ROC) curve method, utilizing historical data on wildfire occurrences relying on the EFFIS database. The results of ROC analysis suggest that the relative weighted factors per each criteria are context-dependent, and must be calculated referring to local occurrences of wildfire. This study suggests that the urbanization and transportation network planning have a direct impact on the wildfire risk for the vegetated wildland urban interface (WUI). This study recommends the identification of wildfire-prone areas of metropolitan forest surfaces to be considered by policy-making bodies which are responsible for the disaster risk reduction at metropolitan level.