The compound effect of topography, weather, and fuel type on the spread and severity of the largest wildfire in NW of Turkey

The large wildfire sequence took place in July and August 2023 in Çanakkale, recorded as the largest wildfire incident in NW, Türkiye. The total affected area in two successive wildfires is 79.1 km2. This study presents an observation-based instance and statistical model findings of how topography as a major determinant controls wildfire propagation direction and burn severity with the contribution of weather conditions (particularly wind and temperature) and specific land use and land cover (LULC) types. The findings reveal that the Çanakkale Strait and Biga Mountains as regional geomorphic units that extend from northeast to southwest portray the main direction of wildfire incidents guided by prevailing wind patterns and specific LULC types. The marginal section of the Biga Mountains, where the topographic relief and slope largely increase, constrain wildfire propagation, while vegetation density is higher in the steeper areas. Notably, the specific LULC which is a harvested wheat field plays an important role in determining the major direction of wildfire, primarily influenced by the prevailing northeast-to-southwest wind direction observed in the July case. Furthermore, the ordinary least square model results showed that rougher topography tends to exhibit higher burn severity which is the case for the August wildfire. The local topographic conditions (i.e., valley shape morphology) offer an appropriate observational insight for general mathematical models with the increased burn severity, and the main direction of fire and impeding areas in the August case. This study also sheds light on the significance of wind direction that can surpass the slope orientation for burn severity which is expected higher potential in equator-faced compared to the polar-faced.