Abstract
During the 2017 wildfire season in Portugal, unprecedented episodes burned 6% of the country’s area and underscored the need for a long-term comprehensive solution to mitigate future wildfire disasters. In this study, we built and calibrated a national-scale fire simulation system including the underlying fuels and weather data and used the system to quantify wildfire exposure to communities and natural areas. We simulated 10,000 fire season replicates under extreme weather to generate 1.6 million large wildfire perimeters and estimate annual burn probability and fire intensity at 100 m pixel resolution. These outputs were used to estimate wildfire exposure to buildings and natural areas. The results showed a fire exposure of 10,394 structures per year and that 30% of communities accounted for 82% of the total. The predicted burned area in natural sites was 18,257 ha yr−1, of which 9.8% was protected land where fuel management is not permitted. The main burn probability hotspots were in central and northern regions. We highlighted vital priorities to safeguard the most vulnerable communities and promote landscape management programs at the national level. The results can be useful to inform Portugal’s new national plan under implementation, where decision-making is based on a probabilistic methodology. The core strategies include protecting people and infrastructure and wildfire management. Finally, we discuss the next steps necessary to improve and operationalize the framework developed here. The wildfire simulation modeling approach presented in this study is extensible to other fire-prone Mediterranean regions where predicting catastrophic fires can help anticipate future disasters.
Highlights
Extreme wildfires pose an increasing threat to people, property, and natural resources in Mediterranean areas [1,2,3,4]
The difference between the lowest and highest value areas was more significant in the annual burn probability than in the conditional flame length
The highest fire intensity values (>3 m) corresponded to high fuel load shrublands and forest types predominantly located in southern-southwestern facing steep slopes, which present the same orientation as the dominant wind directions (Table 1)
Summary
Extreme wildfires pose an increasing threat to people, property, and natural resources in Mediterranean areas [1,2,3,4]. Most European countries are developing comprehensive fire management strategies, with a particular focus on increasing suppression capacity and installing strategic fuel treatments [5,6]. The fire weather index (FWI) values exceeded 75 in much of mainland Portugal and sustained wind speed over 25 km h−1 plus extreme 1-h fuel moisture content values between 3 and 6 for several hours [8]. These weather conditions triggered spread rates reaching 4000 ha h−1 during the fire growth peak in the most catastrophic Pedrógão Grande fire [10]. Many of the large fire events occurred around rural communities where an aging population has limited capacity to respond and adapt to extreme wildfire events [11]
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