Assessing wildfire risk to critical infrastructure in central Chile: application to an electrical substation

Background. Wildfires have caused significant damage in Chile, with critical infrastructure being vulnerable to extreme wildfires. Aim. This work describes a methodology for estimating wildfire risk that was applied to an electrical substation in the wildland–urban interface (WUI) of Valparaíso, Chile. Methods. Wildfire risk is defined as the product between the probability of a wildfire reaching infrastructure at the WUI and its consequences or impacts. The former is determined with event trees combined with modelled burn probability. Wildfire consequence is considered as the ignition probability of a proxy fuel within the substation, as a function of the incident heat flux using a probit expression derived from experimental data. The heat flux is estimated using modelled fire intensity and geometry and a corresponding view factor from an assumed solid flame. Key results. The probability of normal and extreme fires reaching the WUI is of the order of 10^-4 and 10^-6 events/year, respectively. Total wildfire risk is of the order of 10^-5 to 10^-4 events/year Conclusions. This methodology offers a comprehensive interpretation of wildfire risk that considers both wildfire likelihood and consequences. Implications. The methodology is an interesting tool for quantitatively assessing wildfire risk of critical infrastructure and risk mitigation measures.