Regional hazard and exposure modeling for wildfire risk assessment

Gabriela Calana Somoza, Neetesh Sharma, Jack Baker

Wildfires threaten communities worldwide, and recent times have seen increased threats to life and property. Forest management and fire suppression practices have let fuels build up. At the same time, hotter and drier conditions from climate change, and the development in the wildland-urban interface, have increased the frequency of damaging wildfires. Furthermore, human activity and the existence of critical infrastructure facilities affect both the occurrence rates of ignitions and the value at risk. Electrical infrastructure is an important component in wildfire risk, as power utility companies have been found responsible for multiple catastrophic wildfires, resulting in devastating community losses. Costs related to wildfire impacts and mitigation have also led to significant increases in power rates. This work aims to model wildfire risk to support risk mitigation and power utility price regulation by simulating wildfire scenarios and assessing their respective losses at the regional level. To model the wildfire hazard, we investigated the spatial patterns of wildfire ignitions over Sonoma County, a historically vulnerable region in Northern California. We then used state-of-the-art software tools to model the spread of wildfire and simulated 7,980 wildfire scenarios. We collected exposure data regarding the locations and physical and financial attributes of structures and power infrastructure assets to assess the liability and replacement losses resulting from the different wildfire scenarios at a regional level. Beyond quantifying the direct financial impact of these wildfire scenarios, estimating the likelihood of ignitions from power infrastructure can inform mitigation actions and potential liability costs in future wildfire events.

Figure: The proposed modeling framework for wildfire risk mitigation has several components. (a) collecting the information for the interdependent systems, (b) modeling the ignition probability over space given the proximity to powerlines (c) modeling the spread of wildfire considering the ignition, weather and vegetation/fuel characteristics; (d) assessing the damage and loss to various assets for each wildfire scenario; (e) Evaluating the absolute of risk of various levels of socio-economic losses, and (f) Considering the cost-benefit analysis of mitigation actions by the utilities considering the portion of risk transferable to liability costs.