An offline coupling of fire spread models to simulate the 2021 Marshall Fire

Background: Existing fire spread models focus exclusively on wildland or urban fire simulation. Aims: This study aims at an offline coupling of two fire spread models to enable a continuous simulation of a wildfire incident transitioning from wildland into wildland-urban interface (WUI) communities, evaluate the effects of wind input on simulation results and study the influence of building types on fire spread patterns. Methods: The selected models are WRF-Fire, a wildland fire behaviour simulation platform, and SWUIFT, a model for fire spread inside the WUI. The 2021 Marshall Fire serves as the case study. A map of the fire's timeline and location is generated using public information. Three simulation scenarios are analysed to study the effects of wind input resolution and building type on the predicted fire spread and damage. Key results: The most accurate results are obtained using a high-resolution wind input and when incorporating different building types. Conclusions: The offline coupling of models provides a reliable solution for fire spread simulation. Fire-resistant buildings likely helped limit community fire spread during the Marshall Fire. Implications: The research is a first step toward developing simulation capabilities to predict the spread of wildfires within the wildland, WUI and urban environments.