A household-level approach to staging wildfire evacuation warnings using trigger modeling

Wildfire evacuation trigger points are prominent geographic features (e.g., ridges, roads, and rivers) utilized in wildfire evacuation and suppression practices, such that when a fire crosses a feature, an evacuation is recommended for the communities or firefighters in the path of the fire. Recent studies of wildfire evacuation triggers have used Geographic Information Systems (GIS) and fire-spread modeling to calculate evacuation trigger buffers around a location or community that provide a specified amount of warning time. Wildfire evacuation trigger modeling has been applied in many scenarios including dynamic forecast weather conditions, community-level evacuation planning, pedestrian evacuation, and protecting firefighters. However, little research has been conducted on household-level trigger modeling. This work explores the potential uses of wildfire evacuation trigger modeling in issuing household-level staged evacuation warnings. The method consists of three steps: 1) calculating trigger buffers for each household; 2) modeling fire-spread to trigger the evacuation of all households; and 3) ranking households by their available (or lead) time, which enables emergency managers to develop a staged evacuation warning plan for these homes. A case study of Julian, California is used to test the method's potential and assess its advantages and disadvantages.