Accounting for the effects of fire suppression and containment efforts has posed a challenge in wildfire modeling. Fire suppression is a complex phenomenon depending on factors such as resource availability, weather, terrain, and fire suppression priorities in a given place and time. Suppression is an influential factor in wildfire growth though, and should be considered in models. We developed a generalized model of fire containment by utilizing daily reports on size and percent containment of wildfires in the United States. We used this model to support wildfire risk analysis simulations in the Large Fire Simulation System (FSim). The suppression model determines the daily proportion of fire containment as a function of the proportion of the fire’s duration that has elapsed and a regression coefficient, or suppression factor. This suppression factor allows differing patterns of fire containment to be represented.

In this analysis, we tested the influence of the suppression model on FSim simulations by running simulations in four regions with a range of nine suppression factors, and one simulation run without the suppression model. To test whether the suppression model resulted in fire shapes that were more similar to historical observed fires, we calculated six metrics of shape complexity from the simulated wildfire perimeters. We then compared these shape metrics to shape metrics of the historical wildfire perimeters in each region. This established that the suppression model contributed to closer agreement in shape metrics between simulated and historical fire perimeters, and that the suppression factor where this agreement was maximized differed between simulation areas.