Burn severity mapping using simulation modelling and satellite imagery

Abstract

Although burn severity maps derived from satellite imagery provide a landscape view of fire impacts, fire effects simulation models can provide spatial fire severity estimates and add a biotic context in which to interpret severity. In this project, we evaluated two methods of mapping burn severity in the context of rapid post-fire assessment for four wildfires in western Montana using 64 plots as field reference: (1) an image-based burn severity mapping approach using the Differenced Normalised Burn Ratio, and (2) a fire effects simulation approach using the FIREHARM model. The image-based approach was moderately correlated with percentage tree mortality but had no relationship with percentage fuel consumption, whereas the simulation approach was moderately correlated with percentage fuel consumption and weakly correlated with percentage tree mortality. Burn severity maps produced by the two approaches had mixed results among the four sampled wildfires. Both approaches had the same overall map agreement when compared with a sampled composite burn index but the approaches generated different severity maps. Though there are limitations to both approaches and more research is needed to refine methodologies, these techniques have the potential to be used synergistically to improve burn severity mapping capabilities of land managers, enabling them to quickly and effectively meet rehabilitation objectives.