Mapping South Florida Daily Fire Risk for Decision Support Using Fuel Type, Water Levels, and Burn History

Abstract

Mapping fire risk in South Florida depends on spatially varying water levels, fuel characteristics, and topography. When surface water levels recede below the lowest topographic features (cypress strands, marshes, etc.), the ecosystem loses its natural, wetted fire breaks, and landscape-level fire risk increases. We developed a geospatial method to generate daily, categorical fire risk maps; the maps visualize low-to-high risk areas using a newly developed 100 m DEM, modeled water levels, fuel types, and fire management units. We assigned fire risk by creating a water level distribution for each unique combination of fuel type and fire management unit; fire risk was then assigned for each pixel based on risk percentiles commonly used by fire management agencies. Assigning risk based on unique fuel types and management units helped avoid over- or under-assigning fire risk that may occur when applying landscape-level “average” risk relationships. Daily maps also incorporated (1) energy release component data to better estimate fuel moisture and (2) historical burn footprints to reduce risk in recently burned areas. Our data-driven approach generated at management-relevant spatial scales may enable more informed prescribed burn planning and may increase the efficiency of staff and resource allocation across the landscape on high-wildfire-risk days.

Development of an Index for Forest Fire Risk Assessment Considering Hazard Factors and the Hazard-Formative Environment

“…Based on the relationship between the fire risk indicators and fire occurrences and utilizing the data from all kilometer grid cells from 2010 to 2019 within the study area, we established a classification standard for forest fire risk levels (Table 7). This classification ranges from one to ten [58,68,69], referencing the relevant literature and exploration of different indicators. We investigated the pairwise importance of hazard factors, the hazard-formative environment, and the hazard-affected body with the AHP in terms of the quantity and characteristics of fire indicators (Table 8).…”

“…Hence, we used specific indicators, such as population density and roading density, to represent the influence of human habitats on forest fires within the hazard-formative environment. Bodies of water, such as rivers, can act as barriers to prevent the spread of forest fires and increase air humidity [58]. Terrain factors directly affect the occurrence and development of forest fires.…”

“…Our hazard-affected body was the forest, and the vegetation categories differed in their combustibility; hence, we selected the vegetation category as a factor to represent its vulnerability [59]. Forests of the study area were categorized into five classes and assigned different vulnerability values based on the following correlation analysis [58].…”