Resource information
In response to the needs of local fire managers, we developed a map of wildfire hazard for La Plata County in southwestern Colorado, USA. Our measure of fire hazard had two components: (i) the probability, should fire occur under dry weather conditions, that fire behavior will be extreme, and (ii) the human values that may be lost or damaged if extreme fire behavior occurs. Using a classification approach in a GIS environment, we developed quantitative indices of potential heat release, flame length, and rate of spread for each vegetation type in the County. This is based on output of the Behave fire behavior system and adjusted for effects of slope and aspect. We then overlaid a map of residential developments to identify locations where homes are most vulnerable to wildfire damage. Results revealed a zone in the central part of the county where extensive exurban development is occurring within pine, juniper, and oak vegetation, leading to a high potential for extreme fire behavior. This assessment is notable in that (1) it treats a wide range of land ownership types including public lands, private lands, and American Indian reservations; (2) it encompasses substantial variability in vegetation/fuel types, from low-elevation semi-arid grasslands and woodlands to alpine forests and meadows to cultivated and residential lands; and (3) it maps wildfire hazard at relatively fine resolution (1 ha) for a large area (ca 4,500 km2) based on quantitative indices of wildfire behavior. Formal validation of this kind of map is nearly impossible, but we tested the final product by asking local experts to evaluate our interpretations for specific locations with which they were familiar. Feedback from the experts led us to revise some of our initial fire behavior indices, by developing custom fuel models. The same experts concluded that the final product was very accurate. By developing a relatively simple mapping algorithm, and drawing upon spatial data sources readily available to local land managers, our wildfire hazard map for La Plata County provides a template for more extensive fire hazard mapping throughout southwestern Colorado and portions of adjacent states, for use in prioritization of fire mitigation treatments and public education.
