Assessing the likelihood of wildfire and planning for mitigating the damage of wildfire to people and property requires accurate information. Fire behavior indices are commonly used to predict the ignition and spread of wildfire. Assessing the effectiveness of those indices or their suitability for the unique aspects of the Alaska fire regime is a challenging task. AK CASC scientists have worked to analyze the effectiveness of various fire risk indices in collaboration with their colleagues at the Alaska Interagency Coordination Center. The results of this collaborative research were recently published in the journal Forests.
A variety of these integrative indices are used by fire managers around the globe for planning and management. These indices bring together variables including humidity, temperature, precipitation, and more to predict the likelihood of wildfire ignition and the likely extent of any given wildfire’s spread. This information can then be used by fire managers to plan personnel and equipment needs, and prioritize their efforts.
Unlike the continental United States, Alaska fire managers typically use the Fire Weather Index (FWI) to predict fire risk and guide management decisions. This index was developed as part of the Canadian Forest Fire Danger Rating system and specifically addresses the unique aspects of North America’s boreal forests, which are fundamentally different from the forests of the western U.S.
The research team found that two indices contained within the FWI performed best for Alaska’s needs: one which measures the relative moisture of a fire fuel called “duff” and one which combines fuel dryness with measures of drought. These two variables are part of the Canadian system and are already used extensively by fire managers across the state, reinforcing the confidence of the fire managers that these variables perform well.
A novel and promising variable was, however, found to perform well. The Vapor Pressure Deficit (VPD) monitors atmospheric moisture conditions by combining temperature and relative humidity and performs nearly as well as the standard variables already in widespread use. Additionally, the VPD responds rapidly to day-to-day changes in atmospheric variables, accurately reflecting changes in the current situation after a lag time of about 24 hours. Future incorporation of this index could therefore prove a valuable addition to Alaska fire managers’ tool belt.
Most of all,the research shows the value of analyzing variables and critiquing indices in order to create more effective tools to manage wildfire on the ground. The authors state that the work demonstrates the “societal value of research that joins new academic research results with operational needs.”
Read more in the Journal Forests.