Background Information
Canadian Forest Fire Behavior Prediction (FBP) System
Summary
The Canadian Forest Fire Behavior Prediction (FBP) System provides quantitative estimates of potential head fire spread rate, fuel consumption, and fire intensity, as well as fire descriptions. With the aid of an elliptical fire growth model, the FBP system gives estimates of fire area, perimeter, perimeter growth rate, and fire behavior at the head, flanks, and back of a fire.
Structure of the FBP System
The diagram below illustrates the components of the FBP System, including the necessary inputs and the outputs the system produces.
Descriptions of the primary outputs are given below:
Rate of Spread
Rate of Spread (ROS) is the predicted speed of the fire at the front or head of the fire (where the fire moves fastest) and takes into account both crowning and spotting. It is measured in meters per minute and is based on the Fuel Type, Initial Spread Index, Buildup Index, and several fuel-specific parameters such as phenological state (leafless or green) in deciduous trees, crown base height in coniferous trees, and percent curing in grasses.
Total Fuel Consumption
Total Fuel Consumption (TFC) is the predicted weight of fuel consumed by the fire both on the forest floor and in the crowns of the trees. It is measured in kilograms per square meter of ground surface and is based on Foliar Moisture Content, Surface Fuel Consumption, and Rate of Spread.
Head Fire Intensity
Head Fire Intensity (HFI) is the predicted intensity, or energy output, of the fire at the front or head of the fire. It has become one of the standard gauges by which fire managers estimate the difficulty of controlling a fire and select appropriate suppression methods. It is measured in kilowatts per meter of fire front and is based on the Rate of Spread and the Total Fuel Consumption.
Crown Fraction Burned
Crown Fraction Burned (CFB) is the predicted fraction of the tree crowns consumed by the fire. It is based on Buildup Index, Foliar Moisture Content, Surface Fuel Consumption, and Rate of Spread.
Fire Type
Fire Type (FT) provides a general description of the fire. It is based on the Crown Fraction Burned (CFB). If the CFB is less than 0.1 (10%), then the fire is a surface fire. If the CFB is 0.9 (90%) or more, the fire is a continuous crown fire. If the CFB is between 0.1 and 0.9, the fire is an intermittent crown fire.