HexFire Model Notes

The original version of HexFire was described in the 2022 paper published in Land.

The current version of the HexFire model has been renamed "HexFire Single-Season", and includes the following enhancements:

A new version of HexFire model named "HexFire Multi-Season" is now included in the workspace. This model makes it possible for users to simulate a sequence of wildfires spanning multiple years. HexFire Multi-Season includes features for simulating fire severity and the regrowth of vegetation. Within a season, HexFire Multi-Season is essentially identical to HexFire Single-Season. Thus, the original publication describing HexFire (see above) also captures the principal mechanics built into HexFire Multi-Season.

Features that are unique to HexFire Multi-Season are discussed below:

Suppose a hexagon has a value of 0.9 in the Relative Flammability map. That implies the hexagon has a relatively high fuel load. Assume that the hexagon's score in the Relative Burn Severity map is 0.4, and that the Fire Severity Range [%] parameter has been set to 20%. If this hexagon burns, then it will select a random burn severity value in the range [0.4 - 0.08, 0.4 + 0.08], which equals [0.32, 0.48]. Let's suppose the hexagon selects a random burn severity value of 0.35. Then when it burns, the corresponding hexagon in the dynamic Flammability map will be lowered by an amount equal to 0.9 x 0.35. The first term in this product is the hexagon's value in the static Relative Flammability map, and the second term is the random burn severity. Values in the Flammability map are never reduced below 0.