Fuel Models and Fire Whirls

Dr Chris Dicus

Dr Chris Dicus of Cal Poly showed us around his fire lab where he teaches wildland fire and fuel management as part of the Bachelor of Science, Forestry and Natural Resources. In the fire lab students learn to use Scott and Burgan Standard Fire Behavior Fuel Models as well as a suite of fire behavior models based on Rothermel's Surface Fire Spread Model  developed in 1972.

While teaching at the Fire Training Center in Arizona during the late 70’s and 80’s, Richard Rothermel cautioned students to ‘use the model to the best of your ability, and then use what your eyes are telling you. One without the other is incomplete’.

Rothermel developed a surface fire spread model for predicting fire behavior in 1972 and his computations were based on a list of 11 fuel models that was expanded to 13 fuel models by Albini in 1976. The fuel models are representations of typical fuel profiles and contain a complete set of inputs for the mathematical fire spread model.

Later in 2005 a new set of 40 dynamic fuel models were developed by Scott and Burgan that refer to fuels types, not vegetation types as the original 13 fuel models did. The newer dynamic fuel models include a fuel moisture component and aimed to improve the accuracy of fire behavior predictions for times outside of extreme fire conditions; to take account of areas of high humidity; to include forest with a grass or shrub understory; and to improve the ability of the model to simulate changes in fire behavior as a result of fuel treatments. 

In the lab Chris demonstrated the ‘Fire Whirl’  – a device used to demonstrate the formation of fire whirls or fire devils (vertically swirling fire) that develop under certain conditions on the fire ground and can be extraordinarily destructive. The ‘Fire Whirl’ is used by the fire faculty to ignite the imagination of potential students who may be considering studying at the Cal Poly.

Smoky Bear and me

Thanks Dr Chris!