5th Symposium on Fire and Forest Meteorology and the 2nd International Wildland Fire Ecology and Fire Management Congress

Monday, 17 November 2003: 4:00 PM
A new set of standard fuel models for use with Rothermel's spread model
Joe H. Scott, Systems for Environmental Management, Missoula, MT; and R. Burgan
With the publication of his surface fire spread model in 1972, Rothermel provided a listing of 11 preliminary fuel models. A fuel model is a complete set of fuel inputs needed to use the Rothermel fire spread model (load and surface-are-to-volume ratio by size class and component, extinction moisture, heat content by component, and fuelbed depth). The preliminary fuel model set was expanded to 13 by Albini and later described by Anderson. That set of 13 models, know variously as "Anderson's", "standard", "stylized", "Fire Behavior" and "NFFL" fuel models, has served well, especially for making rapid estimates of fire spread on active fires at relative coarse time and space resolution. We will refer to this set as the NFFL models.

Weaknesses of the NFFL models include poor representation of fuels that burn under high dead fuel moistures (such as occur in the Southeastern United States and Hawaii), and always modeling herbaceous fuels as fully cured. In recent years the NFFL models have also proven insufficient for new uses of Rothermel's spread model, such as modeling fire behavior in blowdown fuels, modeling the initiation of crown fire, simulating the effects of fuel treatments on fire behavior, and simulating changes in fuelbed characteristics over time.

In cooperation with the Missoula Fire Sciences Lab, we have developed a new set of fuel models. The new fuel models have been organized into 6 fuel-type classes: Grass, Grass-shrub, Shrub, Timber-other, Timber litter, Slash-blowdown, and Non-burnable. The new model set is designed to stand alone; none of the NFFL models is repeated exactly in the new set, but the range of behavior they predict encompasses the NFFL models. The fuel model key points to the new fuel models only. However, the NFFL models will still be available. If desired, both the new set and the NFFL models can use used at the same time, on the same map.

Fuel models with an herbaceous component are "dynamic". In a dynamic model, live herbaceous load is transferred to dead as a function of the live herbaceous moisture content. Fire behavior prediction systems must be modified to use the new dynamic models. FARSITE, FLAMMAP, BehavePlus and NEXUS have been or will soon be updated to accommodate dynamic fuel models.

The new set of fuel models is available now. Visit www.firelab.org to read more about the new fuel models and how to use them.

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