Fuel Models

A fuel model is a mathematical representation of one of several natural fuel conditions that is used in fire behavior prediction systems or fire danger rating systems. Specifically, these models describe vegetation in terms that are required by the Rothermel fire spread model (for example, surface area to volume ratio, fuel load, size, shape, compactness, horizontal and vertical continuity, moisture of extinction, etc.).

A series of fuels model classifications systems exist. These systems evolved from a simple conceptual classification of fuels into four groups (grasses, brush, timber, and logging slash), to a 13-model system initiated by Rothermel in 1972 (FBPS fuel models), to a 20-model system developed for the NFDRS in 1978. The most recent advancement in fuel model classification is the Fire Characteristic Classification System (FCCS) system currently being developed by the USDA Forest Service.

• Four basic fuel types: grasses, brush, timber litter, and logging slash.
• FBPS fuel models: Fuel models in this 13-model system, developed by Rothermel in 1972 and later expanded by Albini, are used in fire behavior prediction systems (FBPS) such as BEHAVE.
• NFDRS fuel models: These fuel models, similar to the FBPS fuel models but with extra parameters needed for fire danger prediction, are typically used in fire danger rating systems such as the NFDRS.
• Fire Characteristic Classification System: This system offers a more comprehensive description of a fuel bed than earlier fuel models. A prototype system currently classifies over 200 fuel types in the US.