2. Seasonal and yearly changes in the amount and arrangement of fuel cannot be 

 accommodated . 



3. Prediction of fire behavior using changing fuel and weather conditions is not 

 possible. 



4. The systems are qualitative. They require experienced people to assess the 

 fuels providing a precise meaning only to those closely familiar with the fuels. 



A quantitative basis for fuel appraisal, such as provided by a mathematical model, 

 facilitates uniform interpretation of appraisals and makes predictability and flexi- 

 bility possible. Predictability permits assessment of anticipated land management 

 practices upon the vegetation as fuel. For example, the fuel conditions created by 

 harvesting and thinning could be predicted and appraised before cutting, and plans 

 formulated for proper treatment of the expected hazard. Flexibility means that the 

 application of fuel appraisals could be as broad or specific as desired, depending on 

 the fuel characteristics used as modeling input and their representativeness, 



A system of fuel appraisal consists of two phases: (1) Measurement and descriptio 

 of fuel properties required as input to the system; and (2) rating the fire behavior 

 potential indicated by the fuel properties. This paper concerns the second phase; 

 specifically, it reports on tests to determine the accuracy of a mathematical rate-of- 

 fire-spread model designed by Rothermel (1972) . 



2 



