Fire Intensity Levels

Fire intensity levels (FILs) provide "an expression of fireline intensity, based on typical and/ or calculated flame length of a fire behavior condition. FILs are used in the analysis to reflect the differences in difficulty of suppression and fire effects on natural and cultural resources." (Ref. FSH5109.19 ch40.5 9/85) FPA uses the following FIL categories:

Table 1- Fire Intensity Level Categories

FIL	Flame Length	Burning Index (BI)
1	0-2	0-20
2	2.1-4	21-40
3	4.1-6	41-60
4	6.1-8	61-80
5	8.1-12	81-120
6	12 and over	121 and over

Since fire events at different intensities, even during the same sensitivity period, may require a different response, or may have different effects on land management objectives, FPA enables you to consider these needs when entering data into the system.

Where Fire Intensity Levels are Used:

FILs are used in several areas of FPA-PM. Click the appropriate link for more information about how sensitivity periods work with each item listed <<blue text like this equals online only info>:

• Establishing FMU Objectives (coming in version 1.3)
• Grouping FMUs by Objective (coming in version 1.3)
• Determining Weights

Critical Data Needed for Fire Intensity Levels

Before working with FILs in FPA-PM, you need to develop the following information for each FMU:

• Fuel Composition
• Land Management Objectives
• Fire Preparedness Season
• Relative Importance of Each Sensitivity Period

Relationship to Sensitivity Periods

Depending on the time of year and the management objectives, even low intensity fires can be detrimental in certain areas. In other areas, low intensity fires may be desirable, but high intensity ones could be devastating. FPA enables you to determine the aggressiveness of your initial response, based on all of the above factors. Remember, a sensitivity period can be as short as two weeks, or as long as the entire fire season. Each FMU must have at least one sensitivity period, but no more than 26 periods.

Relationship to Weights

When developing weights for each sensitivity period, it's important to consider the effect of FILs on the FMU, and to relate that effect to the other FMUs in your FPU for the sensitivity period in question. For example, if a sensitivity period contains a breeding season, it may be more important to protect the area from moderate to high FILs fires than from low FIL fires. Therefore, the weights should reflect the difference in the importance of protecting the area from different FILs.

Related Topics

For more information, see the following topics:

• Land Management Objectives
• Sensitivity Periods
• Weighting