Moisture Inputs for Fire Behavior Fuel Models
Each fire behavior fuel model requires different moisture inputs. In this table, an “x” represents the required moisture input(s) for a particular fuel model. For example, GR8 (high load, very coarse, humid climate grass) uses 1-hour, 10-hour, and live herbaceous moisture parameters in the calculation of surface fire behavior.
Tip: IFTDSS will always prompt you to populate all necessary fuel moisture inputs. The information below is intended to help you understand the different fuel moisture parameters used by different fire behavior fuel models.
| Fuel Model # | Fuel Model Description | Moisture (%) | ||||
|---|---|---|---|---|---|---|
| 1-hour | 10-hour | 100-hour | Live Herbaceous | Live Woody | ||
| FM 1 | Short grass (1 ft) | x | ||||
| FM 2 | Timber (grass and understory) | x | x | x | x | |
| FM 3 | Tall grass (2.5 ft) | x | ||||
| FM 4 | Chaparral (6 ft) | x | x | x | x | |
| FM 5 | Brush (2 ft) | x | x | x | ||
| FM 6 | Dormant brush, hardwood slash | x | x | x | ||
| FM 7 | Southern rough | x | x | x | x | |
| FM 8 | Closed timber litter | x | x | x | ||
| FM 9 | Hardwood litter | x | x | x | ||
| FM 10 | Timber (litter and understory) | x | x | x | x | |
| FM 11 | Light logging slash | x | x | x | ||
| FM 12 | Medium logging slash | x | x | x | ||
| FM 13 | Heavy logging slash | x | x | x | ||
| GR1 (101) | Short, sparse dry climate grass | x | x | |||
| GR2 (102) | Low load, dry climate grass | x | x | |||
| GR3 (103) | Low load, very coarse, humid climate grass | x | x | x | ||
| GR4 (104) | Moderate load, dry climate grass | x | x | |||
| GR5 (105) | Low load, humid climate grass | x | x | |||
| GR6 (106) | Moderate load, humid climate grass | x | x | |||
| GR7 (107) | High load, dry climate grass | x | x | |||
| GR8 (108) | High load, very coarse, humid climate grass | x | x | x | ||
| GR9 (109) | Very high load, humid climate grass | x | x | x | ||
| GS1 (121) | Low load, dry climate grass-shrub | x | x | x | ||
| GS2 (122) | Moderate load, dry climate grass-shrub | x | x | x | x | |
| GS3 (123) | Moderate load, humid climate grass shrub | x | x | x | x | |
| GS4 (124) | High load, humid climate grass-shrub | x | x | x | x | x |
| SH1 (141) | Low load, dry climate shrub | x | x | x | x | |
| SH2 (142) | Moderate load, dry climate shrub | x | x | x | x | |
| SH3 (143) | Moderate load, humid climate shrub | x | x | x | ||
| SH4 (144) | Low load, humid climate timber-shrub | x | x | x | x | |
| SH5 (145) | High load, dry climate shrub | x | x | x | ||
| SH6 (146) | Low load, humid climate shrub | x | x | x | ||
| SH7 (147) | Very high load, dry climate shrub | x | x | x | x | |
| SH8 (148) | High load, humid climate shrub | x | x | x | x | |
| SH9 (149) | Very high load, humid climate shrub | x | x | x | x | |
| TU1 (161) | Low load, dry climate timber-grass-shrub | x | x | x | x | x |
| TU2 (162) | Moderate load, humid climate timber-shrub | x | x | x | x | |
| TU3 (163) | Moderate load, humid climate timber-grass-shrub | x | x | x | x | x |
| TU4 (164) | Dwarf conifer with understory | x | x | |||
| TU5 (165) | Very high load, dry climate timber-shrub | x | x | x | x | |
| TL1 (181) | Low load, compact conifer litter | x | x | x | ||
| TL2 (182) | Low load, broadleaf litter | x | x | x | ||
| TL3 (183) | Moderate load, conifer litter | x | x | x | ||
| TL4 (184) | Small downed logs | x | x | x | ||
| TL5 (185) | High load, conifer litter | x | x | x | ||
| TL6 (186) | Moderate load, broadleaf litter | x | x | x | ||
| TL7 (187) | Large downed logs | x | x | x | ||
| TL8 (188) | Long-needle litter | x | x | x | ||
| TL9 (189) | Very high load, broadleaf litter | x | x | x | ||
| SB1 (201) | Low load, activity fuel | x | x | x | ||
| SB2 (202) | Moderate load, activity fuel or low load, blowdown | x | x | x | ||
| SB3 (203) | High load, activity fuel or moderate load, blowdown | x | x | x | ||
| SB4 (204) | High load blowdown | x | x | x | ||