Modeling Forest Fire Behaviour in Controlled and Accidental Ignitions in Iranian Northern Zagros Forests, with an Emphasis on Fuel Load

The behavior, spread, and intensity of forest fires are heavily influenced by the type and volume of fuels in a natural region, as well as topography and climate. Assessing the volume of fuels in different forest canopies ‎is very important for crisis management and the prevention of possible fires. The purpose of this study is to ‎determine the amount and type of fuels and fire behavior of Iranian Northern Zagros forests in Sardasht ‎County in different forest densities.

Therefore, according to the statistics of recent fires in Sardasht, the ‎study areas (Nalas and Shiomereh) were selected based on the percentage of forest vegetation cover (open, ‎relatively dense, and dense). In this study, one square meter samples were used to measure the ‎properties of fuels such as average vegetation height, 1-, 10-, and 100-hr time-lag fuels, total fuel ‎volume, and litter volume and depth. Study of fire behavior and spread in two ‎areas was performed using FlamMap and FARSITE fire models using slope, aspect, elevation, fuel ‎model, and canopy cover maps.

The results showed that the total fuel volume in the studied forest ‎areas is 3.9 kg/m2. Also, the maximum 1-hr fuel volume was calculated in dense forest (Shiomereh). ‎The highest fuel volumes of 10-, and 100-hr time-lag fuels were observed in forest areas with relatively ‎dense canopy (Shiomereh). The calculation of the fuel moisture content percentage (FMC%) also ‎showed that forest areas with dense canopy have the highest amount of FMC% among forest lands with ‎relatively dense (Shiomereh) and open (Nalas) canopy. Also, comparison of the real fire spot and the ‎simulated fire spread map ‎in the Nalas region with unintentional fire (with open canopy) with a kappa ‎coefficient of ‎‎0.83 was highly consistent and the model was able to have a significant agreement with ‎‎the actual extent of fire spread. The agreement coefficient in the Shiomereh region with a ‎dense and ‎relatively dense canopy cover due to a deliberate and controlled fire showed a 0.05 ‎agreement. ‎

These findings showed that in addition to the characteristics of the forest fuels, the cause of the fire (intentional and controlled or accidental and unintentional) is also effective in simulating the behavior and spread of fire. The ‎results of this study can be used in firefighting, crisis management, and many studies related to the ‎study of fire behavior and management of forest areas.