The Relationship between wildfire areas and physiographic features in the Zagros vegetation area, Kermanshah province

Wildfires are one of the most important challenges of natural resources management causing a lot of damages to these natural ecosystems, annually. Although, reportedly almost all of the wildfires are human caused in the Zagros region, environmental factors play a key role in fire spreading and burned area.  Hence, the aim of this study was to determine the relationship between burned area and physiographic factors (slope, aspect and elevation) from 2001 to 2018 using Moderate Resolution Imaging Spectro-radiometer (MODIS) fire data.

MODIS burned area data were collected for the statistical period of 2001-2018 with the resolution of 500m include spatial and temporal information of fire incidents. Then the physiographic maps including slope (five classes), aspect (five classes) and elevation (six classes) maps of study area were prepared, using a 90m DEM. Kolmogorov–Smirnov test was used to check the normal distribution of the data. Since the data did not follow the normal distribution, non-parametric tests such as Kruskal–Wallis and Mann–Whitney U tests were used for comparing the statistical differences between the median of burned area in different classes of physiographic factors. Furthermore, the specific burned area (SBA) index were calculated by overlaying the layers of burned area, vegetation type (rangeland and forest) and physiographic factors to remove the effect of the surface area of physiographic classes.

The results showed that the larger burned area was observed in the larger physiographic classes. In other words, the surface area of physiographic classes is the most effective factor on burned area. However, the values of specific burned area (SBA) in each classes showed a different result. In both vegetation types, the value of specific burned area index was highest in the elevation class of 500-1000m and the eastern aspect. Furthermore, the value of SBA was highest in slope class of 15-30% and more than 80% in rangelands and forests, respectively. Since the value of SBA index is not dependent to the extent of relevant physiographic classes, it could be used to indicate the natural potential of each physiographic classes for fire spreading in different regions.

It was concluded that the specific burned area in comparison with burned area is a more appropriate index for investigating the effects of physiographic factors on fire spreading.