Forest fire intensity in Japan: Estimation of byram's fireline intensity using rothermel's fire spread model

Abstract

Byram's fireline intensity values were calculated in order to estimate the intensities of Japanese forest fires by simulating a test fire using Rothermel's fire spread model, which has been widely employed in analyses of North American forested ecosystems. The sensitivity of the fireline intensity approximation was determined by examining the variation in each of the fuel parameters. The results showed that none of the parameters, with the exception of surface-area-to-volume ratio, had a significant effect on fireline intensity. Therefore, constant values of these parameters could be used in the calculation, regardless of the type of fuel. The estimated fireline intensities were higher for fern grasslands than for forests, and were influenced by both the wind velocity and the slope. The fireline intensity values for most Japanese forests were calculated as below 850 kW m-1 and were similar to those reported for North American forested ecosystems. However, fireline intensities in Pinus densiflora forests with dense Dicranopteris lincaris undergrowth reached values of more than 20,000 kW m-1; similar values have been reported for Mediterranean-type ecosystems, such as fynbos and chaparral, which are widely considered to be adapted to recurrent fires.