Re-examining the assumption of dominant regional wind and fire spread directions

Abstract

The goal of decreasing wildfire hazard as much as possible, using minimal fuel treatments, has led to increasing scholarly interest in fuel reduction spatial optimisation. Most models in the field rest on the assumption of a known wind direction and a corresponding dominant direction of fire spread, and plan firebreaks in perpendicular directions. This strategy is effective when the wind blows in the hypothesised direction, but is quite ineffective when the wind direction is parallel to the firebreaks. In this article, we re-examine this assumption using a global fire dataset covering more than a decade. We perform a variety of circular statistical analyses including circular variance and principal component analysis (PCA). We find that the direction of fire spread in most regions is not limited to a single direction. We also find that the wind direction during fire weather is characterised by a high variance in a substantial fraction of regions around the globe. We validate this finding with a dataset comprised of over a hundred meteorological stations in Israel. We conclude that forest management should consider regional historical data of wind directions and fire spread directions, but also should plan firebreaks so that they are effective in various fire scenarios.