Snow avalanche penetration into mature forest from timber-harvested terrain

Abstract

Clear-cut logging in British Columbia, Canada, is creating new avalanche start zones from which snow avalanches sufficient in size to penetrate and destroy mature forest cover can initiate. In addition to creating new start zones, the presence of these logging cut blocks can augment the destructive potential of previously existing avalanche paths. Forest-penetrating avalanches can pose a significant risk to down-slope structures and resources. This study is the first to develop and utilize a database containing information on penetration distances and lateral spread from avalanches that have penetrated forest cover. The study area for this research spans the Southern Coast and Columbia Mountains of British Columbia, Canada. Analysis focuses on terrain characteristics related to forest penetration and the resultant destruction of mature standing forest. Physical terrain and vegetation characteristics in the avalanche starting zone, track, and runout zone of 45 forest-penetrating avalanches are described, measured, and parameterized. The results provide tools to assess and evaluate potential forest-penetrating avalanche terrain, and runout models for avalanches in forested terrain.