Mapping snow avalanche chutes in the Canadian Rockies using Landsat TM and DEM data

Snow avalanches are a common occurrence within the Canadian Rockies. Such features result in a distinctive biogeographic response that can be associated with characteristic land cover patterns. These patterns are most visible when avalanches penetrate through mature forest stands, leaving a narrow track of open ground aligned parallel to the fall line. The recurrence of avalanches in the same location perpetuates the disruption of the forest canopy, leaving more avalanche-resistant shrubs and herbs to colonize these areas. To date, no reliable method to map snow avalanche features using satellite sensor data has been reported. The use of image segmentation and digital elevation model (DEM) derivatives provides a solution to this shortcoming. Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) data covering areas in the Canadian Rockies are used in conjunction with specific geomorphometry and image segmentation to isolate image objects that conform to the geomorphic and spectral characteristics consistent with avalanche tracks. Accuracy assessment using a database derived from manual inspection of stereo aerial photographs indicates approximately 80% accuracy for both errors of omission and errors of commission.