SITE CHARACTERISTICS OF DEBRIS FLOWS AND THEIR RELATIONSHIP TO ALPINE TREELINE

Publisher Website
Google Scholar
Abstract
Over 150 debris flows in eastern Glacier National Park, Montana, were mapped from a combination of aerial photograph analysis and fieldwork, and categorized as to site characteristics that are suggestive of causal processes. The debris-flow sites were digitized and entered into an integrated geographic information system for subsequent analysis. Principal components analysis was carried out to assess which terrain characteristics exert the most influence over debris-flow location. The greatest number of mapped debris flows were debris torrents occurring within the confines of snow-avalanche paths, followed by snow-patch debris flows, debris torrents unassociated with snow-avalanche paths, and moraine debris flows. Elevation, snow potential, and snow distribution exerted the greatest control over debris-flow location. The impact of debris flows into the alpine treeline ecotone was especially pronounced in two valleys, but debris flows act to depress treeline below its climatic optimum throughout the valleys of the study area. [Key words: debris flow, alpine treeline, snowavalanche path, snow patch, geographic information system, Glacier National Park.]