A DENDROGEOMORPHOLOGICAL ANALYSIS OF SNOW AVALANCHES IN THE COLORADO FRONT RANGE, USA

Abstract

Despite the growing risk of avalanche-related death and property damage associated with the burgeoning tourist industry in the Colorado Front Range, no dendro-geomorphological studies have been conducted to assess avalanche history in this region. In this study, dendrogeomorphological techniques are used to develop avalanche event chronologies and to reconstruct past slide magnitude at two sites located near Loveland Pass. At Mount Bethel, historical data compiled by the Colorado Department of Transportation (CDOT) and the Westwide Data Network for the period between 1974 and 1996 corroborate four of eight dendrochronologically dated event years. At Grizzly Peak, four of five dendrochronologically determined event years occurring between 1981 and 1996 are supported by historical data kept by CDOT, the Westwide Data Network and the Arapaho Basin Ski Patrol. Avalanche path reconstruction and the examination of vegetative indicator species reveal periodic fluctuations in slide magnitude at both sites, suggesting that larger avalanches have run outside the present tracks multiple times. The chronicling and assessment of each path's slide history informs of past occurrences and alerts us to future risks. [Key words: avalanche, dendrogeomorphology, Colorado Front Range.]