Snowmobile Impacts on the Physical and Mechanical Properties of Different Snowpacks in Colorado, U.S.A.

Abstract. Physical and material properties of the snowpack, including snow density, temperature, stratigraphy, hardness, and ram resistance were measured from snow pit profiles to examine the statistical difference between no use and varying degrees of snowmobile use (low, medium and high). The properties were examined across the entire snowpack, from the surface to its base, and for the basal layer of the snowpack. Experimental snow compaction study plots were located near Rabbit Ears Pass near Steamboat Springs, Colorado and at Fraser Experimental Forest near Fraser, Colorado. Significant changes in snowpack properties are associated with snowmobile use beginning early in the snow accumulation season when the snowpack is shallow, as well as earlier in the winter and at the base of the snowpack. These effects were amplified when snowmobile use occurred on a shallow snow covered environment and with increasing degrees of snowmobile use. On the contrary, snowmobile use that began on a deeper snowpack showed no significant changes in snowpack properties suggesting later initiation of use minimizes impacts to snowpack properties from snowmobile use.