Watershed-scale controls on snow distribution in a montane watershed

Abstract

Snow accumulation in mountain headwater basins is vitally important to southern Alberta, where snowmelt supplies more than 80% of annual downstream runoff. This study evaluated two snow measurement techniques, and snow accumulation in southwestern Alberta. The SnowHydro sampler was compared with existing designs and observed to perform better under the forest canopy. A total station was evaluated for remotely measuring snow depth in avalanche terrain, but found to have accuracy limitations in low snow accumulation conditions. Field data were combined with indices of snow accumulation drivers to run classification and regression tree analysis (C&RT). Results quantified controls on accumulation over two years, and created spatial distributions of snow water equivalent across the watershed. Elevation was the dominant control between years, while canopy closure, slope angle, and aspect varied in importance between years and within seasons. Accurate representations of SWE suggest that C&RT could improve annual provincial water supply forecasts.