Understanding the Spatial Distribution of Snow Water Equivalent and Subsequent Snowmelt Runoff Patterns of Paired Basins in Southwest Montana

This paper presents the initial results of a research project with the primary goal of investigating the hydrologic role of avalanche activity alongside the physiographic variables (i.e. elevation, slope, aspect, wind shelter/exposure, landcover, and solar radiation) that the snow hydrology community widely consider to be the dominant controls on the spatial distribution of snow water equivalent (SWE) and subsequent snowmelt runoff in alpine basins. An extensive field campaign was conducted in two adjacent alpine basins in southwest Montana from January 31 to August 21, 2013, consisting of three survey periods to capture snowpack metrics during the phases of (1) accumulation; (2) peak SWE, and (3) ablation/snowmelt runoff. During each period, the same stratified random sampling methods were used to measure snow depth and SWE at transects along elevation contours. Transects were spatially distributed with the goal of acquiring a representative sample of the aforementioned physiographic variables as well as the components of avalanche paths. After quantifying the contribution of each of these variables to the distribution of SWE, we will also consider their impact on the timing and magnitude of snowmelt runoff. This will be determined by correlation to stream discharge measurements that were collected throughout the 2012- 2013 water year. The initial results are discussed as are the future steps.