Hydrologic Flowpath Development Varies by Aspect during Spring Snowmelt in Complex Subalpine Terrain

Ryan W. Webb, Steven R. Fassnacht, Michael N. Gooseff
2017 The Cryosphere Discussions  
In many mountainous regions around the world, snow and soil moisture are key components of the hydrologic cycle. Preferential flowpaths of snowmelt water through snow have been known to occur for years with few studies observing the effect on soil moisture. In this study, statistical analysis of the topographical and hydrological controls on the spatio-temporal variability of snow water equivalent and soil moisture during snowmelt was undertaken at a subalpine forested setting with north,
more » ... and flat aspects as a seasonally persistent snowpack melts. We investigated if preferential flowpaths in snow can be observed and the effect on soil moisture through measurements of snow water equivalent and near surface soil moisture in addition to observing how SWE and near surface soil moisture vary on hillslopes relative to the toes of hillslopes and flat areas. We then compared snowmelt infiltration beyond the near surface soil between flat and sloping terrain during the entire snowmelt season using soil moisture sensor profiles. This study was conducted during varying snowmelt seasons representing above normal, relatively normal, and below normal snow seasons in northern Colorado. Evidence is presented of preferential meltwater flowpaths at the snow-soil interface on the north facing slope with the effects observed in changes in SWE and infiltration into the soil at 20 cm depth; less association is observed in the near surface soil moisture (top 7 cm). We present a conceptualization of the meltwater flowpaths that develop based on slope aspect and soil properties. The resulting flowpaths are shown to increase the snow water equivalent by as much as 170 % at the base of a north facing hillslope. Results from this study show that snow acts as an extension of the vadose zone during spring snowmelt and future hydrologic investigations will benefit from studying the snow and soil together.
doi:10.5194/tc-2017-12 fatcat:kaecxqdrj5gcnkvfkhf6s3tyqe