Assessment of Hydrologic Impacts of Snowdrift in a Snow Dominated Watershed

Snowdrifts have long been recognized as a significant melt water resource, especially in late melt season and summer. Despite their significance, quantitative assessment of snowdrifts’ impact on streamflow, groundwater, soil moisture and evapotranspiration at watershed scale has gone reported. It is not clear if the additional melt from snowdrifts late in the melt season is enough to have any appreciable impact on summer baseflow or if it is mostly lost back to the atmosphere as evapotranspiration loss. Using a linked a snow model (Isnobal) and a distributed hydrologic model (PIHM) in a snow-dominated watershed, we explore how water yield from the snowdrifts have varied hydrologic impacts from year to year. Our analysis suggests that melt water yield from snowdrifts amounts to less than 15% of the total melt from the watershed. However, after snow melt out at a reference snow pillow site, percentage of melt water from snowdrifts can be as large as 70% of the melt yield from the entire watershed. Inter-annual variations of the impacts suggest that fractional melt yield from drifts is generally larger in wetter years.