Geostatistical Methods for Estimating Snowmelt Contribution to an Alpine Water Balance

The performance of nine spatial interpolation models was evaluated to estimate snowmelt contributions to streamflow in the West Glacier Lake watershed. In April 2005, peak accumulation snow depth and snow density measurements were collected within West Glacier Lake watershed. The distribution of snow water equivalent (SWE) was calculated as the product of snow depth, snow density, and snow-covered area (SCA). Snow depths were spatially distributed throughout the watershed through spatial interpolation methods. Snow densities were spatially distributed through multiple linear regression analysis. The nine spatial snow depth models explained 18% to 94% of the observed variance in the measured snow depths. Co-kriging with solar radiation produced the best results explaining 94% of the observed variance in snow depth measurements. Estimated SWE from the field survey data was 67% greater than winter precipitation gauge estimates. The annual water balance, expressed as equivalent water depths was total precipitation (1,481 mm), snow sublimation (251 mm), and streamflow (1,000 mm), resulting in an estimate of evapotranspiration (230 mm). Winter precipitation as snow accounted for 85% of the annual precipitation.