Defining Actual Daily Snowmelt Rates from In Situ Snow Water Equivalent Measurements

Seasonal snow plays an essential role in the Earth's hydrological cycle and melted water flows into rivers, and reservoirs, which will then be managed for different water uses. Research has shown a concerning decline in the snowpack over the last century, but an accurate way to calculate the snowmelt rate has not been developed. Traditionally it is the maximum snow water equivalent (SWE) divided by the time from SVVE peak to complete SWE melt out. However, this does not account for scenarios where melt occurs during the accumulation period or when accumulation occurs during the melt period. Four computational techniques were investigated to improve the traditional snowmelt rate method. Approach 1 removes all melt prior to post-peak accumulation to implement the algorithm. Approach 2 removes the daily melt-accumulation fluctuations to optimize the snowmelt rate. Approach 3 uses snow depth and precipitation as a reference to determine if rain or snow is falling. Approach 4 uses 80% of the peak SWE to replace the peak SWE in the traditional approach to ease computation. While we did not determine the optimal method to estimate the snowmelt rate, Approach 3 seems to be most appropriate as it adjusts SWE to consider the precipitation during melt, rather than removing those values (approaches 1 and 2). This third approach shows less variability in the computed snowmelt rate.