AN APPROACH TO USING THE DEGREE DAY METHOD FOR URBAN SNOW DEPOSIT MELT / Graddagarsmetoden för beräkning av smältning av snötippar

Snow melt and snow handling are of great concern for the municipalities in cold regions. Urban run off is influenced by the piling of snow. In order to design deposit areas, storm water systems, etc. forecasts of urban snow melt run off should consider melting of snow piles. Piling of snow delays the melt and dampens the flow rates. The changing geometry of melting snow piles has been observed on small snow cylinders (0.1 m3) and two large pilot snow deposits (200-225 m3). The degree day method has been modified to take the shrinking area exposed to the ambient air (top and side area) into account. The degree day predictions are compared to run off measurements from the large pilot snow deposits. This modified model seems to be applicable to snow-deposit melt. It only requires initial data of the deposit geometry (here angle of slope, height and base diameter), the snow density, and an air temperature series. The estimated degree day coefficients for winter and spring (3 and 11 mm/°C-day, respectively) are in agreement with literature values of urban snow cover degree day coefficients.