Snowmelt in a forest and clearcut

Methods for obtaining daily snowmelt rates in forest and clearcut environments were evaluated at high elevation sites in the southern interior of British Columbia, Canada (Upper Penticton Creek Watershed Experiment). Snowmelt was measured during spring 1998 to 2002 in a clearcut with snowmelt lysimeters and calculated for the clearcut and a forest from the daily snow pack depth and snow density. Daily melt rate was calculated in the forest and clearcut from weather station data using an air temperature index method and with the energy balance. Measurements were used to calibrate clearcut and forest snow albedo models, to determine solar radiation transmission through the forest canopy and to calculate the canopy view factor for longwave radiation in the forest. Snow temperature measurements were used to define the beginning and end of the melt season when modelling snowmelt. Lysimeter and snow depth and density based measurements of snowmelt agreed quite well. The air temperature index method gave acceptable estimates of melt but tended to overestimate melt in the forest. The energy balance calculations slightly overestimated melt in the clearcut and slightly underestimated melt in the forest. Net radiation provides almost all the energy for melt in the forest and about 75% of the energy in the clearcut. Snowmelt rates of over 40 mm d-1 were measured in the clearcut and up to two thirds of this in the forest under the same weather condition.