Snow accumulation, melt and infiltration on forested and clearcut slopes, Turkey Lakes Watershed, central Ontario.

摘要

Snow accumulation, melt and infiltration on north- and south-facing slopes in the Turkey Lakes Watershed (TLW) in central Ontario were compared for a mature hardwood maple stand and an adjacent clearcut in late winter and spring of 2000 and 2001. Snow accumulation in the clearcut exceeded that in the forest. Melt was significantly larger in the south-facing clearcut and forest relative to corresponding north-facing sites. Daily melt in the clearcut was slightly greater and more spatially variable than in the adjacent forest. The effect of aspect on spatial variations in melt was larger than that due to clearcutting. There was a slight increase in melt rate with decreased canopy density in the south-facing clearcut and forest; however, variations in canopy density did not explain inter-point differences in daily melt within either the north-facing clearcut or the forest. Near-surface soil water contents in the clearcut responded quickly to water inputs and often reached saturation. In the forest the near-surface soil water content was not as quick to respond to water inputs as the clearcut locations, and saturation was not reached. Reduced mixing between incoming event and resident pre-event water at depth in the clearcut resulted in longer soil water residence times compared to the forest. Infiltration in the clearcut suggests a short-circuiting mechanism whereby larger inputs combined with greater saturation of the soil profile promotes downslope diversion of event water inputs via near-surface pathways. This has important implications for the quantity and quality of water delivered from harvested hillslopes to receiving streams and lakes.