Temporal variation in snowcover area during melt in prairie and alpine environments

Abstract

Image analyses are applied to aerial photographs taken during snowmelt on two small watersheds: one in Sasketchewan, the other in the Austrian Alps. Results suggest that the soil and melting snow patches behave as fractals, ie. their perimeter-area and area-frequency characteristics can be described by simple power equations with patch area. The perimeter-area ratio of the soil and snow patches decreases with increasing size of patch, but at a smaller rate than for Euclidean objects. The area-frequency characteristics of snow patches follow a hyperbolic distribution with relatively few large patches and numerous small patches. It is suggested that the soil and snow patches have the same fractal dimension and that snow patches are not random and their size distribution is predictable. The variation in the edge length of a snow field per unit basin area during ablation is demonstrated. A maximum value of the ratio is reached when a basin has 45-65% snowcover. With snow coverage in this range the potential for local advection increasing melt is greatest. -from Authors