A LAND COVER-BASED SNOW COVER REPRESENTATION FOR DISTRIBUTED HYDROLOGIC-MODELS

A snow cover depletion curve (SDC) summarizes the relationship between snow cover distribution and an average snow cover property, such as d epth or water equivalent, for a given area. Snow cover depletion curve s have been developed for, and applied in, hydrological models on a wa tershed or elevation zone basis. However, land cover-based SDCs are no t prominent in the literature. For this study the areal distribution o f snow cover for dominant land cover units was measured during the win ters of 1991 and 1992 in the Laurel Creek watershed in southern Ontari o, Canada. On the basis of these data a general model for land cover-b ased SDCs is developed for these land cover units, namely, short grass , ploughed fields, and deciduous forests. This model is derived from t he three-parameter lognormal distribution, which is shown to character ize the areal depletion curves of the land cover units studied. The SD Cs based on this new model provide a formal distributed snow cover rep resentation that can be used in vegetation-based distributed hydrologi cal models requiring accurate spatial representations of snow cover at tributes.