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Conventional equations that relate snowpack drag to glide velocity take no account of the possible influences of free water at or near the snow‐earth interface. For this reason two of the most important applications of snow mechanics, predicting maximum forces on structures and predicting the release of full‐depth avalanches, lie beyond the scope of present theory. Here we discuss two effects that can decrease snowpack drag and increase glide velocity: (1) reduction of snow viscosity by the presence of water in the lowest layers, and (2) partial separation of the snowpack from the glide interface. For partial separation we show how the presence of free water covering portions of the interface reduces the effective roughness and increases glide speed; for significant enhancement of the glide rate a substantial fraction of the bed must be water covered.
McClung et al. (Wed,) studied this question.