Feasibility Study of a "Snow Dam" Concept

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Recently in Japan, there is a mounting interest in using snow for various purposes that better serve life in snowy areas. This study reports feasibility of a totally new idea of gathering and storing snow as a "snow dam" , and using the delayd meltwater to supplement water demand in summer.The idea is not to build a structure that stands like a concrete dam, but to gather snow in gorges where siting conditions and technology are appropriate. Technology is needed both to gather snow in gorges and to reduce rates of melting, so that water can be extracted to provide a supply when it is most needed. Various kinds of technologies are reviewed. It is concluded that Gaz.ex, an avalanche-blasting device recently developed in France, appears a promising technology for this purpose and that further experimental studies should be needed for getting a quantitative answer as to how much snow can be gathered.A fluid dynamical model of powder-snow avalanches is developed for prediction of the debris volume and the running course height and speed of the artificial avalanches. This model takes into account three-dimensional topography of mountain slopes. It consists of the two-dimensional treatment of momentum balance, the mass conservation equations of air and snow, and an approximate equation of conservation of turbulent energy.Technology to control and delay the melting consists of treating snow dams and predicting snowmelt runoff. The latter requires research on small-scale runoff analysis in a dam located deep in a gorge, and the calculation has to be done well through the summer season. A distribution snow melt runoff model was developed and applied to several conceptual snow dams, which takes into account both topographical and meteorological distributions. A snowmelt calculation in the Nakano River basin started on April 3,1990, demonstrates that the conceptual snow dams increase summer stream flow well into August.