Item: Avalanche forecasting in a heavy snowfall area using the snowpack model
Title: Avalanche forecasting in a heavy snowfall area using the snowpack model
Proceedings: Proceedings of the 2006 International Snow Science Workshop, Telluride, Colorado
Authors: Hiroyuki Hirashima, Kouichi Nishimura, Satoru Yamaguchi, Atsushi Sato and Michael Lehning, Snow and Ice Research Center, NIED, Suyoshi, Maeyama, Nagaoka 940-0821, Japan, Faculty of Science, Niigata University, Ikarashi, Niigata 950-2181, Japan
Abstract: We describe the use of a snow cover model — SNOWPACK — for a heavy snowfall area. The area along the Sea of Japan received record-breaking snowfall in the winter of 2005/2006. Avalanche forecasting was carried out at Tunan, Niigata prefecture where snow exceeded 4m. Automated Meteorological Data Acquisition System operated by the Japan Meteorological Agency (AMEDAS) was used as the model input data. To verify the model output, snow pit observations were carried out in 10-day intervals. The snow profiles simulated using the SNOWPACK model agreed fairly well with the observed profiles. However, the equations for the stability index (SI) were not suitable for the study area considered. The empirical equations formulated by Yamanoi and Endo (2002) were most suitable for this region for simulating SI; therefore, they were incorporated into the SNOWPACK model. To expand the forecasting area to include the area around route 405, a national road, the distributions of meteorological parameters in the study area were estimated for grid points with 10-m spacing. One of the avalanches caused a disaster in which a car was pushed away from the road into a valley on 24th December. The snow depth increased by about 70cm within 24 hours; this caused a large load before densification. Thus, snow stability decreased. This was reproduced by the SNOWPACK model. Further, the stability index maps showed that most of slopes were dangerous on that day.
Keywords: snowpack model, avalanche forecasting, heavy snow, stability index
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