THE METHOD FOR ESTIMATING OUTFLOW FROM THE SNOWPACK USING THE SIMPLIFIED HEATBALANCE MODEL AND THE PERCOLATION MODEL

To ensure the safety of train operations, it is important to estimate the outflow from the bottom of snowpack which might incur a full-depth avalanche. Therefore, the authors examined a simpli- fied method for estimating the outflow from the bottom of snowpack, which can be applied to railway dis- aster prevention, on the basis of heat balance observations, snowmelt observations and previous studies. Consequently, the simplified method, which combines a snowmelt (heat balance) model and a percolation model, yields a good estimate of the outflow from the bottom of snowpack at 1hour intervals using four input data available from the nearest AMeDAS: i.e., air temperature, precipitation, wind speed and dura- tion of sunshine.