| Water infiltration of snowpack plays an important role in wet avalanche formation. Several studies have examined water infiltration of snowpacks on flat land. However, because the infiltration process includes uniform flow as well as preferential flow (e.g., vertical flow through a water channel), the effect of water infiltration into snowpack may differ between flat land and slopes, where avalanches may occur. We simultaneously observed snow pits on flat land and on a slope (40° incline, northeast aspect). The observations, conducted from January to April 2012, showed that the Melt Form (MF) ratio (the ratio of the total thickness of the layers comprising the MF to the thickness of all the layers of the snowpack) was on average 26% higher for the snowpack on the slope than for the snowpack on flat land. The largest difference between the MF ratios of the slope and flat land was observed in early March, when the MF ratio was 99% for the slope and 54% for the flat land. We analyzed these observations using a multi-layer snowpack model proposed by Katsushima et al. (2009). The model included parameterization of the vertical water channel process in a snowpack. Of the total amount of infiltrated water, the amount infiltrating through vertical water channels was 14% for the slope and 47% for the flat land. Our results suggest that the notable difference in the MF ratios was attributable to the differences in the water infiltration process between the sites. |
