Water retention curve of snow with different grain sizes

The water retention curve (WRC), which shows the relationship between volumetric water content (θv) and suction (h), is fundamental for characterizing hydraulic properties. Thus, to model water movement through the snow cover, a formulation for the WRC as a function of snow characteristics must be established. In order to examine the dependence of the WRC on the grain size of snow, we measured the WRCs of snow (550 kg m−3) of various grain sizes in gravity drainage column experiments. Our experiments revealed many similarities between the WRCs of snow and sand. Thus, we applied two soil physics models, the Brooks and Corey model (BC model) and the van Genuchten model (VG model), which are standard models in soil physics to analyze the WRC of snow. Two parameters in both models that affected the shape of the WRC had a strong relationship with sample grain size. The parameter related to the value of the reverse of air entry suction increased with an increase in grain size, whereas the parameter related to the gradient of θv versus h (dθv / dh) decreased with an increase in grain size. From these results, we obtained linear equations between those two parameters and grain size. Our results suggest that the WRC of snow can be described as a function of grain size using soil physics models.