Point physical model of movement of ions through natural snow cover

A one-dimensional physical model which simulates vertical movement of water and dissolved anions in snowpack was developed. The input information for this model is the meteorological data and the anion concentrations of precipitation. The basic chemical and physical properties in different depths of the snow and their dynamic changes are the output from the model. The model was applied to the observed vertical profiles of snow density and anion concentrations obtained from the observation of natural snow cover for two winter seasons. The changes in the observed vertical profile of snow density were well reproduced by the model, implying that the movement of water through the snow cover is simulated properly by the model. The changes in the observed vertical profiles of chloride, sulfate and nitrate concentrations were also approximately reproduced. The physical properties of natural snow cover which affect the elution from snow were estimated by trial and error using the model. The results showed the validity of expressing the unsaturated hydraulic conductivity, the water diffusivity and the hydrodynamic dispersion coefficient of natural snow cover as functions of water content and dry snow density.