Measurements of unsaturated hydraulic conductivity of snow.

Abstract

Measurements of unsaturated hydraulic conductivity K of snow were carried out by a steady method with constant flux in a booth kept at 0 ± 0.1°C. Three types of snow samples were used, namely fine-grains (mean grain size : 0.5 mm) of compacted snow (density : 530 kg/m3), medium-grains (1.3 mm) of granular snow (620 kg/m3) and coarse-grains (1.7 mm) of granular snow (610 kg/m3). From the measured values of water flux, water (weight) content θw, and suction due to capillary pressure, relationships between K and θw were obtained. It was found that K decreased with n th power of θ, where n was 1.9 for fine-grains, 4.8 for medium-grains, and 6.3 for coarse-grains. At high water-content conditions, K of granular snow is higher than K of compacted snow, whereas at low water-content, the relation is in an opposite trend. This result suggests that some structures of snow, which consist of coarse-grains of granular snow and fine-grains of compacted snow, would hinder water percolation depending on water content and may cause a layer of high water content above the layer boundary.