1Department of Civil and Environmental Engineering, Politecnico di Milano, Milano, Italy
2Snow and Ice Research Center, National Research Institute for Earth Science and
Disaster Resilience, Suyoshi-machi, Nagaoka-shi, Niigata-ken, 940-0821, Japan
3Meteorological Risk and Buffer Forest Laboratory, Department of Meteorological
Environment, Forestry and Forest Products Research Institute, Tsukuba-shi, Ibaraki-ken, 305-8687, Japan
Received: 10 Oct 2015 – Published in The Cryosphere Discuss.: 03 Dec 2015
Abstract. Data of liquid water flow around a capillary barrier in snow are still limited. To gain insight into this process, we carried out observations of dyed water infiltration in layered snow at 0 °C during cold laboratory experiments. We considered three different finer-over-coarser textures and three different water input rates. By means of visual inspection, horizontal sectioning, and measurements of liquid water content (LWC), capillary barriers and associated preferential flow were characterized. The flow dynamics of each sample were also simulated solving the Richards equation within the 1-D multi-layer physically based snow cover model SNOWPACK. Results revealed that capillary barriers and preferential flow are relevant processes ruling the speed of water infiltration in stratified snow. Both are marked by a high degree of spatial variability at centimeter scale and complex 3-D patterns. During unsteady percolation of water, observed peaks in bulk volumetric LWC at the interface reached ∼ 33–36 vol % when the upper layer was composed by fine snow (grain size smaller than 0.5 mm). However, LWC might locally be greater due to the observed heterogeneity in the process. Spatial variability in water transmission increases with grain size, whereas we did not observe a systematic dependency on water input rate for samples containing fine snow. The comparison between observed and simulated LWC profiles revealed that the implementation of the Richards equation reproduces the existence of a capillary barrier for all observed cases and yields a good agreement with observed peaks in LWC at the interface between layers.
Revised: 02 Aug 2016 – Accepted: 10 Aug 2016 – Published: 09 Sep 2016
Avanzi, F., Hirashima, H., Yamaguchi, S., Katsushima, T., and De Michele, C.: Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments, The Cryosphere, 10, 2013-2026, doi:10.5194/tc-10-2013-2016, 2016.