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The Cryosphere An interactive open-access journal of the European Geosciences Union
The Cryosphere, 10, 2013-2026, 2016
https://doi.org/10.5194/tc-10-2013-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
09 Sep 2016
Observations of capillary barriers and preferential flow in layered snow during cold laboratory experiments
Francesco Avanzi1, Hiroyuki Hirashima2, Satoru Yamaguchi2, Takafumi Katsushima3, and Carlo De Michele1 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
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.

Citation: 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, https://doi.org/10.5194/tc-10-2013-2016, 2016.
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We investigate capillary barriers and preferential flow in layered snow during nine cold laboratory experiments. The dynamics of each sample were replicated solving Richards equation within the 1-D multi-layer physically based SNOWPACK model. Results show that both processes affect the speed of water infiltration in stratified snow and are marked by a high degree of spatial variability at cm scale and complex 3-D patterns.
We investigate capillary barriers and preferential flow in layered snow during nine cold...
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