scholarly journals Rainwater propagation through snow pack during rain-on-snow events under different snow condition

2016 ◽  
Author(s):  
Roman Juras ◽  
Sebastian Würzer ◽  
Jirka Pavlásek ◽  
Tomáš Vitvar ◽  
Tobias Jonas
Keyword(s):  
Liquid Water ◽  
Field Experiments ◽  
Preferential Flow ◽  
Liquid Water Content ◽  
Hydrograph Separation ◽  
Runoff Generation ◽  
Total Runoff ◽  
Artificial Rainfall ◽  
Snow Condition ◽  
Wet Snow

Abstract. The mechanisms of rainwater propagation and runoff generation during rain-on-snow (ROS) are still insufficiently known. Understanding the behaviour of liquid water within the natural snowpack is crucial especially for forecasting of natural hazards such as floods and wet snow avalanches. In this study, rainwater percolation through snow was investigated by sprinkling deuterium enriched water on snow and applying an advanced hydrograph separation technique on samples collected from the snowpack runoff. This allowed quantifying the contribution of rainwater and snowmelt in the water released from the snowpack. Four field experiments were carried out during the winter 2015 in the vicinity of Davos, Switzerland. For this purpose, large blocks of natural snow were isolated from the surrounding snowpack to inhibit lateral exchange of water. These blocks were exposed to artificial rainfall with 41 mm of deuterium enriched water. The sprinkling was run in four 30 minutes periods separated by three 30 minutes non-sprinkling periods. The runoff from the snow block was continuously gauged and sampled for the deuterium concentration. At the onset of each experiment initially present liquid water content was first pushed out by the sprinkling water. Hydrographs showed four pronounced peaks corresponding to the four sprinkling bursts. The contribution of rainwater to snowpack runoff consistently increased over the course of the experiment but never exceeded 86 %. An experiment conducted on a cold snowpack suggested the development of preferential flow paths that allowed rainwater to efficiently propagate through the snowpack limiting the time for mass exchange processes to take effect. On the contrary, experiments conducted on ripe isothermal snowpack showed a slower response behaviour and resulted in a total runoff volume which consisted of less than 50 % of the rain input.

scholarly journals Rainwater propagation through snowpack during rain-on-snow sprinkling experiments under different snow conditions

2017 ◽  
Vol 21 (9) ◽  
pp. 4973-4987 ◽  
Author(s):  
Roman Juras ◽  
Sebastian Würzer ◽  
Jirka Pavlásek ◽  
Tomáš Vitvar ◽  
Tobias Jonas
Keyword(s):  
Liquid Water ◽  
Field Experiments ◽  
Preferential Flow ◽  
Hydrograph Separation ◽  
Runoff Generation ◽  
Total Runoff ◽  
Artificial Rainfall ◽  
Wet Snow ◽  
Natural Snow ◽  
Snow Conditions

Abstract. The mechanisms of rainwater propagation and runoff generation during rain-on-snow (ROS) events are still insufficiently known. Understanding storage and transport of liquid water in natural snowpacks is crucial, especially for forecasting of natural hazards such as floods and wet snow avalanches. In this study, propagation of rainwater through snow was investigated by sprinkling experiments with deuterium-enriched water and applying an alternative hydrograph separation technique on samples collected from the snowpack runoff. This allowed us to quantify the contribution of rainwater, snowmelt and initial liquid water released from the snowpack. Four field experiments were carried out during winter 2015 in the vicinity of Davos, Switzerland. Blocks of natural snow were isolated from the surrounding snowpack to inhibit lateral exchange of water and were exposed to artificial rainfall using deuterium-enriched water. The experiments were composed of four 30 min periods of sprinkling, separated by three 30 min breaks. The snowpack runoff was continuously gauged and sampled periodically for the deuterium signature. At the onset of each experiment antecedent liquid water was first pushed out by the sprinkling water. Hydrographs showed four pronounced peaks corresponding to the four sprinkling bursts. The contribution of rainwater to snowpack runoff consistently increased over the course of the experiment but never exceeded 86 %. An experiment conducted on a non-ripe snowpack suggested the development of preferential flow paths that allowed rainwater to efficiently propagate through the snowpack limiting the time for mass exchange processes to take effect. In contrast, experiments conducted on ripe isothermal snowpack showed a slower response behaviour and resulted in a total runoff volume which consisted of less than 50 % of the rain input.

scholarly journals Modelling liquid water transport in snow under rain-on-snow conditions – considering preferential flow

2017 ◽  
Vol 21 (3) ◽  
pp. 1741-1756 ◽  
Author(s):  
Sebastian Würzer ◽  
Nander Wever ◽  
Roman Juras ◽  
Michael Lehning ◽  
Tobias Jonas
Keyword(s):  
Water Transport ◽  
Liquid Water ◽  
Field Experiments ◽  
Preferential Flow ◽  
Richards Equation ◽  
European Alps ◽  
Wet Snow ◽  
Snow Conditions ◽  
Dual Domain ◽  
Grain Properties

Abstract. Rain on snow (ROS) has the potential to generate severe floods. Thus, precisely predicting the effect of an approaching ROS event on runoff formation is very important. Data analyses from past ROS events have shown that a snowpack experiencing ROS can either release runoff immediately or delay it considerably. This delay is a result of refreeze of liquid water and water transport, which in turn is dependent on snow grain properties but also on the presence of structures such as ice layers or capillary barriers. During sprinkling experiments, preferential flow was found to be a process that critically impacted the timing of snowpack runoff. However, current one-dimensional operational snowpack models are not capable of addressing this phenomenon. For this study, the detailed physics-based snowpack model SNOWPACK is extended with a water transport scheme accounting for preferential flow. The implemented Richards equation solver is modified using a dual-domain approach to simulate water transport under preferential flow conditions. To validate the presented approach, we used an extensive dataset of over 100 ROS events from several locations in the European Alps, comprising meteorological and snowpack measurements as well as snow lysimeter runoff data. The model was tested under a variety of initial snowpack conditions, including cold, ripe, stratified and homogeneous snow. Results show that the model accounting for preferential flow demonstrated an improved overall performance, where in particular the onset of snowpack runoff was captured better. While the improvements were ambiguous for experiments on isothermal wet snow, they were pronounced for experiments on cold snowpacks, where field experiments found preferential flow to be especially prevalent.

scholarly journals Modeling liquid water transport in snow under rain-on-snow conditions – considering preferential flow

2016 ◽  
Author(s):  
Sebastian Würzer ◽  
Nander Wever ◽  
Roman Juras ◽  
Michael Lehning ◽  
Tobias Jonas
Keyword(s):  
Water Transport ◽  
Liquid Water ◽  
Field Experiments ◽  
Preferential Flow ◽  
Richards Equation ◽  
European Alps ◽  
Wet Snow ◽  
Snow Conditions ◽  
Dual Domain ◽  
Grain Properties

Abstract. Rain-on-snow (ROS) has the potential to generate severe floods. Thus, precisely predicting the effect of an approaching ROS event on runoff formation is very important. Data analyses from past ROS events have shown that a snowpack experiencing ROS can either release runoff immediately or delay it considerably. This delay is a result of refreeze of liquid water and water transport mechanisms in the snowpack. Water percolation is depending on snow grain properties but also on the presence of structures such as ice layers or capillary barriers. During sprinkling experiments, preferential flow was found to be a process that critically impacted the timing of snowpack runoff. However, current one-dimensional snowpack models are not capable of addressing this phenomenon correctly. For this study, the detailed physics-based snowpack model SNOWPACK is extended with a water transport scheme accounting for preferential flow. The implemented Richards' Equation solver is modified using a dual-domain approach to simulate water transport under preferential flow conditions. To validate the presented approach, we used an extensive dataset of over 100 ROS events from several locations in the European Alps, comprising meteorological and snowpack measurements as well as snow lysimeter runoff data. The model was tested under a variety of initial snowpack conditions, including cold, ripe, stratified and homogeneous snow. Results show that the model accounting for preferential flow (PF) demonstrated an improved overall and in particular more balanced performance. While the improvements were small for experiments on isothermal wet snow, they were pronounced for experiments on cold snowpacks, where field experiments found preferential flow to be especially prevalent.

scholarly journals Liquid water infiltration into a layered snowpack: evaluation of a 3-D water transport model with laboratory experiments

2017 ◽  
Vol 21 (11) ◽  
pp. 5503-5515 ◽  
Author(s):  
Hiroyuki Hirashima ◽  
Francesco Avanzi ◽  
Satoru Yamaguchi
Keyword(s):  
Liquid Water ◽  
Laboratory Experiments ◽  
Preferential Flow ◽  
Transport Model ◽  
Three Dimensional ◽  
Water Infiltration ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Capillary Barriers ◽  
Wet Snow

Abstract. The heterogeneous movement of liquid water through the snowpack during precipitation and snowmelt leads to complex liquid water distributions that are important for avalanche and runoff forecasting. We reproduced the formation of capillary barriers and the development of preferential flow through snow using a three-dimensional water transport model, which was then validated using laboratory experiments of liquid water infiltration into layered, initially dry snow. Three-dimensional simulations assumed the same column shape and size, grain size, snow density, and water input rate as the laboratory experiments. Model evaluation focused on the timing of water movement, thickness of the upper layer affected by ponding, water content profiles and wet snow fraction. Simulation results showed that the model reconstructs relevant features of capillary barriers, including ponding in the upper layer, preferential infiltration far from the interface, and the timing of liquid water arrival at the snow base. In contrast, the area of preferential flow paths was usually underestimated and consequently the averaged water content in areas characterized by preferential flow paths was also underestimated. Improving the representation of preferential infiltration into initially dry snow is necessary to reproduce the transition from a dry-snow-dominant condition to a wet-snow-dominant one, especially in long-period simulations.

scholarly journals Retrieval of Snow Water Equivalent, Liquid Water Content, and Snow Height of Dry and Wet Snow by Combining GPS Signal Attenuation and Time Delay

2019 ◽  
Vol 55 (5) ◽  
pp. 4465-4487 ◽  
Author(s):  
Franziska Koch ◽  
Patrick Henkel ◽  
Florian Appel ◽  
Lino Schmid ◽  
Heike Bach ◽  
...  
Keyword(s):  
Time Delay ◽  
Water Content ◽  
Liquid Water ◽  
Snow Water Equivalent ◽  
Liquid Water Content ◽  
Signal Attenuation ◽  
Wet Snow ◽  
Snow Water

scholarly journals Relationships between Surface Properties and Snow Adhesion and Its Shedding Mechanisms

2020 ◽  
Vol 10 (16) ◽  
pp. 5407
Author(s):  
Jamie Heil ◽  
Behrouz Mohammadian ◽  
Mehdi Sarayloo ◽  
Kevin Bruns ◽  
Hossein Sojoudi
Keyword(s):  
Surface Energy ◽  
Surface Temperature ◽  
Water Content ◽  
Adhesion Strength ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Snow Accumulation ◽  
Dispersive Surface Energy ◽  
Wet Snow ◽  
Intermediate Surface

Understanding the mechanisms of snow adhesion to surfaces and its subsequent shedding provides means to search for active and passive methods to mitigate the issues caused by snow accumulation on surfaces. Here, a novel setup is presented to measure the adhesion strength of snow to various surfaces without altering its properties (i.e., liquid water content (LWC) and/or density) during the measurements and to study snow shedding mechanisms. In this setup, a sensor is utilized to ensure constant temperature and liquid water content of snow on test substrates, unlike inclined or centrifugal snow adhesion testing. A snow gun consisting of an internal mixing chamber and ball valves for adjusting air and water flow is designed to form snow with controlled LWC inside a walk-in freezing room with controlled temperatures. We report that snow adheres to surfaces strongly when the LWC is around 20%. We also show that on smooth (i.e., RMS roughness of less than 7.17 μm) and very rough (i.e., RMS roughness of greater than 308.33 μm) surfaces, snow experiences minimal contact with the surface, resulting in low adhesion strength of snow. At the intermediate surface roughness (i.e., RMS of 50 μm with a surface temperature of 0 °C, the contact area between the snow and the surface increases, leading to increased adhesion strength of snow to the substrate. It is also found that an increase in the polar surface energy significantly increases the adhesion strength of wet snow while adhesion strength decreases with an increase in dispersive surface energy. Finally, we show that during shedding, snow experiences complete sliding, compression, or a combination of the two behaviors depending on surface temperature and LWC of the snow. The results of this study suggest pathways for designing surfaces that might reduce snow adhesion strength and facilitate its shedding.

scholarly journals A portable calorimeter for measuring liquid-water content of wet snow

1998 ◽  
Vol 26 ◽  
pp. 103-106 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Toru Endo ◽  
Yukari Takeuchi
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Total Weight ◽  
Light Weight ◽  
High Mountains ◽  
Insulating Materials ◽  
Wet Snow ◽  
Snow Water

In order to facilitate the measurement of liquid-water content of snow in high mountains, a portable calorimeter named “Endo-type snow-water content meter” was developed. It is composed of a metal-coated container made of insulating materials and a lid of the container with a small-thermistor thermometer. Its strong points are its light weight, small size and easy fabrication with cheap materials. The total weight of the device is as light as 250 g, which is less than 10% of the snow-water content meter widely used in Japan (Akitaya-type snow-water content meter). The results of experiments have revealed that the device is capable of measuring the liquid-water content within 2 minutes with an accuracy of 2% by weight.

Snow Wetness Influence on Impulse Radar Snow Surveys Theoretical and Laboratory Study

2000 ◽  
Vol 31 (2) ◽  
pp. 89-106 ◽  
Author(s):  
A. Lundberg ◽  
H. Thunehed
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Snow Water Equivalent ◽  
Liquid Water Content ◽  
Late Winter ◽  
Propagation Time ◽  
Reservoir Water ◽  
A Value ◽  
Wet Snow ◽  
Snow Water

The snow-water equivalent of late-winter snowpack is of utmost importance for hydropower production in areas where a large proportion of the reservoir water emanates from snowmelt. Impulse radar can be used to estimate the snow-water equivalent of the snowpack and thus the expected snowmelt discharge. Impulse radar is now in operational use in some Scandinavian basins. With radar technology the radar wave propagation time in the snowpack is converted into snow-water equivalent with help of a parameter usually termed the a-value. Use of radar technology during late winter brings about risk for measurements on wet snow. The a-value for dry snow cannot be used directly for wet snow. We have found that a liquid-water content of 5% (by volume) reduces the a-value by approximately 20%. In this paper an equation, based on snow density and snow liquid water content, for calculation of wet-snow a-value is presented.

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