scholarly journals Nährstoffaustrag aus einer schmelzenden Schneedecke im Alptal (Kanton Schwyz) am Beispiel von Nitrat | Nitrate Release from a Melting Snow Pack in Alptal (Canton of Schwyz, Switzerland)

2000 ◽  
Vol 151 (6) ◽  
pp. 198-204 ◽  
Author(s):  
Peter Waldner ◽  
Martin Schneebeli ◽  
Hans Wunderli
Keyword(s):  
Snow Cover ◽  
Open Field ◽  
Preferential Flow ◽  
Nitrate Concentration ◽  
Temporal Heterogeneity ◽  
Snow Pack ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Spatial And Temporal Heterogeneity ◽  
Melt Water

The evolution of the release of nutrients from a snow cover may essentially determine their availability for plants. In this study, the nitrate release from a snow pack on an open field in Alptal (canton of Schwyz, Switzerland) was measured in the winter of 1998/99. With the diminution of the nitrate concentration in single snow layers, a hint for ionic fractionation has been found. The measurements allowed to estimate the variability of the water and nitrate release from the snow pack. Its high spatial and temporal heterogeneity is explained with preferential flow paths of the melt water.

scholarly journals Simulating ice layer formation under the presence of preferential flow in layered snowpacks

2016 ◽  
Vol 10 (6) ◽  
pp. 2731-2744 ◽  
Author(s):  
Nander Wever ◽  
Sebastian Würzer ◽  
Charles Fierz ◽  
Michael Lehning
Keyword(s):  
Snow Cover ◽  
Water Flow ◽  
Liquid Water ◽  
Preferential Flow ◽  
Layer Formation ◽  
Flow Paths ◽  
One Dimensional ◽  
Preferential Flow Paths ◽  
Matrix Flow ◽  
Dual Domain

Abstract. For physics-based snow cover models, simulating the formation of dense ice layers inside the snowpack has been a long-time challenge. Their formation is considered to be tightly coupled to the presence of preferential flow, which is assumed to happen through flow fingering. Recent laboratory experiments and modelling techniques of liquid water flow in snow have advanced the understanding of conditions under which preferential flow paths or flow fingers form. We propose a modelling approach in the one-dimensional, multilayer snow cover model SNOWPACK for preferential flow that is based on a dual domain approach. The pore space is divided into a part that represents matrix flow and a part that represents preferential flow. Richards' equation is then solved for both domains and only water in matrix flow is subjected to phase changes. We found that preferential flow paths arriving at a layer transition in the snowpack may lead to ponding conditions, which we used to trigger a water flow from the preferential flow domain to the matrix domain. Subsequent refreezing then can form dense layers in the snowpack that regularly exceed 700 kg m−3. A comparison of simulated density profiles with biweekly snow profiles made at the Weissfluhjoch measurement site at 2536 m altitude in the Eastern Swiss Alps for 16 snow seasons showed that several ice layers that were observed in the field could be reproduced. However, many profiles remain challenging to simulate. The prediction of the early snowpack runoff also improved under the consideration of preferential flow. Our study suggests that a dual domain approach is able to describe the net effect of preferential flow on ice layer formation and liquid water flow in snow in one-dimensional, detailed, physics-based snowpack models, without the need for a full multidimensional model.

scholarly journals Simulating ice layer formation under the presence of preferential flow in layered snowpacks

2016 ◽  
Author(s):  
Nander Wever ◽  
Sebastian Würzer ◽  
Charles Fierz ◽  
Michael Lehning
Keyword(s):  
Snow Cover ◽  
Water Flow ◽  
Liquid Water ◽  
Preferential Flow ◽  
Swiss Alps ◽  
Layer Formation ◽  
Flow Paths ◽  
One Dimensional ◽  
Preferential Flow Paths ◽  
Dual Domain

Abstract. For physics based snow cover models, simulating the formation of dense ice layers inside the snowpack has been a long time challenge. Their formation is considered to be tightly coupled to the presence of preferential flow, which is assumed to happen through flow fingering. Recent laboratory experiments and modelling techniques of liquid water flow in snow have advanced the understanding of conditions under which preferential flow paths or flow fingers form. We propose a modelling approach in the one-dimensional, multi-layer snow cover model SNOWPACK for preferential flow that is based on a dual-domain approach. The pore space is divided into a part that represents matrix flow and a part that represents preferential flow. Richards equation is then solved for both domains. We found that preferential flow paths arriving at a layer transition in the snowpack may lead to ponding conditions. Subsequent refreezing then can form dense layers in the snowpack, that regularly exceed 700 kg m−3. A comparison of simulated density profiles with bi-weekly snow profiles made at the Weissfluhjoch measurement site at 2536 m altitude in the Eastern Swiss Alps for 16 snow seasons showed that several ice layers that were observed in the field could be reproduced. However many profiles remain challenging to simulate. The prediction of the early snowpack runoff also improved under the consideration of preferential flow. Our study suggests that a dual domain approach is able to describe the net effect of preferential flow on ice layer formation and liquid water flow in snow in one-dimensional, detailed, physics based snowpack models, without the need for a full multi-dimensional model.

Visualizing Preferential Flow Paths using Ammonium Carbonate and a pH Indicator

2002 ◽  
Vol 66 (2) ◽  
pp. 347 ◽  
Author(s):  
Zhi Wang ◽  
Jianhang Lu ◽  
Laosheng Wu ◽  
Thomas Harter ◽  
William A. Jury
Keyword(s):  
Preferential Flow ◽  
Ammonium Carbonate ◽  
Ph Indicator ◽  
Flow Paths ◽  
Preferential Flow Paths

Equation for Describing Solute Transport in Field Soils with Preferential Flow Paths

2005 ◽  
Vol 69 (2) ◽  
pp. 291-300 ◽  
Author(s):  
Young-Jin Kim ◽  
Christophe J. G. Darnault ◽  
Nathan O. Bailey ◽  
J.-Yves Parlange ◽  
Tammo S. Steenhuis
Keyword(s):  
Solute Transport ◽  
Preferential Flow ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Field Soils

Dynamic Modeling of Channel Formation During Fluid Injection Into Unconsolidated Formations

SPE Journal ◽  
2015 ◽  
Vol 20 (04) ◽  
pp. 689-700 ◽  
Author(s):  
S.. Ameen ◽  
A. Dahi Taleghani
Keyword(s):  
Preferential Flow ◽  
Volume Fraction ◽  
Injection Pressure ◽  
Internal Erosion ◽  
Fluid Injection ◽  
Critical Threshold ◽  
Model Parameters ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Stress Changes

Summary Injectivity loss is a common problem in unconsolidated-sand formations. Injection of water into a poorly cemented granular medium may lead to internal erosion, and consequently formation of preferential flow paths within the medium because of channelization. Channelization in the porous medium might occur when fluid-induced stresses become locally larger than a critical threshold and small grains are dislodged and carried away; hence, porosity and permeability of the medium will evolve along the induced flow paths. Vice versa, flowback during shut-in might carry particles back to the well and cause sand accumulation inside the well, and subsequently loss of injectivity. In most cases, to maintain the injection rate, operators will increase injection pressure and pumping power. The increased injection pressure results in stress changes and possibly further changes in channel patterns around the wellbore. Experimental laboratory studies have confirmed the presence of the transition from uniform Darcy flow to a fingered-pattern flow. To predict these phenomena, a model is needed to fill this gap by predicting the formation of preferential flow paths and their evolution. A model based on the multiphase-volume-fraction concept is used to decompose porosity into mobile and immobile porosities where phases may change spatially, evolve over time, and lead to development of erosional channels depending on injection rates, viscosity, and rock properties. This model will account for both particle release and suspension deposition. By use of this model, a methodology is proposed to derive model parameters from routine injection tests by inverse analysis. The proposed model presents the characteristic behavior of unconsolidated formation during fluid injection and the possible effect of injection parameters on downhole-permeability evolution.

Biofilm development and the dynamics of preferential flow paths in porous media

Biofouling ◽  
2013 ◽  
Vol 29 (9) ◽  
pp. 1069-1086 ◽  
Author(s):  
Simona Bottero ◽  
Tomas Storck ◽  
Timo J. Heimovaara ◽  
Mark C.M. van Loosdrecht ◽  
Michael V. Enzien ◽  
...  
Keyword(s):  
Porous Media ◽  
Preferential Flow ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Biofilm Development

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 A model of hydrological and mechanical feedbacks of preferential fissure flow in a slow-moving landslide

2013 ◽  
Vol 17 (3) ◽  
pp. 947-959 ◽  
Author(s):  
D. M. Krzeminska ◽  
T. A. Bogaard ◽  
J.-P. Malet ◽  
L. P. H. van Beek
Keyword(s):  
Slope Stability ◽  
Preferential Flow ◽  
Water Pressure ◽  
Flow Paths ◽  
Landslide Activity ◽  
Hydrological Responses ◽  
Preferential Flow Paths ◽  
Slow Moving ◽  
Groundwater Drainage ◽  
Opening And Closing

Abstract. The importance of hydrological processes for landslide activity is generally accepted. However, the relationship between precipitation, hydrological responses and movement is not straightforward. Groundwater recharge is mostly controlled by the hydrological material properties and the structure (e.g., layering, preferential flow paths such as fissures) of the unsaturated zone. In slow-moving landslides, differential displacements caused by the bedrock structure complicate the hydrological regime due to continuous opening and closing of the fissures, creating temporary preferential flow paths systems for infiltration and groundwater drainage. The consecutive opening and closing of fissure aperture control the formation of a critical pore water pressure by creating dynamic preferential flow paths for infiltration and groundwater drainage. This interaction may explain the seasonal nature of the slow-moving landslide activity, including the often observed shifts and delays in hydrological responses when compared to timing, intensity and duration of precipitation. The main objective of this study is to model the influence of fissures on the hydrological dynamics of slow-moving landslide and the dynamic feedbacks between fissures, hydrology and slope stability. For this we adapt the spatially distributed hydrological and slope stability model (STARWARS) to account for geotechnical and hydrological feedbacks, linking between hydrological response of the landside and the dynamics of the fissure network and applied the model to the hydrologically controlled Super-Sauze landslide (South French Alps).

scholarly journals Dye staining and excavation of a lateral preferential flow network

2009 ◽  
Vol 13 (6) ◽  
pp. 935-944 ◽  
Author(s):  
A. E. Anderson ◽  
M. Weiler ◽  
Y. Alila ◽  
R. O. Hudson
Keyword(s):  
Slope Stability ◽  
Solute Transport ◽  
Preferential Flow ◽  
Runoff Generation ◽  
Flow Paths ◽  
Soil Matrix ◽  
Preferential Flow Paths ◽  
Dye Staining ◽  
Hillslope Scale ◽  
Surrounding Soil

Abstract. Preferential flow paths have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, very few studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation to determine the morphology and spatial pattern of a preferential flow network over a large scale (30 m). We explore the feasibility of extending small-scale dye staining techniques to the hillslope scale. We determine the lateral preferential flow paths that are active during the steady-state flow conditions and their interaction with the surrounding soil matrix. We also calculate the velocities of the flow through each cross-section of the hillslope and compare them to hillslope scale applied tracer measurements. Finally, we investigate the relationship between the contributing area and the characteristics of the preferential flow paths. The experiment revealed that larger contributing areas coincided with highly developed and hydraulically connected preferential flow paths that had flow with little interaction with the surrounding soil matrix. We found evidence of subsurface erosion and deposition of soil and organic material laterally and vertically within the soil. These results are important because they add to the understanding of the runoff generation, solute transport, and slope stability of preferential flow-dominated hillslopes.

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