scholarly journals Two-dimensional liquid water flow through snow at the plot scale in continental snowpacks: simulations and field data comparisons

2021 ◽  
Vol 15 (3) ◽  
pp. 1423-1434
Author(s):  
Ryan W. Webb ◽  
Keith Jennings ◽  
Stefan Finsterle ◽  
Steven R. Fassnacht
Keyword(s):  
Water Flow ◽  
Liquid Water ◽  
Water Movement ◽  
Ground Surface ◽  
Two Dimensional ◽  
Longitudinal Flow ◽  
Flow Paths ◽  
Sloping Ground ◽  
Spatial And Temporal Scales ◽  
A Site

Abstract. Modeling the multidimensional flow of liquid water through snow has been limited in spatial and temporal scales to date. Here, we present simulations using the inverse TOUGH2 (iTOUGH2) model informed by the model SNOWPACK, referred to as SnowTOUGH. We use SnowTOUGH to simulate snow metamorphism, melt/freeze processes, and liquid water movement in two-dimensional snowpacks at the plot scale (20 m) on a sloping ground surface during multi-day observation periods at three field sites in northern Colorado, USA. Model results compare well with sites below the treeline and above the treeline but not at a site near the treeline. Results show the importance of longitudinal intra-snowpack flow paths (i.e., parallel to ground surface in the downslope direction and sometimes referred to as lateral flow), particularly during times when the snow surface (i.e., snow–atmosphere interface) is not actively melting. At our above-treeline site, simulations show that longitudinal flow can occur at rates orders of magnitude greater than vertically downward percolating water flow at a mean ratio of 75:1 as a result of hydraulic barriers that divert flow. Our near-treeline site simulations resulted in slightly less longitudinal flow than vertically percolating water, and the below-treeline site resulted in negligible longitudinal flow of liquid water. These results show the increasing influence of longitudinal intra-snowpack flow paths with elevation, similar to field observations. Results of this study suggest that intra-snowpack longitudinal flow may be an important process for consideration in hydrologic modeling for higher-elevation headwater catchments.

scholarly journals Two-Dimensional Liquid Water Flow through Snow at the Plot Scale in Continental Snowpacks: Simulations and Field Data Comparisons

2020 ◽  
Author(s):  
Ryan W. Webb ◽  
Keith S. Jennings ◽  
Stefan Finsterle ◽  
Steven R. Fassnacht
Keyword(s):  
Water Flow ◽  
Liquid Water ◽  
Water Movement ◽  
Ground Surface ◽  
Two Dimensional ◽  
Flow Paths ◽  
Sloping Ground ◽  
Spatial And Temporal Scales ◽  
Northern Colorado ◽  
Flow Through

Abstract. Modelling the multi-dimensional flow of liquid water through snow has been limited in spatial and temporal scales to date. Here we present simulations using the iTOUGH2 model informed by the model SNOWPACK, referred to as SnowTOUGH. We use SnowTOUGH to simulate snow metamorphism, melt/freeze processes, and liquid water movement in two-dimensional snowpacks at the plot scale (20 m) on a sloping ground surface during multi-day observation periods at three field sites in northern Colorado, USA. Model results compare well with subalpine and alpine sites, but not a treeline site. Results show the importance of longitudinal (i.e. parallel to ground surface in the downslope direction) intra-snowpack flow paths, particularly during times when the snow surface (i.e. snow-atmosphere interface) is not actively melting. Simulations show that longitudinal flow can occur at rates orders of magnitude greater than vertically downward percolating water flow (a ratio of > 250 : 1) as a result of hydraulic barriers.

scholarly journals A 2D model for simulating heterogeneous mass and energy fluxes through melting snowpacks

2016 ◽  
Author(s):  
Nicolas R. Leroux ◽  
John W. Pomeroy
Keyword(s):  
Water Flow ◽  
Liquid Water ◽  
Preferential Flow ◽  
Initial Conditions ◽  
Surface Fluxes ◽  
Porous Media Flow ◽  
Accurate Estimation ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
The Impact

Abstract. Accurate estimation of the water flux through melting snowpacks is of primary importance for runoff prediction. Lateral flows and preferential flow pathways in porous media flow have proven critical for improving soil and groundwater flow models, but though many physically-based layered snowmelt models have been developed, only 1D matrix flow over level ground is currently accounted for in snow models. Snowmelt models that include these processes may improve snowmelt discharge timing and contributing area calculations in hydrological models. A two-dimensional snow model (SMPP – Snowmelt Model with Preferential flow Paths) is presented that simulates heat and water flows through both snowpack matrix and preferential flow paths, as well as snowmelt and refreezing of meltwater. The model assumes thermodynamic equilibrium between solid and liquid phases and uses the latest improvements made in snow science to estimate snow hydraulic and thermal properties. A finite volume method is applied to solve for the 2D heat and water equations. The use of a water entry pressure for dry snow combined with consideration of the impact of heterogeneities in surface fluxes and internal snow properties – density, grain size and layer thickness – allowed calculation of the formation of preferential flow paths in the snowpack. The simulation of water flow through preferential flow paths resulted in liquid water reaching the base of the snowpack earlier than for a homogeneous wetting front. Moreover, the preferential flow paths in the model increased the exchange of energy between the snow surface and the internal snowpack, resulting in faster warming of the snowpack. A sensitivity analysis, conducted on the snow internal properties showed that initial conditions such as density and temperature, should be carefully measured in the field to accurately estimate liquid water percolating through the snowpack. Furthermore, two empirical coefficients used in the water flow equation were showed to greatly impact model outputs. This heterogeneous flow model is an important tool to help understand snowmelt flow processes in complex and level terrains and to demonstrate how uncertainty in snowmelt-derived runoff calculations might be reduced.

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 Experimental and Numerical Investigations of Influence on Overland Flow and Water Infiltration by Fracture Networks in Soil

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Lei Zhu ◽  
Dongjun Fan ◽  
Rong Ma ◽  
Yonggen Zhang ◽  
Yuanyuan Zha
Keyword(s):  
Soil Water ◽  
Water Flow ◽  
Surface Runoff ◽  
Preferential Flow ◽  
Water Movement ◽  
Water Infiltration ◽  
Two Dimensional ◽  
Soil Matrix ◽  
Soil Water Infiltration ◽  
Soil Water Movement

Preferential flow is common in clay or expansive clay soils, involving water bypassing a large portion of the soil matrix. Dye tracer experiment and numerical modeling are used to simulate the surface runoff and subsurface preferential flow patterns influenced by the soil fracture network of a relatively steep hillslope system (slope angle equals to 10 degrees). The result of the experiments indicates that part of the water is infiltrated through cracks, leading to the delay of the initial runoff-yielding time and reduction of the discharge of the surface runoff. The soil water flow is mainly in the matrix when the intensity of precipitation is low. With the increasing of precipitation, soil water movement may become in the form of preferential flow through cracks. In addition, the nonuniformity of soil water infiltration and the depth of the average water infiltration increase as the precipitation intensity increases. To this end, the complete coupling model was established by using the surface-matrix-crack (SMC) model to simulate water flow within discrete fracture as well as to simulate water flow in the soil matrix based on the concept of dual permeability using the traditional Richards’ equation. In this model, the “cubic law” of fluid motion in cracks within smooth parallel plates and the two-dimensional diffusion wave approximation to Saint-Venant equations with momentum term ignored (two-dimensional shallow water equations) were used. The model divides soil water infiltration into two forms and uses the overall method to calculate the exchange of water between the crack networks and matrix regions as well as the exchange water between surface runoff and infiltration water. Results indicate that the SMC model has better performance compared with the traditional equivalent continuum model when those models are used to simulate the surface runoff movement and the soil water movement in the presence of cracks.

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.

scholarly journals Carbonate-silicate cycle predictions of Earth-like planetary climates and testing the habitable zone concept

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Owen R. Lehmer ◽  
David C. Catling ◽  
Joshua Krissansen-Totton
Keyword(s):  
Liquid Water ◽  
Physicochemical Parameters ◽  
Silicate Weathering ◽  
Habitable Zone ◽  
Two Dimensional ◽  
Land Area ◽  
Incident Flux ◽  
Earth Like Planets ◽  
Surface Liquid ◽  
Log Linear

AbstractIn the conventional habitable zone (HZ) concept, a CO2-H2O greenhouse maintains surface liquid water. Through the water-mediated carbonate-silicate weathering cycle, atmospheric CO2 partial pressure (pCO2) responds to changes in surface temperature, stabilizing the climate over geologic timescales. We show that this weathering feedback ought to produce a log-linear relationship between pCO2 and incident flux on Earth-like planets in the HZ. However, this trend has scatter because geophysical and physicochemical parameters can vary, such as land area for weathering and CO2 outgassing fluxes. Using a coupled climate and carbonate-silicate weathering model, we quantify the likely scatter in pCO2 with orbital distance throughout the HZ. From this dispersion, we predict a two-dimensional relationship between incident flux and pCO2 in the HZ and show that it could be detected from at least 83 (2σ) Earth-like exoplanet observations. If fewer Earth-like exoplanets are observed, testing the HZ hypothesis from this relationship could be difficult.

scholarly journals Discontinuous finite volume element method of two-dimensional unsaturated soil water movement problem

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Fan Chen ◽  
Zhixiao Xu
Keyword(s):  
Soil Water ◽  
Finite Volume ◽  
Unsaturated Soil ◽  
Water Movement ◽  
Optimal Error Estimate ◽  
Two Dimensional ◽  
Fully Discrete ◽  
Volume Method ◽  
Movement Problem ◽  
Soil Water Movement

AbstractIn this paper, a numerical approximation method for the two-dimensional unsaturated soil water movement problem is established by using the discontinuous finite volume method. We prove the optimal error estimate for the fully discrete format. Finally, the reliability of the method is verified by numerical experiments. This method is not only simple to calculate, but also stable and reliable.

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