scholarly journals Understanding the relative importance of vertical and horizontal flow in ice-wedge polygons

2020 ◽  
Vol 24 (3) ◽  
pp. 1109-1129 ◽  
Author(s):  
Nathan A. Wales ◽  
Jesus D. Gomez-Velez ◽  
Brent D. Newman ◽  
Cathy J. Wilson ◽  
Baptiste Dafflon ◽  
...  
Keyword(s):  
Preferential Flow ◽  
Horizontal Flow ◽  
Relative Importance ◽  
Hydrological Models ◽  
Water Fluxes ◽  
Flow And Transport ◽  
Hydrological Characteristics ◽  
Warming Climate ◽  
Conservative Tracer ◽  
Ice Wedge

Abstract. Ice-wedge polygons are common Arctic landforms. The future of these landforms in a warming climate depends on the bidirectional feedback between the rate of ice-wedge degradation and changes in hydrological characteristics. This work aims to better understand the relative roles of vertical and horizontal water fluxes in the subsurface of polygonal landscapes, providing new insights and data to test and calibrate hydrological models. Field-scale investigations were conducted at an intensively instrumented location on the Barrow Environmental Observatory (BEO) near Utqiaġvik, AK, USA. Using a conservative tracer, we examined controls of microtopography and the frost table on subsurface flow and transport within a low-centered and a high-centered polygon. Bromide tracer was applied at both polygons in July 2015 and transport was monitored through two thaw seasons. Sampler arrays placed in polygon centers, rims, and troughs were used to monitor tracer concentrations. In both polygons, the tracer first infiltrated vertically until encountering the frost table and was then transported horizontally. Horizontal flow occurred in more locations and at higher velocities in the low-centered polygon than in the high-centered polygon. Preferential flow, influenced by frost table topography, was significant between polygon centers and troughs. Estimates of horizontal hydraulic conductivity were within the range of previous estimates of vertical conductivity, highlighting the importance of horizontal flow in these systems. This work forms a basis for understanding complexity of flow in polygonal landscapes.

scholarly journals Understanding the Relative Importance of Vertical and Horizontal Flow in Ice-Wedge Polygons

2019 ◽  
Author(s):  
Nathan A. Wales ◽  
Jesus D. Gomez-Velez ◽  
Brent D. Newman ◽  
Cathy J. Wilson ◽  
Baptiste Dafflon ◽  
...  
Keyword(s):  
Preferential Flow ◽  
Horizontal Flow ◽  
Relative Importance ◽  
Water Fluxes ◽  
Field Scale ◽  
Flow And Transport ◽  
Hydrological Characteristics ◽  
Warming Climate ◽  
Conservative Tracer ◽  
Ice Wedge

Abstract. Ice-wedge polygons are common Arctic landforms. The future of these landforms in a warming climate depends on the bidirectional feedback between the rate of ice-wedge degradation and changes in hydrological characteristics. This work aims to better understand the relative roles of vertical and horizontal water fluxes in the subsurface of polygonal landscapes, providing new insights and data to test and calibrate hydrology models. Field-scale investigations were conducted at an intensively-instrumented location on the Barrow Environmental Observatory (BEO) near Utqiaġvik, AK, USA. Using a conservative tracer, we examined controls of microtopography and the frost table on subsurface flow and transport within a low-centered and a high-centered polygon. Bromide tracer was applied at both polygons in July 2015 and transport was monitored through two thaw seasons. Samplers arrays placed in polygon centers, rims, and troughs were used to monitor tracer concentrations. In both polygons, the tracer first infiltrated vertically until encountering the frost table, then was transported horizontally. Horizontal flow occurred in more locations and at higher velocities of fluxes in the low-centered polygon than in the high-centered polygon. Preferential flow, influenced by frost table topography, was significant between polygon centers and troughs. Estimates of horizontal hydraulic conductivity were within the range of previous estimates of vertical conductivity, highlighting the importance of horizontal flow in these systems. This work forms a basis for understanding complexity of flow in polygonal landscapes.

Characterization of hydraulic properties in the upper vadose zone for two aquifers in Slovenia

2021 ◽  
Author(s):  
Vesna Zupanc ◽  
Matjaž Glavan ◽  
Miha Curk ◽  
Urša Pečan ◽  
Michael Stockinger ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Soil Water ◽  
Water Flow ◽  
Vadose Zone ◽  
Hydraulic Properties ◽  
Isotope Composition ◽  
Transport Processes ◽  
Precipitation Event ◽  
Water Fluxes ◽  
Flow And Transport

<p>Environmental tracers, present in the environment and provided by nature, provide integrative information about both water flow and transport. For studying water flow and solute transport, the hydrogen and oxygen isotopes are of special interest, as their ratios provide a tracer signal with every precipitation event and are seasonally distributed. In order to follow the seasonal distribution of stable isotopes in the soil water and use this information for identifying hydrological processes and hydraulic properties, soil was sampled three times in three profiles, two on Krško polje aquifer in SE Slovenia and one on Ljubljansko polje in central Slovenia. Isotope composition of soil water was measured with the water-vapor-equilibration method. Based on the isotope composition of soil water integrative information about water flow and transport processes with time and depth below ground were assessed. Porewater isotopes were in similar range as precipitation for all three profiles.  Variable isotope ratios in the upper 60 cm for the different sampling times indicated dynamic water fluxes in this upper part of the vadose zone. Results also showed more evaporation at one sampling location, Brege. The information from stable isotopes will be of importance for further analyzing the water fluxes in the vadose zone of the study sties. <br>This research was financed by the ARRS BIAT 20-21-32 and IAEA CRP 1.50.18 Multiple isotope fingerprints to identify sources and transport of agro-contaminants.  </p>

RAT (Robustness Assessment Test): a straightforward evaluation of hydrological model robustness to a changing climate

2021 ◽  
Author(s):  
Vazken Andréassian ◽  
Léonard Santos ◽  
Torben Sonnenborg ◽  
Alban de Lavenne ◽  
Göran Lindström ◽  
...  
Keyword(s):  
Climate Change ◽  
Hydrological Model ◽  
Hydrological Models ◽  
Climate Variables ◽  
Data Set ◽  
Hydrological Characteristics ◽  
Changing Climate ◽  
Split Sample ◽  
Sample Test ◽  
Model Robustness

<p>Hydrological models are increasingly used under evolving climatic conditions. They should thus be evaluated regarding their temporal transferability (application in different time periods) and extrapolation capacity (application beyond the range of known past conditions). In theory, parameters of hydrological models are independent of climate. In practice, however, many published studies based on the Split-Sample Test (Klemeš, 1986), have shown that model performances decrease systematically when it is used out of its calibration period. The RAT test proposed here aims at evaluating model robustness to a changing climate by assessing potential undesirable dependencies of hydrological model performances to climate variables. The test compares, over a long data period, the annual value of several climate variables (temperature, precipitation and aridity index) and the bias of the model over each year. If a significant relation exists between the climatic variable and the bias, the model is not considered to be robust to climate change on the catchment. The test has been compared to the Generalized Split-Sample Test (Coron et al., 2012) and showed similar results.</p><p>Here, we report on a large scale application of the test for three hydrological models with different level of complexity (GR6J, HYPE, MIKE-SHE) on a data set of 352 catchments in Denmark, France and Sweden. The results show that the test behaves differently given the evaluated variable (be temperature, precipitation or aridity) and the hydrological characteristics of each catchment. They also show that, although of different level of complexity, the robustness of the three models is similar on the overall data set. However, they are not robust on the same catchments and, then, are not sensitive to the same hydrological characteristics. This example highlights the applicability of the RAT test regardless of the model set-up and calibration procedure and its ability to provide a first evaluation of the model robustness to climate change.</p><p> </p><p><strong>References</strong></p><p>Coron, L., V. Andréassian, C. Perrin, J. Lerat, J. Vaze, M. Bourqui, and F. Hendrickx, 2012. Crash testing hydrological models in contrasted climate conditions: An experiment on 216 Australian catchments, Water Resour. Res., 48, W05552, doi:10.1029/2011WR011721</p><p>Klemeš, V., 1986. Operational testing of hydrological simulation models, Hydrol. Sci. J., 31, 13–24, doi:10.1080/02626668609491024</p><p> </p>

Preferential Flow and Transport of Cryptosporidium parvum Oocysts through the Vadose Zone: Experiments and Modeling

2004 ◽  
Vol 3 (2) ◽  
pp. 736-736 ◽  
Author(s):  
Christophe J.G. Darnault ◽  
Tammo S. Steenhuis ◽  
Patricia Garnier ◽  
Young-Jin Kim ◽  
Michael Jenkins ◽  
...  
Keyword(s):  
Cryptosporidium Parvum ◽  
Vadose Zone ◽  
Preferential Flow ◽  
Flow And Transport ◽  
Cryptosporidium Parvum Oocysts

Transport of Nanoplastic under groundwater aquifer flow and transport conditions

2020 ◽  
Author(s):  
Sascha Müller ◽  
Tonci Balic-Zunic ◽  
Nicole R. Posth
Keyword(s):  
Preferential Flow ◽  
Particle Diameter ◽  
Steric Interaction ◽  
Colloidal Transport ◽  
Flow And Transport ◽  
Aquifer Material ◽  
Transport Behavior ◽  
Groundwater Aquifers ◽  
Groundwater Aquifer ◽  
Aquifer Flow

<p>In terrestrial environments soils are hypothesized sinks for plastic particles. Nonetheless, due to the existence of preferential flow paths as well as a variety of geochemical and microbiological processes, this sink may only be temporary. A vertical translocation from soils to groundwater aquifers eventually occurs along different pathways. In these conditions Nanoplastic transport characteristics are similar to colloidal transport behavior. Therby the magnitude of plastic transport is eventually governed by complex interplay between the particle with its surrounding media (particle-particle, particle-solvent, particle- porous media) masked by different hydro-geochemical and microbiological conditions. The physical entrapment of particles (straining) may be significant when the particle diameter exceeds 5% of the median grain size diameter. Below that size additional electrostatic, van der Waals or steric interaction become increasingly important.</p><p>We present a preliminary dataset on the interaction between Nano-sized Polystyrene (PS) with different surface coatings and a variety of common minerals occurring in groundwater aquifers under the presence of Natural Organic Matter (NOM). The reference aquifer material is based on the Danish subsurface structure of Quaternary and Miocene aquifer material, e.g. quartz, calcite and pyrite among others. In our study, batch scale interactions are up-scaled in column flow and transport experiments, simulating different groundwater aquifer flow conditions in the presence of selected minerals and NOM.</p><p>This aims to clarify transport behavior of plastic pollutant in the subsurface environment. Furthermore, it serves as guide in qualitatively assessing and quantifying the vulnerability of groundwater aquifers to Nanoplastic pollution.</p>

Preferential Flow and Transport of Oocysts through the Vadose Zone

2004 ◽  
Vol 3 (1) ◽  
pp. 262 ◽  
Author(s):  
Christophe J. G. Darnault ◽  
Tammo S. Steenhuis ◽  
Patricia Garnier ◽  
Young-Jin Kim ◽  
Michael B. Jenkins ◽  
...  
Keyword(s):  
Vadose Zone ◽  
Preferential Flow ◽  
Flow And Transport

Preferential Flow and Transport of Cryptosporidium parvum Oocysts through the Vadose Zone: Experiments and Modeling

2004 ◽  
Vol 3 (2) ◽  
pp. 736-736 ◽  
Author(s):  
C. J.G. Darnault ◽  
T. S. Steenhuis ◽  
P. Garnier ◽  
Y.-J. Kim ◽  
M. Jenkins ◽  
...  
Keyword(s):  
Cryptosporidium Parvum ◽  
Vadose Zone ◽  
Preferential Flow ◽  
Flow And Transport ◽  
Cryptosporidium Parvum Oocysts

Flow and transport in fractured tuff at Yucca Mountain: numerical experiments on fast preferential flow mechanisms

2000 ◽  
Vol 43 (3-4) ◽  
pp. 211-238 ◽  
Author(s):  
Robert G. McLaren ◽  
Peter A. Forsyth ◽  
Edward A. Sudicky ◽  
Joel E. VanderKwaak ◽  
Franklin W. Schwartz ◽  
...  
Keyword(s):  
Numerical Experiments ◽  
Preferential Flow ◽  
Yucca Mountain ◽  
Flow And Transport ◽  
Flow Mechanisms

It’s a macroporous world; we just model in it

2020 ◽  
Author(s):  
Ryan Stewart ◽  
Jesse Radolinski
Keyword(s):  
Preferential Flow ◽  
Physical Models ◽  
Catchment Scale ◽  
Equilibrium Conditions ◽  
Flow And Transport ◽  
Physical Mechanisms ◽  
Physical Heterogeneity ◽  
Uncertain Factor ◽  
Simplifying Assumptions ◽  
Domain Models

<p>Many soil physical models assume a homogeneous domain and equilibrium conditions, even as decades of evidence have suggested that such states are rarely present in the real world. Instead, natural soils tend to be characterized by physical heterogeneity (e.g., macropores) and non-equilibrium movement of water, solutes and gases (e.g., preferential flow and transport), making it critical to develop physically realistic yet parsimonious descriptors of these processes. In this presentation we discuss recent advances using multi-domain descriptions of soils to model preferential flow and subsurface contaminant movement under field conditions. Here we emphasize the use of simplifying assumptions and straightforward parameterizations, and consider whether those factors constrain the ability of such models to realistically represent underlying physical mechanisms. We also discuss results of an innovative field experiment aimed at constraining macropore porosity, which is a key yet highly uncertain factor in such multi-domain models. Finally, we consider the relevant scales of these multi-domain models, and whether such approaches merit consideration in larger (e.g., hillslope- or catchment-scale) simulations.    </p>

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