scholarly journals Simulating nonequilibrium movement of water, solutes and particles using hydrus – a review of recent applications

2008 ◽  
Vol 3 (Special Issue No. 1) ◽  
pp. S42-S51 ◽  
Author(s):  
J. Šimůnek ◽  
M. Köhne ◽  
R. Kodešová ◽  
M. Šejna
Keyword(s):  
Water Flow ◽  
Vadose Zone ◽  
Preferential Flow ◽  
Chemical Nonequilibrium ◽  
Nonequilibrium Processes ◽  
Modeling Tools ◽  
Flow And Transport ◽  
Wide Range ◽  
Flow Pathways ◽  
Physical And Chemical

Water and contaminants moving through the vadose zone are often subject to a large number of simultaneous physical and chemical nonequilibrium processes. Traditional modeling tools for describing flow and transport in soils either do not consider nonequilibrium processes at all, or consider them only separately. By contrast, a wide range of nonequilibrium flow and transport modeling approaches are currently available in the latest versions of the HYDRUS software packages. The formulations range from classical models simulating uniform flow and transport, to relatively traditional mobile-immobile water physical and two-site chemical nonequilibrium models, to more complex dual-permeability models that consider both physical and chemical nonequilibrium. In this paper we briefly review recent applications of the HYDRUS models that used these nonequilibrium features to simulate nonequilibrium water flow (water storage in immobile domains and/or preferential water flow in structured soils with macropores and other preferential flow pathways), and transport of solutes (pesticides and other organic compounds) and particles (colloids, bacteria and viruses) in the vadose zone.

scholarly journals Combining cross-hole geophysical and vadose zone monitoring systems for vadose zone characterization at industrial contaminated sites

2016 ◽  
Author(s):  
Natalia Fernández de Vera ◽  
Jean Beaujean ◽  
Pierre Jamin ◽  
David Caterina ◽  
Marnik Vanclooster ◽  
...  
Keyword(s):  
Water Flow ◽  
Vadose Zone ◽  
Preferential Flow ◽  
Pyrite Oxidation ◽  
Contaminated Site ◽  
Heterogeneous Distribution ◽  
Borehole Geophysics ◽  
Flow And Transport ◽  
Flow Mechanisms ◽  
Intermediate Part

Abstract. Water flow and solute transport through a fractured vadose zone underneath an industrial contaminated site in Belgium were studied with a new methodological concept. The Vadose Zone Experimental Setup (VZES) combines a vadose zone monitoring system (VMS) with cross-borehole geophysics. The VMS provides continuous chemical and hydraulic information at multiple depths in the vadose zone. When combining such information with multidirectional subsurface imaging from geophysical measurements, flow and transport can be characterized at a scale that covers the spatial variability of the subsurface. The setup was installed on site and monitoring was carried out under natural recharge conditions. Results reveal quick rises in water content as a response to rainfall events in the upper and intermediate part of the vadose zone (down to 3.65 m depth). Macropore, micropore, matrix and preferential flow mechanisms are identified at these depth ranges. At greater depths, flow dynamics is slower and dominated by matrix flow. The governance of water flow mechanisms at different directions is controlled by the heterogeneous distribution of geological materials. Results from sampled waters across the vadose zone reveal that the chemistry of water collected from matrix is different from that collected from fractures. In addition, analysis of heavy metals indicates that Ni is leaching across the vadose zone, and its release might be a consequence of pyrite oxidation from backfilled materials. Results obtained from VZES indicate that the combination of different techniques providing in situ quantitative and qualitative information improves conceptual models of flow and transport in a heterogeneous subsurface.

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>

Vadose Zone, Part I : Characterization and Flow Processes

2003 ◽  
Author(s):  
Yoram Rubin
Keyword(s):  
Porous Media ◽  
Water Flow ◽  
Governing Equation ◽  
Vadose Zone ◽  
Stochastic Analysis ◽  
Transport Processes ◽  
Richards Equation ◽  
Saturated Porous Media ◽  
Flow And Transport ◽  
Flow Processes

Many of the principles guiding stochastic analysis of flow and transport processes in the vadose zone are those which we also employ in the saturated zone, and which we have explored in earlier chapters. However, there are important considerations and simplifications to be made, given the nature of the flow and of the governing equations, which we explore here and in chapter 12. The governing equation for water flow in variably saturated porous media at the smallest scale where Darcy’s law is applicable (i.e., no need for upscaling of parameters) is Richards’ equation (cf. Yeh, 1998)

scholarly journals Editorial of Special Issue “Advances in Groundwater Flow and Solute Transport: Pushing the Hidden Boundary”

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 457
Author(s):  
Hongbin Zhan ◽  
Quanrong Wang ◽  
Zhang Wen
Keyword(s):  
Numerical Methods ◽  
Groundwater Flow ◽  
Solute Transport ◽  
Vadose Zone ◽  
Regional Scale ◽  
Chemical Transport ◽  
Low Permeability ◽  
Special Issue ◽  
Flow And Transport ◽  
Wide Range

The theme of this special issue is to explore the new territories beyond conventional subsurface flow and transport theories. We have selected 12 articles in this special issue and these articles cover a wide range of problems including (1) Non-Fickian chemical transport in various environments; (2) Non-Darcian flow; (3) Flow and transport in low-permeability media; (4) Vadose zone process; (5) Regional scale groundwater flow and groundwater-surface interaction; (6) Innovative numerical methods. The major contributions of these papers are summarized in this editorial.

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

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

Emerging Measurement Techniques for Vadose Zone Characterization

1999 ◽  
Author(s):  
Jan W. Hopmans ◽  
Jan M. H. Hendrickx
Keyword(s):  
Solute Transport ◽  
Water Flow ◽  
Vadose Zone ◽  
Measurement Techniques ◽  
Soil Physics ◽  
Flow And Transport ◽  
Regional Project ◽  
The Difference ◽  
Magnetic Resonance Imaging Mri ◽  
Western Regional

Variables and parameters required to characterize soil water flow and solute transport are often measured at different spatial scales from those for which they are needed. This poses a problem since results from field and laboratory measurements at one spatial scale are not necessarily valid for application at another. Herein lies a challenge that vadose zone hydrologists are faced with. For example, vadose zone studies can include flow at the groundwater-unsaturated zone as well as at the soil surface-atmosphere interface at either one specific location or representing an entire field or landscape unit. Therefore, vadose zone measurements should include techniques that can monitor at large depths and that characterize landsurface processes. On the other end of the space spectrum, microscopic laboratory measurement techniques are needed to better understand fundamental flow and transport mechanisms through observations of pore-scale geometry and fluid flow. The Vadose Zone Hydrology (VZH) Conference made very clear that there is an immediate need for such microscopic information at fluid-fluid and solid-fluid interfaces, as well as for methodologies that yield information at the field/landscape scale. The need for improved instrumentation was discussed at the ASA-sponsored symposium on “Future Directions in Soil Physics” by Hendrickx (1994) and Hopmans (1994). Soil physicists participating in the 1994-1999 Western Regional Research Project W-188 (1994) focused on “improved characterization and quantification of flow and transport processes in soils,” and prioritized the need for development and evaluation of new instrumentation and methods of data anlysis to further improve characterization of water and solute transport. The regional project documents the critical need for quantification of water flow and solute transport in heterogeneous, spatially variable field soils, specifically to address preferential and accelerated contaminant transport. Cassel and Nielsen (1994) describe the contributions in computed tomography (CT) using x-rays or magnetic resonance imaging (MRI) as “an awakening,” and they envision these methodologies to become an integral part of vadose zone research programs. The difference in size between measurement and application scales poses a dilemma for the vadose zone hydrologist.

scholarly journals Observations of englacial water passages:a fracture-dominated system

2005 ◽  
Vol 40 ◽  
pp. 25-30 ◽  
Author(s):  
Andrew G. Fountain ◽  
Robert B. Schlichting ◽  
Peter Jansson ◽  
Robert W. Jacobel
Keyword(s):  
Water Flow ◽  
Preferential Flow ◽  
Complex Geometry ◽  
Unknown Origin ◽  
Video Camera ◽  
Glacier Surface ◽  
Test Models ◽  
Flow Speeds ◽  
Flow Pathways ◽  
Preferential Flow Pathways

AbstractTo test models of the hydraulics and geometry of englacial conduits, 48 holes (3900m of ice) were drilled into Storglaciaren, Sweden, in search of conduits. About 79% of the holes intersected a hydraulically connected englacial feature. A video camera was used to examine the features and measure local water-flow rates. Because of the extremely clear ice that surrounded most features, their geometry could not be discerned. Of the remaining features, 80% (36) were fracture-like, 16%(6) were of complex geometry, and 4%(2) exhibited a conduit-like geometry. The fracture-like features exhibited steep plunges (∼70˚), narrow openings (∼40mm) and slow water-flow speeds (∼10mms–1). We argue that these fracture-like features are indeed englacial fractures of unknown origin. The depth to fractures intersection varied from near the glacier surface to 96% of local ice depth, with a maximum depth of 131 m. Few hydraulically connected fractures exhibited water motion, indicating some preferential flow pathways exist. We found one ‘traditional’ englacial conduit after an intentional search in a field of moulins. These results suggest that englacial water flow is conveyed through a ubiquitous network of fractures and that conduits are relatively rare.

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