Evaluating the Role of Preferential Flow on Solute Transport Through Unsaturated Field Soils

Abstract. While rapid movement of solutes through structured soils constitutes the risk of groundwater contamination, simulation of solute transport in field soils is challenging. A modification in an existing preferential flow model was tested using replicated Chloride and Lithium leachings carried out at constant flow rates through four soils differing in grades and type of structure. Flow rates generated by +10 mm, −10 mm, −40 mm, and −100 mm water heads at the surface of 35 cm diameter 50 cm height field columns. Three well-structured silty clay soils under ponding had concurrent breakthrough of Chloride and Lithium within a few cm of drainage, and a delayed and reduced peak concentration of Lithium with decrease in flow rate controlled by the negative heads. Massive sandy loam soil columns had delayed but uniform breakthrough of the solutes over the flow rates. Macropore flow in well-structured silty clay/clay loam soils reduced retardation, R (1.5 to 4.5) and effective porosity, θe (0.05 to 0.15), and increased macropore velocity, vm (20 to 30 cm cm−1 drainage) compared to the massive sandy soils. The existing simple preferential flow equation (single layer) fitted the data well only when macropore flow was dominant. The modified preferential flow equations (two layers) fitted equally well both for the adsorbing and nonadsorbing solutes. The later had high goodness of fit for a large number of solute breakthroughs, and gave almost identical retardation coefficient R as that calculated by two-domain CDE. With fewer parameters, the modified preferential flow equation after testing on some rigorous model selection criteria may provide a base for future modeling of chemical transport.

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

10.13031/2013.2136 ◽

2013 ◽

Cited By ~ 2

Author(s):

T.S. Steenhuis ◽

Y.-J. Kim ◽

J.-Y. Parlange ◽

M.S. Akhtar ◽

B.K. Richards ◽

...

Keyword(s):

Solute Transport ◽

Preferential Flow ◽

Flow Paths ◽

Preferential Flow Paths ◽

Field Soils

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The Role of Faults in Groundwater Circulation before and after Seismic Events: Insights from Tracers, Water Isotopes and Geochemistry

Water ◽

10.3390/w13111499 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1499

Author(s):

Davide Fronzi ◽

Francesco Mirabella ◽

Carlo Cardellini ◽

Stefano Caliro ◽

Stefano Palpacelli ◽

...

Keyword(s):

Preferential Flow ◽

Central Italy ◽

Tracer Tests ◽

Integrated Approach ◽

Fault System ◽

Tectonic Structures ◽

Fault Systems ◽

Isotopic Analyses ◽

Before And After

The interaction between fluids and tectonic structures such as fault systems is a much-discussed issue. Many scientific works are aimed at understanding what the role of fault systems in the displacement of deep fluids is, by investigating the interaction between the upper mantle, the lower crustal portion and the upraising of gasses carried by liquids. Many other scientific works try to explore the interaction between the recharge processes, i.e., precipitation, and the fault zones, aiming to recognize the function of the abovementioned structures and their capability to direct groundwater flow towards preferential drainage areas. Understanding the role of faults in the recharge processes of punctual and linear springs, meant as gaining streams, is a key point in hydrogeology, as it is known that faults can act either as flow barriers or as preferential flow paths. In this work an investigation of a fault system located in the Nera River catchment (Italy), based on geo-structural investigations, tracer tests, geochemical and isotopic recharge modelling, allows to identify the role of the normal fault system before and after the 2016–2017 central Italy seismic sequence (Mmax = 6.5). The outcome was achieved by an integrated approach consisting of a structural geology field work, combined with GIS-based analysis, and of a hydrogeological investigation based on artificial tracer tests and geochemical and isotopic analyses.

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Dye staining and excavation of a lateral preferential flow network

Hydrology and Earth System Sciences ◽

10.5194/hess-13-935-2009 ◽

2009 ◽

Vol 13 (6) ◽

pp. 935-944 ◽

Cited By ~ 77

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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One-dimensional numerical modelling of solute transport in streams: The role of longitudinal dispersion coefficient

Journal of Hydrology ◽

10.1016/j.jhydrol.2015.05.061 ◽

2015 ◽

Vol 527 ◽

pp. 978-989 ◽

Cited By ~ 25

Author(s):

Kamal El Kadi Abderrezzak ◽

Riadh Ata ◽

Fabrice Zaoui

Keyword(s):

Numerical Modelling ◽

Solute Transport ◽

Dispersion Coefficient ◽

Longitudinal Dispersion ◽

Longitudinal Dispersion Coefficient ◽

One Dimensional

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The Daisy agroecological system model: A physically based model for preferential water flow and solute transport in drained agricultural fields

10.5194/egusphere-egu21-14783 ◽

2021 ◽

Author(s):

Efstathios Diamantopoulos ◽

Maja Holbak ◽

Per Abrahamsen

Keyword(s):

Solute Transport ◽

Water Flow ◽

Preferential Flow ◽

Column Experiment ◽

Soil Matrix ◽

Physically Based Model ◽

Physically Based ◽

Rapid Transport ◽

Preferential Water

<p>Preferential water flow and solute transport in agricultural systems affects not only the quality of groundwater but also the quality of surface waters like streams and lakes. This is due to the rapid transport of agrochemicals, immediately after application, through subsurface drainpipes and surface water. Experimental evidence attributes this to the occurrence of continuously connected pathways, connecting the soil surface directly with the drainpipes. We developed a physically-based model describing preferential flow and transport in biopores and implemented it in the agroecological model Daisy. The model simulates the often observed rapid transport of chemicals from&#160;&#160; the upper soil layers to the drainpipes or to deeper layers of the soil matrix. Based on field investigations, biopores with specific characteristics can be parameterized as classes with different vertical and horizontal distributions. The model was tested against experimental data from a column experiment with an artificial biopore and showed good results in simulating preferential flow dynamics. We illustrate the performance of the new approach, by conducting five simulations assuming a two-dimensional simulation domain with different biopore parametrizations, from none to several different classes. The simulation results agreed with experimental observations reported in the literature, indicating rapid transport from the soil to the drainpipes. Furthermore, the different biopore parametrizations resulted in distinctly different leaching patterns, raising the expectation that biopore properties could be estimated or constrained based on observed leaching data and direct measurements.</p>

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Agricultural hillslope soil heterogeneity challenges: first experimental results from SUPREHILL critical zone observatory

10.5194/ismc2021-44 ◽

2021 ◽

Author(s):

Vedran Krevh ◽

Jasmina Defterdarović ◽

Lana Filipović ◽

Zoran Kovač ◽

Steffen Beck-Broichsitter ◽

...

Keyword(s):

Numerical Modeling ◽

Soil Moisture ◽

Solute Transport ◽

Soil Water ◽

Water Flow ◽

Preferential Flow ◽

Soil Heterogeneity ◽

Local Scale ◽

Soil Water Flow ◽

Critical Zone Observatory

<p>SUPREHILL is a new (2020) and first Croatian critical zone observatory (CZO), focused on local scale agricultural e.g., vineyard hillslope processes. The experimental setup includes an extensive sensor-based network accompanied by weighing lysimeters and instruments for surface and subsurface hydrology measurement. The field measurements are supported by novel laboratory and numerical quantification methods for the determination of water flow and solute transport. This combined approach will allow the research team to accurately determine soil water balance components (soil water flow, preferential flow/transport pathways, surface runoff, evapotranspiration), the temporal origin of water in hillslope hydrology (isotopes), transport of agrochemicals, and to calibrate and validate numerical modeling procedures for describing and predicting soil water flow and solute transport. First results from sensors indicate increased soil moisture on the hilltop, which is supported by precipitation data from rain gauges and weighing lysimeters. The presence of a compacted soil horizon and compacted inter-row parts (due to trafficking) of the vineyard seems to be highly relevant in regulating water dynamics. Wick lysimeters confirm the sensor soil moisture data, while showing a significant difference in its repetitions which suggests a possibility of a preferential flow imposed by local scale soil heterogeneity. Measured values of surface and subsurface runoff suggest a crucial role of these processes in the hillslope hydrology, while slope and structure dynamics additionally influence soil hydraulic properties. We are confident that the CZO will give us new insights in the landscape heterogeneity and substantially increase our understanding regarding preferential flow and nonlinear solute transport, with results directly applicable in agricultural (sloped agricultural soil management) and environmental (soil and water) systems. Challenges remain in characterizing local scale soil heterogeneity, dynamic properties quantification and scaling issues for which we will rely on combining CZO focused measurements and numerical modeling after substantial data is collected.</p>

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