Modeling preferential water flow and solute transport in unsaturated soil using the active region model

Feng, Shaokong; Wang, Kang; Zhang, Renduo; Liu, Hui‐Hai

doi:10.1007/s12665-010-0633-0

Cited by 15 publications

(6 citation statements)

References 35 publications

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“…They did not report NSE; however, they indicated that the model was considered acceptable for NSE ≥ 0.15. Sheng et al (2011) used Cl − as a tracer to evaluate solute transport in unsaturated soil. The two models developed had NSE values of 0.30 and 0.83.…”

Section: Calibrated Source Concentrationmentioning

confidence: 99%

Chloride Dispersion across Silt Deposits in a Glaciated Bedrock River Valley

2014

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Soil and groundwater from the Neponset River floodplain deposit that receive high concentrations of deicing agents from nearby highways were investigated. The silty sand floodplain is separated by a silty aquitard from the underlying aquifer that serves as a public water supply. We made a transport-based assessment of the capacity of the aquitard to protect the underlying aquifer. One hundred seventeen soil samples and 469 groundwater samples collected during a period of 4 yr from boreholes and 10 wells grouped in two well clusters were analyzed for dissolved Cl concentration. The soil characterization and groundwater monitoring results agreed, showing a very slow change in subsurface Cl contamination with time. These data also calibrated a vertical one-dimensional advective-dispersive transport model across the deposits. Advective transport dominated only in the top 3.37 m of the floodplain deposit, with dispersion being the main transport mechanism below this depth. Due to the silty nature of the aquitard, dispersion rather than diffusion was the main transport mechanism into the floodplain-aquitard system. Soil and groundwater quality data confirmed a Cl concentration at the floodplain surface near the highway runoff drainage outlets of 2450 mg L. The model estimated a vertical dispersivity at the site of 8 mm and a vertical hydrodynamic dispersion coefficient of 3.71 × 10 m s. These data confirmed the aquitard's capacity to contain deicing agents, protecting the underlying aquifer from contamination.

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Section: Calibrated Source Concentrationmentioning

confidence: 99%

Chloride Dispersion across Silt Deposits in a Glaciated Bedrock River Valley

2014

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“…Moreover, the active region model assumes that preferential flow and transport only takes place in a part of the subsurface, the active region, whose fraction increases with the saturation (Liu et al, 2005;Sheng et al, 2011). Considering flow and pesticide transport modeling in structured soil Köhne et al (2009a; concluded that dual-continua approaches are the most widespread.…”

Section: Transport Equationsmentioning

confidence: 99%

Water Transport, Retention, and Survival ofEscherichia coliin Unsaturated Porous Media: A Comprehensive Review of Processes, Models, and Factors

Engström

Thunvik

Kulabako

et al. 2014

Critical Reviews in Environmental Science and Technology

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The vadose zone can function as both a filter and a passage for bacteria. This review evaluates when and why either effect will apply based on available literature. It summarizes theories and experimental research that address the related, underlying bacterial attenuation processes, the applied macro-scale modeling approaches, and the influencing factors -including the cell, soil, solution and system characteristics. Results point to that the relative importance of each removal mechanism depends on the moisture content and the solution ionic strength. The limitations of available modeling approaches are discussed. It remains unclear in which contexts these are reliable for predictions. The temporal first-order kinetic Escherichia coli ( E. coli) removal coefficient ranges three orders of magnitude, from 10 −4 to 10 −1 /min. Results suggest that this rate depends on the pore-water velocity. Spatial filtration of E. coli increases with slower flow and higher collector surface heterogeneity. It could be insignificant in the case of heavy and sudden infiltration and subsequent transport in preferential flow paths, induced, for example, by plant roots or cracks in clayey soils. Future research 2 E. Engström et al. thus needs to address transport as an effect of extreme weather events such as droughts and subsequent floods.

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“…Preferential flow, without conforming to Darcy's flow, is well recognized as a potentially important mechanism in soils [1][2][3]. This kind of flow can increase the leaching potential of soils and limit the storage, filter, and buffer functions of soils, and associate with a large number of inaccuracies in water and solute transport predictions [4][5][6][7][8][9][10]. Continuous root channels can generate preferential flow paths, and promote movement of water and solutes with little resistance [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Influence of Root Distribution on Preferential Flow in Deciduous and Coniferous Forest Soils

Luo

Niu

Xie

et al. 2019

Forests

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Root-induced channels are the primary controlling factors for rapid movement of water and solute in forest soils. To explore the effects of root distribution on preferential flow during rainfall events, deciduous (Quercus variabilis BI.) and coniferous forest (Platycladus orientalis (L.) Franco) sites were selected to conduct dual-tracer experiments (Brilliant Blue FCF and Bromide [Br−]). Each plot (1.30 × 1.30 m) was divided into two subplots (0.65 × 1.30 m), and two rainfall simulations (40 mm, large rainfall and 70 mm, extreme rainfall) were conducted in these. Vertical soil profiles (1.00 m × 0.40 m) were excavated, and preferential flow path features were quantified based on digital image analysis. Root (fine and coarse) abundance and Br− concentration were investigated for each soil profile. In deciduous forest, accumulated roots in the upper soil layer induce larger lateral preferential flow as compared to the coniferous forest soil during large rainfall events. Compared with deciduous forest, coniferous forest soil, with higher (horizontal and vertical) spatial variability of preferential flow paths, promotes higher percolation and solute leaching to deeper soil layers during extreme rainfall events. Fine roots, accounting for a larger proportion of total roots (compared to coarse roots), facilitate preferential flow in the 0–40 cm forest soil layer. Overall, our results indicate that the root distribution pattern of different tree species can exert diverse effects on preferential flow in forest soils.

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Modeling preferential water flow and solute transport in unsaturated soil using the active region model

Cited by 15 publications

References 35 publications

Chloride Dispersion across Silt Deposits in a Glaciated Bedrock River Valley

Chloride Dispersion across Silt Deposits in a Glaciated Bedrock River Valley

Water Transport, Retention, and Survival ofEscherichia coliin Unsaturated Porous Media: A Comprehensive Review of Processes, Models, and Factors

Influence of Root Distribution on Preferential Flow in Deciduous and Coniferous Forest Soils

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