Modeling contaminant transport in a two-aquifer system with an intervening aquitard

Liu, Chih Tien; Yeh, Hund‐Der; Yeh, Li-Ming

doi:10.1016/j.jhydrol.2013.06.050

Cited by 10 publications

(5 citation statements)

References 20 publications

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“…The slow groundwater velocities in aquitards suggest that solute transport is dominated by vertical dispersion and molecular diffusion rather than advection (Desaulniers et al, 1981;Hendry and Wassenaar, 1999). Analytical models rarely take into account advection in aquitard systems, although Bester et al (2006) and Barbour et al (2012) considered it in numerical simulations, while Liu et al (2013) and Rezaei et al (2013) incorporated advection in semi-analytical (one-and two-dimensional, respectively) solute transport models of aquitard systems. The system studied by Bester et al (2006) was represented by the Waterloo Moraine located in the Waterloo region in southwestern Ontario, a complex of till sheets and coarse glacio-fluvial material.…”

Section: Chloride Dispersion Across Silt Deposits In a Glaciated Bedrmentioning

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: Chloride Dispersion Across Silt Deposits In a Glaciated Bedrmentioning

confidence: 99%

Chloride Dispersion across Silt Deposits in a Glaciated Bedrock River Valley

2014

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“…As a result, the assumptions included in the "averaged approximation" models might be invalid for solute transport in the aquifer-aquitard system (Wang and Zhan, 2013). Then, the "averaged approximation" models have been extended by including the advective effect in the aquitard, such as Tang and Aral (1992); Zhan et al (2009a); Zhan et al (2009b); Liu et al (2013); Rezaei et al (2013); Wang and Zhan (2013); and Rezaei et al (2016). Rezaei et al (2016) considered two-dimensional (2D) dispersion and 1D advection in both aquifer and aquitard.…”

Section: Introductionmentioning

confidence: 99%

“…However, the currently published analytical models contain an assumption that the source concentration was treated as a constant (Liu et al, 2013;Rezaei et al, 2016) or a temporaldependent variable which exponentially changes with time (Fujikawa and Fukui, 1990;Starr et al, 1985;Tang and Aral, 1992). Actually, such treatment could not be used to describe the variation of the source concentration in the laboratory-controlled experiments.…”

Section: Introductionmentioning

confidence: 99%

A Novel Analytical Model of Solute Transport in an Aquifer-Aquitard System with Mixing Processes in the Reservoirs

Shi

Wang

2022

Preprint

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Analytical models have been widely used to aid understanding the physical and chemical processes of tracer (or chemicals) in an aquifer-aquitard system in the laboratory-controlled experiment, when the observation data is few or not available during the experiment. When injecting tracer into (or extracting them from) the aquifer-aquitard system during experiments, the pre-inlet and after-outlet reservoirs are indispensable. However, the concentration variation in the reservoirs was not treated properly in previous analytical models, resulting in poor performance in interpreting experimental data. In this study, new mathematical models describing the concentration variation in the pre-inlet and the after-outlet reservoirs are proposed, and they are integrated into the novel analytical model. The novel analytical model is developed under the mobile-immobile (MIM) framework in the aquifer-aquitard system, considering the longitudinal and vertical dispersion, the advection, and the first-order chemical reaction in both aquifer and aquitard. A finite-difference solution is developed and the experimental data are employed to test the new analytical model. Results indicate that the concentration variation in the reservoirs is important to solute transport in the aquifer-aquitard system in the laboratory-controlled experiment, and the new analytical model outperforms the previous models in interpreting experimental data. The global sensitivity analysis demonstrates that the output concentration of solute transport in the aquifer-aquitard system is most sensitive to the volume of water in the pre-inlet reservoir. The contribution of the diffusion effect to the total mass flux of tracer crossing the aquifer-aquitard interface is much smaller than the contribution of the dispersive and advective effects.

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“…This is because ADE becomes a hyperbolic equation from the parabolic equation when advection is dominating. Chen [10][11], Chen et al [12], Chen et al [13], and Liu et al [14] introduced the Crump technique [15] for the inverse Laplace transform. This method employed the epsilon algorithm to calculate the real part of the complex Fourier series when conducting the integral of the inverse Laplace transform.…”

Section: Introductionmentioning

confidence: 99%