Solute transport through fractured rock: Radial diffusion into the rock matrix with several geological layers for an arbitrary length decay chain

Mahmoudzadeh, Batoul; Liu, Longcheng; Moreno, Luis; Neretnieks, Ivars

doi:10.1016/j.jhydrol.2016.02.046

Cited by 22 publications

(6 citation statements)

References 46 publications

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“…with the material property group for the rock matrix given by (Mahmoudzadeh et al 2013(Mahmoudzadeh et al , 2016)…”

Section: Mathematical Model and Solution Proceduresmentioning

confidence: 99%

“…When matrix diffusion is also taken into consideration, the results shown in Fig. 8 suggest that matrix diffusion (Neretnieks 1980) causes strong retardation of solute transport, due to the great capacity of the porous rock in retaining the solute (Mahmoudzadeh et al 2016), and therefore it dominates eventually over hydrodynamic dispersion in determining the spreading of a tracer pulse. Radioactive decay is, on the other hand, also an important factor decisive for the late tail of the breakthrough curves (Shahkarami et al 2015); however, the general features shown in Fig.…”

Section: Comparison Of the Model Predictionsmentioning

confidence: 99%

“…1. The half-aperture b should, however, be understood as the ratio between the flow volume, FLV, and the flow-wetted-surface area, FWS, of each of the flow channels, through which matrix diffusion occurs (Mahmoudzadeh et al 2016)…”

Section: Appendix C: Characterization Of Flow Channels In Natural Framentioning

confidence: 99%

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Solute transport along a single fracture in a porous rock: a simple analytical solution and its extension for modeling velocity dispersion

et al. 2017

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A simple and robust solution is developed for the problem of solute transport along a single fracture in a porous rock. The solution is referred to as the solution to the singleflow-path model and takes the form of a convolution of two functions. The first function is the probability density function of residence-time distribution of a conservative solute in the fracture-only system as if the rock matrix is impermeable. The second function is the response of the fracture-matrix system to the input source when Fickian-type dispersion is completely neglected; thus, the effects of Fickian-type dispersion and matrix diffusion have been decoupled. It is also found that the solution can be understood in a way in line with the concept of velocity dispersion in fractured rocks. The solution is therefore extended into more general cases to also account for velocity variation between the channels. This leads to a development of the multi-channel model followed by detailed statistical descriptions of channel properties and sensitivity analysis of the model upon changes in the model key parameters. The simulation results obtained by the multi-channel model in this study fairly well agree with what is often observed in field experiments-i.e. the unchanged Peclet number with distance, which cannot be predicted by the classical advectiondispersion equation. In light of the findings from the aforementioned analysis, it is suggested that forced-gradient experiments can result in considerably different estimates of dispersivity compared to what can be found in naturalgradient systems for typical channel widths.

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“…with the material property group for the rock matrix given by (Mahmoudzadeh et al 2013(Mahmoudzadeh et al , 2016)…”

Section: Mathematical Model and Solution Proceduresmentioning

confidence: 99%

Section: Comparison Of the Model Predictionsmentioning

confidence: 99%

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Solute transport along a single fracture in a porous rock: a simple analytical solution and its extension for modeling velocity dispersion

et al. 2017

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“…The radial diffusion method was selected to apply in this study, because of its suitability for lowpermeability aquitards and its high efficiency [41][42][43]. The radial diffusion device was developed with special stainless steel, consisting of a tube, the upper cap, and the lower cap [44].…”

Section: Diffusion Testingmentioning

confidence: 99%

Cl⁻ as a Chemical Fingerprint of Solute Transport in the Aquitard-Aquifer System of the North Jiangsu Coastal Plain, China

Ge¹,

Liang²,

Jin³

et al. 2017

Geofluids

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Detailed vertical profiles of Cl− in porewaters through the aquitard-aquifer system were used to yield solute transport mechanism and build a conceptual model regarding evolution processes and transport time of natural tracer migration in North Jiangsu coastal plain, China. One-dimensional vertical simulated models of Cl − profiles illustrate that diffusion appeared to be the dominant solute transport mechanism in the aquitard-aquifer system. A downward groundwater flow did not improve the fitness between simulated and measured values. Several simulated models were constructed and suggested that the evolution of the Cl − profiles is mainly ascribed to the introduction of seawater and freshwater of transgression-regression to the first confined aquifer and the upper boundary. Groundwater in the first confined aquifer recharged by the Late Pleistocene glacial meltwater (25-15 ka BP) was supported in response to the low Cl − concentrations. The shallow groundwater in the first confined aquifer and porewater with high salt were attributable to the Holocene seawater intrusion. These timeframes were also consistent favorably with the results of previous studies into the palaeohydrology of the study area.

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“…The CNM is sometimes also referred to as pipe network. Flow equations in the CNM are locally one‐dimensional and can be solved analytically in the Laplace domain, and sometimes even in the time domain (Moreno & Neretnieks, 1993; Sharma, Dessirier, et al., 2022; Sharma, Geier, et al., 2022), while transport in the channels and interactions with the rock matrix can be modeled by particle‐tracking methods (Liu et al., 2017; Mahmoudzadeh et al., 2013, 2016; Neretnieks, 2006; Shahkarami et al., 2016), which alleviates the need for a numerical discretization of the domain and allows to focus more directly on the network structure and connectivity to reproduce field data (Dessirier et al., 2018; Li et al., 2014). Some CNM frameworks use full lattices of channels and stereological arguments to infer lattice spacing and flow‐wetted surface from observations along borehole sections (e.g., Gylling et al., 1999).…”

Section: Introductionmentioning

confidence: 99%

Channel Network Modeling of Flow and Transport in Fractured Rock at the Äspö HRL: Data‐Worth Analysis for Model Development, Calibration and Prediction

Dessirier

Sharma

Pedersen

et al. 2023

Water Resources Research

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Performance assessment of nuclear waste disposal in deep crystalline bedrock demands a thorough understanding of the related flow and transport processes. Uncertainties may arise both from the selection of the conceptual model as well as the estimation of the related model parameters. Discrete fracture network (DFN) models are widely used for such modeling while channel network models (CNM) provide an alternative representation, the latter focusing on the fact that flow and transport in deep fractured media often are dominated by a small number of long preferential flow paths. This study applies the principle of channel networks, implemented in the Pychan3d simulator, to analyze the hydraulic and tracer transport behavior in a 450‐m‐deep fractured granite system at the Äspö Hard Rock Laboratory in Sweden, where extensive site characterization data, including hydraulic and tracer test data are available. Semi‐automated calibration of channel conductances to field characterization data (flow rates, drawdowns, and tracer recoveries) is performed using PEST algorithm. It was observed that an optimal CNM connectivity map for channel conductance calibration can only be developed by jointly fitting flow rates, drawdowns and tracer mass recovery values. Results from data‐calibrated CNM when compared to a corresponding calibrated DFN model shows that the CNM calibrates and adapts better than a DFN model with uniform fracture surfaces. This comparative study shows the differences and uncertainties between two models as well as examines the implications of using them for long term model predictions.

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Solute transport through fractured rock: Radial diffusion into the rock matrix with several geological layers for an arbitrary length decay chain

Cited by 22 publications

References 46 publications

Solute transport along a single fracture in a porous rock: a simple analytical solution and its extension for modeling velocity dispersion

Solute transport along a single fracture in a porous rock: a simple analytical solution and its extension for modeling velocity dispersion

Cl⁻ as a Chemical Fingerprint of Solute Transport in the Aquitard-Aquifer System of the North Jiangsu Coastal Plain, China

Channel Network Modeling of Flow and Transport in Fractured Rock at the Äspö HRL: Data‐Worth Analysis for Model Development, Calibration and Prediction

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Solute transport through fractured rock: Radial diffusion into the rock matrix with several geological layers for an arbitrary length decay chain

Cited by 22 publications

References 46 publications

Solute transport along a single fracture in a porous rock: a simple analytical solution and its extension for modeling velocity dispersion

Solute transport along a single fracture in a porous rock: a simple analytical solution and its extension for modeling velocity dispersion

Cl− as a Chemical Fingerprint of Solute Transport in the Aquitard-Aquifer System of the North Jiangsu Coastal Plain, China

Channel Network Modeling of Flow and Transport in Fractured Rock at the Äspö HRL: Data‐Worth Analysis for Model Development, Calibration and Prediction

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Cl⁻ as a Chemical Fingerprint of Solute Transport in the Aquitard-Aquifer System of the North Jiangsu Coastal Plain, China