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Comparative Study of Analytical Solutions for Time-Dependent Solute Transport Along Unsteady Groundwater Flow in Semi-infinite Aquifer  [PDF]
Mritunjay Kumar Singh, Nav Kumar Mahato, Priyanka Kumar
International Journal of Geosciences (IJG) , 2011, DOI: 10.4236/ijg.2011.24048
Abstract: A comparative study is made among Laplace Transform Technique (LTT) and Fourier Transform Technique (FTT) to obtain one-dimensional analytical solution for conservative solute transport along unsteady groundwater flow in semi-infinite aquifer. The time-dependent source of contaminant concentration is considered at the origin and at the other end of the aquifer is supposed to be zero. Initially, aquifer is not solute free which means that the solute concentration exits in groundwater system and it is assumed as a uniform concentration. The aquifer is considered homogeneous and semi-infinite. The time-dependent velocity expressions are considered. The result may be used as preliminary predictive tools in groundwater management and benchmark the numerical code and solutions.
On stochastic modeling of groundwater flow and solute transport in multi-scale heterogeneous formations
Hu, Bill X.;Wu, Jichun;He, Changming;
Computational & Applied Mathematics , 2004,
Abstract: a numerical moment method (nmm) is applied to study groundwater flow and solute transport in a multiple-scale heterogeneous formation. the formation is composed of various materials and conductivity distribution within each material is heterogeneous. the distribution of materials in the study domain is characterized by an indicator function and the conductivity field within each material is assumed to be statistically stationary. based on this assumption, a general expression is derived for the covariance function of the composite field in terms of the covariance of the indicator variables and the statistical properties of the composite materials. the nmm is used to investigate the effects of various uncertain parameters on flow and transport predictions in two case studies. it is shown from the study results that the two-scale stochastic processes of heterogeneity will both significantly influence the flow and transport predictions, especially for the variances of hydraulic head and solute fluxes. this study also shows that the nmm can be used to study flow and transport in complex subsurface environments. therefore, the method may be applicable to complex environmental projects.
On stochastic modeling of groundwater flow and solute transport in multi-scale heterogeneous formations  [cached]
Bill X. Hu,Jichun Wu,Changming He
Computational and Applied Mathematics , 2004,
Abstract: A numerical moment method (NMM) is applied to study groundwater flow and solute transport in a multiple-scale heterogeneous formation. The formation is composed of various materials and conductivity distribution within each material is heterogeneous. The distribution of materials in the study domain is characterized by an indicator function and the conductivity field within each material is assumed to be statistically stationary. Based on this assumption, a general expression is derived for the covariance function of the composite field in terms of the covariance of the indicator variables and the statistical properties of the composite materials. The NMM is used to investigate the effects of various uncertain parameters on flow and transport predictions in two case studies. It is shown from the study results that the two-scale stochastic processes of heterogeneity will both significantly influence the flow and transport predictions, especially for the variances of hydraulic head and solute fluxes. This study also shows that the NMM can be used to study flow and transport in complex subsurface environments. Therefore, the method may be applicable to complex environmental projects.
Solute transport dynamics in small, shallow groundwater-dominated agricultural catchments: insights from a high-frequency, multisolute 10 yr-long monitoring study
A. H. Aubert, C. Gascuel-Odoux, G. Gruau, N. Akkal, M. Faucheux, Y. Fauvel, C. Grimaldi, Y. Hamon, A. Jaffrézic, M. Lecoz-Boutnik, J. Molénat, P. Petitjean, L. Ruiz,P. Merot
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2013,
Abstract: High-frequency, long-term and multisolute measurements are required to assess the impact of human pressures on water quality due to (i) the high temporal and spatial variability of climate and human activity and (ii) the fact that chemical solutes combine short- and long-term dynamics. Such data series are scarce. This study, based on an original and unpublished time series from the Kervidy-Naizin headwater catchment (Brittany, France), aims to determine solute transfer processes and dynamics that characterise this strongly human-impacted catchment. The Kervidy-Naizin catchment is a temperate, intensive agricultural catchment, hydrologically controlled by shallow groundwater. Over 10 yr, five solutes (nitrate, sulphate, chloride, and dissolved organic and inorganic carbon) were monitored daily at the catchment outlet and roughly every four months in the shallow groundwater. The concentrations of all five solutes showed seasonal variations but the patterns of the variations differed from one solute to another. Nitrate and chloride exhibit rather smooth variations. In contrast, sulphate as well as organic and inorganic carbon is dominated by flood flushes. The observed nitrate and chloride patterns are typical of an intensive agricultural catchment hydrologically controlled by shallow groundwater. Nitrate and chloride originating mainly from organic fertilisers accumulated over several years in the shallow groundwater. They are seasonally exported when upland groundwater connects with the stream during the wet season. Conversely, sulphate as well as organic and inorganic carbon patterns are not specific to agricultural catchments. These solutes do not come from fertilisers and do not accumulate in soil or shallow groundwater; instead, they are biogeochemically produced in the catchment. The results allowed development of a generic classification system based on the specific temporal patterns and source locations of each solute. It also considers the stocking period and the dominant process that limits transport to the stream, i.e. the connectivity of the stocking compartment. This mechanistic classification can be applied to any chemical solute to help assess its origin, storage or production location and transfer mechanism in similar catchments.
Numerical solution of steady-state groundwater flow and solute transport problems: Discontinuous Galerkin based methods compared to the Streamline Diffusion approach  [PDF]
A. Q. T. Ngo,P. Bastian,O. Ippisch
Computer Science , 2014,
Abstract: In this study, we consider the simulation of subsurface flow and solute transport processes in the stationary limit. In the convection-dominant case, the numerical solution of the transport problem may exhibit non-physical diffusion and under- and overshoots. For an interior penalty discontinuous Galerkin (DG) discretization, we present a $h$-adaptive refinement strategy and, alternatively, a new efficient approach for reducing numerical under- and overshoots using a diffusive $L^2$-projection. Furthermore, we illustrate an efficient way of solving the linear system arising from the DG discretization. In $2$-D and $3$-D examples, we compare the DG-based methods to the streamline diffusion approach with respect to computing time and their ability to resolve steep fronts.
Solute transport modeling application in groundwater organic contaminant source identification
溶质迁移模型在地下水有机污染源识别中的应用

Wang Shu-Fang,Wang Li-Ya,Wang Xiao-Hong,Lin Pei,Liu Jiu-Rong,Xin Bao-Dong,He Guo-Ping,
Wang SF
,Wang LY,Wang XH,Lin P,Liu JR,Xin BD,He GP

环境科学 , 2012,
Abstract: Investigation and numerical simulation, based on RT3D (reactive transport in 3-dimensions)were used to identify the source of tetrachloroethylene (PCE) and trichloroethylene (TCE) in the groundwater of a city in the north of China and reverse the input intensity. Multiple regressions were applied to analyze the influenced factors of input intensity of PCE and TCE using Stepwise function in Matlab. The results indicate that the factories and industries are the source of the PCE and TCE in groundwater. Natural attenuation was identified and the natural attenuation rates are 93.15%, 61.70% and 61.00% for PCE, and 70.05%, 73.66% and 63.66% for TCE in 173 days. The 4 source points identified by the simulation have released 0.910 6 kg PCE and 95.693 8 kg TCE during the simulation period. The regression analysis results indicate that local precipitation and the thickness of vadose zone are the main factors influencing organic solution transporting from surface to groundwater. The PCE and TCE concentration are found to be 0 and 5 mg x kg(-1) from surface to 35 cm in vadose zone. All above results suggest that PCE and TCE in groundwater are from the source in the surface. Natural attenuation occurred when PCE and TCE transporting from the surface to groundwater, and the rest was transported to groundwater through vadose zone. Local precipitation was one of the critical factors influencing the transportation of PCE and TCE to aquifer through sand, pebble and gravel of the Quaternary.
Microforces and the Theory of Solute Transport  [PDF]
Eliot Fried,Shaun Sellers
Physics , 1999,
Abstract: A generalized continuum framework for the theory of solute transport in fluids is proposed and systematically developed. This framework rests on the introduction of a generic force balance for the solute, a balance distinct from the macroscopic momentum balance associated with the mixture. Special forms of such a force balance have been proposed and used going back at least as far as Nernst's 1888 theory of diffusion. Under certain circumstances, this force balance yields a Fickian constitutive relation for the diffusive solute flux, and, in conjunction with the solute mass balance, provides a generalized Smoluchowski equation for the mass fraction. Our format furnishes a systematic procedure for generalizing convection-diffusion models of solute transport, allowing for constitutive nonlinearities, external forces acting on the diffusing constituents, and coupling between convection and diffusion.
Solute transport in a heterogeneous aquifer: a search for nonlinear deterministic dynamics  [PDF]
B. Sivakumar,T. Harter,H. Zhang
Nonlinear Processes in Geophysics (NPG) , 2005,
Abstract: The potential use of a nonlinear deterministic framework for understanding the dynamic nature of solute transport processes in subsurface formations is investigated. Time series of solute particle transport in a heterogeneous aquifer medium, simulated using an integrated probability/Markov chain (TP/MC) model, groundwater flow model, and particle transport model, are studied. The correlation dimension method, a popular nonlinear time series analysis technique, is used to identify nonlinear determinism. Sensitivity of the solute transport dynamics to the four hydrostratigraphic parameters involved in the TP/MC model: (1) number of facies; (2) volume proportions of facies; (3) mean lengths (and thereby anisotropy ratio of mean length) of facies; and (4) juxtapositional tendencies (i.e. degree of entropy) among the facies is also studied. The western San Joaquin Valley aquifer system in California is considered as a reference system. The results indicate, in general, the nonlinear deterministic nature of solute transport dynamics (dominantly governed by only a very few variables, on the order of 3), even though more complex behavior is possible under certain (extreme) hydrostratigraphic conditions. The sensitivity analysis reveals: (1) the importance of the hydrostratigraphic parameters (in particular, volume proportions of facies and mean lengths) in representing aquifer heterogeneity; and (2) the ability of the correlation dimension method in capturing the (extent of) complexity of the underlying dynamics. Verification and confirmation of the present results through use of other nonlinear deterministic techniques and assessment of their reliability for a wide range of solute transport scenarios are recommended.
Solute transport in a coupled fracture-matrix system with sinusoidal fracture geometry
N.Natarajan,,G. Suresh Kumar
International Journal of Engineering Science and Technology , 2010,
Abstract: Modeling of fluid flow and solute transport through fractured rock is an important component of engineering analysis in many disciplines including groundwater contamination, nuclear waste disposal, petroleum and gas production, mine excavation and geothermal production. Several studies have been conducted on single rock fracture using parallel plate model. An attempt has been made to simulate solute transport in sinusoidal fracture-matrix coupled systemnumerically. Results suggest that the spatial variation of the fracture aperture along the fracture affects the flux transfer at the fracture-matrix interface. The sinusoidal fracture geometry increases the residence time of the solutes.
Effect of linear sorption on solute transport in a coupled fracture-matrix system with sinusoidal fracture geometry  [PDF]
N.Natarajan
Iranica Journal of Energy and Environment (IJEE) , 2010,
Abstract: Modeling of solute transport through fractured rock is an important component of in many disciplines especially groundwater contamination and nuclear waste disposal. Several studies have been conducted on single rock fracture using parallel plate model and recently solute and thermal transport has been numerically modeled in the sinusoidal fracture matrix coupled system. The effect of linear sorption has been studied on the same. Results suggest the high matrix porosity and matrix diffusion coefficient enhance the sorption process and reduce the matrix diffusion of solutes. The velocity of the fluid reduces with increment in fracture aperture.
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