Download or read book Tools and Analysis of Spatio temporal Dynamics in Heterogeneous Aquifers Applications to Artificial Recharge and Forced gradient Solute Transport written by Daniele Pedretti and published by . This book was released on 2013 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis deals with the development of tools and analysis to characterize and predict artificial recharge and radial convergent solute transport processes in heterogeneous media. The goal is to provide new insights to understand how heterogeneity, which is the main natural source of uncertainty in decision-making processes related with groundwater applications, can be controlled and its effects predicted for practical purposes in these topics. For hydrogeological applications, accurate modeling of phenomena is needed, but it is uncertain. Uncertainty is derived from the spatio-temporal random distribution of hydrodynamic (physical, chemical and biological) variables affecting groundwater processes, which is translated into random distribution of modeling parameters and equations. Such randomness is of two types: epistemic, when it can be reduced increasing the sample frequency of an experiment; aleatory, when it cannot be reduced when more information is analyzed. Sometimes hydrodynamic processes occur at so small scales that they become impossible to characterize with traditional methods, and from a practical perspective, this is analogous to deal with aleatoric model parameters. However, if some constitutive relationship (either empirically, theoretically or physically based) can be built between processes across different scales, then small-scale processes can be reproduced by equivalent large-scale model parameters. Uncertainty becomes amenable to be treated as epistemic randomness, and large-scale characterization techniques can be used to improve the description, interpretation or prediction of these processes. This thesis deals with these topics. The manuscript is composed by two main parts (the first on artificial recharge and the second on solute transport), each of them divided into three chapters. In chapter 1 of each part, a tool is developed to obtain quantitative information to model a selected variable at coarse grid resolutions. In the case of artificial recharge, satellite images are used to model the spatial variability of the infiltration capacity on top soils with a metric-scale detail. In the case of solute transport, a new method to estimate density from particle distribution is shown. In chapters 2, it is explored what processes occurring at the fine scales can affect the interpretation of artificial recharge and solute transport processes at larger scales. In the first part, a combined method that joins satellite images and field data along with a simple clogging model is used to display the equally-possible spatio-temporal mapping of the infiltration capacity of topsoil during artificial pond flooding activities. In the second part, numerical three-dimensional models are used to simulate transport in heterogeneous media under convergent radial flow to a well at fine scale. It is shown that an appropriate model framework can reproduce similar observations on contaminant temporal distribution at controlling section similar to those obtained in the field tracer tests. It is also provided a physical explanation to describe the so-called anomalous late-time behavior on breakthrough curves which is sometimes observed in the reality at larger scales. In the chapters 3, models are used to define the uncertainty around operating parameters in the optic of prediction and management on artificial recharge and solute transport. In the first case, a probability framework is built to define the engineering risk of management of artificial recharge ponds due to random variability of the initial distribution of infiltration, which controls several important clogging factors based on theoretical approaches. In the case of solute transport, it is discussed how equivalent parameters based on mass-transfer models can be related with the geometrical distribution of hydraulic parameters in anisotropic formation, when convergent flow tracer tests are used.

Download or read book Stochastic Analysis of Solute Transport in Heterogeneous Aquifers Subject to Random Recharge and Contaminant Source Fields written by Liyong Li and published by . This book was released on 1998 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Introduction to Solute Transport in Heterogeneous Geologic Media written by Tian-Chyi Jim Yeh and published by Cambridge University Press. This book was released on 2023-02-28 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a unified and comprehensive overview of physical explanations of the stochastic concepts of solute transport processes, important scaling issues, and practical tools for the analysis of solute transport.

Download or read book Flow and Transport in Porous Formations written by Gedeon Dagan and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the mid-seventies, a new area of research has emerged in subsurface hydrology, namely sto chastic modeling of flow and transport. This development has been motivated by the recognition of the ubiquitous presence of heterogeneities in natural formations and of their effect upon transport and flow, on the one hand, and by the vast expansion of computational capability provided by elec tronic machines, on the other. Apart from this, one of the areas in which spatial variability of for mation properties plays a cardinal role is of contaminant transport, a subject of growing interest and concern. I have been quite fortunate to be engaged in research in this area from its inception and to wit ness the rapid growth of the community and of the literature on spatial variability and its impact upon subsurface hydrology. In view of this increasing interest, I decided a few years ago that it would be useful to present the subject in a systematic and comprehensive manner in order to help those who wish to engage themselves in research or application of this new field. I viewed as my primary task to analyze the large scale heterogeneity of aquifers and its effect, presuming that the reader already possesses a background in traditional hydrology. This is achieved in Parts 3, 4 and 5 of the text which incorporate the pertinent material.

Download or read book Applied Flow and Solute Transport Modeling in Aquifers written by Vedat Batu and published by CRC Press. This book was released on 2005-07-12 with total page 698 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over recent years, important contributions on the topic of solving various aquifer problems have been presented in numerous papers and reports. The scattered and wide-ranging nature of this information has made finding solutions and best practices difficult. Comprehensive and self-contained, Applied Flow and Solute Transport Modeling in Aquifers co

Download or read book Development of experimental monitoring and mathematical methods to quantify water fluxes and transport in heterogeneous aquifer system models written by Marko Hünniger and published by Cuvillier Verlag. This book was released on 2011-08-04 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present study provides experimental and mathematical methods for the understanding and quantification of the water fluxes and solute transport in heterogeneous layered porous groundwater systems characterised by differences in hydraulic conductivities. On the one hand, multi-layered porous groundwater systems with different hydraulic conductivities are characterised by a heterogeneous flow field, which causes a heterogeneous mass transport. On the other hand, extreme differences in hydraulic conductivities create regions of immobile water which influence the mass transport. These two different structural heterogeneities – variable hydraulic conductivities and immobile/stagnant water zones – were investigated experimentally in different laboratory aquifer models. The influence of immobile and stagnant water zones on mass transport was investigated with multi-tracer tests using tracers with different diffusion properties, namely; uranine, bromide, deuterium, oxygen-18 as well as tritium-labelled water, in two-dimensional packed sediment column setups. Two separate column setups were filled. One column setup was filled with clay and sandy material while a second was filled with two different sand sediments. The observed tracer concentration breakthrough curves showed differences in peak concentrations and pronounced tails. Qualitative evaluation of tracer concentration curves led to the assumption that these effects were caused by a diffusive exchange of tracers between immobile and stagnant water regions. The measured data was modelled for the first time in porous media using the Single-Fissure Dispersion Model (SFDM). This model, which was developed for fissured aquifers, yielded a very good fit with all of the tracer concentration curves observed. Further quantitative evaluation of the system parameters (porosities of both materials, diameter of the water¬-bearing layer) in columns consisting of clay and sandy materials produced values that closely matched those independently known. This agreement of parameters confirmed that the model was valid for the heterogeneous systems tested. The model was able to calibrate the tracer curves and to estimate the parameters for the main water-bearing layer for the column consisting of two sandy materials with different hydraulic conductivities. The exchange into the bordering stagnant water occurred via both diffusion and an additional local transport by focusing the flow field into the more conductive material. Thus, in cases where the two materials have rather similar properties, the quantitative evaluation of the parameters of the less permeable layer is only possible when the porosity of that layer is known independently. Both types of experiments with a heterogeneous porous material showed that in groundwater sediments consisting of layers with different hydraulic conductivities the majority of mass is transported in the more conductive layer. The application of the SFDM in porous systems clearly proved that diffusive exchange into regions of immobile or stagnant water is an extremely important factor which has to be quantified. The study clearly demonstrated that multi-tracer experiments modelled with the SFDM are a very useful tool for solving the inverse problem, i.e. for quantifying parameters in such a heterogeneous porous medium. The influence of the local hydraulic conductivity differences on the flow field and mass transport was additionally experimentally investigated in a multi-layered large-scale indoor aquifer model (480 cm x 80 cm x 70 cm). A hydraulically more conductive layer caused a heterogeneous flow field which was traced by an instantaneous injection of uranine, bromide and tritium labelled water. Tracer observations performed in 2-D (vertical) at a high spatial and temporal resolution resulted in single tracer concentration curves. The tracer concentration curves clearly showed that multi-flow-path effects dominated. It was found that these can be adequately analysed using the Multi-Flow Dispersion Model (MFDM). The qualitative analyses showed that the more conductive sediment layer first focused the flow field, and that the water flux split into three different flow paths after leaving the focusing layer, as to be expected. The quantitative evaluation with the MFDM yielded the parameters of these flow paths. The volumetric water fluxes for flow paths with velocities of 2.7 m/d, 1.9 m/d and 1.3 m/d were estimated to be 55 %, 26 % and 19 % of the total water flux, respectively. It was also found that these flow paths were observed only over very short flow distances. After 2.5 m, all water fluxes characterised by different water velocities joined into one water flux which exhibited the mean water velocity but also showed higher dispersivity. This finding is extremely important for the further evaluation of pollutant migration and biodegradation. The present study clearly demonstrated that even in complex groundwater systems with a variety of structural heterogeneities the determination and quantification of different flow paths, and/or mobile and immobile water zones is possible by performing multi-tracer experiments using tracers with different diffusion properties, combined with an adequate modelling approach.

Download or read book Spatio temporal Analysis of Aquifer Recharge and Groundwater Potentiometric Levels in the Basin of Mexico Through the Development of a Regional Database and an Open Source Tool for Groundwater Flow Modelling written by Jaime Jesús Carrera-Hernández and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stochastic Methods for Modeling the Transport of Kinetically Sorbing Solutes in Heterogeneous Groundwater Aquifers written by Alison Elaine Lawrence and published by . This book was released on 2004 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Dual domain Mass Transfer Approach for Modeling Solute Transport in Heterogeneous Aquifers written by C. Erin Feehley and published by . This book was released on 1999 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical Controls on Water Flow and Solute Transport in Coastal Aquifers written by Xiaolong Geng and published by . This book was released on 2014 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Groundwater flow and associated subsurface solute fates have a significant impact on the structure and productivity of near-shore coastal ecosystems. For proper assessment and management of these coastal groundwater resources, it is quite essential to investigate the key factors (tides, waves, evaporation, and freshwater recharge etc.) affecting coastal groundwater systems. The main objective of this study is to examine and quantify two important physical control factors, oceanic waves and evaporation, on the groundwater flow and solute transport in near-shore aquifers. For the investigation of wave effects, a Computational Fluid Dynamics (CFD) modeling tool, Fluent, is used to simulate wave- induced sea level oscillations. A flow-averaged approach is developed to generalize wave motions acting onto the beach for the sake of the feasibility of numerical computation. A two-dimensional numerical model MA RU N is used to simulate variably saturated, variable density groundwater flow and subsurface solute transport in coastal aquifers. To investigate evaporation effects, a classic bulk aerodynamic formulation is adopted as a module to the model MARUN for simulating groundwater flow and subsurface solute transport in bare saline soils subjected to transient evaporation. The simulation results reveal that these two factors significantly impact beach hydrodynamics. Wave forcing induces pore water circulations in the swash zone of the near-shore aquifers; wave forcing also modifies the pathways of solute transport in the beach prior to discharge into the ocean, and subsequently impacts plume's residence time, migration speed, discharge location, and discharge rate. The evaporation decreases the moisture at shallow layer of the beach and subsequently impacts the subsurface salinity distribution.

Download or read book Solutions Manual Applied Flow and Solute Transport Modeling in Aquifers written by Batu Vedat and published by CRC Press. This book was released on 2005-06 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solute Transport in Spatially Heterogeneous Aquifers written by Charles F. Harvey and published by . This book was released on 1996 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Solute Transport Model for Analysis and Prediction of Artificial Recharge to a Glacial Aquifer written by Girish V. Reddy and published by . This book was released on 1994 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Large scale Dispersive Transport in Aquifers written by Stephen P. Garabedian and published by . This book was released on 1988 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large-scale natural-gradient tracer test was conducted to examine the transport of reactive and nonreactive tracers in a sand and gravel aquifer on Cape Cod, Massachusetts. The movement and spreading of bromide, a nonreactive tracer, and lithium, a reactive tracer, were monitored over time using a three-dimensional sampling network and analyzed using spatial moments. Calculated total mass of bromide for each sampling date varied between 86 to 105 percent of the total injected mass. The lack of any trend in the calculated mass over time confirms conservative transport of the bromide ion. The horizontal displacement of the bromide center of mass followed a predicted velocity of 0.43 meters per day. During the early part of the test the bromide cloud sank rapidly due to the density difference between the native ground water and the bromide cloud. The bromide cloud moved more slowly downward during the later part of the test due to the accretion of recharge. A nonlinear trend in the bromide longitudinal variance with travel distance was observed during the first 40 meters of distance traveled, indicating the dispersion process was non-Fickian in the early part of the test. After 40 meters the longitudinal variance followed a linear trend, apparently reaching a Fickian limit. The longitudinal dispersivity, given by one-half the change in variance with travel distance, is about 0.96 meters. Transverse horizontal dispersivity is much smaller, about 1.8 centimeters, and transverse vertical dispersivity is even smaller, about 0.15 centimeters. The distribution and movement of the reactive solute, lithium, was strongly affected by adsorption to the aquifer sediments. The mass of lithium in solution showed a large decrease during the first 300 days of transport until about 10 percent of the injected mass remained in solution. The velocity of the lithium in solution was initially the same as bromide velocity (0.43 m/d) and then decreased to about 0.05 m/d after 300 days. The distribution coefficient for the lithium adsorption was estimated to be about 2.0 mL/g for the later part of the test. The change in longitudinal variance for lithium showed a strong nonlinear trend, concave upward, which in the later part of the test indicated a dispersivity ten times larger than that for bromide. In contrast, the values of the transverse horizontal and vertical dispersivities did not differ greatly from those for bromide. A theoretical analysis of reactive solute macrodispersion was developed to explain, in part, the enhanced spreading of reactive solutes relative to nonreactive solutes. The approach used in this analysis was to postulate correlations between hydraulic conductivity and both porosity and the distribution coefficient. Using a spectral analysis method it was found that longitudinal dispersivity can be significantly increased by a negative correlation of hydraulic conductivity to porosity and the distribution coefficient. It was also found that the effective retardation coefficient is the arithmetic mean. Although the theoretical analysis provides an explanation of the enhanced longitudinal mixing for lithium, the enhanced spreading of lithium could also be caused by a kinetically controlled reaction.

Download or read book A Stochastic Model of Reactive Solute Transport in a Heterogeneous Aquifer written by Zbigniew Jan Kabala and published by . This book was released on 1990* with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reactive Solute Transport in a Physically and Chemically Heterogeneous Aquifer written by Jesper Skovdahl Christiansen and published by . This book was released on 2000 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Concentration Variability in Transport in Heterogeneous Aquifers written by Efstratios George Vomvoris and published by . This book was released on 1987 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: