Download or read book Nonlinear Model Reduction for Groundwater Flow and Solute Transport written by zachary p stanko and published by . This book was released on 2019 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Groundwater flow and solute transport models are necessary for understanding the quantity and quality of water in the subsurface. As these models get increasingly complex, their computational runtimes often increase. Reduced models can be developed to approximate the full complex model with reasonable accuracy and shorter runtimes. In this research, proper orthogonal decomposition (POD) is used to identify a lower dimensional subspace that captures most of the information contained in the full model system. Then, because of the nonlinearities present in many flow and transport models, a discrete empirical interpolation method (DEIM) is used to identify an additional lower dimensional subspace that captures the nonlinear dynamics. The reduced modeling framework is implemented within the MODFLOW and MT3DMS software families for groundwater flow and solute transport, respectively. The combined POD-DEIM approach is first applied to an unconfined groundwater flow model where dimensions were reduced by two and three orders of magnitude. The same approach is then applied to a solute transport model simulating nonlinear sorption where dimensions were also reduced by two and three orders of magnitude. The reduced models performed with sufficient accuracy and faster runtimes. The faster runtimes could allow for the reduced models to be embedded into an optimization or uncertainty analysis where thousands to millions of model runs could be required. With the developed POD-DEIM approach, reduced modeling is now viable for any existing MODFLOW or MT3DMS model.

Download or read book Analytical Modeling of Solute Transport in Groundwater written by Mark Goltz and published by John Wiley & Sons. This book was released on 2017-02-28 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Teaches, using simple analytical models how physical, chemical, and biological processes in the subsurface affect contaminant transport Uses simple analytical models to demonstrate the impact of subsurface processes on the fate and transport of groundwater contaminants Includes downloadable modeling tool that provides easily understood graphical output for over thirty models Modeling tool and book are integrated to facilitate reader understanding Collects analytical solutions from many sources into a single volume and, for the interested reader, shows how these solutions are derived from the governing model equations

Download or read book A Practical Guide to Groundwater and Solute Transport Modeling written by Karlheinz Spitz and published by Wiley-Interscience. This book was released on 1996-04-12 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Focusing on modeling applications, this outstanding reference provides a step-by-step, non-mathematical approach to constructing and using realistic workable groundwater models on a daily basis. Extensive detailed drawings, case studies, practical examples, and sample models illustrate important concepts. Includes data on hydrogeologic features and pollutants plus a glossary of terms.

Download or read book Solute Transport Modelling written by Randolf Rausch and published by . This book was released on 2005 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling Groundwater Flow and Contaminant Transport written by Jacob Bear and published by Springer Science & Business Media. This book was released on 2010-01-18 with total page 851 pages. Available in PDF, EPUB and Kindle. Book excerpt: In many parts of the world, groundwater resources are under increasing threat from growing demands, wasteful use, and contamination. To face the challenge, good planning and management practices are needed. A key to the management of groundwater is the ability to model the movement of fluids and contaminants in the subsurface. The purpose of this book is to construct conceptual and mathematical models that can provide the information required for making decisions associated with the management of groundwater resources, and the remediation of contaminated aquifers. The basic approach of this book is to accurately describe the underlying physics of groundwater flow and solute transport in heterogeneous porous media, starting at the microscopic level, and to rigorously derive their mathematical representation at the macroscopic levels. The well-posed, macroscopic mathematical models are formulated for saturated, single phase flow, as well as for unsaturated and multiphase flow, and for the transport of single and multiple chemical species. Numerical models are presented and computer codes are reviewed, as tools for solving the models. The problem of seawater intrusion into coastal aquifers is examined and modeled. The issues of uncertainty in model input data and output are addressed. The book concludes with a chapter on the management of groundwater resources. Although one of the main objectives of this book is to construct mathematical models, the amount of mathematics required is kept minimal.

Download or read book Applied Groundwater Modeling written by Mary P. Anderson and published by Academic Press. This book was released on 2015-08-13 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second edition is extensively revised throughout with expanded discussion of modeling fundamentals and coverage of advances in model calibration and uncertainty analysis that are revolutionizing the science of groundwater modeling. The text is intended for undergraduate and graduate level courses in applied groundwater modeling and as a comprehensive reference for environmental consultants and scientists/engineers in industry and governmental agencies. - Explains how to formulate a conceptual model of a groundwater system and translate it into a numerical model - Demonstrates how modeling concepts, including boundary conditions, are implemented in two groundwater flow codes-- MODFLOW (for finite differences) and FEFLOW (for finite elements) - Discusses particle tracking methods and codes for flowpath analysis and advective transport of contaminants - Summarizes parameter estimation and uncertainty analysis approaches using the code PEST to illustrate how concepts are implemented - Discusses modeling ethics and preparation of the modeling report - Includes Boxes that amplify and supplement topics covered in the text - Each chapter presents lists of common modeling errors and problem sets that illustrate concepts

Download or read book Groundwater Modeling written by Paul Van der Heijde and published by . This book was released on 1988 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effective Groundwater Model Calibration written by Mary C. Hill and published by John Wiley & Sons. This book was released on 2006-08-25 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods and guidelines for developing and using mathematical models Turn to Effective Groundwater Model Calibration for a set of methods and guidelines that can help produce more accurate and transparent mathematical models. The models can represent groundwater flow and transport and other natural and engineered systems. Use this book and its extensive exercises to learn methods to fully exploit the data on hand, maximize the model's potential, and troubleshoot any problems that arise. Use the methods to perform: Sensitivity analysis to evaluate the information content of data Data assessment to identify (a) existing measurements that dominate model development and predictions and (b) potential measurements likely to improve the reliability of predictions Calibration to develop models that are consistent with the data in an optimal manner Uncertainty evaluation to quantify and communicate errors in simulated results that are often used to make important societal decisions Most of the methods are based on linear and nonlinear regression theory. Fourteen guidelines show the reader how to use the methods advantageously in practical situations. Exercises focus on a groundwater flow system and management problem, enabling readers to apply all the methods presented in the text. The exercises can be completed using the material provided in the book, or as hands-on computer exercises using instructions and files available on the text's accompanying Web site. Throughout the book, the authors stress the need for valid statistical concepts and easily understood presentation methods required to achieve well-tested, transparent models. Most of the examples and all of the exercises focus on simulating groundwater systems; other examples come from surface-water hydrology and geophysics. The methods and guidelines in the text are broadly applicable and can be used by students, researchers, and engineers to simulate many kinds systems.

Download or read book Groundwater Models for Resources Analysis and Management written by Aly I. El-Kadi and published by CRC Press. This book was released on 2017-11-22 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by renowned experts in the field, this book assesses the status of groundwater models and defines models and modeling needs in the 21st century. It reviews the state of the art in model development and application in regional groundwater management, unsaturated flow/multiphase flow and transport, island modeling, biological and virus transport, and fracture flow. Both deterministic and stochastic aspects of unsaturated flow and transport are covered. The book also introduces a unique assessment of models as analysis and management tools for groundwater resources. Topics covered include model vs. data uncertainty, accuracy of the dispersion/convection equation, protocols for model testing and validation, post-audit studies, and applying models to karst aquifers.

Download or read book A New Direct Inverse Method of Groundwater Flow and Solute Transport written by Jianying Jiao and published by . This book was released on 2022 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Groundwater is the largest accessible source of drinking water and water for irrigation. With increasing population and economic development, the demand for drinking water and water for irrigation is increasing. Therefore, the water table map, groundwater depletion, and solute transport in the shallow groundwater are very significant to humanity and ecosystems. Because observations of the water table and concentrations are rare, the maps of the accurate water table, groundwater depletion, and concentrations are difficult to obtain in the local regions and around the globe. This dissertation addresses how to solve these problems, estimating maps of the water table, groundwater depletion, and concentration in local and continental regions. Because the inverse method is one of the more extensive and effective methods for solving these problems, the inverse method was used in our study. However, the traditional inverse method requires a forward model including boundary and initial conditions. Uncertainty of boundary and initiation conditions leads to large uncertainty of inverted results. According to issues of the traditional inverse method, in the dissertation, we proposed a new direct inverse method that does not require boundary and initial conditions. First, this method was used to estimate maps of the water table and groundwater depletion in the High Plain Aquifer and the continental US. Results show that the water table of the Texas High Plain Aquifer declined 0.5 meters per year from 2000 which is consistent with observations. Expanding from local regions to the continental US, the inverted water table map and standard deviation map in the continental US were presented. Second, we used our inverse method to estimate the groundwater depletion in the continental US and compared our inverted results with data from the Gravity Recovery and Climate Experiment (GRACE) and groundwater withdrawals from USGS. Then, to identify contaminant trajectory and source in a non-uniform flow field, this study proposes a new inverse method by developing local approximate solutions (LAS) of concentration and by conditioning them to measure breakthrough concentrations. The key difference between this new approach and the majority of existing inversion techniques is that standard regression techniques are not employed. Thus, a solute transport forward model does not need to be built and simulated to optimize a model-data mismatch, as a result, non-uniqueness in inversions that is due to an incorrect assumption of transport BC is eliminated. To verify the solute transport inverse method, A series of bromide tracer experiments were performed in an intermediate-scale two-dimensional laboratory soil testbed. The resulting concentration breakthrough measurements, made at increasing monitoring well densities, were used to validate this method that can identify leakage sources and pathways under unknown initial and boundary conditions.

Download or read book Model Reduction of Unconfined Groundwater Flow Using Proper Orthogonal Decomposition and the Discrete Empirical Interpolation Method written by Zachary Paul Stanko and published by . This book was released on 2016 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear groundwater flow models have the propensity to be overly complex leading to burdensome computational demands. Reduced modelling techniques are used to develop an approximation of the original model that has smaller dimensionality and faster run times. The reduced model proposed is a combination of proper orthogonal decomposition (POD) and the discrete empirical interpolation method (DEIM). Solutions of the full model (snapshots) are collected to represent the physical dynamics of the system and Galerkin projection allows the formulation of a reduced model that lies in a subspace of the full model. Interpolation points are added through DEIM to eliminate the reduced model's dependence on the dimension of the full model. POD is shown to effectively reduce the dimension of the full model and DEIM is shown to speed up the solution by further reducing the dimension of the nonlinear calculations. To show the concept can work for unconfined groundwater flow model, with added nonlinear forcings, one-dimensional and two-dimensional test cases are constructed in MODFLOW-OWHM. POD and DEIM are added to MODFLOW as a modular package. Comparing the POD and the POD-DEIM reduced models, the experimental results indicate similar reduction in dimension size with additional computation speed up for the added interpolation. The hyper-reduction method presented is effective for models that have fine discretization in space and/or time as well as nonlinearities with respect to the state variable. The dual reduction approach ensures that, once constructed, the reduced model can be solved in an equation system that depends only on reduced dimensions.

Download or read book Design and Calibration of RFI Groundwater Flow and Solute Transport Model written by Gary R. Hecox and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development and Application of a Geographically based Groundwater Flow and Solute Transport Model written by Scott A. Underhill and published by . This book was released on 1993 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mathematical Modeling of Groundwater Pollution written by Ne-Zheng Sun and published by Springer Science & Business Media. This book was released on 2014-07-08 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Groundwater is one of the most important resources in the world. In many areas, water supplies for industrial, domestic, and agricultural uses are de pendent on groundwater. As an "open" system, groundwater may exchange mass and energy with its neighboring systems (soil, air, and surface water) through adsorption, ion-exchange, infiltration, evaporation, inflow, outflow, and other exchange forms. Consequently, both the quantity and quality of groundwater may vary with environmental changes and human activities. Due to population growth, and industrial and agricultural development, more and more groundwater is extracted, especially in arid areas. If the groundwater management problem is not seriously considered, over extraction may lead to groundwater mining, salt water intrusion, and land subsidence. In fact, the quality of groundwater is gradually deteriorating throughout the world. The problem of groundwater pollution has appeared, not only in developed countries, but also in developing countries. Ground water pollution is a serious environmental problem that may damage human health, destroy the ecosystem, and cause water shortage.

Download or read book Groundwater Flow and Solute Transport Modeling for Assessment and Prediction at the Superfund Site in Florida written by D. W. Chen and published by . This book was released on 1996 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Geostatistical formulations of the groundwater flow and solute transport equations written by Francisco Javier Sánchez Vila and published by . This book was released on 1995 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optimal Management of Flow in Groundwater Systems written by David P. Ahlfeld and published by Academic Press. This book was released on 2000-01-10 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: CD-ROM contains: Complete FORTRAN source code for MODOFC -- Executable compiled using the Lahey F77L-EM/32 FORTRAN 77 Compiler -- Documentatiion for MODOFC -- Sample problems -- HTML files from the MODOFC Web site.