Download or read book Field scale Testing and Validation of a Numerical Model Code for Modelling Groundwater Flow and Contaminant Transport in a Porous Media microform written by Dankyi Nicholas Osei and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 1995 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Calibration of a Groundwater Flow and Contaminant Transport Computer Model written by and published by . This book was released on 1989 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: A groundwater flow and contaminant transport model calibration was performed to evaluate the ability of a typical, verified computer code to simulate groundwater tracer migration in the shallow aquifer of the Conasauga Group. Previously, standard practice site data interpretation and groundwater modeling resulted in inaccurate simulations of contaminant transport direction and rate compared with tracer migration behavior. The site's complex geology, the presence of flow in both fractured and weathered zones, and the transient character of flow in the shallow aquifer combined to render inaccurate assumptions of steady-state, homogeneous groundwater flow. The improvement of previous modeling results required iterative phases of conceptual model development, hypothesis testing, site field investigations, and modeling. The activities focused on generating a model grid that was compatible with site hydrogeologic conditions and on establishing boundary conditions based on site data. An annual average water table configuration derived from site data and fixed head boundary conditions was used as input for flow modeling. The contaminant transport model was combined with the data-driven flow model to obtain a preliminary contaminant plume. Calibration of the transport code was achieved by comparison with site tracer migration and concentration data. This study documents the influence of fractures and the transient character of flow and transport in the shallow aquifer. Although compatible with porous medium theory, site data demonstrate that the tracer migration pathway would not be anticipated using conventional porous medium analysis. 126 figs., 22 refs., 5 tabs.
Download or read book Calibration of MADE 2 Groundwater Flow and Contaminant Transport Models written by and published by . This book was released on 1996 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: Public domain computer programs were used to simulate groundwater flow and contaminant migration through a site at the Columbus Air Force Base Mississippi In the MADE-2 (Macrodispersion Experiment a pulse of dissolved contaminants in the saturated zone of an alluvial aquifer was monitored for 15 months. MODFLOW solved for head and seepage velocity for input to the transport code, MT3D. The contaminant transport equation was solved separately from the flow equation since buoyancy effects were assumed to be negligible. Initial simulations of the tritlum plume did not extend far enough from the injection site. An ad hoc assumption of horizontal anisotropy applied to the conductivity field produced good agreement with the observed plumes. Although the simulated plumes were realistic, the horizontally anisotropic conductivity field used to achieve these predictions was not. The principal axes were not aligned with the directions suggested by pump tests or geology, the anisotropy ratio was in excess of any previously observed, and the effective conductivity was above what had been measured at the site. The use of public domain software to model contaminant transport at heterogeneous sites is technically practical; but in the absence of exhaustive field measurements, little confidence can be placed in the predictions.
Download or read book Calibration and Reliability in Groundwater Modelling written by Karel Kovar and published by IAHS Press. This book was released on 1996 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Large Scale Groundwater Flow and Contaminant Transport Modeling written by Karl Bandilla and published by . This book was released on 2009 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work introduces a combination of the vertically integrated Analytic Element and deterministic Streamline methods for watershed-scale groundwater flow and contaminant transport modeling. This new method combines the Analytic Element Method's ability of modeling large spatial domains while preserving stream-scale details, with the conceptional elegance of the Streamline method. Both methods allow for parallel processing in order to reduce model run-times. The intended use of this new method is the study of non-point source contaminant transport on the watershed scale (e.g., nutrient loading to surface water from agricultural fields). A new iterative Analytic Element Method algorithm is devised for solving 2D steady-state groundwater flow models containing large numbers of head-specified elements (e.g. rivers and lakes).^The new algorithm improves convergence of models containing head-specified elements by explicitly computing fluxes of all such features at the start of each iteration. The new algorithm alsoenables the use of efficient parallel processing on distributed-memory super-computers. The combination of parallel processing and reduced number of iterations significantly extends the size and complexity of problems that can be modeled using the Analytic Element Method. The vertically integrated Analytic Element Method flow solution is used to construct three-dimensional particle tracks that define the geometry of the Streamline Method by approximating vertical flow. The inherently parallel nature of the algorithm supports the development of reactive transport models for spatial domains much larger than current grid-based methods.^The applicability of the new approach is verified for cases with negligible transverse dispersion through comparisons to analytic solutions and existing numerical solutions, and parallel performance is demonstrated through a realistic test problem based on the regional-scale transport of agricultural contaminants from spatially distributed sources.
Download or read book Calibration and Reliability in Groundwater Modelling written by Karel Kovar and published by . This book was released on 2003 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1991 with total page 1270 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Contaminant Transport Model Validation written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In the complex geologic setting on the Oak Ridge Reservation, hydraulic conductivity is anisotropic and flow is strongly influenced by an extensive and largely discontinuous fracture network. Difficulties in describing and modeling the aquifer system prompted a study to obtain aquifer property data to be used in a groundwater flow model validation experiment. Characterization studies included the performance of an extensive suite of aquifer test within a 600-square-meter area to obtain aquifer property values to describe the flow field in detail. Following aquifer test, a groundwater tracer test was performed under ambient conditions to verify the aquifer analysis. Tracer migration data in the near-field were used in model calibration to predict tracer arrival time and concentration in the far-field. Despite the extensive aquifer testing, initial modeling inaccurately predicted tracer migration direction. Initial tracer migration rates were consistent with those predicted by the model; however, changing environmental conditions resulted in an unanticipated decay in tracer movement. Evaluation of the predictive accuracy of groundwater flow and contaminant transport models on the Oak Ridge Reservation depends on defining the resolution required, followed by field testing and model grid definition at compatible scales. The use of tracer tests, both as a characterization method and to verify model results, provides the highest level of resolution of groundwater flow characteristics. 3 refs., 4 figs.
Download or read book Groundwater Modeling written by Paul Van der Heijde and published by . This book was released on 1989 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Impact of Representative Scale in Groundwater Modeling written by Evan Norris Ulrich and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inherent in the continuum equations that describe flow and transport in porous media is a component of scale. This is an artifact of the underlying assumptions necessary for transforming the complex pore-scale characteristics of soil into manageable state variables and parameters that are readily measurable in the field (e.g., piezometric head and hydraulic conductivity). The mechanism used to formulate the upscaled porous medium equations involves Averaging Theory in which a representative elementary volume (REV) is used. This REV acts as an integration volume where pore-scale quantities are averaged over a macroscale volume. The REV defines all aspects of the modeling process-from the coefficients that describe the soil parameters, to the state variables that the models predict. Despite its ubiquity, knowledge of its actual size or its impact on numerical model outputs is unknown. The work presented here includes five experiments involving a highly instrumented physical bench-top sandbox model that provide insights into the impact scale plays on a physical groundwater system. State variable measurements including piezometric head and solute concentration are determined at different scales using an areal averaging technique. These measurements are used to calculate the relevant soil hydraulic and transport parameters at well-defined scales. The resulting parameters are then employed in an equivalent numerical simulation. Comparisons between the measured and simulated outputs at the same scale show that the REV averaging size plays an important role in model results. A convergence of simulated head and solute concentration data with consistently averaged measured values occurs at larger REV sizes, however at a loss of some macroscale heterogeneities. The results of this work suggest that the optimal REV for modeling flow and transport in porous media is dependent on the soil type as well as the characteristics of the entire system to be modeled. They also reveal the importance of interpreting numerical models in the context of the scale at which they are created.
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 Validation of a Groundwater Flow and Contaminant Transport Computer Model written by Robert Rue Lee and published by . This book was released on 1990* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Calibration and Reliability in Groundwater Modelling written by Fritz Stauffer and published by . This book was released on 2000 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Calibration and Reliability in Groundwater Modelling written by Marc F. P. Bierkens and published by . This book was released on 2006 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several of the papers here deal with decision making under uncertainty.
Download or read book Stochastic Simulation and the Modeling of Groundwater Flow and Contaminant Transport in Heterogeneous and Anisotropic Porous Media written by Zhonghe Wang and published by . This book was released on 1996 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Modeling of the Groundwater Flow and Contamination Transport at the Made 2 Site Using Seco Codes written by Mandar M. Sarangdhar and published by . This book was released on 1996 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Report 1989 90 written by New Brunswick. Department of Transportation and published by . This book was released on 1991 with total page 1272 pages. Available in PDF, EPUB and Kindle. Book excerpt: General activity review of associated branches and agencies to the Department which includes corporate securities registrations, a list of tenders received, and general financial data. Branches and agencies reviewed are responsible for motor vehicle activity, highway construction, traffic engineering, telecommunications and public utilities.
