Download or read book Development of Discrete Flow Paths in Unsaturated Fractures at Yucca Mountain written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have carried out numerical modeling studies to investigate the development of discrete fracture flow paths and flow-focusing phenomena in the unsaturated rock of the potential repository horizon at Yucca Mountain, Nevada. These studies are based on two- and three dimensional (2-D and 3-D) numerical models using site-specific parameters. The 2-D and 3-D models use high-resolution spatial discretization to explicitly include effects of discrete fractures with stochastically developed fracture permeabilities and a continuum approach. The permeability field is generated based on air-permeability measurements at various scales. For most of the cases considered, uniform infiltration with different average rates (1 to 500 mm/yr) is prescribed at the top of the model, while variability in outflow at the bottom of the model is used to evaluate the degree of flow focusing. In addition, scenarios involving nonuniform infiltration at the top boundary, different permeability correlation lengths, and different flow-allocation schemes were analyzed. The modeling results obtained from all of the cases showed a remarkably similar flow-focusing pattern at the repository horizon. Furthermore, tracer transport simulation results also revealed additional features of focused flow and transport through the fracture network.
Download or read book Hydrology and Geochemistry of Yucca Mountain and Vicinity Southern Nevada and California written by John S. Stuckless and published by Geological Society of America. This book was released on 2012 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Conceptual Models of Flow and Transport in the Fractured Vadose Zone written by National Research Council and published by National Academies Press. This book was released on 2001-05-21 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid flow and solute transport within the vadose zone, the unsaturated zone between the land surface and the water table, can be the cause of expanded plumes arising from localized contaminant sources. An understanding of vadose zone processes is, therefore, an essential prerequisite for cost-effective contaminant remediation efforts. In addition, because such features are potential avenues for rapid transport of chemicals from contamination sources to the water table, the presence of fractures and other channel-like openings in the vadose zone poses a particularly significant problem, Conceptual Models of Flow and Transport in the Fractured Vadose Zone is based on the work of a panel established under the auspices of the U.S. National Committee for Rock Mechanics. It emphasizes the importance of conceptual models and goes on to review the conceptual model development, testing, and refinement processes. The book examines fluid flow and transport mechanisms, noting the difficulty of modeling solute transport, and identifies geochemical and environmental tracer data as important components of the modeling process. Finally, the book recommends several areas for continued research.
Download or read book Advances in Groundwater Flow and Solute Transport Pushing the Hidden Boundary written by Hongbin Zhan and published by MDPI. This book was released on 2019-10-01 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent decades, the study of groundwater flow and solute transport has advanced into new territories that are beyond conventional theories, such as Darcy’s law and Fick’s law. The studied media have changed from permeable porous and fractured ones to much less permeable ones, such as clay and shale. The studied pore sizes have also changed from millimetres to micro-meters or even nano-meters. The objective of this Special Issue is to report recent advances in groundwater flow and solute transport that push the knowledge boundary into new territories which include, but are not limited to, flow and transport in sloping aquifer/hillslopes, coupled unsaturated and saturated flow, coupled aquifer-vertical/horizontal/slant well flow, interaction of aquifer with connected and disconnected rivers, non-Darcian flow, anomalous transport beyond the Fickian scheme, and flow and transport in extremely small pore spaces such as shale and tight sandstones. Contributions focusing on innovative experimental, numerical, and analytical methods for understanding unconventional problems, such as the above-listed ones, are encouraged, and contributions addressing flow and transport at interfaces of different media and crossing multiple temporal and spatial scales are of great value
Download or read book Flow and Contaminant Transport in Fractured Rock written by Jacob Bear and published by Academic Press. This book was released on 2012-12-02 with total page 575 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past two or three decades, fractured rock domains have received increasing attention not only in reservoir engineering and hydrology, but also in connection with geological isolation of radioactive waste. Locations in both the saturated and unsaturated zones have been under consideration because such repositories are sources of heat and potential sources of groundwater contamination. Thus, in addition to the transport of mass of fluid phases in single and multiphase flow, the issues of heat transport and mass transport of components have to be addressed.
Download or read book Preliminary Three dimensional Discrete Fracture Model of the Topopah Spring Tuff in the Exploratory Studies Facility Yucca Mountain Area Nye County Nevada written by and published by . This book was released on 1998 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discrete-fracture modeling is part of site characterization for evaluating Yucca Mountain, Nye County, Nevada, as a potential high-level radioactive-waste repository site. Because most of the water and gas flow may be in fractures in low-porosity units, conventional equivalent-continuum models do not adequately represent the flow system. Discrete-fracture modeling offers an alternative to the equivalent-continuum method. This report describes how discrete-fracture networks can be constructed and used to answer concerns about the flow system at Yucca Mountain, including quantifying fracture connectivity, deriving directional-permeability distributions for one-and two-phase flow, determining parameters of anisotropy at different scales, and determining at what scale the rock functions as an equivalent continuum. A three-dimensional discrete-fracture model was developed to investigate the effects of fractures on flow of water and gas in the Topopah Spring tuff of Miocene age in the Exploratory Studies Facility at Yucca Mountain. Fracture data, used as model input, were taken exclusively from detailed line surveys in the Exploratory Studies Facility and converted into input parameters for simulation. A simulated fracture network was calibrated to field data. The simulated discrete fracture network was modified by eliminating nonconductive fractures determined from field-derived permeabilities. Small fractures also were removed from the simulated network without affecting the overall connectivity. Fractures, as much as 1.50 meters in length, were eliminated (a large percentage of the total number of fractures) from the network without altering the number of connected pathways. The analysis indicates that the fracture system in the Exploratory Studies Facility has numerous connected fractures that have relatively large permeabilities, but there are relatively few connected pathways across the simulated region. The fracture network was, therefore, sparse.
Download or read book Research Program to Develop and Validate Conceptual Models for Flow and Transport Through Unsaturated Fractured Rock Yucca Mountain Site Characterization Project written by and published by . This book was released on 1991 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of the Yucca Mountain Project, our research program to develop and validate conceptual models for flow and transport through unsaturated fractured rock integrates fundamental physical experimentation with conceptual model formulation and mathematical modeling. Our research is directed toward developing and validating macroscopic, continuum-based models and supporting effective property models because of their widespread utility within the context of this project. Success relative to the development and validation of effective property models is predicted on a firm understanding of the basic physics governing flow through fractured media, specifically in the areas of unsaturated flow and transport in a single fracture and fracture-matrix interaction.
Download or read book Viability Assessment of a Repository at Yucca Mountain Total system performance assessment written by and published by . This book was released on 1998 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The American West at Risk written by Howard G. Wilshire and published by Oxford University Press. This book was released on 2008-06-05 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: The American West at Risk summarizes the dominant human-generated environmental challenges in the 11 contiguous arid western United States - America's legendary, even mythical, frontier. When discovered by European explorers and later settlers, the west boasted rich soils, bountiful fisheries, immense, dense forests, sparkling streams, untapped ore deposits, and oil bonanzas. It now faces depletion of many of these resources, and potentially serious threats to its few "renewable" resources. The importance of this story is that preserving lands has a central role for protecting air and water quality, and water supplies--and all support a healthy living environment. The idea that all life on earth is connected in a great chain of being, and that all life is connected to the physical earth in many obvious and subtle ways, is not some new-age fad, it is scientifically demonstrable. An understanding of earth processes, and the significance of their biological connections, is critical in shaping societal values so that national land use policies will conserve the earth and avoid the worst impacts of natural processes. These connections inevitably lead science into the murkier realms of political controversy and bureaucratic stasis. Most of the chapters in The American West at Risk focus on a human land use or activity that depletes resources and degrades environmental integrity of this resource-rich, but tender and slow-to-heal, western U.S. The activities include forest clearing for many purposes; farming and grazing; mining for aggregate, metals, and other materials; energy extraction and use; military training and weapons manufacturing and testing; road and utility transmission corridors; recreation; urbanization; and disposing of the wastes generated by everything that we do. We focus on how our land-degrading activities are connected to natural earth processes, which act to accelerate and spread the damages we inflict on the land. Visit www.theamericanwestatrisk.com to learn more about the book and its authors.
Download or read book Yucca Mountain Site Characterization Project Bibliography 1994 1995 written by and published by . This book was released on 1996 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow and Transport in Unsaturated Fractured Rock written by and published by . This book was released on 2002 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The heterogeneity of hydrogeologic properties at different scales may have different effects on flow and transport processes in a subsurface system. A model for the unsaturated zone of Yucca Mountain, Nevada, is developed to represent complex heterogeneity at two different scales: (1) layer scale corresponding to geologic layering and (2) local scale. The layer-scale hydrogeologic properties are obtained using inverse modeling, based on the available measurements collected from the Yucca Mountain site. Calibration results show a significant lateral and vertical variability in matrix and fracture properties. Hydrogeologic property distributions in a two-dimensional, vertical cross section of the site are generated by combining the average layer-scale matrix and fracture properties with local-scale perturbations generated using a stochastic simulation method. The unsaturated water flow and conservative (nonsorbing) tracer transport through the cross section are simulated for different sets of matrix and fracture property fields. Comparison of simulation results indicates that the local-scale heterogeneity of matrix and fracture properties has a considerable effect on unsaturated flow processes, leading to fast flow paths in fractures and the matrix. These paths shorten the travel time of a conservative tracer from the source (repository) horizon in the unsaturated zone to the water table for small fractions of total released tracer mass. As a result, the local-scale heterogeneity also has a noticeable effect on global tracer transport processes, characterized by an average breakthrough curve at the water table, especially at the early arrival time of tracer mass. However, the effect is not significant at the later time after 20 percent tracer mass reaches the water table. The simulation results also verify that matrix diffusion plays an important role in overall solute transport processes in the unsaturated zone at Yucca Mountain.
Download or read book Site Characterization Progress Report written by and published by . This book was released on 1996 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Conceptual Hydrologic Model of Flow in the Unsaturated Zone Yucca Mountain Nevada written by Parviz Montazer and published by . This book was released on 1984 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preliminary Three dimensional Discrete Fracture Model Tiva Canyon Tuff Yucca Mountain Area Nye County Nevada written by and published by . This book was released on 1998 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: A three-dimensional discrete fracture model was completed to investigate the potential effects of fractures on the flow of water at Yucca Mountain, Nye County, Nevada. A fracture network of the Exploratory Studies Facility starter tunnel area was simulated and calibrated with field data. Two modeled volumes were used to simulate three-dimensional fracture networks of the Tiva Canyon tuff. One volume had a width and length of 150 meters, and the other had a width and length of 200 meters; both volumes were 60 meters thick. The analysis shows that the fracture system in the Exploratory Studies Facility starter tunnel area has numerous connected fractures that have relatively large permeabilities. However, pathway analysis between three radial boreholes indicated there were few pathways and little connection, which is consistent with results of cross-boreholes pressure testing. Pathway analysis also showed that at the scales used there was only one pathway connecting one end of the flow box to the opposite end. The usual vertical pathway was along one large fracture, whereas in four horizontal directions the pathway was from multiple fracture connections. As a result, the fracture network can be considered sparse. The fracture network was refined by eliminating nonconductive fractures determined from field-derived permeabilities. Small fractures were truncated from the simulated network without any effect on the overall connectivity. Fractures as long as 1.25 meters were eliminated (a large percentage of the total number of fractures) from the network without altering the number of pathways. Five directional permeabilities were computed for the 150- and 200-meter-scale flow box areas. Permeabilities for the 150-meter scale vary by almost two orders of magnitude, with the principal permeability direction being easterly. At the 200-meter scale, however, the flow box permeabilities only vary by a factor of four, with the principal permeability direction being vertical.
Download or read book Index Medicus written by and published by . This book was released on 2003 with total page 1748 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. for 1963- include as pt. 2 of the Jan. issue: Medical subject headings.
Download or read book Rock Fractures and Fluid Flow written by National Research Council and published by National Academies Press. This book was released on 1996-08-27 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific understanding of fluid flow in rock fracturesâ€"a process underlying contemporary earth science problems from the search for petroleum to the controversy over nuclear waste storageâ€"has grown significantly in the past 20 years. This volume presents a comprehensive report on the state of the field, with an interdisciplinary viewpoint, case studies of fracture sites, illustrations, conclusions, and research recommendations. The book addresses these questions: How can fractures that are significant hydraulic conductors be identified, located, and characterized? How do flow and transport occur in fracture systems? How can changes in fracture systems be predicted and controlled? Among other topics, the committee provides a geomechanical understanding of fracture formation, reviews methods for detecting subsurface fractures, and looks at the use of hydraulic and tracer tests to investigate fluid flow. The volume examines the state of conceptual and mathematical modeling, and it provides a useful framework for understanding the complexity of fracture changes that occur during fluid pumping and other engineering practices. With a practical and multidisciplinary outlook, this volume will be welcomed by geologists, petroleum geologists, geoengineers, geophysicists, hydrologists, researchers, educators and students in these fields, and public officials involved in geological projects.
Download or read book Hydrologic Mechanisms Governing Fluid Flow in Partially Saturated Fractured Porous Tuff at Yucca Mountain written by and published by . This book was released on 1984 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: In contrast to the saturated zone where fluid moves rapidly along fractures, the fractures (with apertures large relative to the size of matrix pores) will desaturate first during drainage process and the bulk of fluid flow would be through interconnected pores in the matrix. Within a partially drained fracture, the presence of a relatively continuous air phase will produce practically an infinite resistance to liquid flow in the direction parallel to the fracture. The residual liquid will be held by capillary force in regions around fracture contact areas where the apertures are small. Normal to the fracture surfaces, the drained portion of the fractures will reduce the effective area for liquid flow from one matrix block to another matrix block. A general statistical theory is constructed for flow along the fracture and for flow between the matrix blocks to the fractures under partially saturated conditions. Results are obtained from an aperture distribution model for fracture saturation, hydraulic conductivity, and effective matrix-fracture flow areas as functions of pressure. Drainage from a fractured tuff column is simulated. The parameters for the simulations are deduced from fracture surface characteristics, spacings and orientations based on core analyses, and from matrix characteristics curve based on laboratory measurements. From the cases simulated for the fractured, porous column with discrete vertical and horizontal fractures and porous matrix blocks explicitly taken into account, it is observed that the highly transient changes from fully saturated conditions to partially saturated conditions are extremely sensitive to the fracture properties. However, the quasi-steady changes of the fluid flow of a partially saturated, fractured, porous system could be approximately simulated without taking the fractures into account. 22 references, 16 figures.
