Download or read book Characterization of Vadose Zone In situ Moisture Content and an Advancing Wetting Front Using Cross borehole Ground Penetrating Radar written by Lee Taylor Paprocki and published by . This book was released on 2000 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation of Cross Borehole Ground Penetrating Radar Measurements for Characterizing the 2D Moisture Content Distribution in the Vadose Zone written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of cross-borehole ground penetrating radar (GPR) imaging for determining g the two dimensional (2D) in situ moisture content distribution within the vadose zone is being investigated. The ultimate goal is to use the GPR images as input to a 2D hydrologic inversion scheme for recovering the van Genuchten parameters governing unsaturated, hydraulic flow. Initial experiments conducted on synthetic data have shown that at least in theory, cross-borehole GPR measurements can provide realistic estimates of the spatial variation in moisture content that are needed for this type of hydrologic inversion scheme. However, the method can not recover exact values of moisture content due to the break down of the empirical expression often employed to convert GPR velocity images to moisture content, and to the smearing nature of the imaging algorithm. To test the applicability of this method in a real world environment cross- borehole GPR measurements were made at a hydrologic/geophysical vadose zone test site in Socorro, New Mexico. Results show that the GPR images compare well with the uncalibrated borehole neutron log data. GPR data acquisition will continue once an infiltration test has started, and the results from these measurements will be employed in a 2D hydrologic inverse scheme.
Download or read book Hydrogeophysics written by Yorum Rubin and published by Springer Science & Business Media. This book was released on 2006-05-06 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt: This ground-breaking work is the first to cover the fundamentals of hydrogeophysics from both the hydrogeological and geophysical perspectives. Authored by leading experts and expert groups, the book starts out by explaining the fundamentals of hydrological characterization, with focus on hydrological data acquisition and measurement analysis as well as geostatistical approaches. The fundamentals of geophysical characterization are then at length, including the geophysical techniques that are often used for hydrogeological characterization. Unlike other books, the geophysical methods and petrophysical discussions presented here emphasize the theory, assumptions, approaches, and interpretations that are particularly important for hydrogeological applications. A series of hydrogeophysical case studies illustrate hydrogeophysical approaches for mapping hydrological units, estimation of hydrogeological parameters, and monitoring of hydrogeological processes. Finally, the book concludes with hydrogeophysical frontiers, i.e. on emerging technologies and stochastic hydrogeophysical inversion approaches.
Download or read book An Analysis of a Coupled Geophysical Tomography hydrological Modeling Method to Characterize Hydraulic Properties and Flow and Transport Process in the Vadose Zone written by Ping-Yu Chang and published by . This book was released on 2003 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Expanded Abstracts with Biographies written by and published by . This book was released on 2003 with total page 1260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Mexico Geology written by and published by . This book was released on 2000 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Use of Radar Methods to Determine Moisture Content in the Vadose Zone written by and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Water content is a critical parameter affecting both liquid-phase and vapor-phase contaminant transport in the vadose zone. This means that accurate estimates of in situ water content must be obtained in order to design for the appropriate handling or remediation of a contaminated region of the vadose zone. Traditional methods of sampling the subsurface by drilling and/or direct sampling are very time consuming, limited in terms of spatial coverage, and have the associated risk of contacting and increasing the size of the contaminated area. One solution is to use geophysical methods which can provide a high-resolution, non-invasive means of sampling or imaging the subsurface. The overall objective of our research, defined at the start of this project, was to advance the usefulness of radar methods (ground-based and borehole) as a means of characterizing water content in the vadose zone. We have met this objective by providing research results that can be used to (1) improve the accuracy of water content estimates from radar measurements; (2) provide estimates of the potential error in water content estimates from radar measurements; (3) improve the clarity of radar images; (4) develop large-scale models of the subsurface ''architecture'' using radar images; (5) develop ways of quantifying the spatial heterogeneity of the subsurface through analysis of radar images. We have also been able to identify the critical areas where more research is needed in order to be able to use radar methods most effectively as an accurate means of subsurface characterization.
Download or read book Handbook of Vadose Zone Characterization Monitoring written by L. Gray Wilson and published by Routledge. This book was released on 2018-05-02 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is written in a simple, straightforward manner without complicated mathematical derivatives. Compiled by experienced practitioners, this guide covers topics such as basic principles of vadose zone hydrology and prevalent monitoring techniques. Case studies present actual field experiences for the benefit of the reader. The Handbook provides practitioners with the information they need to fully understand the principles, advantages, and limitations of the monitoring techniques that are available. The Handbook of Vadose Zone Characterization & Monitoring expands and consolidates the useful and succint information contained in various ASTM documents, EPA manuals, and other similar texts on the subject, making it an invaluable aid to new practioners and a useful reference for seasoned veterans in the field.
Download or read book Three Dimensional Electromagnetics written by P.E. Wannamaker and published by Elsevier. This book was released on 2002-07-08 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: "3-D modeling and inversion is a reality, and not an illusion." This is the clear conclusion of the Second International Symposium on Three-Dimensional Electromagnetics held at the University of Utah in 1999. Containing papers submitted by 36 authors, this volume, by the sheer number of works, their diversity, and the truly international character of the efforts attests to the vigor with which the problems of the field are pursued today. The papers in this book are grouped in three parts: 3-D EM modeling; 3-D EM inversion; and 3-D EM in practice. They cover a wide range of topics in forward modeling and inversion based on new fast approximate approaches and new efficient solutions by integral equation, finite difference and finite elements techniques. If the 1980s were the decade of rapid development in 3D seismics, the 1990s became the decade of growing interest of practical geophysicists in 3D EM modeling and inversion methods. The contributions contained in this volume represent a snapshot of today's state-of-the-art in three-dimensional electromagnetics.
Download or read book Evaluating Vadose Zone Moisture Dynamics Using Ground penetrating Radar written by Colby Michael Steelman and published by . This book was released on 2012 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: Near-surface sediments in the vadose zone play a fundamental role in the hydrologic system. The shallow vadose zone can act as a buffer to delay or attenuate surface contaminants before they reach the water table. It also acts as a temporary soil moisture reservoir for plant and atmospheric uptake, and regulates the seasonal groundwater recharge process. Over the past few decades, geophysical methods have received unprecedented attention as an effective vadose zone characterization tool offering a range of non-invasive to minimally invasive techniques with the capacity to provide detailed soil moisture information at depths typically unattainable using conventional point-measurement sensors. Ground-penetrating radar (GPR) has received much of this attention due to its high sensitivity to the liquid water phase in geologic media. While much has been learned about GPR soil moisture monitoring and characterization techniques, it has not been evaluated across highly dynamic natural soil conditions. Consequently, GPR's capacity to characterize a complete range of naturally occurring vadose zone conditions including wetting/drying and freeze/thaw cycles, is not yet fully understood. Further, the nature of GPR response during highly dynamic moisture periods has not been thoroughly investigated. The objective of this thesis is to examine the capacity of various surface GPR techniques and methodologies for the characterization of soil moisture dynamics in the upper few meters of vadose zone, and to develop measurement strategies capable of providing quantitative information about the current and future state of the shallow hydrologic system. To achieve this, an exhaustive soil moisture monitoring campaign employing a range of GPR antenna frequencies and survey acquisition geometries was initiated at three different agricultural field sites located in southern Ontario, Canada, between May 2006 and October 2008. This thesis represents the first attempt to evaluate multiple annual cycles of soil conditions and associated hydrological processes using high-frequency GPR measurements. The works embodied in this thesis demonstrate the effectiveness of high-frequency GPR as a non-invasive soil moisture monitoring tool under a full range of naturally occurring moisture conditions with the temporal and vertical resolution necessary to quantitatively examine shallow vadose zone moisture dynamics. Because this study encompassed an unprecedented range of naturally occurring soil conditions, including numerous short and long duration wetting/drying and freezing/thawing cycles, complex geophysical responses were observed during highly dynamic soil moisture processes. Analysis and interpretation of these geophysical responses yielded both qualitative and quantitative information about the state of the hydrologic system, and hence, provided a non-invasive means of characterizing soil moisture processes in shallow vadose zone environments. In the future, these GPR soil moisture monitoring strategies should be incorporated into advanced land-surface hydrological modeling studies to improve our understanding of shallow hydrologic systems and its impacts on groundwater resources.
Download or read book Improved Analysis of Borehole Ground Penetrating Radar to Monitor Transient Water Flow in the Vadose Zone PHD written by Dale Franklin Rucker and published by . This book was released on with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Resolution Analysis of Two Geophysical Imaging Methods for Characterizing and Monitoring Hydrologic Conditions in the Vadose Zone written by and published by . This book was released on 2007 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research project analyzed the resolution of two geophysical imaging techniques, electrical resistivity tomography (ERT) and cross-borehole ground penetrating radar (XBGPR), for monitoring subsurface flow and transport processes within the vadose zone. The study was based on petrophysical conversion of moisture contents and solute distributions obtained from unsaturated flow forward modeling. This modeling incorporated boundary conditions from a potable water and a salt tracer infiltration experiment performed at the Sandia-Tech Vadose Zone (STVZ) facility, and high-resolution spatial grids (6.25-cm spacing over a 1700-m domain) and incorporated hydraulic properties measured on samples collected from the STVZ. The analysis process involved petrophysical conversion of moisture content and solute concentration fields to geophysical property fields, forward geophysical modeling using the geophysical property fields to obtain synthetic geophysical data, and finally, inversion of this synthetic data. These geophysical property models were then compared to those derived from the conversion of the hydrologic forward modeling to provide an understanding of the resolution and limitations of the geophysical techniques.
Download or read book Ground Penetrating Radar in Hydrogeophysics written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To meet the needs of a growing population and to provide us with a higher quality of life, increasing pressures are being placed on our environment through the development of agriculture, industry, and infrastructures. Soil erosion, groundwater depletion, salinization, and pollution have been recognized for decades as major threats to ecosystems and human health. More recently, the progressive substitution of fossil fuels by biofuels for energy production and climate change have been recognized as potential threats to our water resources and sustained agricultural productivity. The vadose zone mediates many of the processes that govern water resources and quality, such as the partition of precipitation into infiltration and runoff, groundwater recharge, contaminant transport, plant growth, evaporation, and energy exchanges between the Earth's surface and its atmosphere. It also determines soil organic carbon sequestration and carbon-cycle feedbacks, which could substantially impact climate change. The vadose zone's inherent spatial variability and inaccessibility precludes direct observation of the important subsurface processes. In a societal context where the development of sustainable and optimal environmental management strategies has become a priority, there is a strong prerequisite for the development of noninvasive characterization and monitoring techniques of the vadose zone. In particular, hydrogeophysical approaches applied at relevant scales are required to appraise dynamic subsurface phenomena and to develop optimal sustainability, exploitation, and remediation strategies. Among existing geophysical techniques, ground penetrating radar (GPR) technology is of particular interest for providing high-resolution subsurface images and specifically addressing water-related questions. Ground penetrating radar is based on the transmission and reception of VHF-UHF (30-3000 MHz) electromagnetic waves into the ground, whose propagation is determined by the soil electromagnetic properties and their spatial distribution. As the dielectric permittivity of water overwhelms the permittivity of other soil components, the presence of water in the soil principally governs GPR wave propagation. Therefore, GPR-derived dielectric permittivity is usually used as surrogate measure for soil water content. In the areas of unsaturated zone hydrology and water resources, GPR has been used to identify soil stratigraphy, to locate water tables, to follow wetting front movement, to estimate soil water content, to assist in subsurface hydraulic parameter identification, to assess soil salinity, and to support the monitoring of contaminants. The purpose of this special section of the Vadose Zone Journal is to present recent research advances and applications of GPR in hydrogeophysics, with a particular emphasis on vadose zone investigations. This special section includes contributions presented at the European Geosciences Union General Assembly 2006 (EGU 2006, Vienna, Austria) and the 11th International Conference on Ground Penetrating Radar (GPR 2006, Columbus, OH). The studies presented here deal with a wide range of surface and borehole GPR applications, including GPR sensitivity to contaminant plumes, new methods for soil water content determination, three-dimensional imaging of the subsurface, time-lapse monitoring of hydrodynamic events and inversion techniques for soil hydraulic properties estimation, and joint interpretation of GPR and electric resistivity tomography (ERT) data.
Download or read book Investigation on the Combined Use of Ground Penetrating Radar Cone Penetrometer and High Resolution Seismic Data for Near Surface and Vadose Zone Characterization in the A written by and published by . This book was released on 1997 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study compares data from Cone Penetrometer Tests (CPT), high resolution surface reflection seismic (HRS) data and ground penetrating radar (GPR) data in the upper 120 feet (40 meters) of the A/M Area, Upper Three Runs Watershed at the Savannah River Site in South Carolina. The CPT, GPR, and HRS data were obtained along the Silverton Road in the western sector of the A/M Area groundwater plume, and adjacent to Geophysical Correlation Boring {number_sign}1 (GCB-1). This location allows for multiple correlations to be made between the various data sources, and supports shallow investigations for near surface affects of the Crackerneck Fault, a major structural feature in the area. Borehole geophysical data from GCB-1 were used to provide subsurface constraints on the CPT, GPR, and HRS data. core data, natural gamma ray, spectral gamma data, multi-level induction resistivity, density and sonic data were utilized to distinguish clays, sands and silts. The CPT data provided tip bearing and sleeve stress, as an indicator of stratigraphy. Reflection seismic data provided continuous subsurface profiles of key marker horizons. Ground Penetrating Radar provided information on shallow subsurface geological features. Conclusions from this study suggest that there is a high degree of correlation between the CPT and borehole geophysical data, specifically, the Friction Ratio and gamma/spectral gamma curves. The Upland/Tobacco Road, Tobacco Road/Dry Branch, Dry Branch/Santee, Santee/Warley Hill and the Warley Hill/Congaree contacts are discernible. From these contacts it is possible to map structural relationships in the shallow subsurface that are tied to regional data. Because formation contacts are discernible, CPT, HRS, GPR, and geophysical log intra-formational anomalies are mappable. These features allow for stratigraphic and facies mapping using the GPR and HRS data for continuity and the CPT and geophysical data for lithofacies analysis. It is possible to use the combination of these tools to map shallow, stratigraphy and structure across the A/M Area.
Download or read book The Use of Radar Methods to Determine Moisture Content in the Vadose Zone written by Rosemary Knight and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Moisture content is a critical parameter affecting both liquid-phase and vapor-phase contaminant transport in the vadose zone. The objective of our three-year research project is to determine the optimal way to use radar methods as a non-invasive means of determining in situ moisture content.
Download or read book Analysis of Borehole radar Reflection Logs from Selected HC Boreholes at the Project Shoal Area Churchill County Nevada written by and published by . This book was released on 2001 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Resolution Imaging of Vadose Zone Transport Using Crosswell Radar and Seismic Methods written by and published by . This book was released on 2001 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: The summary and conclusions are that overall the radar and seismic results were excellent. At the time of design of the experiments we did not know how well these two methods could penetrate or resolve the moisture content and structure. It appears that the radar could easily go up to 5, even 10 meters between boreholes at 200 Mhz and even father (up to 20 to 40 m) at 50 Mhz. The seismic results indicate that at several hundred hertz propagation of 20 to 30 meters giving high resolution is possible. One of the most important results, however is that together the seismic and radar are complementary in their properties estimation. The radar being primarily sensitive to changes in moisture content, and the seismic being primarily sensitive to porosity. Taken in a time lapse sense the radar can show the moisture content changes to a high resolution, with the seismic showing high resolution lithology. The significant results for each method are: Radar: (1) Delineated geological layers 0.25 to 3.5 meters thick with 0.25 m resolution; (2) Delineated moisture movement and content with 0.25 m resolution; (3) Compared favorably with neutron probe measurements; and (4) Penetration up to 30 m. Radar results indicate that the transport of the riverwater is different from that of the heavier and more viscous sodium thiosulfate. It appears that the heavier fluids are not mixing readily with the in-situ fluids and the transport may be influenced by them. Seismic: (1) Delineated lithology at .25 m resolution; (2) Penetration over 20 meters, with a possibility of up to 30 or more meters; and (3) Maps porosity and density differences of the sediments. Overall the seismic is mapping the porosity and density distribution. The results are consistent with the flow field mapped by the radar, there is a change in flow properties at the 10 to 11 meter depth in the flow cell. There also appears to be break through by looking at the radar data with the denser sodium thiosulfate finally penetrating the barrier, but not the river water. The radar and seismic data imply that the fluid property differences (density, viscosity, surface tension) between the river water and the sodium thiosulfate do make a difference in flow characteristics.
