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  • 1
    Electronic Resource
    Electronic Resource
    Dipole Probe: Design and Field Applications of a Single-Borehole Device for Measurements of Vertical Variations of Hydraulic Conductivity (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 36 (1998), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A dipole probe (DP) for measuring vertical variations of hydraulic conductivity has been designed, constructed, and tested in field conditions. The variable-length device designed for the dipole flow test (DFT) consists of three packers separated by changeable spacer rods. The assembled DP is lowered into a well with a long screened interval. The packers are inflated, isolating two screened sections (chambers) between them. A small submersible pump, mounted on the central packer, transfers water from the upper (extraction) chamber into the lower (injection) chamber. This simultaneous injection and extraction creates a recirculatory flow within the aquifer. The chamber head responses are measured by two pressure transducers in the DP chambers. The DP can be used at discrete intervals along the entire well screen length. The DP has been successfully tested in a specially constructed well with a continuous screen in a highly conductive sand and gravel aquifer. During drilling, disturbed samples were collected using the split spoon method and the vertical profile of K was estimated from grain-size analysis. A total of 153 DFTs were performed with various DP geometries. Results indicate that the chamber head changes are sensitive to aquifer properties, reach steady state rapidly, vary linearly with redrculation pumping rate, and can be controlled by changes in DP dimensions. Vertical profiles of K compare well with grain-size analysis estimates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1998.tb02095.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of Shallow Penetration and Streambed Sediments on Aquifer Response to Stream Stage Fluctuations (Analytical Model) (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 37 (1999), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: An analytical model of stream-aquifer interaction is proposed that considers the effects from a small degree of aquifer penetration and low-permeability sediments on the head response to an arbitrary stream-stage hydrograph. Aquifer sections under the stream and beyond are considered in a single model. The model of ground water flow in the aquifer is based on the Dupuit assumptions corrected for leakage from the stream. The model can use stream-stage hydrographs in both analytical and tabular forms. The nondimensional linear boundary value problem is solved for hydraulic head in the aquifer using numerical Laplace transforms and a convolution algorithm. The proposed solution is used to assess the impact of shallow penetration and low-permeability streambed sediments on head responses by comparison with available solutions which neglect these factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1999.tb01147.x
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  • 3
    Electronic Resource
    Electronic Resource
    Drawdown and Stream Depletion Produced by Pumping in the Vicinity of a Partially Penetrating Stream (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 39 (2001), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Commonly used analytical approaches for estimation of pumping-induced drawdown and stream depletion are based on a series of idealistic assumptions about the stream-aquifer system. A new solution has been developed for estimation of drawdown and stream depletion under conditions that are more representative of those in natural systems (finite width stream of shallow penetration adjoining an aquifer of limited lateral extent). This solution shows that the conventional assumption of a fully penetrating stream will lead to a significant overestimation of stream depletion (〉 100%) in many practical applications. The degree of overestimation will depend on the value of the stream leakance parameter and the distance from the pumping well to the stream. Although leakance will increase with stream width, a very wide stream will not necessarily be well represented by a model of a fully penetrating stream. The impact of lateral boundaries depends upon the distance from the pumping well to the stream and the stream leakance parameter. In most cases, aquifer width must be on the order of hundreds of stream widths before the assumption of a laterally infinite aquifer is appropriate for stream-depletion calculations. An important assumption underlying this solution is that stream-channel penetration is negligible relative to aquifer thickness. However, an approximate extension to the case of nonnegligible penetration provides reasonable results for the range of relative penetrations found in most natural systems (up to 85%). Since this solution allows consideration of a much wider range of conditions than existing analytical approaches, it could prove to be a valuable new tool for water management design and water rights adjudication purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.2001.tb02354.x
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  • 4
    Electronic Resource
    Electronic Resource
    The Steady-State Dipole-Flow Test for Characterization of Hydraulic Conductivity Statistics in a Highly Permeable Aquifer: Horkheimer Insel Site, Germany (2001)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 39 (2001), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Over the last decade the dipole-flow test (DFT) evolved from the general idea of using recirculatory flow to evaluate aquifer properties, to the development of prototype instrumentation and feasibility studies, to a reliable tool for characterization of aquifer heterogeneity. The DFT involves the interpretation of head in recirculatory flow between injection and extraction sections (chambers) in a single well isolated from each other by a multipacker system. In this study, the steady-state dipole flow test (DFT) has been used to characterize the statistics of horizontal hydraulic conductivity (Kr) of the highly permeable, heterogeneous, and thin aquifer at the Horkheimer Insel site, Germany. In previous studies, Kr estimates were based on the steady-state head difference between chambers. A new by-chamber interpretation is proposed that is based on drawdown within each individual chamber. This interpretation yields more detailed information on structure of heterogeneity of the aquifer without introducing complexity into the analysis. The DFT results indicate that Kr ranges from 49 to 6000 m/day (mean In Kr [(m/s)]∼—4, and variance of In Kr [(m/s)] ∼ 1–2). Descriptive statistics from the DFT compare well with those from previous field and laboratory tests (pumping, borehole flowmeter, and permeameter tests and grain-size analysis) at this site. It is shown that the role of confining boundaries in the DFT interpretation is negligible even in this case of a thin (〈 4 m thick) aquifer. This study demonstrates the flexibility of the DFT and expands the potential application of this method to a wide range of hydrogeologic settings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.2001.tb02339.x
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  • 5
    Electronic Resource
    Electronic Resource
    A Simple Constant-Head Injection Test for Streambed Hydraulic Conductivity Estimation (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 41 (2003), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A fast, efficient constant-head injection test (CHIT) for in situ estimation of hydraulic conductivity (K) of sandy streambeds is presented. This test uses constant-head hydraulic injection through a manually driven piezometer. Results from CHIT compare favorably to estimates from slug testing and grain-size analysis. The CHTT combines simplicity of field performance, data interpretation, and accuracy of K estimation in flowing streams.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.2003.tb02428.x
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of Anisotropy on the Capture Zone of a Partially Penetrating Well (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 35 (1997), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Dimensional analysis is used to show the effects of aquifer anisotropy on capture zone geometry for a partially penetrating well that is screened from the top of a confined aquifer. Dimensionless similarity criteria are identified which allow an extension of results for advective transport modeling from isotropic conditions to anisotropic ones. Using published results of modeling capture zones in isotropic aquifers, it is shown that anisotropy is important in determining the size and shape of the capture zone under two conditions: (1) the pumping rate is small compared to the scaled regional flow velocity, and (2) the well has a low degree of penetration. Examples are used to show that disregard of even modest aquifer anisotropy can significantly affect estimates of capture zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.1997.tb00152.x
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  • 7
    Electronic Resource
    Electronic Resource
    Asymmetric Dipole-Flow Test in a Fractured Carbonate Aquifer (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 40 (2002), S. 0 
    Details
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: In this study, a new method-the asymmetric dipole-flow test—is proposed and tested for characterization of conductive properties and structure of fractured aquifers. Analytical solutions were developed and then used for interpretation of a modification of the dipole-flow test with a single packer at the Bissen Quarry test site (Wisconsin, USA). The asymmetric dipole-flow tests were conducted by packing a well at various elevations, and fluids were pumped from the upper section (chamber) of the well to the lower section (chamber). The head was then monitored at 11 observation points and in both sections of the well, and the conductivities of the well segments were determined. The tests at seven packer elevations in the well were rapid (less than one hour to reach steady state). The asymmetric dipole-flow test demonstrates the potential to quantify heterogeneities of a fractured aquifer and delineate the applicability of the continuum and discrete approaches for conceptualization of ground water flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6584.2002.tb02533.x
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  • 8
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    Review: Regional groundwater flow modeling in heavily irrigated basins of selected states in the western United States (2013)
    Springer
    Details
    Publication Date: 2013-07-06
    Print ISSN: 1431-2174
    Electronic ISSN: 1435-0157
    Topics: Geosciences
    Published by Springer
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  • 9
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    Combined use of frequency-domain electromagnetic and electrical resistivity surveys to delineate near-lake groundwater flow in the semi-arid Nebraska Sand Hills, USA (2010)
    Springer
    Details
    Publication Date: 2010-06-09
    Print ISSN: 1431-2174
    Electronic ISSN: 1435-0157
    Topics: Geosciences
    Published by Springer
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  • 10
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    Mapping mean annual groundwater recharge in the Nebraska Sand Hills, USA (2011)
    Springer
    Details
    Publication Date: 2011-07-28
    Print ISSN: 1431-2174
    Electronic ISSN: 1435-0157
    Topics: Geosciences
    Published by Springer
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