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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 04 February 2014, Vol.111(5), pp.E531
    Description: Author contributions: J.J.B., G.C.B., A.E.B., G.L., D.O.W., and B.B.W. analyzed data and wrote the paper.
    Keywords: Agriculture ; Groundwater
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    Language: English
    In: The Value Line Investment Survey (Part 3 - Ratings & Reports), August 12, 2011, Vol.66(51), p.2438(1)
    Keywords: Industrial Equipment Industry -- Securities ; Stock Prices -- Evaluation ; Pall Corp.
    ISSN: 0042-2401
    Source: Cengage Learning, Inc.
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  • 3
    In: Geophysical Research Letters, 16 March 2016, Vol.43(5), pp.2004-2010
    Description: Aquifers supporting irrigated agriculture are under stress worldwide as a result of large pumping‐induced water deficits. To aid in the formulation of more sustainable management plans for such systems, we have developed a water balance approach for assessing the impact of proposed management actions and the prospects for aquifer sustainability. Application to the High Plains aquifer (HPA) in the state of Kansas in the United States reveals that practically achievable reductions in annual pumping (〈22%) would have stabilized areally averaged water levels over much of the Kansas HPA from 1996 to 2013. This demonstrates that modest pumping reductions can have a significant impact and highlights the importance of reliable pumping data for determining the net inflow (capture) component of the water balance. The HPA is similar to many aquifers supporting critically needed agricultural production, so the presented approach should prove of value far beyond the area of this initial application. Water balance approach developed to assess prospects for sustainability of heavily stressed aquifers Net inflow (capture) term in water balance is directly estimated from water level and pumping data Modest pumping reductions can lead to stable water levels over much of High Plains aquifer in Kansas
    Keywords: Aquifer Sustainability ; Irrigation ; High Plains Aquifer ; Groundwater Levels ; Groundwater Pumping
    ISSN: 0094-8276
    E-ISSN: 1944-8007
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  • 4
    Language: English
    In: Journal of Hydrology, 19 September 2014, Vol.517, pp.54-63
    Description: Aquifer storage and recovery (ASR) methods are increasingly used to overcome the temporal imbalance between water demand and availability. Common ASR recharge methods utilize large-diameter injection wells or surface infiltration basins and trenches, and can be costly to implement. A new low-cost ASR recharge method is currently being developed. This approach is based on recharge via gravity in small-diameter wells installed with direct-push (DP) technology. Numerical modeling is used here to assess the potential of this new approach under conditions commonly faced in field settings. The primary objective is to investigate if a battery of small-diameter DP wells can serve as a viable alternative to a surface basin under typical field conditions, while the secondary objective is to assess which subsurface parameters have the greatest control on DP well performance. Simulation results indicate that gravity recharge via small-diameter wells appears to have a distinct advantage over recharge via surface infiltration basins. For example, two 0.05-m shallow vadose-zone wells with 9-m screens can recharge water at a greater rate than a 60 m basin. Also, results reveal that, contrary to an infiltration basin, the recharge rate in a DP well has a much stronger dependence on the horizontal component of hydraulic conductivity than on the vertical component. Moreover, near-surface layers of low hydraulic conductivity, which can significantly reduce the recharge capacity of a surface basin, have a relatively small impact on the recharge capacity of a well as long as a significant portion of the well screen is installed below those layers. Given that installation and operation costs can be low in comparison to common ASR recharge methods, this new approach appears to have great potential for recharging good quality water in shallow unconsolidated aquifers. A field investigation has recently been initiated to follow up the findings of this simulation assessment.
    Keywords: Aquifer Storage and Recovery ; Direct-Push ; Artificial Recharge ; Groundwater Modeling ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 5
    Language: English
    In: Journal of Hydrology, 24 July 2013, Vol.496, pp.195-204
    Description: The characterization of hydraulic conductivity ( ) variations in heterogeneous aquifers has proven to be a significant challenge. Recent field and numerical assessments, however, have demonstrated the considerable potential of direct-push profiling for characterization of vertical variations at the resolution needed for contaminant site investigations. The direct-push permeameter (DPP), in particular, has been found to be an effective characterization tool (0.4-m resolution in current configuration) over the range expected in aquifers. The potential of this tool is explored further here through numerical simulations to assess the probe configuration and the analysis approach that are most appropriate for profiling in highly permeable heterogeneous systems. A probe configuration with transducers placed between 0.1 and 0.4 m from the injection screen appears to be most suitable for general field applications, as it can yield a reasonable resolution (few decimeters) in the presence of a typical level of sensor noise. DPP data are commonly analyzed using the spherical form of Darcy’s Law. Although this approach will provide reliable estimates in many situations, it can introduce error in the presence of thin (relative to the distance between injection screen and transducers) layers of vastly differing . Simultaneous numerical inversion (under steady-shape conditions) of all DPP tests in a profile can yield improved results if information about aquifer structure is available. DPP estimates have little sensitivity to the zone of compaction created during probe advancement, but estimates are sensitive to channeling along the probe surface. Proper probe design (probe shape and position of transducers) and test procedures (low injection rates) can reduce the potential for and impact of such channeling. These points are demonstrated using data from an outcrop study in which varies by orders of magnitude on the scale of a few decimeters.
    Keywords: Direct-Push Permeameter ; Hydraulic Conductivity ; Numerical Simulation ; High-Resolution Profiling ; Site Characterization ; Geography
    ISSN: 0022-1694
    E-ISSN: 1879-2707
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  • 6
    Language: English
    In: Journal of Hydrology, Sept 19, 2014, Vol.517, p.54(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhydrol.2014.05.003 Byline: Falk Handel, Gaisheng Liu, Peter Dietrich, Rudolf Liedl, James J. Butler Abstract: acents Small-diameter direct-push (DP) wells are a viable ASR recharge approach. acents Two 0.05-m shallow vadose-zone wells have a larger recharge rate than a 60m.sup.2 basin. acents Near-surface, low K-layers have a small impact on the well recharge capacity. acents DP well has a strong dependence on the horizontal component of hydraulic conductivity. Article History: Received 10 January 2014; Revised 3 May 2014; Accepted 4 May 2014 Article Note: (miscellaneous) This manuscript was handled by Peter K. Kitanidis, Editor-in-Chief, with the assistance of Ty Ferre, Associate Editor
    Keywords: Hydrogeology -- Analysis
    ISSN: 0022-1694
    Source: Cengage Learning, Inc.
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  • 7
    In: Geophysical Research Letters, March 2011, Vol.38(6), pp.n/a-n/a
    Description: Full‐resolution 3D Ground‐Penetrating Radar (GPR) data were combined with high‐resolution hydraulic conductivity () data from vertical Direct‐Push (DP) profiles to characterize a portion of the highly heterogeneous MAcro Dispersion Experiment (MADE) site. This is an important first step to better understand the influence of aquifer heterogeneities on observed anomalous transport. Statistical evaluation of DP data indicates non‐normal distributions that have much higher similarity within each GPR facies than between facies. The analysis of GPR and DP data provides high‐resolution estimates of the 3D geometry of hydrostratigraphic zones, which can then be populated with stochastic fields. The lack of such estimates has been a significant limitation for testing and parameterizing a range of novel transport theories at sites where the traditional advection‐dispersion model has proven inadequate.
    Keywords: Hydraulic Conductivity ; Full‐Resolution Gpr ; Hydrostratigraphy ; Heterogeneous Aquifer ; Made Site ; Direct‐Push Profiling
    ISSN: 0094-8276
    E-ISSN: 1944-8007
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  • 8
    Language: English
    In: Oecologia, 2010, Vol.162(2), pp.283-292
    Description: During a record drought (2006) in southwest Kansas, USA, we assessed groundwater dynamics in a shallow, unconfined aquifer, along with plant water sources and physiological responses of the invasive riparian shrub Tamarix ramosissima . In early May, diel water table fluctuations indicated evapotranspirative consumption of groundwater by vegetation. During the summer drought, the water table elevation dropped past the lowest position previously recorded. Concurrent with this drop, water table fluctuations abruptly diminished at all wells at which they had previously been observed despite increasing evapotranspirative demand. Following reductions in groundwater fluctuations, volumetric water content declined corresponding to the well-specific depths of the capillary fringe in early May, suggesting a switch from primary dependence on groundwater to vadose-zone water. In at least one well, the fluctuations appear to re-intensify in August, suggesting increased groundwater uptake by Tamarix or other non-senesced species from a deeper water table later in the growing season. Our data suggest that Tamarix can rapidly shift water sources in response to declines in the water table. The use of multiple water sources by Tamarix minimized leaf-level water stress during drought periods. This study illustrates the importance of the previous hydrologic conditions experienced by site vegetation for controlling root establishment at depth and demonstrates the utility of data from high-frequency hydrologic monitoring in the interpretation of plant water sources using isotopic methods.
    Keywords: Diel water table fluctuations ; Ecohydrology ; Phreatophyte ; Stable isotopes
    ISSN: 0029-8549
    E-ISSN: 1432-1939
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  • 9
    In: Geophysical Research Letters, 16 November 2014, Vol.41(21), pp.7560-7565
    Description: Successful prediction of groundwater flow and solute transport through highly heterogeneous aquifers has remained elusive due to the limitations of methods to characterize hydraulic conductivity () and generate realistic stochastic fields from such data. As a result, many studies have suggested that the classical advective‐dispersive equation (ADE) cannot reproduce such transport behavior. Here we demonstrate that when high‐resolution data are used with a fractal stochastic method that produces fields with adequate connectivity, the classical ADE can accurately predict solute transport at the macrodispersion experiment site in Mississippi. This development provides great promise to accurately predict contaminant plume migration, design more effective remediation schemes, and reduce environmental risks. Non‐Gaussian transport behavior at the MADE site is unraveledADE can reproduce tracer transport in heterogeneous aquifers with no calibrationNew fractal method generates heterogeneous K fields with adequate connectivity
    Keywords: Made Site ; Fractal Method ; Non‐Gaussian Transport ; Advective‐Dispersive Equation ; Hydraulic Conductivity ; Aquifer Characterization
    ISSN: 0094-8276
    E-ISSN: 1944-8007
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  • 10
    In: Ground Water, November 2010, Vol.48(6), pp.809-824
    Description: We offer a cautionary note in response to an increasing level of enthusiasm regarding high‐resolution aquifer characterization with hydraulic tomography. We use synthetic examples based on two recent field experiments to demonstrate that a high degree of nonuniqueness remains in estimates of hydraulic parameter fields even when those estimates are based on simultaneous analysis of a number of carefully controlled hydraulic tests. We must, therefore, be careful not to oversell the technique to the community of practicing hydrogeologists, promising a degree of accuracy and resolution that, in many settings, will remain unattainable, regardless of the amount of effort invested in the field investigation. No practically feasible amount of hydraulic tomography data will ever remove the need to regularize or bias the inverse problem in some fashion in order to obtain a unique solution. Thus, along with improving the resolution of hydraulic tomography techniques, we must also strive to couple those techniques with procedures for experimental design and uncertainty assessment and with other more cost‐effective field methods, such as geophysical surveying and, in unconsolidated formations, direct‐push profiling, in order to develop methods for subsurface characterization with the resolution and accuracy needed for practical field applications.
    Keywords: Aquifers -- Analysis ; Tomography -- Analysis ; Geophysical Surveying -- Analysis;
    ISSN: 0017-467X
    E-ISSN: 1745-6584
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