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  • 1
    Electronic Resource
    Electronic Resource
    Effective hydraulic conductivity of nonstationary aquifers (1994)
    Springer
    Stochastic environmental research and risk assessment 8 (1994), S. 1-17 
    Details
    ISSN: 1436-3259
    Keywords: Stochastic diffusion equations ; effective hydraulic conductivity ; correlation scale ; heterogeneous aquifers ; spectral representation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Assuming that the ln hydraulic conductivity in an aquifer is mathematically approximated by a spatial deterministic “surface”, or trend, plus a stationary random noise, we treat the problem of finding what the effective hydraulic conductivity of that aquifer is. This problem is tackled by spectral methods applied to a type of diffusion equation of groundwater flow, together with suitable coordinate transformations. Analytical (exact) solutions in terms of elementary functions are presented for one- and three-dimensional finite and infinite domains. Stability criteria are obtained for the solutions, in terms of a critical parameter, that turns out to involve the product of correlation scale and trend gradient. For the case of finite and symmetrical domains, additional provisions to insure the stability of numerical calculations of effective hydraulic conductivity are provided. Effective hydraulic conductivity is an important property, with potential applications in the calibrations of groundwater and transport numerical models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01581388
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of Two-Dimensional Mass Transport Modeling on Groundwater Monitoring Configurations (2000)
    Springer
    Bulletin of environmental contamination and toxicology 64 (2000), S. 1-7 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001289910001
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  • 3
    Electronic Resource
    Electronic Resource
    Groundwater modeling applied to production well management in a contaminated aquifer (1994)
    Springer
    Environmental geology 23 (1994), S. 119-124 
    Details
    ISSN: 1432-0495
    Keywords: Well field production ; Numerical modeling ; Groundwater pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A study was conducted to evaluate production strategies for a well field system near a source of groundwater contamination. Numerical modeling of groundwater flow was employed to generate hydraulic head configurations for different production scenarios. For a given scenario, an evaluation of contamination susceptibility was made by comparing head distributions in two aquifer units to the positions of the contaminant source and discharging water supply wells. The results of this study suggest that groundwater flow modeling can be a useful technique for planning the production of water supply wells in aquifers at risk of contamination from anthropogenic pollution sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00766985
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  • 4
    Electronic Resource
    Electronic Resource
    Evaluation of a capture zone overlay method for designing groundwater remediation systems (1997)
    Springer
    Environmental geology 31 (1997), S. 21-26 
    Details
    ISSN: 1432-0495
    Keywords: Key words Groundwater remediation ; Capture zones ; Pumping wells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Simplified approaches are often used to model the removal of groundwater contamination. These approaches can yield poor remediation schemes because they incorrectly portray the effects of multiple pumping wells. In this study, a pumping configuration designed by graphically overlaying capture zones having an identical, quasi-elliptical shape was evaluated with a numerical mass transport model. After a 3-year period (within which the hypothetical aquifer was to be remediated) the contaminant mass had been reduced by 77%. Due to stagnation zones which developed between extraction wells, approximately 15 years of pumping was required to remediate the aquifer with the overlay configuration. An alternative design, consisting of an extraction well between two injection wells along the long axis of the plume, removed the contaminant within the 3-year design period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002540050159
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  • 5
    Electronic Resource
    Electronic Resource
    Distribution of indoor radon concentrations and uranium-bearing rocks in Texas (1996)
    Springer
    Environmental geology 28 (1996), S. 29-33 
    Details
    ISSN: 1432-0495
    Keywords: Key words Radon ; Texas ; Uranium-bearing rock formations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The purpose of this study was to compare regional patterns of indoor radon concentration with uranium-bearing rock zones and county populations in Texas. Zones yielding radon concentrations that are relatively high for Texas include shale and sandstone in northwest Texas; red beds in north-central Texas; felsic volcanic rocks in west Texas; and sandstone, limestone, and igneous rocks in central Texas. Located in northwest Texas, only five of the 202 counties evaluated have mean indoor radon concentrations above 4.0 pCi l–1. Two of those counties have populations above the state median of 20 115. The highest county mean concentration is 8.8 pCi l–1. Results of this study suggest that (1) regional geology influences indoor radon concentrations in Texas, (2) statewide, the radon concentrations are relatively low, (3) highly populated counties do not coincide with regions of high indoor radon concentration, and (4) regions that may warrant further monitoring include northwest Texas and, to a lesser degree, west and central Texas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002540050075
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  • 6
    Electronic Resource
    Electronic Resource
    Effective porosity of unconsolidated sand; Estimation and impact on capture zone geometry (1994)
    Springer
    Environmental geology 24 (1994), S. 140-143 
    Details
    ISSN: 1432-0495
    Keywords: Effective porosity ; Groundwater capture zone ; Permeameter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Effective and total porosity were measured for three sand samples, and a computer model was used to evaluate the impact of effective porosity (n e ) on the geometry of a groundwater capture zone. Estimates of effective porosity ranged from 90 to 94 percent of values obtained for total porosity. While the magnitude of effective porosity is inversely proportional to capture zone area, the upgradient radius of capture is most sensitive to changes in the magnitude ofn e . Incremental changes in the magnitude ofn e have the greatest impact on capture zone radii for low values ofn e . The results of this study suggest that: (1) a simple permeameter and vacuum pump apparatus can facilitate the estimation of effective porosity for unconsolidated sands, (2) the magnitude of effective porosity is close to that of total porosity for unconsolidated sand, and (3) accurate estimates of effective porosity are important for modeling the remediation of contaminated groundwater with capture zones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00767887
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  • 7
    Electronic Resource
    Electronic Resource
    Procedure for Upgrading Contaminant-Detection Networks in Aquifers (2000)
    Springer
    Bulletin of environmental contamination and toxicology 65 (2000), S. 62-69 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s0012800095
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  • 8
    Electronic Resource
    Electronic Resource
    Stochastic groundwater flow analysis in the presence of trends in heterogeneous hydraulic conductivity fields (1993)
    Springer
    Mathematical geology 25 (1993), S. 161-176 
    Details
    ISSN: 1573-8868
    Keywords: hydraulic conductivity ; spectral theory ; groundwater flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Due to changes in lithostatic pressure, differential fracturing across bedding planes and irregularities in depositional environments, hydraulic conductivity exhibits heterogeneities and trends at various spatial scales. Using spectral theory, we have examined the effect of trends in hydraulic conductivity on (1) the solution of the mean equation for hydraulic head, (2) the covariance of hydraulic head, (3) the cross-covariances of hydraulic head and log-hydraulic conductivity perturbations and their gradients, and (4) the effective hydraulic conductivity. It is shown that the field of hydraulic head is sensitive to the presence of trends in ways that cannot be predicted by the classical analysis based on stationary hydraulic conductivity fields. The controlling variables for the second moments of hydraulic head are the mean hydraulic gradient, the correlation scale of log-hydraulic conductivity and its variance, and the slope of the trend in log-hydraulic conductivity. The mean hydraulic gradient introduces complications in the analysis since it is, in general, spatially variable. In this respect, our results are approximate, yet indicative of the true role of spatially variable patterns of log-hydraulic conductivity on groundwater flow systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00893271
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  • 9
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    Effects of Two-Dimensional Mass Transport Modeling on Groundwater Monitoring Configurations (2000)
    Springer
    Details
    Publication Date: 2000-01-01
    Print ISSN: 0007-4861
    Electronic ISSN: 1432-0800
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Springer
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  • 10
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    Monitoring Groundwater at Landfills Equipped with Leachate Collection Systems (2001)
    Springer
    Details
    Publication Date: 2001-02-01
    Print ISSN: 0007-4861
    Electronic ISSN: 1432-0800
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Springer
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