Modeling the Usefulness of Spatial Correlation Analysis on Karst Systems     

by Trevor J. Budge  and John M. Sharp Jr. 《Ground water》2009,47(3):427-437

Cross-correlation analyses on field data collected in karst aquifer systems can be used to develop a conceptual understanding of the aquifer. This includes the use of many data sets from the same aquifer to develop an understanding of how properties vary spatially. We focus on a method for characterizing the distribution of recharge, which is becoming increasingly important in regions where urban development encroaches on these important sources of water. Spatially varying precipitation data and cross-correlation analysis provide a means of spatially characterizing recharge locations on a karst aquifer. Our work expands on the numerical experiments conducted by Padilla and Pulido-Bosch (1995) using the numerical ground water model MODFLOW to introduce spatially varying parameters. The numerical experiments include conduit-controlled, matrix-controlled, and mixed karst systems with more than one precipitation time series input. The results show that spatially varying parameters can be inferred based on the cross-correlation of precipitation data and spring discharge. Simulations were completed using aquifer parameters derived from studies of the Barton Springs segment of the Edwards Aquifer. The simulations indicate that spatial variability within an aquifer can be inferred using cross-correlation analysis. A field study using these methods is summarized for Barton Springs near Austin, Texas.  相似文献   

William "Bill" Back: An Incisive Geochemist and a Great Mentor     

by Mary Jo Baedecker  and Warren W. Wood 《Ground water》2009,47(2):314-318

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Springs and the Origin of Bourbon     

by Alan E. Fryar 《Ground water》2009,47(4):605-610

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Distinguishing Iron-Reducing from Sulfate-Reducing Conditions   总被引：2，自引：0，他引：2  

by Francis H. Chapelle  Paul M. Bradley  Mary Ann Thomas  and Peter B. McMahon 《Ground water》2009,47(2):300-305

Ground water systems dominated by iron‐ or sulfate‐reducing conditions may be distinguished by observing concentrations of dissolved iron (Fe²⁺) and sulfide (sum of H₂S, HS^?, and S⁼ species and denoted here as “H₂S”). This approach is based on the observation that concentrations of Fe²⁺ and H₂S in ground water systems tend to be inversely related according to a hyperbolic function. That is, when Fe²⁺ concentrations are high, H₂S concentrations tend to be low and vice versa. This relation partly reflects the rapid reaction kinetics of Fe²⁺ with H₂S to produce relatively insoluble ferrous sulfides (FeS). This relation also reflects competition for organic substrates between the iron‐ and the sulfate‐reducing microorganisms that catalyze the production of Fe²⁺ and H₂S. These solubility and microbial constraints operate in tandem, resulting in the observed hyperbolic relation between Fe²⁺ and H₂S concentrations. Concentrations of redox indicators, including dissolved hydrogen (H₂) measured in a shallow aquifer in Hanahan, South Carolina, suggest that if the Fe²⁺/H₂S mass ratio (units of mg/L) exceeded 10, the screened interval being tapped was consistently iron reducing (H₂～0.2 to 0.8 nM). Conversely, if the Fe²⁺/H₂S ratio was less than 0.30, consistent sulfate‐reducing (H₂～1 to 5 nM) conditions were observed over time. Concomitantly high Fe²⁺ and H₂S concentrations were associated with H₂ concentrations that varied between 0.2 and 5.0 nM over time, suggesting mixing of water from adjacent iron‐ and sulfate‐reducing zones or concomitant iron and sulfate reduction under nonelectron donor–limited conditions. These observations suggest that Fe²⁺/H₂S mass ratios may provide useful information concerning the occurrence and distribution of iron and sulfate reduction in ground water systems.  相似文献   

Recollections of an Inquiring Engineer     

by Ken Rushton 《Ground water》2009,47(5):745-749

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Joint Sustainability of Petroleum Energy Production and Water Resources     

by John E. McCray  Geoffrey D. Thyne 《Ground water》2009,47(5):611-611

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KT3D_H2O: A Program for Kriging Water Level Data Using Hydrologic Drift Terms     

by Marinko Karanovic  Matthew Tonkin  David Wilson 《Ground water》2009,47(4):580-586

It is often necessary to estimate the zone of contribution to, or the capture zone developed by, pumped wells: for example, when evaluating pump-and-treat remedies and when developing wellhead protection areas for supply wells. Tonkin and Larson (2002) and Brochu and Marcotte (2003) describe a mapping-based method for estimating the capture zone of pumped wells, developed by combining universal kriging (kriging with a trend) with analytical expressions that describe the response of the potentiometric surface to certain applied stresses. This Methods Note describes (a) expansions to the techinque described by Tonkin and Larson (2002) ; (b) the concept of the capture frequency map (CFM), a technique that combines information from multiple capture zone maps into a single depiction of capture; (c) the development of a graphical user interface to facilitate the use of the methods described; and (d) the integration of these programs within the MapWindow geographic information system environment. An example application is presented that illustrates ground water level contours, capture zones, and a CFM prepared using the methods and software described.  相似文献   

The Word Style "Groundwater" Reflects Increased Public Awareness of the Resource     

by Vicki Kretsinger Grabert 《Ground water》2009,47(4):470-474

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Fracture Control of Ground Water Flow and Water Chemistry in a Rock Aquitard     

Comment by Vedat Batu 《Ground water》2009,47(4):488-489

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Using Orthogonal Array Sampling to Cope with Uncertainty in Ground Water Problems     

by Husam Baalousha 《Ground water》2009,47(5):709-713

Uncertainty in ground water hydrology originates from different sources. Neglecting uncertainty in ground water problems can lead to incorrect results and misleading output. Several approaches have been developed to cope with uncertainty in ground water problems. The most widely used methods in uncertainty analysis are Monte Carlo simulation (MCS) and Latin hypercube sampling (LHS), developed from MCS. Despite the simplicity of MCS, many runs are required to achieve a reliable result. This paper presents orthogonal array (OA) sampling as a means to cope with uncertainty in ground water problems. The method was applied to an analytical stream depletion problem. To examine the convergence rate of the OA sampling, the results were compared to MCS and LHS. This study shows that OA can be applied to ground water problems. Results reveal that the convergence rate of the OA sampling is faster than MCS and LHS, with a smaller error of estimate when applied to a stream depletion problem.  相似文献