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Ground Water

William M Alley, Brian R Clark, David M Ely, Claudia C Faunt
The increased availability of global datasets and technologies such as global hydrologic models and the Gravity Recovery and Climate Experiment (GRACE) satellites have resulted in a growing number of global-scale assessments of water availability using simple indices of water stress. Developed initially for surface water, such indices are increasingly used to evaluate global groundwater resources. We compare indices of groundwater development stress for three major agricultural areas of the United States to information available from regional water budgets developed from detailed groundwater modeling...
August 15, 2017: Ground Water
Josué Tago, Antonio Hernández-Espriú
In the oil and gas industry, well test analysis using derivative plots, has been the core technique in examining reservoir and well behavior over the last three decades. Recently, diagnostics plots have gained recognition in the field of hydrogeology; however, this tool is still underused by groundwater professionals. The foremost drawback is that the derivative function must be computed from noisy field measurements, usually based on finite-difference schemes, which complicates the analysis. We propose a B-spline framework for smooth derivative computation, referred to as Constrained Quartic B-Splines with Free Knots...
August 15, 2017: Ground Water
Claire Sayler, Michael Cardiff, Michael D Fort
An understanding of the spatial and hydraulic properties of fast preferential flow pathways in the subsurface is necessary in applications ranging from contaminant fate and transport modeling to design of energy extraction systems. One method for the characterization of fracture properties over interwellbore scales is Multiperiod Oscillatory Hydraulic (MOH) testing, in which the aquifer response to oscillatory pressure stimulations is observed. MOH tests were conducted on isolated intervals of wells in siliciclastic and carbonate aquifers in southern Wisconsin...
August 15, 2017: Ground Water
Helen Fillmore
No abstract text is available yet for this article.
August 14, 2017: Ground Water
Ty P A Ferré
We hydrologists can do a better job of supporting water-resources decision-making. I will argue that we can do this by recognizing that decision makers use qualitative, multiple-narrative approaches. So, rather than providing single-model predictions with quantitative uncertainties, we should develop teams of rival models that inform decision makers about what is known, what is possible, and what is unknown. This requires that we build ensembles of models that include biased, advocacy models that directly represent stakeholders' interests or concerns...
August 9, 2017: Ground Water
Ty P A Ferré
No abstract text is available yet for this article.
August 8, 2017: Ground Water
Crystal D Johnson, Arpita Nandi, T Andrew Joyner, Ingrid Luffman
For health, economic, and aesthetic reasons, allowable concentrations (as suggested by the United States Environmental Protection Agency) of the secondary contaminants iron (Fe) and manganese (Mn) found present in drinking water are 0.3 and 0.05 mg/L, respectively. Water samples taken from private drinking wells in rural communities within Buncombe County, North Carolina contain concentrations of these metals that exceed secondary water quality criteria. This study predicted the spatial distribution of Fe and Mn in the county, and evaluated the effect of site environmental factors (bedrock geology, ground elevation, saprolite thickness, and drinking water well depth) in controlling the variability of Fe and Mn in groundwater...
August 1, 2017: Ground Water
Shuji Tamamura, Kazuya Miyakawa, Noritaka Aramaki, Toshifumi Igarashi, Katsuhiko Kaneko
Gas-saturated groundwater forms bubbles when brought to atmospheric pressure, preventing precise determination of its in situ dissolved gas concentrations. To overcome this problem, a modeling approach called the atmospheric sampling method is suggested here to recover the in situ dissolved gas concentrations of groundwater collected ex situ under atmospheric conditions at the Horonobe Underground Research Laboratory, Japan. The results from this method were compared with results measured at the same locations using two special techniques, the sealed sampler and pre-evacuated vial methods, that have been developed to collect groundwater under its in situ conditions...
August 1, 2017: Ground Water
Franklin W Schwartz, Ganming Liu, Pradeep Aggarwal, Cynthia M Schwartz
Concepts of simplicity and complexity in modeling have been explored in papers, editorials, and talks. The concept is not well understood because there are at least two flavors of simplicity. Modelers envision simplicity (i.e., elegant simplicity) as the sought-after goal in modeling, but naïve simplicity, which is the focus of this paper, is commonly unrecognized and dangerous. The problem is that naïve or simple ideas are often mistaken for settled science and come with the prospect of being more wrong than right...
July 25, 2017: Ground Water
Colin Kikuchi
No abstract text is available yet for this article.
July 21, 2017: Ground Water
Katie M Glodzik
No abstract text is available yet for this article.
July 21, 2017: Ground Water
Kevin Hayley
No abstract text is available yet for this article.
July 21, 2017: Ground Water
Jean Marçais, Jean-Raynald de Dreuzy
No abstract text is available yet for this article.
July 21, 2017: Ground Water
Scott K Hansen, Velimir V Vesselinov
In modeling solute transport with mobile-immobile mass transfer (MIMT), it is common to use an advection-dispersion equation (ADE) with a retardation factor, or retarded ADE. This is commonly referred to as making the local equilibrium assumption (LEA). Assuming local equilibrium, Eulerian textbook treatments derive the retarded ADE, ostensibly exactly. However, other authors have presented rigorous mathematical derivations of the dispersive effect of MIMT, applicable even in the case of arbitrarily fast mass transfer...
July 19, 2017: Ground Water
Xin Peng, Hongbin Zhan
Measuring a disconnected streambed seepage flux using a seepage meter can give important streambed information and help understanding groundwater-surface water interaction. In this study, we provide a correction for calculating the seepage flux rate with the consideration of air compressibility inside the manometer of the Bouwer and Rice seepage meter. We notice that the effect of air compressibility in the manometer is considerably larger when more air is included in the manometer. We find that the relative error from neglecting air compressibility can be constrained within 5% if the manometer of the Bouwer and Rice seepage meter is shorter than 0...
July 17, 2017: Ground Water
Luk J M Peeters
No abstract text is available yet for this article.
July 17, 2017: Ground Water
Anneli Guthke
No abstract text is available yet for this article.
July 17, 2017: Ground Water
Ombretta Paladino, Arianna Moranda, Marco Massabò, Gary A Robbins
Despite the availability of numerical models, interest in analytical solutions of multidimensional advection-dispersion systems remains high. Such models are commonly used for performing Tier I risk analysis and are embedded in many regulatory frameworks dealing with groundwater contamination. In this work, we develop a closed-form solution of the three-dimensional advection-dispersion equation with exponential source decay, first-order reaction, and retardation, and present an approach based on some ease of use diagrams to compare it with the integral open form solution and with earlier versions of the closed-form solution...
July 17, 2017: Ground Water
Andrew T Leaf
No abstract text is available yet for this article.
July 17, 2017: Ground Water
Philip Womble
No abstract text is available yet for this article.
July 17, 2017: Ground Water
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