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Ground Water

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https://www.readbyqxmd.com/read/28297744/a-permanent-multilevel-monitoring-and-sampling-system-in-the-coastal-groundwater-mixing-zones
#1
Xin Luo, King Lun Kwok, Yi Liu, Jimmy Jiao
To study the spatial and temporal variability of water dynamics and chemical reactions within the coastal groundwater mixing zones (CGMZs), high-resolution periodical and spatial groundwater sampling within CGMZs is needed. However, current samplers and sampling systems may require heavy driving machines to install. There is also possible contamination from the metal materials for current samplers and sampling systems. Here, a permanent multilevel sampling system is designed to sample coastal groundwater within CGMZs...
March 15, 2017: Ground Water
https://www.readbyqxmd.com/read/28273686/the-impact-of-the-degree-of-aquifer-confinement-and-anisotropy-on-tidal-pulse-propagation
#2
Pin Shuai, Peter S K Knappett, Saddam Hossain, Alamgir Hosain, Kimberly Rhodes, Kazi Matin Ahmed, M Bayani Cardenas
Oceanic tidal fluctuations which propagate long distances up coastal rivers can be exploited to constrain hydraulic properties of riverbank aquifers. These estimates, however, may be sensitive to degree of aquifer confinement and aquifer anisotropy. We analyzed the hydraulic properties of a tidally influenced aquifer along the Meghna River in Bangladesh using: (1) slug tests combined with drilling logs and surface resistivity to estimate Transmissivity (T); (2) a pumping test to estimate T and Storativity (S) and thus Aquifer Diffusivity (DPT ); and (3) the observed reduction in the amplitude and velocity of a tidal pulse to calculate D using the Jacob-Ferris analytical solution...
March 8, 2017: Ground Water
https://www.readbyqxmd.com/read/28252808/controls-on-methane-occurrences-in-aquifers-overlying-the-eagle-ford-shale-play-south-texas
#3
Jean-Philippe Nicot, Toti Larson, Roxana Darvari, Patrick Mickler, Kristine Uhlman, Ruth Costley
Assessing natural vs. anthropogenic sources of methane in drinking water aquifers is a critical issue in areas of shale oil and gas production. The objective of this study was to determine controls on methane occurrences in aquifers in the Eagle Ford Shale play footprint. A total of 110 water wells were tested for dissolved light alkanes, isotopes of methane, and major ions, mostly in the eastern section of the play. Multiple aquifers were sampled with approximately 47 samples from the Carrizo-Wilcox Aquifer (250-1200 m depth range) and Queen City-Sparta Aquifer (150-900 m depth range) and 63 samples from other shallow aquifers but mostly from the Catahoula Formation (depth <150 m)...
March 2, 2017: Ground Water
https://www.readbyqxmd.com/read/28248422/methane-occurrences-in-aquifers-overlying-the-barnett-shale-play-with-a-focus-on-parker-county-texas
#4
Jean-Philippe Nicot, Patrick Mickler, Toti Larson, M Clara Castro, Roxana Darvari, Kristine Uhlman, Ruth Costley
Clusters of elevated methane concentrations in aquifers overlying the Barnett Shale play have been the focus of recent national attention as they relate to impacts of hydraulic fracturing. The objective of this study was to assess the spatial extent of high dissolved methane previously observed on the western edge of the play (Parker County) and to evaluate its most likely source. A total of 509 well water samples from 12 counties (14,500 km(2) ) were analyzed for methane, major ions, and carbon isotopes. Most samples were collected from the regional Trinity Aquifer and show only low levels of dissolved methane (85% of 457 unique locations <0...
March 1, 2017: Ground Water
https://www.readbyqxmd.com/read/28208223/conceptualization-of-karstic-aquifer-with-multiple-outlets-using-a-dual-porosity-model
#5
Seiyed Mossa Hosseini, Behzad Ataie-Ashtiani
In this study, two conceptual models, the classic reservoir (CR) model and exchange reservoirs model embedded by dual porosity approach (DPR) are developed for simulation of karst aquifer functioning drained by multiple outlets. The performances of two developed models are demonstrated at a less developed karstic aquifer with three spring outlets located in Zagros Mountain in the south-west of Iran using 22-years of daily data. During the surface recharge, a production function based on water mass balance is implemented for computing the time series of surface recharge to the karst formations...
February 16, 2017: Ground Water
https://www.readbyqxmd.com/read/28208211/changes-in-projected-spatial-and-seasonal-groundwater-recharge-in-the-upper-colorado-river-basin
#6
Fred D Tillman, Subhrendu Gangopadhyay, Tom Pruitt
The Colorado River is an important source of water in the western United States, supplying the needs of more than 38 million people in the United States and Mexico. Groundwater discharge to streams has been shown to be a critical component of streamflow in the Upper Colorado River Basin (UCRB), particularly during low-flow periods. Understanding impacts on groundwater in the basin from projected climate change will assist water managers in the region in planning for potential changes in the river and groundwater system...
February 16, 2017: Ground Water
https://www.readbyqxmd.com/read/28152165/estimating-pesticide-attenuation-from-water-dating-and-the-ratio-of-metabolite-to-parent-compound
#7
REVIEW
Julien Farlin, Michael Bayerle, Denis Pittois, Tom Gallé
Although pesticides are primarily degraded in the topsoil, significant attenuation can be expected in groundwater systems where the transit time of pesticides usually are orders of magnitude longer than in the soil. Because degradation and transport processes in the subsurface take place at time scales of months to years or even decades, direct measurements of natural attenuation are hampered by practical and logistical limitations (for instance the limited duration of sampling or a correct estimation of the pesticide flux into groundwater)...
February 2, 2017: Ground Water
https://www.readbyqxmd.com/read/28122410/estimating-river-conductance-from-prior-information-to-improve-surface-subsurface-model-calibration
#8
Yohann Cousquer, Alexandre Pryet, Nicolas Flipo, Célestine Delbart, Alain Dupuy
Most groundwater models simulate stream-aquifer interactions with a head-dependent flux boundary condition based on a river conductance (CRIV). CRIV is usually calibrated with other parameters by history matching. However, the inverse problem of groundwater models is often ill-posed and individual model parameters are likely to be poorly constrained. Ill-posedness can be addressed by Tikhonov regularization with prior knowledge on parameter values. The difficulty with a lumped parameter like CRIV, which cannot be measured in the field, is to find suitable initial and regularization values...
January 25, 2017: Ground Water
https://www.readbyqxmd.com/read/28102897/controls-on-methane-occurrences-in-shallow-aquifers-overlying-the-haynesville-shale-gas-field-east-texas
#9
Jean-Philippe Nicot, Toti Larson, Roxana Darvari, Patrick Mickler, Michael Slotten, Jordan Aldridge, Kristine Uhlman, Ruth Costley
Understanding the source of dissolved methane in drinking-water aquifers is critical for assessing potential contributions from hydraulic fracturing in shale plays. Shallow groundwater in the Texas portion of the Haynesville Shale area (13,000 km(2) ) was sampled (70 samples) for methane and other dissolved light alkanes. Most samples were derived from the fresh water bearing Wilcox formations and show little methane except in a localized cluster of 12 water wells (17% of total) in a approximately 30 × 30 km(2) area in Southern Panola County with dissolved methane concentrations less than 10 mg/L...
January 19, 2017: Ground Water
https://www.readbyqxmd.com/read/28072445/a-joint-analytic-method-for-estimating-aquitard-hydraulic-parameters
#10
Chao Zhuang, Zhifang Zhou, Walter A Illman
The vertical hydraulic conductivity (Kv ), elastic (Sske ), and inelastic (Sskv ) skeletal specific storage of aquitards are three of the most critical parameters in land subsidence investigations. Two new analytic methods are proposed to estimate the three parameters. The first analytic method is based on a new concept of delay time ratio for estimating Kv and Sske of an aquitard subject to long-term stable, cyclic hydraulic head changes at boundaries. The second analytic method estimates the Sskv of the aquitard subject to linearly declining hydraulic heads at boundaries...
January 10, 2017: Ground Water
https://www.readbyqxmd.com/read/28052325/prediction-of-remediation-of-a-heterogeneous-aquifer-a-case-study
#11
Ziv Moreno, Amir Paster
Contaminant plumes whose characteristic length is smaller than the horizontal integral scale of the hydraulic conductivity, K, are abundant in shallow, phreatic aquifers. In such cases, the aquifer can be regarded as layered, with K being only a function of the vertical coordinate. The heterogeneity of K has a critical role upon the efficiency of remediation of such sites, for example, by Pump and Treat schemes. The expected efficiency is a random variable, with uncertainty. Quantifying this uncertainty can be of great importance to decision making...
January 3, 2017: Ground Water
https://www.readbyqxmd.com/read/28268251/ngwa-news
#12
(no author information available yet)
No abstract text is available yet for this article.
March 2017: Ground Water
https://www.readbyqxmd.com/read/28140466/comment-on-drawdown-triggers-a-misguided-strategy-for-protecting-groundwater-fed-streams-and-springs-by-matthew-j-currell-2016-v-54-no-5-619-622
#13
LETTER
Robert Harrington, Keith Rainville, T Neil Blandford
No abstract text is available yet for this article.
March 2017: Ground Water
https://www.readbyqxmd.com/read/28140451/reply-to-harrington-et-al-s-comment-on-drawdown-triggers-a-misguided-strategy-for-protecting-groundwater-fed-streams-and-springs-by-matthew-j-currell-2016-v-54-no-5-619-622
#14
LETTER
https://www.readbyqxmd.com/read/28135400/the-amazingly-rapid-birth-growth-and-maturing-of-digital-computer-modeling-in-hydrogeology
#15
Fred J Molz
No abstract text is available yet for this article.
March 2017: Ground Water
https://www.readbyqxmd.com/read/28076657/geophysics-is-not-a-silver-bullet-but-worth-a-shot
#16
EDITORIAL
Kamini Singha
No abstract text is available yet for this article.
March 2017: Ground Water
https://www.readbyqxmd.com/read/28060995/fitting-the-transport-and-attachment-of-dense-biocolloids-in-one-dimensional-porous-media-colloidfit
#17
Vasileios E Katzourakis, Constantinos V Chrysikopoulos
No abstract text is available yet for this article.
March 2017: Ground Water
https://www.readbyqxmd.com/read/27893932/density-driven-free-convection-model-for-isotopically-fractionated-geogenic-nitrate-in-sabkha-brine
#18
Warren W Wood, J K Böhlke
Subsurface brines with high nitrate (NO3(-) ) concentration are common in desert environments as atmospheric nitrogen is concentrated by the evaporation of precipitation and little nitrogen uptake. However, in addition to having an elevated mean concentration of ∼525 mg/L (as N), NO3(-) in the coastal sabkhas of Abu Dhabi is enriched in (15) N (mean δ(15) N ∼17‰), which is an enigma. A NO3(-) solute mass balance analysis of the sabkha aquifer system suggests that more than 90% of the nitrogen is from local atmospheric deposition and the remainder from ascending brine...
March 2017: Ground Water
https://www.readbyqxmd.com/read/27727479/concurrent-salinization-and-development-of%C3%A2-anoxic-conditions-in-a-confined-aquifer-southern-israel
#19
Avihu Burg, Ittai Gavrieli, Joseph Guttman
An ancient, brackish, anoxic, and relatively hot water body exists within the Yarqon-Tanninim Aquifer in southern Israel. A hydrogeological-geochemical conceptual model is presented, whereby the low water quality is the outcome of three conditions that are met simultaneously: (1) Presence of an organic-rich unit with low permeability that overlies and confines the aquifer; the confining unit contains perched horizons with relatively saline water. (2) Local phreatic/roofed conditions within the aquifer that enable seepage of the organic-rich brackish water from above...
March 2017: Ground Water
https://www.readbyqxmd.com/read/27706812/multimodel-validity-assessment-of-groundwater-flow-simulation-models-using-area-metric-approach
#20
Omkar Aphale, David J Tonjes
We demonstrate the application of the Area Metric developed by Ferson et al. (2008) for multimodel validity assessment. The Area Metric quantified the degree of models' replicative validity: the degree of agreement between the observed data and the corresponding simulated outputs represented as their empirical cumulative distribution functions (ECDFs). This approach was used to rank multiple representations of a case study groundwater flow model of a landfill by their Area Metric scores. A multimodel approach allows to account for uncertainties that may either be epistemic (from lack of knowledge) or aleatory (from variability inherent in the system)...
March 2017: Ground Water
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