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Ground Water

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https://www.readbyqxmd.com/read/28940508/evaluating-renewable-groundwater-stress-with-grace-data-in-greece
#1
Alexandra Gemitzi, Venkat Lakshmi
Groundwater is a resilient water source and its importance is even greater in periods of drought. Areas such as the Mediterranean where adverse climate change effects are expected are bell-weather locations for groundwater depletion and are of considerable interest. The present study evaluates renewable groundwater stress (RGS) as the ratio of groundwater use to groundwater availability, quantifying use as the trend in gravity recovery and climate experiment-derived (GRACE) subsurface anomalies (ΔGWtrend ) and renewable groundwater availability as mean annual recharge...
September 22, 2017: Ground Water
https://www.readbyqxmd.com/read/28940442/presence-of-antibiotics-in-shallow-groundwater-in-the-northern-and-southwestern-regions-of-china
#2
Liang Chen, Hang Lang, Fei Liu, Song Jin, Tao Yan
Antibiotics are widely used, and there is a serious concern about its adverse impacts on the environment and human health. To our knowledge, prior to this work, there was no evidence of the potential presence of antibiotics in groundwater in China, despite populous speculations. This study reported the detection of 35 target antibiotics of 6 groups (chloramphenicois, lincosamides, marcrolides, quinolones, sulfonamides, and tetracyclines), in shallow groundwater samples collected in northern and southwestern China...
September 21, 2017: Ground Water
https://www.readbyqxmd.com/read/28940370/evaluation-of-bias-associated-with-capture-maps-derived-from-nonlinear-groundwater-flow-models
#3
Cara Nadler, Kip Allander, Greg Pohll, Eric Morway, Ramon Naranjo, Justin Huntington
The impact of groundwater withdrawal on surface water is a concern of water users and water managers, particularly in the arid western United States. Capture maps are useful tools to spatially assess the impact of groundwater pumping on water sources (e.g., streamflow depletion) and are being used more frequently for conjunctive management of surface water and groundwater. Capture maps have been derived using linear groundwater flow models and rely on the principle of superposition to demonstrate the effects of pumping in various locations on resources of interest...
September 21, 2017: Ground Water
https://www.readbyqxmd.com/read/28940246/the-elder-problem
#4
Craig T Simmons, John W Elder
No abstract text is available yet for this article.
September 21, 2017: Ground Water
https://www.readbyqxmd.com/read/28940231/the-toth-revolution
#5
John D Bredehoeft
No abstract text is available yet for this article.
September 21, 2017: Ground Water
https://www.readbyqxmd.com/read/28914971/extending-data-worth-analyses-to-select-multiple-observations-targeting-multiple-forecasts
#6
Troels N Vilhelmsen, Ty P A Ferré
Hydrological models are often set up to provide specific forecasts of interest. Owing to the inherent uncertainty in data used to derive model structure and used to constrain parameter variations, the model forecasts will be uncertain. Additional data collection is often performed to minimize this forecast uncertainty. Given our common financial restrictions, it is critical that we identify data with maximal information content with respect to forecast of interest. In practice, this often devolves to qualitative decisions based on expert opinion...
September 15, 2017: Ground Water
https://www.readbyqxmd.com/read/28910853/impacts-of-streambed-heterogeneity-and-anisotropy-on-residence-time-of-hyporheic-zone
#7
Suning Liu, Ting Fong May Chui
The hyporheic zone (HZ), which is the region beneath or alongside a streambed, plays an important role in the stream's ecology. The duration that a water molecule or a solute remains within the HZ, or residence time (RT), is one of the most common metrics used to evaluate the function of the HZ. The RT is greatly influenced by the streambed's hydraulic conductivity (K), which is intrinsically difficult to characterize due to its heterogeneity and anisotropy. Many laboratory and numerical studies of the HZ have simplified the streambed K to a constant, thus producing RT values that may differ from those gathered from the field...
September 14, 2017: Ground Water
https://www.readbyqxmd.com/read/28910852/origin-and-evolution-of-aquitard-porewater-in-the-western-coastal-plain-of-bohai-bay-china
#8
Jing Li, Xing Liang, Menggui Jin, Jilong Yang, Bin Ma, Qin Ge
High-salinity paleowater from low-permeability aquitards in coastal areas can be a major threat to groundwater resources; however, such water has rarely been studied. The chemical and isotopic compositions of porewater extracted from a 200-m-thick Quaternary sedimentary sequence in the western coastal plain of Bohai Bay, China, were analyzed to investigate the salinity origin and chemical evolution of porewater in aquitards. Porewater samples derived at depths shallower than 32 m are characterized by Cl-Na type saline water (total dissolved solids [TDS], 10...
September 14, 2017: Ground Water
https://www.readbyqxmd.com/read/28873502/bioremediation-in-fractured-rock-1-modeling-to-inform-design-monitoring-and-expectations
#9
Claire R Tiedeman, Allen M Shapiro, Paul A Hsieh, Thomas E Imbrigiotta, Daniel J Goode, Pierre J Lacombe, Mary F DeFlaun, Scott R Drew, Carole D Johnson, John H Williams, Gary P Curtis
Field characterization of a trichloroethene (TCE) source area in fractured mudstones produced a detailed understanding of the geology, contaminant distribution in fractures and the rock matrix, and hydraulic and transport properties. Groundwater flow and chemical transport modeling that synthesized the field characterization information proved critical for designing bioremediation of the source area. The planned bioremediation involved injecting emulsified vegetable oil and bacteria to enhance the naturally occurring biodegradation of TCE...
September 5, 2017: Ground Water
https://www.readbyqxmd.com/read/28873499/bioremediation-in-fractured-rock-2-mobilization-of-chloroethene-compounds-from-the-rock-matrix
#10
Allen M Shapiro, Claire R Tiedeman, Thomas E Imbrigiotta, Daniel J Goode, Paul A Hsieh, Pierre J Lacombe, Mary F DeFlaun, Scott R Drew, Gary P Curtis
A mass balance is formulated to evaluate the mobilization of chlorinated ethene compounds (CE) from the rock matrix of a fractured mudstone aquifer under pre- and postbioremediation conditions. The analysis relies on a sparse number of monitoring locations and is constrained by a detailed description of the groundwater flow regime. Groundwater flow modeling developed under the site characterization identified groundwater fluxes to formulate the CE mass balance in the rock volume exposed to the injected remediation amendments...
September 5, 2017: Ground Water
https://www.readbyqxmd.com/read/28873498/a-python-script-to-compute-isochrones-for-modflow
#11
Alessandra Feo, Andrea Zanini, Emma Petrella, Fulvio Celico
MODFLOW constitutes today the most popular modeling tool in the study of water flow in aquifers and in modeling aquifers. To simplify the interface to MODFLOW various GUI have been developed for the creation of model definition files and for the visualization and interpretation of results. Recently Bakker et al. (2016) developed the FloPy interface to MODFLOW that allows to import and use the produced simulation data using Python. This allows to construct model input files, run the models, read and plot simulations results through Python scripts...
September 5, 2017: Ground Water
https://www.readbyqxmd.com/read/28873497/calculating-groundwater-response-times-for-flow-in-heterogeneous-porous-media
#12
Matthew J Simpson
Predicting the amount of time required for a transient groundwater response to take place is a practical question that is of interest in many situations. This time scale is often called the response time. In the groundwater hydrology literature, there are two main methods used to calculate the response time: (1) both the transient and steady-state groundwater flow equations are solved, and the response time is taken to be amount of time required for the transient solution to approach the steady solution within some tolerance; and (2) simple scaling arguments are adopted...
September 5, 2017: Ground Water
https://www.readbyqxmd.com/read/28853150/data-driven-approach-for-analyzing-hydrogeology-and-groundwater-quality-across-multiple-scales
#13
Zachary K Curtis, Shu-Guang Li, Hua-Sheng Liao, David Lusch
Recent trends of assimilating water well records into statewide databases provide a new opportunity for evaluating spatial dynamics of groundwater quality and quantity. However, these datasets are scarcely rigorously analyzed to address larger scientific problems because they are of lower quality and massive. We develop an approach for utilizing well databases to analyze physical and geochemical aspects of groundwater systems, and apply it to a multiscale investigation of the sources and dynamics of chloride (Cl(-) ) in the near-surface groundwater of the Lower Peninsula of Michigan...
August 29, 2017: Ground Water
https://www.readbyqxmd.com/read/28853149/assessing-methane-in-shallow-groundwater-in-unconventional-oil-and-gas-play-areas-eastern-kentucky
#14
Junfeng Zhu, Thomas M Parris, Charles J Taylor, Steven E Webb, Bart Davidson, Richard Smath, Stephen D Richardson, Lisa J Molofsky, Jenna S Kromann, Ann P Smith
The expanding use of horizontal drilling and hydraulic fracturing technology to produce oil and gas from tight rock formations has increased public concern about potential impacts on the environment, especially on shallow drinking water aquifers. In eastern Kentucky, horizontal drilling and hydraulic fracturing have been used to develop the Berea Sandstone and the Rogersville Shale. To assess baseline groundwater chemistry and evaluate methane detected in groundwater overlying the Berea and Rogersville plays, we sampled 51 water wells and analyzed the samples for concentrations of major cations and anions, metals, dissolved methane, and other light hydrocarbon gases...
August 29, 2017: Ground Water
https://www.readbyqxmd.com/read/28853140/groundwater-modeling-with-stakeholders-finding-the-complexity-that-matters
#15
Juan Carlos Castilla-Rho
No abstract text is available yet for this article.
August 29, 2017: Ground Water
https://www.readbyqxmd.com/read/28853137/water-table-uncertainties-due-to-uncertainties-in-structure-and-properties-of-an-unconfined-aquifer
#16
Juerg Hauser, Florian Wellmann, Mike Trefry
We consider two sources of geology-related uncertainty in making predictions of the steady-state water table elevation for an unconfined aquifer. That is the uncertainty in the depth to base of the aquifer and in the hydraulic conductivity distribution within the aquifer. Stochastic approaches to hydrological modeling commonly use geostatistical techniques to account for hydraulic conductivity uncertainty within the aquifer. In the absence of well data allowing derivation of a relationship between geophysical and hydrological parameters, the use of geophysical data is often limited to constraining the structural boundaries...
August 29, 2017: Ground Water
https://www.readbyqxmd.com/read/28834591/estimating-travel-time-in-bank-filtration-systems-from-a-numerical-model-based-on-dts-measurements
#17
Bas F des Tombe, Mark Bakker, Frans Schaars, Kees-Jan van der Made
An approach is presented to determine the seasonal variations in travel time in a bank filtration system using a passive heat tracer test. The temperature in the aquifer varies seasonally because of temperature variations of the infiltrating surface water and at the soil surface. Temperature was measured with distributed temperature sensing along fiber optic cables that were inserted vertically into the aquifer with direct push equipment. The approach was applied to a bank filtration system consisting of a sequence of alternating, elongated recharge basins and rows of recovery wells...
August 23, 2017: Ground Water
https://www.readbyqxmd.com/read/28833070/application-of-groundwater-vulnerability-overlay-and-index-methods-to-the-jijel-plain-area-algeria
#18
Abdelmadjid Boufekane, Omar Saighi
Today, scientists are deeply concerned by the vulnerability of groundwater reservoirs to pollution. Relatively simple overlay and index methods can be used to produce groundwater vulnerability maps in geographic information system. In addition, this study deals with contamination from nonpoint sources. In this study, two such models, DRASTIC and GOD, were applied in the Jijel Plain area of northeast Algeria and compared with measured groundwater nitrate concentrations. This showed that results from DRASTIC were better than GOD, 69% correlation with nitrate compared to 56%...
August 21, 2017: Ground Water
https://www.readbyqxmd.com/read/28810076/groundwater-development-stress-global-scale-indices-compared-to-regional-modeling
#19
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
https://www.readbyqxmd.com/read/28810075/a-b-spline-framework-for-smooth-derivative-computation-in-well-test-analysis-using-diagnostic-plots
#20
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
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