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Ground Water

Jui-Pin Tsai, Ping-Yu Chang, Tian-Chyi Jim Yeh, Liang-Cheng Chang, Chin-Tsai Hsiao
We constructed an apparent geological model with resistivity data from surface resistivity surveys. We developed a data fusion approach by integrating dense electrical resistivity measurements collected with Schlumberger arrays and wellbore logs. This approach includes an optimization algorithm and a geostatistic interpolation method. We first generated an apparent formation factor model from the surface resistivity measurements and groundwater resistivity records with an inverse distance method. We then converted the model into a geology model with the optimized judgment criteria from the algorithms relating the apparent formation factors to the borehole geology...
September 21, 2018: Ground Water
Warren W Wood, Dave Hyndman
No abstract text is available yet for this article.
September 19, 2018: Ground Water
Gaisheng Liu, Robert C Borden, James J Butler
Direct push injection logging (DPIL) has become one of the most widely used approaches for obtaining vertical profiles of hydraulic conductivity (K) in environmental site investigations. Despite its widespread use, however, there has been no rigorous analysis of the underlying physical processes that take place during DPIL or how the approach would perform under different hydrogeological and operating conditions. We address these issues through a series of numerical simulations. Results show that the ratio of DPIL injection rate over pressure can be used for direct determination of K when K is >10-6 m/s...
September 4, 2018: Ground Water
Margaret Shanafield, Peter G Cook, Craig T Simmons
Gas production from unconventional reservoirs has led to widespread environmental concerns. Despite several excellent reviews of various potential impacts to water resources from unconventional gas production, no study has systematically and quantitatively assessed the potential for these impacts to occur. We use empirical evidence and numerical and analytical models to quantify the likelihood of surface water and groundwater contamination, and shallow aquifer depletion from unconventional gas developments...
August 29, 2018: Ground Water
Mahrez Boulabeiz, Stefan Klebingat, Siham Agaguenia
The quaternary coastal Collo aquifer in North-East Algeria (NE-Algeria) marks an important local water resource supporting domestic, industrial and agricultural activities. The aquifer shows signs of contamination due to the existence of various pollution sources, especially nitrogen compounds. Focusing the local identification of key vulnerable zones and related main hazard types for wise future water management, the present study highlights results from a coupled analysis of the well-established GIS-based GOD (Groundwater occurrence, Overall aquifer class, Depth to groundwater) hazard index analysis and the COST Action 620 plan...
August 29, 2018: Ground Water
Lei Ju, Jiangjiang Zhang, Laosheng Wu, Lingzao Zeng
Heat tracing methods have been widely employed for subsurface characterization. Nevertheless, there were very few studies regarding the optimal monitoring design for heat tracing in heterogeneous streambeds. In this study, we addressed this issue by proposing an efficient optimal design framework to collect the most informative diurnal temperature signal for Bayesian estimation of streambed hydraulic conductivities. The data worth (DW) was measured by the expected relative entropy between the prior and posterior distributions of the conductivity field...
August 28, 2018: Ground Water
David W Owens, Randall J Hunt, Aaron D Firnstahl, Maureen A Muldoon, Mark A Borchardt
Fecal contamination by human and animal pathogens, including viruses, bacteria, and protozoa, is a potential human health hazard, especially with regards to drinking water. Pathogen occurrence in groundwater varies considerably in space and time, which can be difficult to characterize as sampling typically requires hundreds of liters of water to be passed through a filter. Here we describe the design and deployment of an automated sampler suited for hydrogeologically and chemically dynamic groundwater systems...
August 28, 2018: Ground Water
Martí Bayer-Raich, Anthony Credoz, Jordi Guimerà, Salvador Jordana, Diego Sampietro, Jordi Font-Capó, Nathalie Nief, Matthieu Grossemy
Currently, monitoring tools can be deployed in observation boreholes to better assess groundwater flow, flux of dissolved contaminants and their mass discharge in an aquifer. The relationship between horizontal water velocity in observation boreholes and Darcy fluxes in the surrounding aquifer has been studied for natural flow conditions (i.e., no pumping). Interpretation of measurements taken with dilution tests, the colloidal borescope, the Heat Pulse Flowmeter, and other techniques require the conversion of observed borehole velocity u to aquifer Darcy flux q∞ ...
August 14, 2018: Ground Water
Willem J Zaadnoordijk, Stefanie A R Bus, Aris Lourens, Wilbert L Berendrecht
The Geological Survey of the Netherlands (TNO-GSN) maintains a public national database of groundwater head observations. Transfer function-noise modeling has been applied to the time series in order to extract the impulse response functions for precipitation and evaporation for each piezometer. An automated procedure has been developed to assess the quality of the time series and of the models. The time series models of sufficient quality offer far more homogeneous data on the piezometric head than the original measurements...
August 14, 2018: Ground Water
John P Ortiz, Mark A Person, Peter S Mozley, James P Evans, Susan L Bilek
We used hydrogeologic models to assess how fault-zone properties promote or inhibit the downward propagation of fluid overpressures from a basal reservoir injection well (150 m from fault zone, Q = 5000 m3 /day) into the underlying crystalline basement rocks. We varied the permeability of the fault-zone architectural components and a crystalline basement weathered layer as part of a numerical sensitivity study. Realistic conduit-barrier style fault zones effectively transmit elevated pore pressures associated with 4 years of continuous injection to depths of approximately 2...
August 9, 2018: Ground Water
Mason O Stahl
Quantifying anthropogenic contributions to elemental cycles provides useful information regarding the flow of elements important to industrial and agricultural development and is key to understanding the environmental impacts of human activity. In particular, when anthropogenic fluxes reach levels large enough to influence an element's overall cycle the risk of adverse environmental impacts rises. While intensive groundwater pumping has been observed to affect a wide-range of environmental processes, the role of intensive groundwater extraction on global anthropogenic element cycles has not yet been characterized...
August 2, 2018: Ground Water
Reynold Chow, Hao Wu, Jeremy P Bennett, Jürnjakob Dugge, Thomas Wöhling, Wolfgang Nowak
This study determines the aspects of river bathymetry that have the greatest influence on the predictive biases when simulating hyporheic exchange. To investigate this, we build a highly parameterized HydroGeoSphere model of the Steinlach River Test Site in southwest Germany as a reference. This model is then modified with simpler bathymetries, evaluating the changes to hyporheic exchange fluxes and transit time distributions. Results indicate that simulating hyporheic exchange with a high-resolution detailed bathymetry using a three-dimensional fully coupled model leads to nested multiscale hyporheic exchange systems...
August 1, 2018: Ground Water
Sahila Beegum, Jiří Šimůnek, Adam Szymkiewicz, K P Sudheer, Indumathi M Nambi
The "HYDRUS package for MODFLOW" is an existing MODFLOW package that allows MODFLOW to simultaneously evaluate transient water flow in both unsaturated and saturated zones. The package is based on incorporating parts of the HYDRUS-1D model (to simulate unsaturated water flow in the vadose zone) into MODFLOW (to simulate saturated groundwater flow). The coupled model is effective in addressing spatially variable saturated-unsaturated hydrological processes at the regional scale. However, one of the major limitations of this coupled model is that it does not have the capability to simulate solute transport along with water flow and therefore, the model cannot be employed for evaluating groundwater contamination...
July 30, 2018: Ground Water
Rami Ben-Zvi, Shidong Jiang, Harvey Scher, Brian Berkowitz
An exposition is given of a finite-element method (FEM) software package to calculate solutions for the continuous time random walk (CTRW) integro-differential equation for non-Fickian (and Fickian) conservative or reactive transport in disordered media. The solutions encompass one-dimensional/two-dimensional (1D/2D) breakthrough curves and spatial concentration profiles for general geometry and grid. The velocity field, used as input to the 2D solutions, may also be calculated by applying a compatible Darcy flow 2D solver...
July 25, 2018: Ground Water
Daniel J Soeder
Hydraulic fracturing (fracking) is a process used for the stimulation and production of ultra-low permeability shale gas and tight oil resources. Fracking poses two main risks to groundwater quality: (1) stray gas migration and (2) potential contamination from chemical and fluid spills. Risk assessment is complicated by the lack of predrilling baseline measurements, limited access to well sites and industry data, the constant introduction of new chemical additives to frack fluids, and difficulties comparing data sets obtained by different sampling and analytical methods...
July 10, 2018: Ground Water
Troy E Gilmore, Vitaly Zlotnik, Mason Johnson
We propose a new method for groundwater recharge rate estimation in regions with stream-aquifer interactions, at a linear scale on the order of 10 km and more. The method is based on visual identification and quantification of classically recognized water table contour patterns. Simple quantitative analysis of these patterns can be done manually from measurements on a map, or from more complex GIS data extraction and curve fitting. Recharge rate is then estimated from the groundwater table contour parameters, streambed gradients, and aquifer transmissivity using an analytical model for groundwater flow between parallel perennial streams...
July 9, 2018: Ground Water
Christopher J Neville, Xiaomin Wang
A general approach is developed for the analysis of solute transport from a source with a finite initial mass. The approach uses an effective retardation factor to assign the initial mass that can be leached from the source. Demonstration analyses are presented to illustrate the approach with the numerical simulator MT3DMS. For cases that are tractable with analytical solutions, comparisons between the numerical and analytical results confirm that the proposed approach yields correct results. The approach is straightforward to apply and can accommodate conditions ranging from pure advection to pure diffusion, effectively extending the capabilities of models to simulate sources with finite leachable masses for complex flow fields, reactions and distributions of sources...
July 3, 2018: Ground Water
Kenneth Belitz, Elise Watson, Tyler D Johnson, Jennifer Sharpe
The U.S. Geological Survey (USGS) previously identified and mapped 62 Principal Aquifers (PAs) in the U.S., with 57 located in the conterminous states. Areas outside of PAs, which account for about 40% of the conterminous U.S., were collectively identified as "other rocks." This paper, for the first time, subdivides this large area into internally-consistent features, defined here as Secondary Hydrogeologic Regions (SHRs). SHRs are areas of other rock within which the rocks or deposits are of comparable age, lithology, geologic or physiographic setting, and relationship to the presence or absence of underling PAs or overlying glacial deposits...
July 3, 2018: Ground Water
(no author information available yet)
No abstract text is available yet for this article.
September 2018: Ground Water
Rob Schincariol
No abstract text is available yet for this article.
September 2018: Ground Water
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