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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 pre-drilling 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 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
Xueru Guo, Rui Zuo, Jinsheng Wang, Li Meng, Yanguo Teng, Rongtao Shi, Xiang Gao, Fei Ding
Hydrogeochemical evolution of interactions between surface water and groundwater is crucial for guaranteeing water supply quality in a riverside water source area. This study focuses on the seasonal and spatial characteristics of hydrogeochemical evolution affected by groundwater exploitation in the Hulan water source area using hydrochemical analyses and stable isotope tracers. Results show that the concentrations of major ions and total dissolved solids (TDS) increase considerably during the dry season. A bicarbonate water type is primarily produced by the dissolution of calcite, dolomite and gypsum, as well as the cation exchange and human activities...
June 23, 2018: Ground Water
David Walker, Geoff Parkin, Petra Schmitter, John Gowing, Seifu A Tilahun, Alemseged T Haile, Abdu Y Yimam
Although most recharge estimation studies apply multiple methods to identify the possible range in recharge values, many do not distinguish clearly enough between inherent uncertainty of the methods and other factors affecting the results. We investigated the additional value that can be gained from multi-method recharge studies through insights into hydrogeological understanding, in addition to characterizing uncertainty. Nine separate groundwater recharge estimation methods, with a total of 17 variations, were applied at a shallow aquifer in northwest Ethiopia in the context of the potential for shallow groundwater resource development...
June 12, 2018: Ground Water
Hyeonju Lee, Min-Ho Koo, Sebong Oh
In South Korea, a significant amount of groundwater is used for the heating of water-curtain insulated greenhouses during the winter dry season, which had led to problems of groundwater depletion. A managed aquifer recharge (MAR) project is currently underway with the goal of preventing such groundwater depletion in a typical cultivation area, located on an alluvial aquifer near the Nam River. In the present study, FEFLOW, a three-dimensional finite element model, was used to evaluate different strategies for MAR of the cultivation areas...
June 12, 2018: Ground Water
Chuanglin Fang, Siao Sun, Shaofeng Jia, Yuanyuan Li
Assessment of historical evolution of groundwater levels is essential for understanding the anthropogenic impact on groundwater exploitation and developing response policies. In this study, regional groundwater level trend was addressed based on the regional Kendall test with correlated spatial data. With a limited number of data at one location, an exponential relation was proposed to be used to approximate covariances of a variable as a function of distances between locations. The effectiveness of the method was demonstrated using synthetic data experiments...
June 12, 2018: Ground Water
Yiding Zhang, Xiaonan Ji, Motomu Ibaraki, Franklin W Schwartz
The academic world is driven by scholarly research and publications. Yet, for many fields, the volume of published research and the associated knowledge base have been expanding exponentially for decades. The result is that scientists are literally drowning in data and information. There are strategies and approaches that could help with this problem. The goal of this paper is to demonstrate the power of computer-based approaches such as data mining and machine learning to evaluate large collections of papers...
June 7, 2018: Ground Water
Jeremy P Bennett, Claus P Haslauer, Martin Ross, Olaf A Cirpka
The spatial distribution of hydraulic properties in the subsurface controls groundwater flow and solute transport. However, many approaches to modeling these distributions do not produce geologically realistic results and/or do not model the anisotropy of hydraulic conductivity caused by bedding structures in sedimentary deposits. We have developed a flexible object-based package for simulating hydraulic properties in the subsurface-the Hydrogeological Virtual Realities (HyVR) simulation package. This implements a hierarchical modeling framework that takes into account geological rules about stratigraphic bounding surfaces and the geometry of specific sedimentary structures to generate realistic aquifer models, including full hydraulic-conductivity tensors...
June 3, 2018: Ground Water
Guillaume Gianni, John Doherty, Philip Brunner
Physical properties of alluvial environments typically feature a high degree of anisotropy and are characterized by dynamic interactions between the surface and the subsurface. Hydrogeological models are often calibrated under the assumptions of isotropic hydraulic conductivity fields and steady-state conditions. We aim at understanding how these simplifications affect predictions of the water table using physically based models and advanced calibration and uncertainty analysis approaches based on singular value decomposition and Bayesian analysis...
June 3, 2018: Ground Water
Shuangpo Ren, Andrew D Parsekian, Ye Zhang, Bradley J Carr
In granite aquifers, fractures can provide both storage volume and conduits for groundwater. Characterization of fracture hydraulic conductivity (K) in such aquifers is important for predicting flow rate and calibrating models. Nuclear magnetic resonance (NMR) well logging is a method to quickly obtain near-borehole hydraulic conductivity (i.e., KNMR ) at high-vertical resolution. On the other hand, FLUTe flexible liner technology can produce a K profile at comparable resolution but requires a fluid driving force between borehole and formation...
May 15, 2018: Ground Water
David L Poulsen, Peter G Cook, Craig T Simmons, James L McCallum, Shawan Dogramaci
Hydraulic head differences across the screened or open interval of a well significantly influence the sampled water mixture. Sample bias can occur due to an insufficient pumping rate and/or due to native groundwater displacement by intraborehole flow (IBF). Proper understanding of the sampled water mixture is crucial for accurate interpretation of environmental tracers and groundwater chemistry data, and hence groundwater characterization. This paper uses numerical modeling to quantify sample bias caused by IBF in an un-pumped high-yield well, and the influence of pumping rate and heterogeneity on the volume of pumpage required to purge an IBF plume...
May 12, 2018: Ground Water
Robert J Agnew, Todd Halihan
The mechanisms leading to the formation of bubbles in springs and wells have received minimal attention beyond causation. Free-phase gas quantification provides insight into a range of topics, from hazards that need to be managed to the economic value of soda waters. The presence of free-phase gas or vapor bubbles in groundwater may provide valuable information about the subsurface flow system. Additionally, free-phase gas or vapor bubbles may strip dissolved gasses from solution and introduce error into the assessment of gasses in springs, affecting analyses such as groundwater dating techniques...
May 8, 2018: Ground Water
R Chesnaux, S Santoni, E Garel, F Huneau
An analytical solution to calculate the recharge of unconfined aquifers with Dupuit-Forchheimer type flow conditions is proposed. This solution is derived from an existing closed-form analytical solution initially developed to determine groundwater travel time when the recharge of the aquifer is known. This existing solution has been modified to determine recharge when groundwater travel time is known. An illustration is given with a field case example for the Bonifacio aquifer of the island of Corsica (France), in the Mediterranean...
May 7, 2018: Ground Water
Aybulat Fatkhutdinov, Catalin Stefan
This study demonstrates the utilization of a multi-objective hybrid global/local optimization algorithm for solving managed aquifer recharge (MAR) design problems, in which the decision variables included spatial arrangement of water injection and abstraction wells and time-variant rates of pumping and injection. The objective of the optimization was to maximize the efficiency of the MAR scheme, which includes both quantitative and qualitative aspects. The case study used to demonstrate the capabilities of the proposed approach is based on a published report on designing a real MAR site with defined aquifer properties, chemical groundwater characteristics as well as quality and volumes of injected water...
April 27, 2018: Ground Water
Behzad Ataie-Ashtiani, Craig T Simmons, Dylan J Irvine
No abstract text is available yet for this article.
April 25, 2018: Ground Water
Rui-Xuan Tang, Jing-Sen Cai, Tian-Chyi Jim Yeh
A first-order moment analysis method is introduced to evaluate the pore-water pressure variability within a hillslope due to spatial variability in saturated hydraulic conductivity (Ks ) during rainfall. The influences of the variance of the natural logarithm of Ks (ln Ks ), spatial structure anisotropy of ln Ks , and normalized vertical infiltration flux (q) on the evaluations of the pore-water pressure uncertainty are investigated. Results indicate different responses of pressure head variability in the unsaturated region and the saturated region...
April 25, 2018: Ground Water
(no author information available yet)
No abstract text is available yet for this article.
July 2018: Ground Water
Reed M Maxwell, Alexis Navarre-Sitchler, Matt Tonkin
No abstract text is available yet for this article.
July 2018: Ground Water
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