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Ground Water

Steven J Berg, Nancy R Grosso, Michael P Sherrier, Kevin Mudrick, Matthias Ohr, Hyoun-Tae Hwang, Young-Jin Park, Michael V Callaghan, Steven K Frey, Edward A Sudicky
The interaction between surface water and groundwater during flood events is a complex process that has traditionally been described using simplified analytical solutions, or abstracted numerical models. To make the problem tractable, it is common to idealize the flood event, simplify river channel geometry, and ignore bank soil heterogeneity, often resulting in a model that only loosely represents the site, thus limiting its applicability to any specific river cross-section. In this study, we calibrate a site-specific fully-integrated surface and subsurface HydroGeoSphere model using flood events for a cross-section along the South River near Waynesboro, VA...
November 8, 2018: Ground Water
Oliver S Schilling, Young-Jin Park, René Therrien, Ranjeet M Nagare
For the simulation of winter hydrological processes a gap in the availability of flow models existed: one either had the choice between (a) physically-based and fully-integrated, but computationally very intensive, or (b) simplified and compartamentalized, but computationally less expensive simulators. To bridge this gap, we here present the integration of a computationally efficient representation of winter hydrological processes (snowfall, snow accumulation, snowmelt, pore water freeze-thaw) in a fully-integrated surface water-groundwater flow model...
November 5, 2018: Ground Water
Alraune Zech, Sabine Attinger, Alberto Bellin, Vladimir Cvetkovic, Peter Dietrich, Aldo Fiori, Georg Teutsch, Gedeon Dagan
Transverse dispersion, or tracer spreading orthogonal to the mean flow direction, which is relevant e.g, for quantifying bio-degradation of contaminant plumes or mixing of reactive solutes, has been studied in the literature less than the longitudinal one. Inferring transverse dispersion coefficients from field experiments is a difficult and error-prone task, requiring a spatial resolution of solute plumes which is not easily achievable in applications. In absence of field data, it is a questionable common practice to set transverse dispersivities as a fraction of the longitudinal one, with the ratio 1/10 being the most prevalent...
October 31, 2018: Ground Water
Nathan L Young, Jacqueline E Reber, William W Simpkins
Fractures in porous media have been documented extensively. However, they are often omitted from groundwater flow and mass transport models due to a lack of data on fracture hydraulic properties and the computational burden of simulating fractures explicitly in large model domains. We present a MATLAB toolbox, FracKfinder, that automates HydroGeoSphere (HGS), a variably-saturated, control volume finite-element model, to simulate an ensemble of discrete fracture network (DFN) flow experiments on a single cubic model mesh containing a stochastically-generated fracture network...
October 31, 2018: Ground Water
Amir Safi, Troels Norvin Vilhelmsen, Ibrahim Alameddine, Majdi Abou Najm, Mutasem El-Fadel
Groundwater model predictions are often uncertain due to inherent uncertainties in model input data. Monitored field-data are commonly used to assess the performance of a model and reduce its prediction uncertainty. Given the high cost of data collection, it is imperative to identify the minimum number of required observation wells and to define the optimal locations of sampling points in space and depth. This study proposes a design methodology to optimize the number and location of additional observation wells that will effectively measure multiple hydrogeological parameters at different depths...
October 30, 2018: Ground Water
Chengcheng Li, Xubo Gao
Dramatic decreases in groundwater quality have raised widespread concerns about water supplies and ecological crises in China. In this study, hydrochemistry, stable isotopes, graphical and multivariate statistical methods are integrated to identify hydrogeochemical processes controlling groundwater quality in the Yuncheng Basin, China. Our results show that groundwater with 21 variables (pH, temperature-T, TDS, major-trace elements and stable isotopes) is chemically classified into three distinct clusters: fresh water [C1], brackish-saline water [C2], and saline water [C3]...
October 30, 2018: Ground Water
Licong Dai, Xiaowei Guo, Yangong Du, Fawei Zhang, Xun Ke, Yingfang Cao, Yikang Li, Qian Li, Li Lin, Guangmin Cao
The Qinghai-Tibet plateau (QTP) has the world's largest area of seasonally frozen ground. Here, shallow groundwater displays behavior that is distinct from that elsewhere in the world. In the present study, we explore the seasonal and interannual variation of the shallow groundwater levels from 2012 to 2016, and attempt to quantitatively evaluate the relative influences of individual driving factors on the shallow groundwater levels based on boosted regression trees (BRT). The results show that: (1) on a seasonal scale, the groundwater levels were characterized by a double peak and double valley relationship, while on an interannual scale the groundwater levels showed a slightly downwards trend from 2012 to 2016; and (2) during the frozen period, the seasonal variation of groundwater levels was determined by mean air temperature through its effect on the soil thaw-freeze process, accounting for 53...
October 16, 2018: Ground Water
Vincenzo Piscopo, Stefano Di Luca, Michele Dimasi, Francesca Lotti
Sustainable use of groundwater in the hydrothermal area of Viterbo (Central Italy) was analyzed. In this area, multipurposes utilization of groundwater coexists: several thermal springs and wells supply spas and public pools, cold and fresh water is used for irrigation and drinking-water. Starting from theoretical concepts, a management plan has been developed to ensure groundwater sustainability in response to the increased demand of withdrawal from thermal wells, by integrating previous hydrogeological studies, new investigations and a new finite-difference model...
October 16, 2018: Ground Water
Lin Yuan, HongGuang Sun, Yong Zhang, YouKuan Zhang, Xiufen Gu, Shawn Dawley
Natural dynamics such as groundwater head fluctuations may exhibit multi-fractionality, likely caused by multi-scale aquifer heterogeneity and other controlling factors, whose statistics requires efficient quantification methods. As a scaling exponent, the Hurst exponent can describe the temporal correlation or multifractal behavior in groundwater level fluctuation processes. However, the scaling behavior may change with time under natural conditions, likely due to the non-stationary evolution of internal and external conditions, which cannot be characterized by traditional methods using a single or several scaling exponents for the complex features of the overall process...
September 27, 2018: Ground Water
Michael J Gefell, Masa Kanematsu, Dimitri Vlassopoulos, David S Lipson
No abstract text is available yet for this article.
September 25, 2018: Ground Water
Jianjun Wang, Xing Liang, Yanfeng Liu, Menggui Jin, Peter S K Knappett, Yalei Liu
The impacts of long-term pumping on groundwater chemistry remain unclear in the Manas River Basin, Northwest China. In this study, major ions within five surface water and 105 groundwater samples were analyzed to identify hydrogeochemical processes affecting groundwater composition and evolution along the regional-scale groundwater flow paths using the multivariate techniques of hierarchical cluster analysis (HCA) and principal components analysis (PCA) and traditional graphical methods for analyzing groundwater geochemistry...
September 23, 2018: 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 northeast 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 Geographical Information System (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
(no author information available yet)
No abstract text is available yet for this article.
November 2018: Ground Water
(no author information available yet)
No abstract text is available yet for this article.
September 2018: Ground Water
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