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The subsurface aquifer zone is significant groundwater source, hence this paper investigates subsurface aquifer zones in Kaiama Community, Kolokuma/Opokuma local government area of Bayelsa State, Nigeria with the purpose of exploring groundwater using geoelectric sounding (GES) surveys. Five survey points were examined using Schlumberger electrode configuration and deploying SAS 1000 Terrameter set, with data processed with IPI2win software. Each survey station revealed distinct layers with varying resistivity, depth, and lithology, offering crucial insights into subsurface features and aquifer systems. For GES 1, indicates five layers showing their resistivity values with respect to depth as 400.7Om with a depth of 0.6m as top soil, 16.14Om-51.01Om with a depth of 3.219-7.4356m as clay and layer 6 expressed as 19527Om with a depth of 30.01m as coarse sand and aquiferous layer. GES 2 along Kaiama's East-West Road delineated four layers with resistivity value of 467.2Om with a dpth of 1.264m as top soil, 54.5Om with a depth of 18.8m as clay and 2738Om with a depth of 40.01m as coarse sand, which also indicates as a potential aquiferous layer. GES 3 at R.PM School 1 Field identified five layers, highlighting 121.1Om with a depth of 0.6m as top soil, 16.67Om-5795Om with depth of 40.2m as clay with a resistivity potential of 237.7Om with a depth of 60.01m as medium sand and subsurface aquiferous layer. GES 4 at Kaiama Grammar School field revealed six layers, with resistivity value of 327.9Om with adepth of 0.6m as top soil, 6.383-20.51Om with depth of 3.219-7.456m as clay and 800Om with depth of 17.27m as medium sand and resistivity of 91599Om with depth of 30.22m as coarse sand medium sand indicating potential aquifer zones. GES 5 at Isokiwari Compound Kaiama showcased five layers: resistivity of 43.7Om with depth of 0.6m as top soil, 300.5Om-417.8Om with depth of 1.39-7,521m as medium sand, 65.17Om-112.5Om with depth of 17.33-40.07m as clay. The findings provide valuable information for groundwater management and resource exploration in the region, emphasizing the significance of understanding subsurface geology for sustainable water access. [ABSTRACT FROM AUTHOR]

The Bekaa Plain in Lebanon, is a major agricultural region known for its fertile soil and extensive crops cultivation using groundwater resources which is recently became under stress due to population growth, urbanization, and climate change. The main aim of this study is to investigate the rate of groundwater recharge (GwR) into this region using APLIS Model which principally depends on altitude, slope, lithology, infiltration, and soil type. Using GIS-based for a multicriteria mapping approach, in this study additional factors were added to the model, by incorporating rainfall rates, stream density, and fracture density. Results revealed various recharge potential area in the Bekaa Plain, with 52 % classified as high to very high GwR zones, equivalent to approximately 42.5 % of precipitated water, which is a testament to the exceptional capacity of the region to replenish groundwater aquifers. The geographic distribution of GwR categories primarily depends on altitude and lithological characteristics. The exceptional GwR potential of the Bekaa Plain holds immense promise for mitigating water scarcity, fostering agricultural productivity, and ensuring the socioeconomic well-being of communities reliant on groundwater resources. [Display omitted] [ABSTRACT FROM AUTHOR]

A study on the analysis of soil and groundwater characteristics due to municipal waste is indispensable to the sustenance of the environment and human health. This study is to evaluate the "Influence of selected Soil properties on groundwater flow around Ariaria dumpsite, Aba Southeast, Nigeria using Particle Size Analysis and Vertical Electrical Sounding (VES) configuration". The sieve analysis shows that the soil samples collected consist of 11.95% of Silt, 83.62% of Sand and 4.42% of little Gravel. The mean permeability of the study area ranges from 0.19 (cm/sec) to 0.49 (cm/sec), the mean infiltration rate ranges from 6840mm/hr to 31320mm/hr. The Longitudinal conductance and Transmissivity values range from 0.0060 to 0.0284Ω-1 and 3.8165 to 16.85892/day. The values of longitudinal conductance and transmissivity indicates that the aquifer has poor protection capacity rating and its classification of well is from very low potential to low potential. The soil samples of the study area are well sorted and the movement of leachate from the dumpsite into the subsurface is very fast because the Permeability (K) is good, Coefficient of uniformity (Cu) and Coefficient of curvature classified the soil samples collected from the area as well graded soil. From the geophysical survey (VES) results, the groundwater depths (upper and lower aquifers) within the study area ranges from 30m (98ft) to 60m (197ft) at average depth of 45m(147ft). The curve types are AHA, HKA and AKA. The SWL of the study area ranges from 12m to 19m deep. The recommend drill depth to groundwater of is 50m (164) for domestic and consumption purpose. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The impact of Geology on groundwater is not fully appreciated in many Nigerian groundwater quality literature. This study investigates the influence of Geology on the hydrogeochemical makeup of groundwater in Igarra and environs, Nigeria. Igarra and environs is underlain by metasediments intruded by Pan African Granites. Ten water samples were collected and analyzed in the laboratory to determine their chemical composition. The results revealed that the pH of most samples was slightly acidic to mainly alkaline, with high electrical conductivity (EC) and total dissolved solids (TDS) values. Correlation and regression analyses showed that the TDS, EC, salinity, chemical oxygen demand, dissolved oxygen, and major and minor constituents positively influenced the pH of the groundwater. Hierarchical cluster analysis demonstrated that the water samples had different compositions and concentrations based on local geological influences. The water samples from Granite, Quartzites, Migmatites and Gneiss rock types shared similar characteristics and had a lower concentration of minerals than the water samples taken from the Quartz Mica Schists and Metaconglomerates. The water in Igarra was predominantly Magnesium Bicarbonate type. However, some of the water samples exceeded the drinking standards for TDS, EC, Cl, Fe, Cr, Cd, and Pb. The study recommends the inclusion of biological parameters to gain a clearer picture of the water quality, particularly from the anthropogenic point of view. [ABSTRACT FROM AUTHOR]

The North-Western Sahara Aquifer System (NWSAS) is a complex multi-layered aquifer system with extraordinary continental groundwater reserves. This largest aquifer in the world straddles three countries: Algeria, Libya, and Tunisia. It contains more than 50,000 billion cubic meters of water; of which 70% is in Algerian territory in the southeast of the country. This water is the result of accumulation over 1 million years. In the Wadi Mya basin (Algeria), this system is characterized by two overlaid aquifer systems: the complex terminal (CT), a shallow aquifer housed in the Senonian-Eocene and Mio-Pliocene formations, and the continental intercalary (CI), a deep aquifer hosted in the Albian, Aptian and Barremian formations. The main purpose of this study is to carry out a correlation between the geochemical composition of the water and the facies of the aquifer formation. The adopted approach will allow deciphering the hydro-chemical relationships between the different levels of the two aquifer systems in the Wadi Mya basin. To acquire the chemical composition of water, the study method goes through a targeted sampling and physicochemical analysis of water followed by a statistical analysis as well as correlation and geochemical modelling: the interpretation of specific diagrams (Piper), correlations between chemical elements in binary graphs, and principal component analysis (PCA). The performed geochemical modelling by examining the saturation index and chemical balance of water helps to better understand the origin of mineralization, elucidate the mixing of waters originating from different aquifers, as well as highlight the relationship between deep and shallow aquifers in the Wadi Mya Basin hydrodynamic conversion. The obtained results indicate that the overall mineralization occurring within the study area is dominated by sodium chloride and calcium chloride-sulfate facies. This can be explained by the dissolution of halite, gypsum, and anhydrite evaporitic rocks, intercalated in the aquifer matrix besides the effects of the extended stay of fossil waters with low recharging and cation exchange reactions resulting from water-rock interactions. The interference recorded between the geochemical signatures of the two aquifers favors the hypothesis of interconnection between aquifers through fractures. Through the implementation of such academic research, this invaluable source of life will stay sustainable for future generations. [ABSTRACT FROM AUTHOR]

The research results obtained with the implementation of this project, intend to provide a contribution to the Municipality of Sincelejo - Sucre, in what concerns to the solution of the technical, economic, operational and social problems that the city currently presents, with respect to the drinking water service, so that by implementing the proposed alternatives, it translates into the provision of a service with better quality and complying with the current regulations that apply for this purpose. As a final result of the study, it can be established the need for the construction of an aqueduct system where the supply source is correctly defined as a requirement to be able to provide an efficient service to the city. [ABSTRACT FROM AUTHOR]

Groundwater (GW) salinization is among several hydro-environmental processes that essentially influence water resources management, freshwater supply, water scarcity and sustainability. Machine Learning (ML) is an effective and robust tool for GW monitoring, primarily when chaotic and interrelated parameters influence the system. The current study presents the first inverse modelling of GW salinization in sandstone aquifer using stand-alone (Elman NN, GRNN, BPNN, and ILR) models coupled with nonlinear ensemble ML (GPR-E, SVR-E, and ANFIS-E) techniques. For this purpose, 25 input parameters were imposed on data mining; subsequently, inversely correlated variables including bicarbonate (HCO 3 −), nitrate (NO 3 −), Temperature (Temp), Lithium (Li), and Manganese (Mn) were used for modelling the Electrical conductivity (EC). Neuro-sensitivity feature selection (NSFS) ranking was used to determine the input combinations. The Modeling schema was based on the actual field and experimental data. The results indicated the potential of GRNN-C1 with a value of NSE = 0.998, and 0.928 in both calibration and validation phases, respectively. The outcomes revealed weaknesses in all other stand-alone models with low efficiency ranged from 0 to 60%. The attained ensemble results proved promising for all, with ANFIS-E-C1 (RMSE = 2.993, MAE = 0.879, and NSE = 0.999) emerging best in the validation phase. The overall proposed ensemble learning proved the excellent capability of ML to handle complex GW processes and served as a reliable predictive tool for water resources management. The contribution-based methodologies explored in this study involved inverse modelling, nonlinear feature selection, and nonlinear ensemble techniques, which was the first study in GW salinization. [ABSTRACT FROM AUTHOR]

The damage of aquifer seriously affects the groundwater environment of mining. Therefore, the risk assessment method of mining geological aquifer damage based on remote sensing monitoring is studied to lay a foundation for aquifer management. The relatively clear image information is obtained by using remote sensing monitoring techniques and the damage risk of aquifer is analyzed at the same time. The risk and images of remote sensing monitoring are combined to establish damage evaluation index system of mining geology aquifer, on this basis, the improved fuzzy analytic hierarchy process is used to construct damage risk evaluation model of mining geological aquifer. The developed model is used to determine the weight of evaluation index and divide the risk grade of aquifer damage to realize the risk assessment of aquifer damage. The case study of a coal mine in North China shows that the final score of the target layer is 1.87, indicating that the damage risk of the geological aquifer is generally serious, and the damage risk is consistent with the remote sensing monitoring image information. According to the damage situation, reasonable management strategy is put forward to reduce the risk of aquifer damage in this region. [ABSTRACT FROM AUTHOR]

We examine capitalization of ethanol plant construction and capacity expansion into surrounding irrigated and nonirrigated farmland values using data on every land transaction in Kansas from 1995 to 2017 in a hedonic price model. We hypothesize that corn prices and thus land values are higher near ethanol plants. We further hypothesize that ethanol market expansion is capitalized into irrigated parcels to a greater extent than into nonirrigated parcels due to differences in water demand and precipitation. We estimate that an irrigated (nonirrigated) parcel within 50 km of an ethanol plant experiences an average price premium of 8.8% (6.3%) relative to more distant parcels. [ABSTRACT FROM AUTHOR]

The Schlumberger vertical electrical sounding method was used to detect aquifer levels in Abraka, Obiaruku and Umutu communities in Delta State respectively. The study recorded the aquifer level in Obiaruku to be between 26m to 34m. In Abraka the aquifer level lied between 20m to about 30m while in Umutu, it was between 50m to 100m. Borehole data showed that portable drinking water lies between 20m to 100m and could easily be assessed in these areas. [ABSTRACT FROM AUTHOR]

The utilization of Riverbank Filtration Systems (RBF) presents a promising approach for obtaining potable water from rivers or streams. However, the effectiveness of this technique relies significantly on two key factors: the width of the river and the presence of a clogging layer beneath the streambed, both of which influence the degree of contamination in the extracted water. Prior studies have predominantly relied on numerical models or simplistic one-dimensional flow assumptions to address these variables. In contrast, this research introduces a 3D analytical model utilizing the Green's function approach to analyze the movement of contaminants from the river towards the extraction well within RBF systems. By accounting for the dynamic interaction between river width and the clogging layer, this model offers a more accurate depiction of contaminant transport in three-dimensional water flow scenarios. The accompanying MATLAB code facilitates numerical integration of model equations, producing graphical representations for various hydrological inputs. Validation against MODFLOW software demonstrates a remarkable agreement, with outcomes aligning at 98–99%. Key findings underscore the exacerbation of pollutant concentrations with heightened clogging, increased river width, and optimal well placement. Moreover, the analysis underscores better predictive accuracy achieved by incorporating actual river width values compared to simple linear approximations. Notably, the research reveals minimal impact on contaminant concentrations when the distance between the river and the well exceeds twice the river's width, offering valuable insights for system design and management. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of groundwater to supply water to citizens is an important component of a country's security strategy, as groundwater is less vulnerable to pollution and can be used even in difficult climatic conditions. Groundwater catchments involve additional investment in research, compared to surface water catchments, because they use an underground source that must be identified through geological and hydrogeological research: the aquifer. From the geological and hydrogeological studies that were carried out in the area, the conclusion is that these aquifers can appear at depths between 15 and 120 m and there is a possibility that they manifest themselves artesian. [ABSTRACT FROM AUTHOR]

Research on the influencing factors of ground hydrogeological characteristics can provide a basis for the prevention and control of mine water flooding. In this paper, a large amount of groundwater data of SX coal mine in China and the Bayesian discriminant method have been used to systematically study the law of groundwater flooding. The research results show that there is a certain correlation between mine water inflow and atmospheric precipitation. The outburst horizons of mine water were analyzed, among them, the Shiqianfeng Formation, Fengfeng Formation, Taiyuan Formation and K2 limestone aquifers can all be excluded. However, the Permian Upper Shihezi Formation middle and lower sandstone aquifers, Lower Shihezi Formation lower sandstone aquifers, and Carboniferous Shanxi Formation lower sandstone aquifers are relatively close to the mineable coal seams, and the water-conducting fissure zone can often form effective communication, which in turn causes water flooding. Ca2+, Na++K+ and SO42- three types of ions can be well used to distinguish the hydraulic connection of aquifers. The coal-measure strata aquifers in the study area can be divided into several independent units, which are interconnected by faults. Faults can enhance the water conductivity of groundwater, and faults in the study area provide a path for communication between Ordovician water and coal-measure clastic rock fissure water. [ABSTRACT FROM AUTHOR]

Copyright of Rudarsko-Geolosko-Naftni Zbornik is the property of Faculty of Mining, Geology & Petroleum Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Key Takeaways: Aquifer storage and recovery, or ASR, is used to provide a stored water source where water supplies are unreliable or to address future demand. A 2013 inventory of ASR systems was updated in 2019 to evaluate project parameters and determine which variables are best at predicting the success of future ASR projects. With a time frame of June 2013 through October 2019, the revised inventory and analysis included data on new ASR sites and existing sites whose status had changed. [ABSTRACT FROM AUTHOR]

Groundwater at an abandoned industrial area near Bergamo, Italy, was historically contaminated by tetrachloroethylene (PCE) (>100 µg/L) and, to a lesser extent, by trichlorethylene (TCE), dichloropropane (DP) and 1,1,2,2-tetrachloroethane (R-130). A liquid reagent (EHC® Liquid) was selected for remediation of groundwater at the site. The reagent is provided in two parts: EHC® Liquid Mix (a soluble organo-iron salt), and ELS® Microemulsion (a lecithin-based carbon substrate), and is designed to promote both in situ chemical reduction (ISCR) and enhanced reductive dechlorination (ERD) to destroy chlorinated organic compounds. The two components are mixed with water and injected into the subsurface. Once in groundwater, EHC® Liquid rapidly generates highly reduced conditions, favouring both biotic and abiotic dechlorination reactions. Less than 6 months after the injection of EHC® Liquid in the main source area, concentrations of the target contaminants had reached the site-specific remediation target values (CSC Legislative Decree 152/06) in the main monitoring piezometers present in the area, thus demonstrating the effective establishment of enhanced biotic and abiotic reducing conditions and degradation of the target compounds. [ABSTRACT FROM AUTHOR]

Comprehensive geological and geophysical investigations were conducted to obtain new data on the structure and physical nature of the discharge site of steam hydrothermal fluids by the example of the Pauzhetka geothermal deposit (southern Kamchatka). An isometric concentric zonal structure has been identified within the temperature, geoelectric, magnetic, and gravimetric fields. It spatially correlates with an elevated tectonic block previously detected in the area of the Upper Pauzhetka thermal field. The central part of this structure includes a consolidated rock block composed presumably of quartz-adularia metasomatites formed at the pre-Holocene stage of evolution of the Pauzhetka hydrothermal system. The rocks form a physical heterogeneity within the structure of the aquifer, which greatly contributes to the distribution of flows of ascending thermal, mixed, and meteoric waters beneath the Upper Pauzhetka thermal field. The central area of the isometric concentric zonal structure is outlined by a zone consisting of local anomalies of positive magnetic-field values. The wide occurrence of subintrusive bodies (sills, dikes, and extrusion roots) of intermediate to rhyolite composition suggests the magmatic nature of the identified anomalies. The peripheral areas correlate with large discharge sites of high-temperature fluids. Thus, it is demonstrated that the structure of the circulation zones of waters of various types in the area of the Upper Pauzhetka thermal field is governed by the concentric zonal structure of the elevated tectonic block and the distribution of physical heterogeneities, both primary (of magmatic or volcanosedimentary nature) and resulted from the hydrothermal metasomatic alteration of the source rocks. [ABSTRACT FROM AUTHOR]

This research investigates the effect of landfill leachate on the groundwater in "Odum", a community that plays host to a dumpsite along Choba/Alakahia road in Obio/Akpor Local Government Area (L.G.A.) of Rivers State, Nigeria. Five vertical electrical soundings (VES) were conducted using the Schlumberger configuration and also five horizontal profiling were done using the Wenner configuration. The field data were acquired using ABEM tarrameter SAS 300C, and processed using the IP TWO WAY software. The results showed that the area is composed of sandstone, clay, laterite, sandy clay, and sand. Also, from careful analysis and interpretation of the processed data it was observed that contaminated zones have low resistivity (high conductivity). Strikingly, areas of low resistivity such as 11.9 Om and others with high resistivity up to greater than 1818 Om do exist. The results show that groundwater around this landfill contaminated area contains highly conductive leachates like sulphur, methane, ammonia gas at depths > 16 m. This indicates that the study area is not a good aquifer zone. [ABSTRACT FROM AUTHOR]

• A multi-criteria-driven approach was based on geological aspects. • Analytical hierarchy process helped to select storage sites of natural gas and CO 2. • A decision-making system allows for a joint analysis of (non-)measurable criteria. This study proposed the use of Analytical Hierarchy Process (AHP) to select potential locations for advanced natural gas storage facilities with a carbon dioxide (CO 2) cushion. The preliminary selection and ranking of such sites can be considered a multi-criteria decision-making problem. The selection criteria for geological structures in deep aquifers for underground gas storage were discussed. Based on 11 criteria concerning the geological storage of CO 2 as well as natural gas storage, a decision model was proposed. A ranking of geological structures in deep aquifers as potential sites for the underground storage of CO 2 and natural gas in Poland was presented. Results showed that the AHP-based approach played a significant role in the initial selection of potential sites for advanced underground storage of natural gas. The proposed model rendered it possible to make an objective decision regarding the best structure for underground gas storage in the deep aquifer, the most satisfactory from the perspective of all the simultaneously adopted decision criteria. [ABSTRACT FROM AUTHOR]

The quality of underground water at a dumpsite in Obigbo, Rivers State, Nigeria, was investigated by collecting 7 vertical electrical soundings (VES) using Wenner electrode configuration with current electrode spacing (AB/2) ranging from 1.0 m to 300 m. Field data were acquired using the SAS 300C resistivity meter and accessories, coordinates and elevation were measured using the Global Positioning System (GPS) at each sounding station. The VES data showed that the area is composed of clay, sandy clay and sand. The contaminated zones have low resistivity and corresponding high conductivity. Two zones were identified, zones of low resistivity and high resistivity with values of 11.3 Ωm to 21.4 Ωm, and 357.0 Ωm to795.0 Ωm respectively. There is thus, both lateral and downward movement of the contaminant leachate plumes. The results also revealed that the surrounding soil and groundwater around the landfill has not been contaminated to depths exceeding 15.6 m, which is shallower than the productive aquifer depth greater than 37.0 m. Judging from the age of the dumpsite, this site has a good protecting capacity, probably as a result of the presence of sufficient confined layers of clay that have impeded or slowed down the percolation of leachate into the aquifer. The aquifer is the underlying rocks of sand and gravel that are porous which constitute the water body. [ABSTRACT FROM AUTHOR]

The need to build an automobile mechanic settlement, abattoir and a proposed meat processing factory at Aboru residential estate necessitated a geophysical assessment (using a Dar-Zarrouk parameter - longitudinal unit conductance, S) of the vulnerability of the subsurface aquifers in the study area against the expected long-term anthropogenic impacts of these facilities on the groundwater system. Thirteen (13) Vertical Electrical Sounding (VES) points and four (4) Dipole-Dipole resistivity profile lines were occupied on four traverse lines across the study area. Isoresistivity and Isopach maps were generated and Total Longitudinal Unit Conductance, S of the earth materials overlying the aquifer was computed and the aquifer protective capacity (APC) map was generated. The VES delineated four (4) geo-electric layers namely; topsoil, pebbly/lateritic sand, clay/clayey/silty sand and sandstone. The depth to the sandstone aquifer ranges from 30.6 - 39.4 m with resistivity values ranging from 851 - 1437 Ωm. The iso-resistivity and isopach maps reveal that the near surface lateritic materials with resistivity values ranging from 350 - 1150 Ωm and thicknesses ranging from 2 - 29 m are pervious. The Total Longitudinal Unit Conductance, S varies from 0.0164 - 0.1168 mhos indicating a poor to weak protective capacity rating across the study area and the APC map reveals that the north-eastern and western parts of the study area show areas with weak protective capacity ratings while other areas are characterized by poor protective capacity rating. As such, the establishment of the proposed service facilities in the study area is strongly discouraged as the nature of their operations has a high potential to contaminate and eventually pollute the sub-surface aquifers on the long-run. If however the inevitability of their establishment cannot be set-aside, then secondary measures must be taken to forestall a direct impact of their operations on the subsurface. [ABSTRACT FROM AUTHOR]

• The predicted CO 2 flow pattern is quite sensitive to fine-scale heterogeneities and the resolution of the numerical mesh. • Co-injected SO 2 and NO 2 readily partition into the aqueous phase in close vicinity of their injection point, whereas O 2 may persist farther in the supercritical CO 2 phase. • Acidification takes place near the wellbore due to the preferential stripping of impurities. • Mineral dissolution (muscovite, chlorite and calcite) and precipitation (ankerite, kaolinite and chalcedony) occur along a lithostratigraphic boundary above the target formation. A demonstration project for the geological storage of CO 2 is currently being considered in the deep Precipice Sandstone formation of the Surat Basin, Queensland, Australia. Because of the presence of potential fresh water resources in this formation, a reservoir-scale two-dimensional reactive-transport model was developed to assess temporal and spatial changes in water quality imposed by co-injecting CO 2 with SO 2 , NO 2 , and O 2 at this location. The model shows that because the injection rate is relatively low (60,000 tons/year), flow is buoyancy-dominated and under these conditions the predicted CO 2 flow pattern is quite sensitive to fine-scale heterogeneities and the resolution of the numerical mesh. The model also shows that SO 2 and NO 2 readily partition into the aqueous phase in close vicinity of their injection point, lowering pH somewhat beyond the acidification from CO 2 dissolution. Only O 2 under redox disequilibrium conditions is modeled to persist in the CO 2 plume away from the injection point, however at sub-ppm levels. This modeling effort demonstrates acidification near the wellbore due to the preferential stripping of gas impurities, and accumulation of CO 2 around a lithostratigraphic boundary above the target formation, where relatively rapid mineral dissolution (muscovite, chlorite and calcite) and precipitation (ankerite, kaolinite and chalcedony) occur. [ABSTRACT FROM AUTHOR]

Geo-electrical resistivity survey was conducted in part of the University of Benin, Benin-City, Ovia Northeast of Edo State, Nigeria, with a view to establishing the most dependable aquifer bearing zone and the lateral and vertical variation of subsurface lithology with distance and depth respectively. In this study, the schlumberger electrode configuration was employed for the acquisition of VES data in the field. A total of 6 VES stations were engaged within the study area. A, H and HK resistivity curve types were identified, reflecting facies or lithological variations in the area. Three patterns of geo-electrical resistivity curves obtained using IP2WIN software can be associated with different rock formations in the study area. Dar Zarruk Parameters were tools used for aquifer characterization in determining the groundwater potential of the area and capacity bearing rating, viz: Total transverse resistance (T) and Total longitudinal conductance (S), Resistivity Contrast (RC) and Resistivity Reflection Coefficient (RRC). Results obtained shows that VES 1 (coordinate N6o 23'56.69", E5o 37' 32.83") with four layers and an A curve type is the most potential source for groundwater compared to other VES points. It is a sandy clay layer of resistivity 198Ωm, with thickness to infinity and well confined at the top by a laterite layer. VES 1 has the highest Total Traverse Resistance 690310 Ωm2 (showing a very good transmmitivity of the layer), Resistivity Contrast (0.01) and Resistivity Reflection Coefficient (0.90), all parameters falling within good prospect for groundwater development, but has a Total Longitudinal Conductance (S) value of 0.002 mho which shows that VES 1 has a poor bearing capacity. In summary, the results of the geo-electrical resistivity survey conducted at the Vice Chancellor's Lodge area of University of Benin using Schlumberger Array, revealed the most dependable aquifer bearing zone and the lateral and vertical variation of subsurface lithology with distance and depth respectively. [ABSTRACT FROM AUTHOR]

This work evaluated the Dar Zarrouk parameters of parts of Federal University of Petroleum Resources, Effurun, Nigeria. The aim of the study is to use Dar Zarrouk parameters to determine the groundwater quality and potentials of the study area. Four (4) Vertical Electrical Sounding (VES) were conducted with maximum electrode spacing of 200 m. The data was acquired using ABEM SAS 4000 Terrameter and processed using IPI2win and Interpex softwares. The Dar Zarrouk parameters evaluated in this work include Longitudinal Conductance (S), Transverse Resistance (T), Coefficient of Electrical Anisotropy (λ), Resistivity for the Formation (pm), Reflection Coefficient (RC) and Resistivity Contrast (FC). Results obtained in this work showered that the study area revealed five (5) geologic layers. Resistivity of the aquifer layer ranged from 364.55 pm (layer 4, VES 3) to 567.66 pm (layer 4, VES 4). Depths to aquifer level for the study area are 15.06 m (VES 1), 14.31 m (VES 2), 12.15 m (VES 3) and 13.79 m (VES 4). All the four VESs showed a poorly protected aquifer of the study area. The Dar Zarrouk parameters evaluated showed that the study area has good groundwater potentials with values of Reflection Coefficient ranging from 0.87 to 0.97, Resistivity Contrast values ranged from 13.78 t0 71.59 while that of Coefficient of Anisotropy ranged from 1.39 to 2.01. [ABSTRACT FROM AUTHOR]

In-situ measurement of depth to aquifer and water table was undertaken in 45 protected dug wells over two seasons. Samples were also analyzed for pH, EC, TDS, Ca, Cl, K, HCO3, CO3, SO4, Mg, K, and Na using universally accepted laboratory techniques. The study was aimed at examining seasonal variations in the chemistry of groundwater in the Lagos Coastal Plain Sand aquifer and its potability using the WHO standards. The study area covered parts of the Lagos Metropolis and the entire settlements of Ikorodu, Epe, and Badagry. The sample locations were mapped with ArcMap 9.3 software while the data were analyzed using descriptive statistics, paired sample T-test, correlation and multivariate statistical techniques using SPSS software 17.0 version. The result shows that about 60% of the samples had pH below the WHO minimum standard of 6.5 in both the dry and wet seasons. Mean EC and TDS levels were excessively high at Igando in both seasons. Some major ions, calcium, magnesium, potassium and sodium, and chloride exceeded the WHO limit at Oko-Oba, Ilogbo, Shomolu and Shogunle in the dry season. They were also excessively high in the wet season at Igando, Oko-Oba, Odo-Onosa, Ilogbo, Shomolu, and Shogunle. Correlation analysis shows that a significant relationship exists between the parameters at p<0.05 with the exception of Mg2+ and K+ in both seasons. The result of the paired sample T-test also shows significant variations among pH, Ca2+, HCO3- and Mg2+ with higher mean values in the dry than the wet season except for pH. Factor analysis identified salinity and anthropogenic activities as the two major sources of pollution. These account for about 74.48% and 84.21% of the total variances in dry and wet seasons, respectively. Consequently, protection of the recharge areas of the aquifer from environmental pollution and formulation and enforcement of appropriate policies that will stem the rate of indiscriminate groundwater exploitation and prevention of saline water intrusion in the coastal settlements are recommended. [ABSTRACT FROM AUTHOR]

Nitrate contamination of groundwater is increasingly becoming a global concern due to its potential risks for human health. Fertilizer overuse is often thought to be the cause and a reduction in fertilizer use considered the most effective way of reducing contamination. The present study, however, presents the case of Zhangye City, Gansu Province, China, in which the nitrate contamination of underground sources of drinking water resulted from a combination of fertilizer overuse and a mismatch between the geological structure of farmland and the crop type cultivated upon it. In addition, a market-induced driver was identified for its role in accelerating the contamination process. This new evidence emphasizes that environmental pollution is often driven by multiple factors of great complexity, demonstrating that causes of environmental problems should be addressed and analyzed with a cross-sectoral perspective. Furthermore, this case revealed that Chinese cabbages cultivated in a drought-stressed region contained very high nitrate concentrations that exceeded Acceptable Daily Intake level, whereas tomatoes and cucumbers from the same region were shown to contain nitrate levels within the safe range. These findings are useful for developing a new policy framework for environmentally sound agricultural planning. [ABSTRACT FROM AUTHOR]

The poor quality of potable water sourced from boreholes and hand dug wells at Yetunde Brown, Gbagada, Lagos informed the integration of geophysical, physicochemical and Water Quality Index (WQI) to assess the condition of groundwater in the study area. Twenty-Five (25) Vertical Electrical Sounding (VES) data were acquired and complemented with water samples collected from three boreholes and two hand-dug wells within the neighborhood of the study area. The VES data were partially curve matched and inverted. Physicochemical parameters were measured in water samples. The results of the VES data revealed four to five geo-electric layers which correspond to the topsoil (with layer thickness and resistivity values from 0.6 to 1.3 m and 20.1 to 361.4 Ωm respectively), clay (with layer thickness and resistivity of 1.7 to 5.2 m and 2.8 to 22.1 Ωm), sandy clay (with layer thickness and resistivity values of 2.8 to 5.9 m and 12.4 to 56.8 Ωm) and clayey sand (with layer thickness and resistivity values of 23.8 to 31.8 m and 7.2 to 94.2 Ωm). The sand in VES 7, 9, 12-18 and 20 has resistivity values ranging from 151 to 331.5 Ωm. The depth to the identified aquifers fluctuates between 23.8 and 90.4 m. The measured iron, chloride and lead ions are above World Health Organization (WHO) recommendation for potable water in some water samples. WQI calculated reflected poor quality for two boreholes only, which could be due to the unconfined aquifers delineated in the second and fourth geo-electric layers making the water vulnerable to contamination. The study recommended that bore hole should be sunk at VES 7, 9, 12, 13, 18 and 20 at depth between 31.8 to 66.6 m for exploitation of good quality water. [ABSTRACT FROM AUTHOR]

Abstract Gas-water-rock interactions during natural gas storage in a low permeability aquifer and main factors affecting the storage capacity were investigated in laboratory with core experiments. The results showed that gas injection flow rate had a major impact on stored gas volume and stored gas volume is higher at high flow rate. Gas storage volume ranged between 6%–20% of the pore space at experimental condition. Enhancing injection pressure can enhance gas storage volume. Statistics showed that injection flow rate had a greater influence on the gas storage volume than pressure. The retention time also had an impact on the gas storage process. Most of the natural gas was trapped in the reservoir and could not be produced after long time of retention. Atomic absorption spectroscopy indicated that ions concentrations of the brine and water evaporation increased when gas was injected into brine saturated core, and precipitation might occur, reducing porosity and permeability of core. Gas chromatography analysis showed that the concentration of carbon dioxide in the natural gas decreased and the concentration of methane increased after storage in the core. [ABSTRACT FROM AUTHOR]

The current trends in Mediterranean climate indicate longer periods of drought and hot temperature in summer and shorter and more intense precipitation in spring and autumn, which require reconsidering the current water management. The Emilia-Romagna coastal area (Northeastern Adriatic Sea, Italy) is entirely drained by a network of channels connected to more than 70 water pumping stations. Although drainage is fundamental in wet periods to keep the land dry, during long periods of stable weather, the fresh portion of drainage water could be reused for irrigation or managed aquifer recharge purposes. The proposed Managed Aquifer Recharge (MAR) project involves the reuse of drainage water towards infiltration trenches for both irrigation and natural infiltration purposes. Four possible locations in the Ravenna area were assessed and recommended for the implementation of drainage/irrigation/infiltration projects. It was estimated that, maintaining a raised level of +0.5 m respect to the current water level, a freshwater recharge of about 0.4 million m3 could be achieved in 120 days of operation by the combined-use of the trenches (total length of 8200 m). If water level in the trench was maintained at +1 m respect to the current level, the freshwater amount available for the aquifer recharge could reach about 0.7 million m3. This additional freshwater availability would allow irrigation for over 1500 hectares of land and could increase the agricultural gross marketable production of 50%. [ABSTRACT FROM AUTHOR]

This study investigated adding energy storage (pumped storage) at a groundwater bank, Willow Springs Water Bank, in Southern California. Two different technologies were evaluated. Aquifer pumped hydro (APH) uses reversible pump turbines, the aquifer as the lower storage reservoir, and a surface storage reservoir as the upper reservoir. APH and peak hour pumped storage (PHPS) can be used with or without demand response (DR), which deliberately curtails pumping to limit energy use at times when energy use and prices are high and shifts pumping to times when energy use and prices are lower. PHPS uses a surface storage reservoir as the lower reservoir, an upper elevation surface reservoir as the upper reservoir, and pumps and a hydroelectric generator to connect the two. Three different water bank operating modes were assessed (wet year—recharge, dry year—extraction, and neutral year—pumped storage). The results of the analysis are that APH was not cost‐effective. PHPS was, but the ability to curtail/adjust pumping and participate in DR was the most valuable resource, more valuable than the ability to generate electricity. [ABSTRACT FROM AUTHOR]

A two dimensional (2D) geoelectrical tomography of Ahmadu Bello University Teaching Hospital Premises was carried out with the aim of identifying a suitable location for siting a borehole. This was sequel to the fact that a borehole drilled without proper geophysical investigation in the quarters for resident doctors did not produce water. State-of-the-art equipment was employed and 2D surveying proved a powerful geological mapping tool, for use in hydrogeological mapping including engineering and environmental applications. The 2D inversion results of the survey were correlated with the lithology information obtained from the boreholes in Jama'a village, and the hostels and the residential quarters of ABUTH. The stratigraphic structure of the study area is very complex and is a product of volcanic and magmatic activities of various ages. Based on the geo-electrical images obtained in the study area, three distinct layers were revealed, the overburden with an average thickness of about 16 m - 26 m. The overburden is immediately underlain by the weathered basement, 5 m - 14 m thick which consists of disintegrated schistose rock materials, sand and gravel. This layer has a relatively low resistivity due to the presence of water and clay, which reduces the permeability, so this layer is thus regarded as the aquifer. The fresh basement rock was encountered at a variable depth of between 21 m and >30 m with resistivity 1223 Om up to 11918 Om. These results agree with the borehole logs. The complete set of borehole logs used in this research were obtained from the original hydro-geologic assessment report of the groundwater research department of the National Water Resources Institute (NWRI), Mando, Kaduna; Kaduna State, Nigeria. [ABSTRACT FROM AUTHOR]

Previous studies revealed that soil properties play a significant role in aquifer contamination. Consequently, it is necessary to understand the nature and properties of soil in carrying out groundwater evaluation. This study evaluates the subsurface geology and groundwater flow direction in Okpagha, Iguomo, Ikhueniro and Okhuahe suburbs in Benin City, Nigeria. Six boreholes were drilled by means of manual (rotary) method in different parts of the study area and each borehole was logged in order to understand the lithology, depth to water table, static water level as well as flow direction. The results obtained show that aquifer within the study areas were confined, semi confined to unconfined and was dominated by sands with minor clay and lignite interbed. It was observed that aquifer becomes shallower towards eastern portion of the study areas with increase in sand and decrease in clay materials. It was also observed that groundwater flow map revealed a flow direction of North-West to South-East from North West to South East. The decrease in the depth of aquifer and increase in sand material could be explained by the closeness to sea level. This phenomenon can enhance the infiltration of contaminants into aquifer thereby contaminating the groundwater bodies. It is therefore necessary to constantly monitor the groundwater quality in this suburbs in order to be aware of the quality of water resources being consumed because poor water quality can impact public health negatively. Furthermore, the authors advise that boreholes should be drilled in the direction of groundwater flow for maximum yield [ABSTRACT FROM AUTHOR]

The study was designed to investigate the analytical simulation of two dimensional advection dispersion equation of contaminant transport. The steady state flow condition of the contaminant transport where inorganic contaminants in aqueous waste solutions are disposed of at the land surface where it would migrate through the verdoze zone to underground water is considered. We solved the two dimensional advection dispersion equation analytically which is solute transport model without sorption or degradation using change of variable method. We critically reviewed two dimensional equations depicting the transport of contaminant in groundwater and investigate with the help of graphical representation the effect of Peclet number on the concentration of contaminant and established real life interpretation of contaminant transport. Two cases were considered, when Peclet number is less than one and when Peclet number is greater than one. The result obtained revealed that the contaminant concentration increases along x direction and decreases along y direction for both values of peclet number greater than one and less than one. The study has contributed to knowledge through the method utilized to achieve the model analytical solution and the Physical interpretation of Peclet number. From the analysis, we recommend for further studies on the contaminant transport which also depends on the available data, that the extension of advection-dispersion model to three dimensions and comparison of travel time of contaminant transport solution to Kinetic or multi-component mode. [ABSTRACT FROM AUTHOR]

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A research-monitoring program is being conducted at the Bell Creek oil field by the Plains CO 2 Reduction Partnership, led by the Energy & Environmental Research Center, to evaluate and demonstrate the cost-effectiveness of strategies for monitoring CO 2 storage associated with a commercial enhanced oil recovery (EOR) project. The Bell Creek oil field, operated by Denbury Onshore LLC as a commercial EOR project, is an oil-bearing, Lower Cretaceous sandstone reservoir located in southeastern Montana, USA. CO 2 injection for commercial EOR began in May 2013 and has resulted in over 3.2 million tonnes of associated CO 2 storage as of July 2016. [ABSTRACT FROM AUTHOR]

Disposal of carbon dioxide (CO 2 ) into underground geological formations is considered a viable strategy for the mitigation of global warming. It aims to reduce greenhouse gases emitted from point sources such as power plants. In order to select and evaluate a potential storage formation, many reservoir properties such as porosity, permeability, lateral and vertical extents, and a variety of residual fluid properties are considered. Injection design, which includes the placement of injectors and their flow rates, should be chosen to optimize injection capacity. One of the most important considerations to be addressed during design stage of sequestration is evaluation of pressure behaviour inside the reservoir during and after injection as the sequestered CO 2 increases the pressure within the formation. In order to maintain the integrity of the reservoir the pressure needs to be maintained below the fracture pressure, typically at least 10% below. Thus evaluation of reservoir pressure is essential to ensure the reservoir remains under the maximum allowable pressure while sequestering the maximum amount of CO 2 for long term storage in the reservoir. The optimal injection rates within a multi well injection site occur when the bottom-hole pressure at each injection site is at the maximum allowable pressure. In this study we present an analytical approach for modeling the pressure evolution during multi well CO 2 injection into saline aquifers and using the model modify the injection rates to optimize injection capacity within a formation. We show that this optimization procedure significantly increases the capacity of formation as opposed to using the same injection rate at each wellbore. [ABSTRACT FROM AUTHOR]

In coastal regimes groundwater aquifers are often vulnerable to saltwater intrusion. Saltwater intrusion is often precipitated by natural hydrodynamic processes and overpumping of groundwater resource. Saltwater intrusion is presumed to have significant effect on quality of groundwater and accountable for lack of access to freshwater in the areas under study. The objective of this study is to use resistivity data obtained from vertical electrical sounding to ascertain the salinity of shallow aquifers, determine depth and thickness of freshwater aquifers. The Schlumberger array configuration was employed in acquisition of data. The maximum and minimum spacing between electrodes (AB/2) ranged from 2m to 250m. Resistivity values ranged from 0.24Ωm to 427Ωm, Values which ranged from 0.2Ωm to 4Ωm was construed to be aquifer saturated with saltwater, brackish water was inferred from resistivity values which vary between 7Ωm and 11Ωm, and clay was assigned to resistivity values that ranged from 17Ωm to 29Ωm. Effect of tide contributes to salinity of shallow aquifer around the seashore area. Aquifers saturated with saltwater are found at the depths of 10.5m, brackish water at 4m to 9m, while freshwater can be located from the depth of 19-46m. The study is able to reveal that groundwater quality has been compromised by intrusion of saltwater. We conclude that there is potential of saltwater intrusion into the freshwater lenses, which may be enhanced in the future by over-development of groundwater. [ABSTRACT FROM AUTHOR]

Carbon dioxide is a greenhouse gas that has the most effect on the phenomenon of global warming. Saline aquifers have higher potential compared to other storage options to store carbon dioxide. Sandstone and carbonate aquifers have good reservoir characteristics and can be appropriate choices for CO 2 storage. The modeling of the process has been performed combining salt precipitation, solubility, region specification and pressure drop models to study the effect of CO 2 injection on gas saturation and pressure distribution profile, skin factor over time, the amount of salt precipitation, porosity and permeability. Sensitivity analysis has been done for temperature, pressure, permeability, porosity, salinity, critical gas saturation and CO 2 injection rate. In order to study chemical reactions, long time simulation of rock-fluid interaction in carbonate and sandstone aquifer is also performed. The permeability reduction is in the range of 0.69–0.86 in all cases of salt precipitation simulation which is consistent with experimental results. The proposed salt precipitation model with an average relative deviation of about 5% for rock-fluid interaction parameters is able to predict the aquifer properties accurately during CO 2 gas injection. The advantage of the model presented in this study compared to Zeidouni's model (2009) is that the proposed model predicts the pressure distribution after injection and estimates mole fraction of components in equilibrium with higher accuracy. The results of this study are shown that CO 2 storage needs an aquifer with lower temperature, higher pressure and lower salinity compared to other options as the solubility trapping of carbon dioxide increases in this case. Permeability change does not influence on determining equilibrium regions and the only effect of the permeability is on the injectivity. Simulation of mineral reactions shows that chemical equilibrium is established after long time (more than 100 years) in sandstone aquifer and it is established in less than one day in carbonate aquifer. It should be noted that mineral trapping capacity of carbonate aquifer is less than sandstone aquifer in the CO 2 storage process. [ABSTRACT FROM AUTHOR]

• The Tampico Misantla giant oil-producing basin is suitable for CCS. • The Tampico Misantla basin has potential to safely store 2128.6 Mt of CO 2 in two different aquifer formations. • Storage volumes identified point out that CCS can help Mexico to reach the targets set by the Paris Agreement. • Even with the most conservative criteria, the Basin scale evaluation involve significant inconsistencies and uncertainties related to technical assumptions and techno-economic and social features. The importance of CO 2 storage in deep geological formations to mitigate CO 2 emissions, has triggered the investigation of possible sites worldwide. This study presents a hierarchical basin-wide evaluation of the Tampico-Misantla basin (TMB), Mexico, following a basin evaluation methodology based on literature criteria and local particularities. The results show that the TMB has significant potential to adequately store CO 2. The stratigraphy evaluation reveals two candidate aquifers: (1) the Cretaceous Tamaulipas and (2) the Jurassic Cahuasas formations. Twenty-three criteria are taken into account to evaluate the storage potential of the area. A numerical scoring and weighting scheme integrate all the criteria in a raster, thus allowing the storage potential to be depicted using a normalized scale. The prospective areas are restricted by the 0.8 isoline normalized value (over 1). Considering the aquifer's volume with potential above 0.8, the effective storage capacity of the basin is estimated to be 972.3 to 1346.0 million tonnes of CO 2. [ABSTRACT FROM AUTHOR]

Reliable modelling and simulation of groundwater management are crucial for sustainable development. Groundwater salinization is considered challenging and has recently led to the development of several emerging advancements and technologies, which grant a feasible solution to integrated water management and desalination processes. For this purpose, Electrical Conductivity (EC) as the early Salinization sign is modelled using various computational techniques, namely, Least Square-boost (LSQ-Boost), Gaussian Process regression (GPR), support vector regression (SVR) and stepwise linear regression (SWLR). The experiment data from sandstone aquifers include parameters from the physical, chemical and hydrogeochemical aspects. Four different input combinations (C1-C4) were developed using linear and ranking nonlinear feature selection and validated modelling results weres assessed by mean square error (MSE), mean absolute error (MAE), root means square error (RMSE), Nash-Sutcliffe efficiency (NSE), and correlation coefficient (R). The analysis also considers the effect of multicollinearity, and the variables affected, such as TDS (mg/L), were not included in the first three combinations. The novel GPR proved superior to other models, with GPR-C1 justified quantitatively (MSE = 0.0255, MAE = 25260.49 and RMSE = 0.1595) in the verification phase. Other intelligent models (SVR, LSQ-Boost) depicted promising for C3 and C4 combinations with more than 88–90% predictive accuracy. The explored novel GPR algorithm offered an excellent and reliable EC prediction tool. The study also suggested using direct correlated positive variables, including hydrochemical and topographic factors, in modelling groundwater salinization. This would lead to more effective water-resources-related planning and decision making. [ABSTRACT FROM AUTHOR]

National Institute of Technology (NIT) Kurukshetra is a 292-acre campus, having more than 7000 residents on the campus. Due to lack of an efficient drainage system, the campus turns into a system of pools at important locations. This accumulation of water for long durations creates an unhealthy environment for the inhabitants besides damaging the roads, pavement and foundation of buildings. Hence, keeping in view all the above problems and status of the campus, rainwater harvesting can be considered as one of the solutions for addressing the problem of accumulated rainwater in the NIT Kurukshetra. The total area of the campus is 11,79,607 sqm, out of which 1,15,941 sqm is built up area and rest of the plain area can be utilized for artificial recharge. In this paper, an efficient design of rainwater harvesting system for the campus is proposed. The detailed design of the components of rainwater harvesting through artificial recharge i.e. filter gallery, recharge well, recharge pit, inspection pit etc are provided. It is expected that the result of the study if implemented will certainly fulfill the dual objective of addressing the menace of water logging in the campus besides enriching the groundwater aquifer. [ABSTRACT FROM AUTHOR]

Moghra territory is one of the most encouraging regions for watered farming and development in the northern part of Western Desert. To achieve that development groundwater is considered the most favorable tool. Geophysical survey in terms of geoelectrical resistivity sounding has been conducted using the Schlumberger array – eleven vertical electrical soundings (VES’s) were measured on the study area. The aim of this study was to investigate the hydrogeological condition at the area under investigation. Three geoelectric sections are prepared; each of them is composed of four units. The first layer has resistivity ranging from 58 to 2029 ohm.m and thicknesses from 0.46 to 10.7 m characterizing a gravely sand facies of Quaternary age (Pleistocene to Holocene). The second geoelectrical layer has resistivity values ranging between 188 and 518 ohm.m which are comparatively high, with various depths varying between 14.7 and 25.8 m from Lower Miocene age. It is formed of sand and gravel. The third geoelectrical layer is considered the aquifer for the area under investigation with moderate electrical resistivity values (17–111 ohm.m), and could be recognized sometimes as the most extreme depth of penetration. At the maximum depth of penetration of this area, the lower layer (fourth layer) was recognized with the highest electrical resistivity values (1227–8935 ohm.m) of basaltic sheet (Precambrian age). Structurally, the study area is influenced by three faults two of them are geological/geoelectrical faults forming a graben structure at the central part; the third fault is a geoelectrical fault and is located to the west of the graben structure forming a horest structure. [ABSTRACT FROM AUTHOR]

Electrical resistivity technique has been used to detect the subsurface stratigraphy and structures around Kharga Oasis, Egypt. 1D inversion approaches have been applied to interpret the electrical data obtained along 10 vertical electrical soundings (VES) using electrode spacing from 3 to 400 m. A preliminary quantitative interpretation of the vertical electrical sounding curves was achieved firstly using two-layer standard curves and generalized Cagniard graphs. The manual models were used as initials to prepare the final model using the algorithm IPI2Win program. Model results were used to construct a geoelectrical section. Three geoelectric units were identified: the superficial geoelectrical layer is composed mainly of sand and gravel with relatively high resistivity values (8–372 ohm m) and low thicknesses (0.523–4.92 m). The age of this layer is from late Pleistocene to Holocene (Quaternary deposits). The second geoelectrical layer is composed of shale (Dakhla Shale). It is characterized by relatively very low electrical resistivity values (0.3–4.92 ohm m). The maximum depth to this layer ranges from 13.8 to 45.7 m. The third layer represents the first Nubian Sandstone aquifer with moderate electrical resistivity values (23.9–233 ohm m) detected at the maximum depth of penetration, a great contrast for values according to the lithological content. [ABSTRACT FROM AUTHOR]

It has been found that a simple fixed delay of the water along a river does not provide accurate enough river flow rates for scheduling of the river power plants. One problem is that production water seems to disappear along the river stretch. Another problem is that the delay time depends on the state of the river and is longer in dry than wet conditions. The first problem has been that only 50-80% of the production water released into the river actually arrives at the downstream power plant (after some delay). The mechanism responsible is identified as loss of river water to the sandy valley-bottom aquifer. While most of the production water is delayed with a few hours river delay, the lost fraction is delayed by days and weeks in the aquifer. A coupled tank model is proposed to describe this mechanism. This model has been able to explain the water flow variation due to upstream production variation. The problem with river state dependence of delay has been approached with the method of characteristics, which provides a fast calculation of water wave movement along the river. The river flow rate is specified as a non-linear function of river water content. A two parameter power law is assumed to be valid for the entire river stretch. With this method, it is possible to reproduce the state dependence observed in the river. The studied stretch has a typical delay of 12 hours, but normal variation in the river state can change the delay by several hours. The improved delay calculation probably contributes to reduced production imbalances in the downstream power plant. [ABSTRACT FROM AUTHOR]

Multiphase, reactive transport modeling was used to identify the mechanisms controlling trace metal release under elevated CO 2 conditions from a well-characterized carbonate aquifer. Modeling was conducted for both batch and column experiments. The column experiments resulted in higher trace metal concentrations because the rock to water ratio was higher. A kinetic desorption model fits the overall trends in release for seven trace metals observed in batch and column experiments exposing Edwards Aquifer material to elevated concentrations of CO 2 . Observed and predicted trace metal concentrations are compared to groundwater concentrations from this aquifer to determine the potential for leaking CO 2 to adversely impact drinking water quality. Finally, a three-dimensional multiphase flow and reactive-transport simulation of CO 2 leakage from an abandoned wellbore into a generalized model of the shallow, unconfined portion of the aquifer is used to determine potential impacts on groundwater quality. As a measure of adverse impacts on groundwater quality, both the EPA’s regulatory limits and the maximum trace metal concentration observed in the aquifer were used as threshold values. Results of the field-scale simulations indicate that CO 2 leakage into a carbonate aquifer is likely to cause decreases in pH and increases in TDS beyond observed ranges in the aquifer and beyond regulatory limits. However, trace metal concentrations are not predicted to exceed either the observed maximums or the regulatory limits. [ABSTRACT FROM AUTHOR]

The hydro-lithostratigraphic units of the coastal area of Akwa Ibom State, Southern Nigeria were investigated involving electrical resistivity tomography (ERT) and Wenner array. This procedure and electrode configuration were adopted because of their wide range of sensitivity and inherent characteristics to geological materials. This study is aimed at defining the extent of saltwater invasions into the coastal and inland aquifers. The investigated area is divided into three zones A (≤0 < 20 km), B (<20 < 40 km), and C (>40 km)) based on the distance from the survey locations to the shoreline. The saline aquifer of the control tomogram obtained at the shoreline (Ibeno Beach) is characterized by the electrical resistivity of 0.159–3.55 Ωm. Within Zone A, (Ukpenekang, Eastern Obolo, and Okoro Ette), the saline aquifer is defined by electrical resistivity values of 0.33–44.0 Ωm, 2.07–48.5 Ωm, and 8.0–60.0 Ωm respectively. In general, the Zone B saline aquifers are defined by electrical resistivity values of 0.602–64.5 Ωm. Furthermore, the third zone which is situated a distance >40 km from the shoreline, is described by relatively higher electrical resistivity values (38.9–3260 Ωm) and indicates a region free from saltwater incursions. Generally, the 2D ERT models showed that electrically resistivity values increase progressively inland. [ABSTRACT FROM AUTHOR]