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18 pages, 7439 KiB

Open AccessArticle

Numerical Simulation of Geophysical Models to Detect Mining Tailings’ Leachates within Tailing Storage Facilities

by Mosaad Ali Hussein Ali, Farag M. Mewafy, Wei Qian, Ajibola Richard Faruwa, Ali Shebl, Saleh Dabaa and Hussein A. Saleem

Water 2024, 16(5), 753; https://doi.org/10.3390/w16050753 - 01 Mar 2024

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Abstract

The effective detection and monitoring of mining tailings’ leachates (MTLs) plays a pivotal role in environmental protection and remediation efforts. Electrical resistivity tomography (ERT) is a non-invasive technique widely employed for mapping subsurface contaminant plumes. However, the efficacy of ERT depends on selecting [...] Read more.

The effective detection and monitoring of mining tailings’ leachates (MTLs) plays a pivotal role in environmental protection and remediation efforts. Electrical resistivity tomography (ERT) is a non-invasive technique widely employed for mapping subsurface contaminant plumes. However, the efficacy of ERT depends on selecting the optimal electrode array for each specific case. This study addresses this challenge by conducting a comprehensive review of published case studies utilizing ERT to characterize mining tailings. Through numerical simulations, we compare the imaging capabilities of commonly used electrode configurations, six ERT arrays, aiming to identify the optimal array for MTLs’ detection and monitoring. In addition, field surveys employing ERT were conducted at the El Mochito mine tailings site to detect zones saturated with leachates within the tailing storage facilities (TSFs). The findings indicate that the “Wenner-Schlumberger” array exhibits superior data resolution for MTL detection. However, the choice of the optimal electrode array is contingent on factors such as survey location, geological considerations, research objectives, data processing time and cost, and logistical constraints. This study serves as a practical guide for selecting the most effective electrode array in the context of pollutant penetration from mining tailings, employing the ERT technique. Furthermore, it contributes valuable insights into characterizing zones saturated with mining tailing leachates within the TSFs, providing a solid foundation for informed environmental management and remediation strategies. Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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14 pages, 4539 KiB

Open AccessArticle

Coil System Design for Multi-Frequency Resistivity Logging Tool Based on Numerical Simulation

by Jiang Jia, Shizhen Ke and Reza Rezaee

Water 2023, 15(24), 4213; https://doi.org/10.3390/w15244213 - 06 Dec 2023

Viewed by 826

Abstract

A coil-type resistivity logging tool has been proposed for multi-frequency operation (250 kHz to 8 MHz) based on electromagnetic wave propagation. Different frequencies are matched with specific transmission coils, while the same two reception coils are used to achieve a consistent depth of [...] Read more.

A coil-type resistivity logging tool has been proposed for multi-frequency operation (250 kHz to 8 MHz) based on electromagnetic wave propagation. Different frequencies are matched with specific transmission coils, while the same two reception coils are used to achieve a consistent depth of investigation (D_OI). By analyzing the electromagnetic attenuation and phase difference of induced signals at different frequencies, the complex resistivity can be jointly inverted. The coil systems were designed with four D_OI options (0.3 m, 0.5 m, 1 m, and 1.5 m) and six measurement frequencies (250 kHz, 500 kHz, 1 MHz, 2 MHz, 4 MHz, and 8 MHz). Their detection performance was evaluated using the finite element method on the COMSOL platform. For higher frequencies or a deeper D_OI, a coil system with a larger source-receiver distance was selected. These designed coil systems can provide qualitative identification of formations with thicknesses greater than 0.05 m and quantitative identification of formations with thicknesses greater than 1.5 m. In the single-transmission, dual-reception coil system, response signals are distorted at the formation boundary, and this distortion increases with the source-receiver distance. Adding a secondary transmission coil can reduce the distortion of response signals at the formation interface without increasing the overall length of the coil system. This research enriches the theoretical framework of complex resistivity spectrum (CRS) logging and contributes to the commercial development of CRS logging tools. Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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33 pages, 16477 KiB

Open AccessArticle

Geophysical and Geochemical Pilot Study to Characterize the Dam Foundation Rock and Source of Seepage in Part of Pensacola Dam in Oklahoma

by Oluseun Sanuade and Ahmed Ismail

Water 2023, 15(23), 4036; https://doi.org/10.3390/w15234036 - 21 Nov 2023

Cited by 1 | Viewed by 1944

Abstract

Pensacola Dam, operated by the Grand River Dam Authority (GRDA), is a multiple-arch buttress dam constructed in 1940. The dam has little or no existing geophysical reports on the integrity of the dam foundation rock and even less knowledge at depth. Visual inspection [...] Read more.

Pensacola Dam, operated by the Grand River Dam Authority (GRDA), is a multiple-arch buttress dam constructed in 1940. The dam has little or no existing geophysical reports on the integrity of the dam foundation rock and even less knowledge at depth. Visual inspection indicated evidence of seepage at some arches of the dam. As a pilot study, we conducted a suite of geophysical surveys inside two arches (Arch-16 and Arch-17) and a part of the downstream berm to characterize the dam foundation rock, delineate seepage zones, and identify the most appropriate geophysical methods for temporal monitoring of the dam’s conditions. The geophysical methods included electrical resistivity tomography (ERT), self-potential (SP), multichannel analysis of surface waves (MASW), compressional (P)-wave refraction, and shear (S)-wave reflection. Water samples were collected for geochemical analysis to investigate the source of the seepage flow inside Arch-16. The geophysical results characterized the dam foundation rock into an unsaturated limestone and chert overlying a water-saturated limestone and chert. The ERT profiles indicated that groundwater is rising inside the arches and significantly dropping under the downstream berm, which can be due to the uplift pressure beneath the dam base. Zones of high seepage potential were detected near the buttress walls of the two surveyed arches, which may be related to previous blasting, excavation of the dam foundation, concrete placement, or improper grouting. The geochemical analysis of water samples taken from the artesian wells inside Arch-16 and the Grand Lake revealed different chemical compositions, suggesting that the source of water could be a mixture of groundwater and lake water or lake water interacting with rock and reaching the surface through fractures; however, more sampling and further analysis are required to ascertain the source of the seeps. This study showed that the ERT, SP, and S-wave reflection methods have effectively characterized the dam foundation rock and seepage zones beneath the arches. The study provided a better understanding of the conditions of the dam foundation rock, evaluated the utilized geophysical methods, and determined the optimum geophysical methods that can be used for the characterization and monitoring of the subsurface conditions along the entire length of the dam. In this study, we have demonstrated that the integration of effective geophysical surveys and geochemical analysis yielded optimum results in solving a complex dam safety problem. This strategy promotes the best practice for dam safety investigation. Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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21 pages, 2990 KiB

Open AccessArticle

Investigating Formation Factor–Hydraulic Conductivity Relations in Complex Geologic Environments: A Case Study in Taiwan

by Shih-Meng Hsu, Guan-Yu Liu, Ming-Chia Dong, Yi-Fan Liao and Jia-Sheng Li

Water 2023, 15(20), 3621; https://doi.org/10.3390/w15203621 - 16 Oct 2023

Viewed by 886

Abstract

The development of cost-effective methods for estimating hydraulic conductivity profiles has been an ongoing effort in the field of engineering practice, which can be used to increase availability to clarify the hydrogeological complexity of fractured rock aquifers for the aid of solving groundwater-related [...] Read more.

The development of cost-effective methods for estimating hydraulic conductivity profiles has been an ongoing effort in the field of engineering practice, which can be used to increase availability to clarify the hydrogeological complexity of fractured rock aquifers for the aid of solving groundwater-related problems. A new methodology is presented, which combines electrical well logs, fluid conductivity logs, double-packer hydraulic tests, Archie’s law, and the Kozeny–Carman-Bear equation to investigate relations between formation factor (F) and hydraulic conductivity (K). Available geophysical and hydraulic test data measured from 88 boreholes in fractured rock formations in Taiwan were collected to perform the correlation studies. The correlation investigation outcomes indicate that the established F-K relations have the potential to serve as the transformation function for estimating hydraulic conductivity through the geological directly. To improve F-K relations in response to the effect of clay mineralogy, two proposed clustering techniques (the natural gamma ray threshold method and the modified Archie’s law method) successfully play an important role in filtering clayed data. The prevalence of clay content in most of Taiwan’s fractured rock formations has been found, which implies that careful consideration of clay-related issues in complex geologic formations is essential while applying Archie’s law theory. Finally, the predictive models for estimating hydraulic conductivity have been developed for three types of lithology (sandstone, schist, and slate). Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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11 pages, 1512 KiB

Open AccessArticle

Shape Factor for Analysis of a Slug Test

by Florimond De Smedt

Water 2023, 15(14), 2551; https://doi.org/10.3390/w15142551 - 12 Jul 2023

Viewed by 1559

Abstract

Hydraulic conductivity is an essential parameter for groundwater investigation and management. A simple technique for determining the hydraulic conductivity of aquifers is the slug test, which consists of measuring the water level in a well after the sudden removal or injection of a [...] Read more.

Hydraulic conductivity is an essential parameter for groundwater investigation and management. A simple technique for determining the hydraulic conductivity of aquifers is the slug test, which consists of measuring the water level in a well after the sudden removal or injection of a small amount of water. The interpretation of a slug test is based on a geometry-dependent shape factor, for which various empirical relationships and approximate solutions have been proposed in the literature. In this study, shape factors are derived numerically for slug tests performed in monitoring wells with screens unaffected by aquifer boundaries. Also presented is a new approximate analytical solution for predicting shape factors for well screens with a large aspect ratio. A comparison with earlier methods reported in the literature shows that our results match or exceed them in terms of accuracy. The approximate analytical solution is promising because it is accurate and very easy to apply in practice. Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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21 pages, 11456 KiB

Open AccessArticle

Delineation of Groundwater Potential Area using an AHP, Remote Sensing, and GIS Techniques in the Ifni Basin, Western Anti-Atlas, Morocco

by Mustapha Ikirri, Said Boutaleb, Ismael M. Ibraheem, Mohamed Abioui, Fatima Zahra Echogdali, Kamal Abdelrahman, Mouna Id-Belqas, Tamer Abu-Alam, Hasna El Ayady, Sara Essoussi and Farid Faik

Water 2023, 15(7), 1436; https://doi.org/10.3390/w15071436 - 06 Apr 2023

Cited by 10 | Viewed by 2865

Abstract

An assessment of potential groundwater areas in the Ifni basin, located in the western Anti-Atlas range of Morocco, was conducted based on a multicriteria analytical approach that integrated a set of geomorphological and hydroclimatic factors influencing the availability of this resource. This approach [...] Read more.

An assessment of potential groundwater areas in the Ifni basin, located in the western Anti-Atlas range of Morocco, was conducted based on a multicriteria analytical approach that integrated a set of geomorphological and hydroclimatic factors influencing the availability of this resource. This approach involved the use of geographic information systems (GIS) and hierarchical analytical process (AHP) models. Different factors were classified and weighted according to their contribution to and impact on groundwater reserves. Their normalized weights were evaluated using a pairwise comparison matrix. Four classes of potentiality emerged: very high, high, moderate, and low, occupying 15.22%, 20.17%, 30.96%, and 33.65%, respectively, of the basin’s area. A groundwater potential map (GWPA) was validated by comparison with data from 134 existing water points using a receiver operating characteristic (ROC) curve. The AUC was calculated at 80%, indicating the good predictive accuracy of the AHP method. These results will enable water operators to select favorable sites with a high groundwater potential. Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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21 pages, 6372 KiB

Open AccessArticle

Combined Application of Hydrogeological and Geoelectrical Study in Groundwater Exploration in Karst-Granite Areas, Jiangxi Province

by Jacob Lubang, Haifei Liu and Rujun Chen

Water 2023, 15(5), 865; https://doi.org/10.3390/w15050865 - 23 Feb 2023

Cited by 6 | Viewed by 2114

Abstract

Drinking water shortage is a major concern in villages across southern Jiangxi, and this has impacted economic and social development. In order to address this challenge, groundwater prospecting was carried out in the villages under the support of Drinking Water Safety Project of [...] Read more.

Drinking water shortage is a major concern in villages across southern Jiangxi, and this has impacted economic and social development. In order to address this challenge, groundwater prospecting was carried out in the villages under the support of Drinking Water Safety Project of China Geological Survey. In this study, we present two example sites in Ningdu County selected to demonstrate the combined hydrogeological survey, and the direct current electrical resistivity method was utilized for the present study for groundwater exploration in karst-granite distribution areas. First, a hydrogeological study was effectively used to delineate shallow severely weathered structural fissures as prospective target water-bearing beds. Then, a direct current electrical resistivity survey was used to confirm the distribution, thickness scale, and water-bearing features. The structural fractured zone whose distribution and trend were first established through hydrogeological surveys and whose development characteristics and water-richness were investigated by the direct current electrical resistivity method is the target layer for water exploration in the karst-granite rock areas. The water-bearing fracture zone shows a groove or strip-shape low resistivity anomaly and can be identified in its aquifer position according to its IP half decay time (Th), apparent polarizability (ηs), and apparent resistivity (ρs). The findings demonstrate that the above methods were successful in locating water potential areas, providing information for comparison and accurate borehole positioning. The results of the subsequent drilling and pumping tests supported the interpretation of the geophysical exploration data, and the water output from both boreholes met the objectives of this study. This groundwater search might serve as a guide for future exploration projects in similar areas. Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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24 pages, 7698 KiB

Open AccessArticle

The Ibadan Hydrogeophysics Research Site (IHRS)—An Observatory for Studying Hydrological Heterogeneities in A Crystalline Basement Aquifer in Southwestern Nigeria

by Kennedy O. Doro, Christianah O. Adegboyega, Ahzegbobor P. Aizebeokhai and Michael A. Oladunjoye

Water 2023, 15(3), 433; https://doi.org/10.3390/w15030433 - 20 Jan 2023

Cited by 2 | Viewed by 3290

Abstract

Crystalline basement aquifers are important drinking water sources in Nigeria and several sub-Saharan African countries. However, an understanding of their local flow and transport processes and pathways is missing due to limited research. The implication has been their suboptimal management, with frequently reported [...] Read more.

Crystalline basement aquifers are important drinking water sources in Nigeria and several sub-Saharan African countries. However, an understanding of their local flow and transport processes and pathways is missing due to limited research. The implication has been their suboptimal management, with frequently reported dry wells and groundwater contaminations. To address this challenge, the Ibadan Hydrogeophysics Research Site was established in 2019 as the first field-scale hydrogeological research laboratory in Nigeria to advance understanding of the geologic, hydraulic, and hydrogeochemical variabilities within crystalline basement aquifers. The over 22,500 m² research site with a 50 m × 50 m area used for active hydraulic testing is located within the University of Ibadan campus and is instrumented with four initial test wells extending through the weathered and fractured zones to a depth of 30 m each. Preliminary hydrogeological and geophysical studies focused on obtaining a conceptual model and knowledge of hydraulic heterogeneities to aid in detailed experimental and numerical studies. A combination of lithological logs and electrical resistivity revealed areas with subvertical fractures as low-resistivity zones (<200 Ωm), and a pumping test revealed a hydraulic conductivity range of 1.9 × 10⁻¹⁰ to 7.2 × 10⁻⁶ m/s. The drawdown–time curve shows flow from single-plane vertical fractures. The results of this study will serve as a basis for further targeted field and numerical studies for the investigation of variability in groundwater flow in complex crystalline basement aquifers. The presented field site is posed to support the adaptation and development of field methods for studying local heterogeneities within these aquifers in Nigeria. Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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10 pages, 1704 KiB

Open AccessTechnical Note

Determination of Aquitard Storage from Pumping Tests in Leaky Aquifers

by Florimond De Smedt

Water 2023, 15(21), 3735; https://doi.org/10.3390/w15213735 - 26 Oct 2023

Viewed by 1031

Abstract

The management of groundwater resources requires a thorough understanding of groundwater flow and storage. Aquitards, in particular, can store large amounts of groundwater, but are generally often overlooked or ignored in groundwater surveys. In this study, we show how a pumping test performed [...] Read more.

The management of groundwater resources requires a thorough understanding of groundwater flow and storage. Aquitards, in particular, can store large amounts of groundwater, but are generally often overlooked or ignored in groundwater surveys. In this study, we show how a pumping test performed in a leaky aquifer can be used to estimate the storage coefficient of an overlying aquitard. A new analytical solution is presented for a constant-rate pumping test in a leaky aquifer taking into account the water released from storage in the aquitard. The utility of the method is demonstrated by a practical application using data from a pumping test conducted in a semi-confined sandy aquifer overlain by an aquitard consisting of a mixture of clay and sand. The results obtained show that the solution enables the accurate calculation of the storage properties of the aquitard. Full article

(This article belongs to the Special Issue Groundwater Exploration and Hydrogeophysical Research)

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