Aquifer Water Research Articles

Equivalent Hydraulic Conductivity of Heterogeneous Aquifers Estimated by Multi-Frequency Oscillatory Pumping

Aquifers are a vital part of our water cycle and modeling groundwater flow is paramount for a number of environmental applications. Modeling requires the estimation of aquifer properties, which is mostly achieved by field pumping tests. Oscillatory pumping tests involve repeated pumping and injection of aquifer water, which generates a periodic head signal. We investigate the estimation of equivalent hydraulic conductivity (Keq) in an oscillatory pumping test with a multi-frequency excitation. Synthetic head data are generated from numerical simulations of pumping in heterogeneous aquifers and an inverse method is applied to estimate Keq. The method involves a Fast Fourier Transform (FFT) analysis for obtaining the spatial distribution of head amplitude and then matching the amplitudes using a semi-analytical solution of a homogeneous aquifer with conductivity Keq. We investigate the dependence of Keq on pumping frequency in view of the previous literature, which has found increasing values for higher frequencies. We did not find this increase in Keq with frequency and minor variations which were observed appear to be a result of numerical error. The result implies that oscillatory pumping field tests can be used for Keq estimation without any corrections for frequency dependence.

Optimizing the operational efficiency of the underground hydrogen storage scheme in a deep North Sea aquifer through compositional simulations

In this study, we evaluate the technical viability of storing hydrogen in a deep UKCS aquifer formation through a series of numerical simulations utilising the compositional simulator CMG-GEM. Effects of various operational parameters such as injection and production rates, number and length of storage cycles, and shut-in periods on the performance of the underground hydrogen storage (UHS) process are investigated in this study.Results indicate that higher H2 operational rates degrade both the aquifer's working capacity and H2 recovery during the withdrawal phase. This can be attributed to the dominant viscous forces at higher rates which lead to H2 viscous fingering and gas gravity override of the native aquifer water resulting in an unstable displacement of water by the H2 gas. Furthermore, analysis of simulation results shows that longer and less frequent storage cycles lead to higher storage capacity and decreased H2 retrieval. We conclude that UHS in the studied aquifer is technically feasible, however, a thorough evaluation of the operational parameters is necessary to optimise both storage capacity and H2 recovery efficiency.

Impure CO2 storage reactions of sandstone, mudstone and carbonate cemented cores: Experimental CO2 SO2 NOX O2 reaction metal mobilisation and fate

CO2 geological storage can be part of the solution to reduce carbon emissions to the atmosphere. An understanding of the geochemical processes occurring during CO2 storage is needed to reduce risk. Drill cores from a low salinity reservoir site proposed for CO2 storage, and the overlying and underlying formations, were characterised for minerals by QEMSCAN, total metals and porosity. Elements including Li, Ba, Sr, K, Mg, V, Zn, REE, Fe, Pb, P, and S were relatively elevated in the Moolayember Formation underlying the reservoir. Synchrotron XFM showed the main host of Mn was siderite, with Rb in K-feldspar, Zn and Cu in sphalerite and chalcopyrite, and As in pyrite in coal pores associated with coal laminations. Drill cores are reacted at reservoir conditions with synthetic formation water and an impure CO2 stream composition of CO2-SOx-NOx-O2 expected to be injected at the site. Elements released were dependant on mineral content, with quartz rich reservoir, lower Precipice Sandstone core reactions resulting in dissolution of trace carbonates, alteration of sulphides and monazite, and variable elevated dissolved Pb, and U. Dissolved Co, Ni, Ca, Zn, Li, Rb, and U were released at relatively elevated concentrations from the mudstone. For carbonate cemented upper Precipice Sandstone or Moolayember Formation core strong dissolution of calcite and ankerite, with corrosion of siderite, Fe-rich chlorite, and sulphides or monazite were observed after reaction. Dissolved elements including Ca, Mg, Mn, Sr, and Ba increased in experiments from the reaction of calcite, siderite, and ankerite. Generally dissolved Fe, Pb, Cr, Cu, Co etc. increased from dissolution, and subsequently decreased in concentration with adsorption and precipitation processes. The fast mobilisation of elements including Fe and Pb are consistent with the release of metals from carbonate dissolution and desorption. The presence of O2 and NOX in the gas stream results in Fe-(oxyhydr)oxide precipitation especially where Fe has been rapidly mobilised from dissolution of siderite and Fe-chlorite. This acts as a sink for Fe and provides new adsorption sites for sequestering a proportion of the trace metals. These processes are applicable to other CO2 storage sites and potential leakage indicators in overlying drinking water aquifers. The findings are also more broadly applicable to subsurface energy storage such as compressed air renewable energy storage, CO2 enhanced recovery, geothermal, natural gas or hydrogen storage.

Partition pattern and environmental consequences of the widespread coalmines and host rocks on the water of selected regions, China.

The massive exploration and random dumping of coals in various regions of China create serious environmental and health problems because of the presence of toxic trace elements (TTEs), which possibly transfer to environment and cause serious health issues. This study was conducted to probe the environmental consequences of coalmines on the aquifer water and their association with health risks and the environment. For this purpose, 100s of water samples was collected from the typical coalmine regions of Hancheng, Huanglong, Binxian, Handan, Langao, and Fusui and analyzed for various parameters. In Handan mining areas, Se, Mn, Fe, TDS, SO42-, and total hardness were higher than the WHOstandard, while in Hancheng, SO42- was > 95%, Ca2+ 40-96%, and Mg2+ was 0-40%, which caused permanent hardness. In the Fusui and Huanglong areas, the SO42- concentration was > 95%, Ca2+ 60-100%, and Mg2+ 20%, causing permanent hardness. In Binxian, HCO3- was 70-90%, Ca2+ 60-80%, and Cl- and SO42- were 20%, causing temporary hardness. In the Kashin-Beck disease (KBD) area, Se in the Middle Triassic was 0.3, Upper Triassic 0.23, and Quaternary 0.01, while fluoride (F) was 124.7, 141.6, and 159 in μgL-1. The Handan water is included in rock-evaporation dominance (a mixed controlling mechanism), Hancheng, Binxian, Huanglong, and Langao water was included in rock dominance, while the Fusui water was included in rock-precipitation dominance. The average daily intake ((ADI) mgkg-1d-1) of Ba, Cd, Co, Cr, Cu, Fe, Ti, Tl, Mo, Ni, Zn, Pb, Be, U, and Sr was comparably higher than No Observed Adverse Effect Level (NOAEL), which surely causes high health risk in selected regions. The elemental contaminants in the water were attributed to the geological environment, geochemical processes, ion exchanges, redox reactions, and dissolution of mineralized rock. For aquifer safety, coal mining, and other geological activities should be avoided to protect the water for future generations.

Hydrochemical and isotopic characteristics of the Lodwar Alluvial Aquifer System (LAAS) in Northwestern Kenya and implications for sustainable groundwater use in dryland urban areas

Groundwater is a crucial resource for dryland regions such as this, where surface water resources are limited and unreliable. This paper presents a study of the Lodwar Alluvial Aquifer System (LAAS) in northwestern Kenya and its hydrochemical and isotopic characteristics, with the goal of understanding how to sustainably manage the groundwater system. As a result, the paper focuses on elucidating the hydrogeochemical and river-groundwater interaction (using environmental isotopes and major ion chemistry) of an aquifer that is located in the north-western dryland of Kenya. The study utilised environmental isotopes of oxygen-18 (18O), deuterium (2H), and tritium (3H) as tracers for establishing recharge sources and origin of groundwater. A sampling campaign involving 112 water samples was conducted to establish isotopic compositions of rain, spring, surface water (rivers, scoop holes, dams and lake) and groundwater at the peak of the wet season in May 2018. The tritium values in the study area ranged from 1.1 to 2.4 TU. Considering the median values of δ18O and δ2H in surface water and groundwater samples, four clusters emerge based on the degree of enrichment; Cluster 1 comprises the lake water (δ18O = +6.01, δ2H = +41.9); Cluster 2 is the Turkwel and Kawalase river water with slightly positive relative to VSMOW and with different δ2H values (+7.6‰ versus −9.8‰). The third cluster is the groundwater of the Shallow Alluvial Aquifer (SAA) and the Deep Aquifer (DA) (δ18O = −0.96‰ and −0.70‰; and δ2H = +0.4‰ and +0.6‰, respectively). The last cluster comprises the most isotope-depleted waters of water pans, scoop holes, Intermediate Aquifer (IA) and Turkana Grit Shall Aquifer (TGSA) with median values ranging from −2.87‰ to −2.48‰ for δ18O and −8.6‰ and −16.4‰ for δ2H. While the SAA is mainly recharge by the Turkwel River, a relationship is observed between the values deuterium in the Kawalase (−9.6‰ VSMOW) and IA (−8.6‰ VSMOW). Understanding recharge sources and aquifer vulnerability of similar strategic aquifers helps scientists appropriately advise policymakers and the water community who develop sustainable water use, aquifer protection and conservation strategies. In addition, the study contributes scientific evidence of isotopic compositions of groundwater in the Horn of Africa. Furthermore, the evidence of surface water-groundwater interaction presents a case of a fragile dryland ecosystem. Future work will involve the installation of piezometers in strategic aquifer zones to monitor groundwater levels in relation to river gauging data to quantify the amount of recharge and establish the impacts of rainfall variability in the upstream catchment.

Integration of Geological, Geochemical Modelling and Hydrodynamic Condition for Understanding the Geometry and Flow Pattern of the Aquifer System, Southern Nyírség–Hajdúság, Hungary

Geological heterogeneity impacts groundwater flow patterns, necessitating a detailed hydrogeological framework for conceptualization process of aquifer systems. This research developed a new conceptual model of detailed geologic geometry by integrating 133 well-logs, 366 hydrodynamic data and 118 water samples. As new results, systematic 3D log correlation detected four distinct hydrostratigraphic units in the Southern Nyírség–Hajdúság Groundwater Body (East Hungary). The primary aquifer was identified as an incised valley 10–13 km wide and a NE–SW strike. Logan’s approach estimated the average hydraulic conductivity of the Incised Valley Unit (IVU) at 11 m/d, higher than the other three aquifers (3.2 m/d to 4.6 m/d). The average specific capacity of wells screening the IVU is 315.6 m3/d/m, in contrast with the remaining aquifers ranging from 31.6 m3/d/m to 92 m3/d/m. Pressure–depth profiles, dynamic pressure increment and hydraulic head maps revealed recharge–discharge zones and hydraulic windows between hydrostratigraphic units. The elongated pattern on the hydraulic head map at the depth of the IVU showed the existence of a preferential path along its axis within the mapped borders of the IVU. Hydrochemical analysis revealed Ca-Mg-HCO3 water type within the primary aquifer and Na-HCO3 water type in the laterally connected aquifer. The saturation index values indicated a transition from undersaturated to supersaturated state inside the main aquifer for calcite and dolomite minerals. The correlation matrix and PCA results demonstrated that the carbonate weathering process is the main factor controlling the groundwater chemistry. This integrated approach holds significance for future applications of the regional conceptual model in water management planning, sustainable aquifer development and contaminant transport modelling. It provides essential contributions to informed decision-making and the formulation of effective strategies, ensuring the long-term availability and utilization of groundwater resources.

Study of the Catastrophic Process of Water–Sand Inrush in a Deep Buried Stope with Thin Bedrock

Taking the 14,030 panel of Zhaogu No. 2 coal mine as its research object, this paper studies the evolution characteristics of the developing height, propagation track and caving arch shape of water-flowing fractures under the influence of thick alluvium by utilizing a physical experiment, theoretical analysis and field investigation. The results show that the height and limit span of the water-flowing fracture zone experience four stages, which include the initial stage, slow-increasing stage, sudden-increasing stage and stable-increasing stage. With the increase in the mining influence range, the shape of the water-flowing fracture in overburden under the influence of thick alluvium is gradually formed. The water in the thick alluvium and the water in the upper phreatic aquifer of the bedrock penetrate each other to form a concentrated danger zone, and the expansion track of the mining water-flowing fracture connects the hydraulic connection between the upper concentrated danger zone of overburden and the panel of No. 2’s first coal seam. A large amount of water mixed with sandstone flows into the fracture surface of the bedrock’s broken rock block through the water-flowing fracture, leading to the instability of the load-bearing structure composed of the thick alluvium caving arch and the towering roof beam, which illustrates the whole process of water–sand inrush accidents in thin bedrock stope with deep thick alluvium.

Diagnosis of Groundwater Quality in North Assiut Province, Egypt, for Drinking and Irrigation Uses by Applying Multivariate Statistics and Hydrochemical Methods

Globally, groundwater is a valuable natural resource that may be relied upon for irrigation and drinking needs. The main purpose of this study is to investigate the groundwater geochemistry in the West of El Qusiya, Assuit, Egypt. Groundwater suitability for irrigation has been estimated with some methods, for instance, electrical conductivity (EC), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), Killey ratio (KR), magnesium hazard (MH), permeability index (PI), Piper trilinear diagram, and USSL diagram. The Piper diagram shows that the sodium and potassium (Na+K) kind dominates the water chemistry, followed by the mixed type. The principal coordinate analysis (PCoA), cluster analysis (CA), principal component analysis (PCA), and Pearson correlation matrix analysis (PCMA) statistical methods reveal that the physicochemical parameters of water collected from the Eocene and Pleistocene aquifers are produced from mixed origins. The geogenic origin reflects the lithologic impact of aquifers matrix and water interactions, in addition to anthropogenic sources caused by infiltration of secondary salts initiated due to fertilizers and agriculture water. These factors are the controller for groundwater’s ionic (Na+, Ca2+, Mg2+, K+, Cl−, SO42−, and HCO3−) variation in the area studied. Based on SAR, KR, and PI results, groundwater is acceptable for irrigation. Consistent with RSC, MH, and Na% results, approximately 50% of the groundwater samples are unsuitable for irrigation use.

Sedimentology of the Jura Molasse: Miocene tidal clastics and freshwater carbonates from the Tramelan-2 Borehole, NW Switzerland

The Tramelan-2 borehole (Canton Bern, Switzerland) continuously cored a 275.60 m sequence of Palaeogene to Neogene sediments, providing a rare opportunity for sedimentological analysis of the Jura Molasse. Lithostratigraphy, sedimentary facies and heavy minerals allow correlation with the classical Swiss Molasse. Evidence for clastic input from Alpine and non-Alpine sources is consistent with deposition at the northern feather edge of the Molasse Basin. Grey sandstones at the base of the succession are tentatively interpreted as fluvial facies of the Lower Freshwater Molasse (USM). These are overlain by erosively-based conglomerates, interpreted as winnowed storm lags of locally-derived clasts and distantly-sourced Alpine material at the transgressive base of the Upper Marine Molasse (OMM). Above this, a range of plane-laminated and cross-bedded bioclastic sandstones are interpreted as the deposits of a meso- or macrotidal flat or estuarine complex. Facies evolution in the upper OMM records a series of stacked regressive cycles within an overall upward trend of reducing current energy, reflecting a transition from offshore to nearshore shallow marine environments. The unconformably overlying Upper Freshwater Molasse (OSM) passes upwards from micaceous siltstones and marls into a series of freshwater carbonates, dominated by lacustrine limestones which are arranged in repeated regressive cycles, each capped by organic-rich horizons. The middle part of the carbonate interval comprises palustrine limestones with pedogenetic fabrics recording periodic subaerial exposure. Stable isotope signatures from the palustrine facies reflect subaerial pedogenetic overprint, while the lacustrine carbonates record cyclical variations in δ13C which may reflect increases in organic material during progressive lake fill and/or an increased influence of aquifer waters during flooding events. The Jura Molasse onlapped a Mesozoic carbonate pediment hosting a regional karst system which remained active at least until the Burdigalian transgression on footwall highs bounding the Delémont Basin, and locally into the Langhian near Tramelan. This configuration controlled subsequent deposition of OSM carbonates which onlapped erosional and potentially early tectonic relief, and were deposited in groundwater-fed seasonal lacustrine/palustrine environments, where the karstic aquifer controls on seasonal hydrology appear to have been comparable to Caribbean freshwater carbonate wetland systems today.

Optimization of distribution networks for water and energy in isolated regions: A multi-objective approach incorporating ocean thermal energy conversion technologies

The limited resources and increased vulnerability to climate change and environmental degradation in isolated regions such as islands and archipelagos make the development of sustainable technologies for water and energy provision a crucial factor in addressing resource scarcity and mitigating anthropogenic impact. This work presents a multi-objective optimization analysis incorporating an Open Cycle Ocean Thermal Energy Conversion (OC-OTEC) plant in the water and energy distribution networks of an isolated region. The optimization considers three interrelated objectives: economic viability measured by annual profit, environmental sustainability reflected in reduced CO2 emissions and aquifer water usage, and social impact through job creation. The optimization results demonstrate the positive impact of integrating the OC-OTEC plant into the Tahiti distribution network, achieving an optimal configuration that balances economic, environmental, and social considerations. Finally, the proposed model is applied to Tahiti of French Polynesia as a case study.

Groundwater Potential Zone Delineation Using Multi-criteria Decision-making Approach: A Case Study

Over-exploitation of groundwater from coastal aquifers causes seawater intrusion and depletion of freshwater resources. As 40 percent of the world’s population live within 100 km of the coast. This will increase the demand for potable water in coastal aquifers. Hence, it is essential to evaluate the sources of fresh-groundwater potential and productivity in coastal aquifers. Nowadays, integrated studies based on geographic-information systems play a major role in groundwater-exploration studies. Thus, the current study was carried out with the objective to delineate groundwater potential in the Nambiyar river basin in Tamil Nadu's southeast coastal area, where groundwater is in a critical condition. In order to improve groundwater recharge, it is very important to identify possible recharge areas. A novel work of the integration of remote sensing, geographic information system (GIS) and multi-criteria decision-making approaches of analytical hierarchical-process methodologies (AHP) was used in the present study. A total of 11 thematic layers, such as slope, curvature, soil, roughness, topographic-wetness index, drainage density, land use/land cover, geology, geomorphology, lineament density and rainfall, were generated for delineating groundwater potential zones. All the thematic maps are weighted using AHP based on the attributes of the classes and the potential capacity of their water supply. The demarked region of groundwater potential was validated by comparing pre-monsoon and post-monsoon groundwater levels. The groundwater potential zone map was classified into five categories: very high, high, moderate, low and very low. Areas with very high and very low potentials are delineated only in very limited areas. 64% of the regions are covered under the moderate-potential zones. The low-and high-groundwater potential zones are delineated at 22% and 14%, respectively. KEYWORDS: GIS, Recharge areas, Groundwater potential, Nambiyar river basin, AHP

Water accounting in the Berrechid plain (Morocco): A process approach

AbstractWater scarcity is a growing challenge to the governance of water resources and to multiple water uses. Dealing with water scarcity requires a better‐shared understanding of water supply and demand dynamics on the part of the different stakeholders who contribute to and/or suffer the consequences of water scarcity. This study highlights the importance of establishing a water accounting system for groundwater management in the Berrechid plain (Morocco) and the conditions under which such accounting may help solve current water issues. The plain is under considerable water stress, and stakeholders are struggling to implement aquifer management plans to ensure groundwater sustainability. The study identified and quantified various components of the water balance and estimated annual groundwater overexploitation for the period 2001–2018 to be 32 million m3. Fractional analysis of the water balance showed that the reason for aquifer water stress was a rapid increase in irrigated land and current intensive agricultural and irrigation practices, which threaten both the sustainability of water resources and economic activities in the plain. To improve water governance, a system of water accounting is required that promotes responsible use and ensures that all stakeholders are answerable and accountable for their water consumption along with any actions that may affect water flows.

Groundwater Quality of Some Parts of Coastal Bhola District, Bangladesh: Exceptional Evidence

The composition of groundwater governs the drinking and irrigation water suitability. A large part of the coastal region of Bangladesh is affected and is responsible for changing the composition of the groundwater. This research attempted to observe the groundwater quality of the Bhola Sadar and Char Fasson upazilas in coastal Bangladesh. Twenty-eight (28) water samples, 27 at depths of 260–430 m (850–1400 ft) and 1 from a crop field, were collected and analyzed. The quality of water samples was determined through the evaluation of odor, color, turbidity, electrical conductivity, pH, total dissolved solids, nitrate (NO3−), ammonium (NH4+), sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn) and arsenic (As) ions. An Atomic Absorption Spectrophotometer was used for heavy metal analysis. The outcomes were compared with the drinking water quality of Bangladesh and the World Health Organization. The results showed that the average values of nearly all of the parameters were underneath or within the standard level, representing that the groundwater was appropriate for drinking purposes. The water quality parameters were also compared with the irrigation water quality of Bangladesh and the Food and Agriculture Organization. It was found that the collected samples were also suitable for irrigation. To do this, the soluble sodium percentage, sodium adsorption ratio, magnesium adsorption ratio, Kelley’s ratio, and total hardness were calculated. The novelty of this research is that, despite being in a coastal district, the deep aquifer water of Bhola was appropriate for drinking and irrigation purposes.

SPATIAL AND TEMPORAL FEATURES OF WATER CHEMISTRY CHANGES IN THE QUATERNARY UNCONFINED AQUIFERS OF THE DNIPRО RIVER BASIN

The article deals with the chemical composition of uppermost aquifers water in the Dnipro River basin. Its study is necessary not only in connection with the implementation the requirements of the EU Water Framework Directive methodological documents in the groundwater monitoring, but primarily because of water supply from these aquifers to rural areas. Unconfined aquifers water is characterized by a complex and heterogeneous chemical composition due to natural and anthropogenic factors. Natural hydrochemical zoning is distinctly visible on the territory of the Dnipro basin. A number of chemical elements and compounds in the water are contained in concentrations exceeding the standards for drinking water established by the State sanitary norms and rules 2.2.4-171-10 “Hygienic requirements for drinking water intended for human consumption” in the natural state. In addition, unconfined aquifers are subject to significant anthropogenic impact, as they are unprotected from pollution. Comparison of the data on total dissolved solids (TDS) and anionic composition of groundwater obtained during hydrogeological surveys in the period 1965–1975 and 2009–2013 on three sheets of the hydrogeological map (scale 1:200,000) in different sub-basins of the Dnipro River showed the widespread deep changes in groundwater chemical composition. In addition to a significant anthropogenic pressure, groundwater is significantly affected by climatic factors. Over a forty-year period, TDS in the north of the Dnipro basin increased by 50 %, in the central and southern parts – twice, due to an increase in the content of sulfates and chlorides. Within the analyzed areas in the Middle and Lower Dnipro sub-basins, nitrate pollution of unconfined aquifers is almost widespread. Thus, in a large area, waters of these aquifers are unsuitable for drinking water supply due to the excessive content of chemical elements and compounds of natural and anthropogenic origin. Therefore, one of the priorities of the post-war reconstruction of Ukraine should be the transfer of the rural population to water supply from protected confined aquifers and the improvement of sanitary conditions in rural areas.

Quantitative analysis and management of sustainable development of ecological water resources and digital financial system based on an intelligent algorithm

Abstract In the modern day, water is a crucial resource for advancing society and preserving ecological balance. Growth, which lessens poverty and increases equality, is often seen as inextricably linked to the effective use of water resources. Traditional water system management aims to optimize surface water and subsurface aquifers to meet conflicting needs. As a result, the special difficulties in water resource management (WRM) would be exacerbated by the added uncertainty brought on by climatic change. Managing the world's water supplies sustainably is crucial to the planet's continued existence and prosperity. However, ecological planning for sustainable water development is difficult because of complex impacts, random processes, and hydrological restrictions. The study was inspired to address the issues head-on by creating a hybrid AI algorithm for ecological water resource sustainability and digital finance (HAI-EWRS-DF) system for solving complex, multi-scale problems in WRM. Control mechanisms, including social, financial, and sustainability on ground-level and surface-level water resource facilities, are recommended to enhance WRM to increase the applicable revenue, promote community well-being, and pave the way for greater economic development.

Temporal and Spatial Evolution Mechanisms of the Water-Conducting Fractured Zone of Overlying Strata in the Kongzhuang Coal Mine

Kongzhuang coal mine of Shanghai Datun Energy Resources Co., Ltd. is a typical deep coal mine in eastern China. The mining disturbance of working face in deep coal mine leads to the fracture and movement of overlying strata and the damage of the aquifer in overlying strata, thereby causing water inrush disaster and posing a serious threat to the safety production in coal mine. Therefore, the temporal and spatial evolution mechanism of the water-conducting fractured zone of overlying strata in the Kongzhuang coal mine is researched systematically in this paper. Especially, the hydro-geological conditions and mining conditions in the Kongzhuang coal mine are analyzed; on this basis, the fracture and movement of overlying strata are simulated by physical similarity simulation test, and the temporal and spatial evolution rule of overlying strata in the Kongzhuang coal mine is obtained. Besides, the development height of “two zones” is measured by double-end water shutoff detection method, and the risk assessment for the water inrush disaster of the coal seam roof is carried out in the Kongzhuang coal mine. The research achievements in this paper indicate that the water-conducting channel formed in the mining process of #7 coal seam is the most important water-filling channel. Quaternary aquifer water recharges the mine indirectly through the bedrock aquifer, and the sandy mudstone with large thickness is the key layer to control the development of a water-conducting fracture zone. Meanwhile, the height of the caving zone is 26.7 m, about 8.3 times of mining height, and the height of the fracture zone is 68.3 m, approximately equal to 16.26 of the mining height. The results of #1 and #2 borehole leakages in the double-end water shutoff detection method show that the height of the water-conducting fractured zone is 63.70 m-65.27 m, and the split-to-mining ratio is 15.17-15.54. The water inrush risk of the coal seam roof shows that most of the 7436 working face is in the transition zone, and a small area around the cutting hole of the working face is in the relatively dangerous zone. Therefore, the innovation of this paper is that the temporal and spatial evolution mechanism of the water-conducting fractured zone of overlying strata in the Kongzhuang coal mine is revealed, which provides the theoretical guidance for the prediction and prevention of water inrush disaster in the coal mine with the similar mining conditions.

Evaluation of the impact of the intensive exploitation of groundwater and the mega-drought based on the hydrochemical and isotopic composition of the waters of the Chacabuco-Polpaico basin in central Chile

A hydrogeochemical and isotopic study has been carried out to understand the hydrogeological functioning of a small alluvial aquifer in central Chile in a context of mega-drought and intensive exploitation of its waters. Additionally, two mine tailings dams from porphyry copper mining are situated in the area. The prolonged mega-drought, which has lasted for over thirteen years, has resulted in a significant decrease in rainfall recharge and a drop of up to 50 m in piezometric levels, although no serious groundwater contamination problems have yet been detected, except for a rise in nitrate contents (ranging between 23 and 45 mg/L NO3) attributed to return irrigation. Groundwaters are calcium-bicarbonate and calcium-sodium-bicarbonate in composition. The values of δ18O and δ2H of the alluvial aquifer indicate fractionation by evaporation that would be explained by the recirculation of water that occurs in the agricultural areas of the basin, where the excess irrigation water that go back to the aquifer presents fractionation by evaporation. The δ34S and δ18O of dissolved sulfate point to pyrite oxidation, which could be related to the pyrite present in the copper porphyry and recognized in the Andes Cordillera. The 87Sr/86Sr isotopic values of the alluvial aquifer waters are close to the isotopic fingerprint of the volcanic rocks of the Abanico Formation. However, the water from the wells located further downstream in the basin and close to the tailing dams show δ34S and δ18O of dissolved sulfate and 87Sr/86Sr consistent with Miocene intrusive mineralogies of the copper porphyry type. The groundwater chemistry does not show water seepage from the tailings dam. Therefore, a minor contribution of minerals related to the intrusive rocks is proposed, which would originate from the movement of fine particles by the wind from the dams to the valley floor. The 14C activities indicate that groundwater is recent.

The Characterization of Groundwater Quality for Safe Drinking Water Wells via Disinfection and Sterilization in Jordan: A Case Study

This work aims to evaluate the quality of drinking water in the Disi aquifer in Jordan. Several water quality parameters are included in the mathematical equation to evaluate the average water quality and establish the suitability of water for drinking purposes. Water sampling zones from three wells were used to calculate the water quality indices (WQI). The water samples were analyzed for several physicochemical parameters, including pH, turbidity, total dissolved solids, Na+, Ca2+, Mg2+, Na+, K+, HCO3−, SO42−, Cl−, NO3−, total hardness, electrical conductivity (EC) and other elements (Fe2+, Zn2+, Mn2+, Cd2+, As2−, Pb4+ and Cu2+), in the groundwater wells. Biological parameters, such as faecal coliform, were also tested. The Weighted Arithmetic WQI indicated that most of the wells were of good to excellent quality. These determined indices support decision making and are beneficial to monitoring the groundwater quality in the Disi aquifer. The relative weight is specific to each parameter and ranges from 1 to 5; it establishes the importance of the water quality parameters for domestic purposes. The WQI analysis rates the water quality between 75 to 65 from good to medium. The water quality of the Disi aquifer for potable drinking water was compared with the guidelines of the World Health Organization (2011) and the Jordan Drinking Standard (JS286); the results indicated that water in the Disi aquifer was of high quality and was fit for drinking.

Multi-isotope identification of key hydrogeochemical processes and pollution pathways of groundwater in abandoned mining areas in Southwest China.

Acid mine drainage (AMD) is considered one of the serious environmental issues in the mining area. Understanding the key processes and pathways of hydrogeochemical evolution is critical for the effective control of AMD pollution. Hydrogeochemical analysis along with environmental isotope tracing was utilized to provide information regarding the hydrogeochemical process of groundwater pollution by using the multi-aquifer of abandoned Dashu pyrite in Southwest China as an example. Using the deuterium excess parameter d of groundwater and the results of 2H, 18O, and T analysis, the water-rock interaction intensity was determined. The distribution characteristics of d-T revealed that the groundwater primarily originated from the Quaternary reservoir platform groundwater and that there was a close hydraulic connection among the aquifers. The results of ion analysis and sulfur isotope tracing indicated that the sulfur in groundwater was primarily derived from gypsum dissolution, whereas the sulfur in mine water was primarily derived from pyrite oxidation. The results of the hydrogeochemical inversion indicated that mining activities altered the water level and flow conditions, promoted water-rock interactions, altered the hydrogeochemical process, and caused aquifer and mine water cross-contamination. The findings provide theoretical guidance for identifying the pollution sources and critical hydrogeochemical processes that affect groundwater in depleted mining areas of multi-aquifers and also provide technical support for developing water source control and prevention techniques.

Impact of Releases from the Kef Eddir Dam on the Recharge of the Oued Damous Aquifer

Artificial recharge is a good way to mobilize water in aquifers and recharge groundwater. Dam release is one of the techniques used for groundwater recharge. The periodic releases programmed by the Kef Eddir dam make it possible to recharge the Damous wadi aquifer located in the coastal wilaya of Tipaza in Algeria, whose overexploitation lowers the level of its water and causes a marine intrusion that pollutes it. In this work, to estimate the impact of these releases on aquifer recharge, we followed the releases of March 2020 and May 2021. The piezometric levels of groundwater were measured before the releases, during flow caused by them, and after them. These measures concern 13 wells located along the Damous wadi watercourse for the first year and 18 wells for the second year. These two years have seven wells in common. It allowed us to compare piezometric levels and recharges between 2020 and 2021. In the absence of releases on our return in May and June 2022, we measured the depth of water presence and took samples from 6 wells to measure the water conductivity. These measurements allow us to evaluate the piezometry of the water table over these three years, and the conductivity will indicate the degree of salinity of its water. Keywords: Artificial recharge; Kef Eddir dam; Oued Damous aquifer; Piezometric level; Releases.