Search Results (210)

Rapid socio-economic development and the impact of human activities have exerted tremendous pressure on the groundwater system of the Dawen River Basin (DRB), the largest tributary in the middle and lower reaches of the Yellow River. Hydrochemical studies on the DRB have largely centered on the upstream Muwen River catchment and downstream Dongping Lake, with some focusing solely on karst groundwater. Basin-wide evaluations suggest good overall groundwater quality, but moderate to severe contamination is confined to the lower Dongping Lake area. The hydrogeologically complex mid-reach, where the Muwen and Chaiwen rivers merge, warrants specific focus. This region, adjacent to populous areas and industrial/agricultural zones, features diverse aquifer systems, necessitating a thorough analysis of its hydrochemistry and origins. This study presents an integrated hydrochemical, isotopic investigation and EWQI evaluation of groundwater quality and formation mechanisms within the multiple groundwater types of the central DRB. Central DRB groundwater has a pH of 7.5–8.2 (avg. 7.8) and TDSs at 450–2420 mg/L (avg. 1075.4 mg/L) and is mainly brackish, with Ca²⁺ as the primary cation (68.3% of total cations) and SO₄²⁻ (33.6%) and NO₃⁻ (28.4%) as key anions. The Piper diagram reveals complex hydrochemical types, primarily HCO₃·SO₄-Ca and SO₄·Cl-Ca. Isotopic analysis (δ²H, δ¹⁸O) confirms atmospheric precipitation as the principal recharge source, with pore water showing evaporative enrichment due to shallow depths. The Gibbs diagram and ion ratios demonstrate that hydrochemistry is primarily controlled by silicate and carbonate weathering (especially calcite dissolution), active cation exchange, and anthropogenic influences. EWQI assessment (avg. 156.2) indicates generally “good” overall quality but significant spatial variability. Pore water exhibits the highest exceedance rates (50% > Class III), driven by nitrate pollution from intensive vegetable cultivation in eastern areas (Xiyangzhuang–Liangzhuang) and sulfate contamination from gypsum mining (Guojialou–Nanxiyao). Karst water (26.7% > Class III) shows localized pollution belts (Huafeng–Dongzhuang) linked to coal mining and industrial discharges. Compared to basin-wide studies suggesting good quality in mid-upper reaches, this intensive mid-reach sampling identifies critical localized pollution zones within an overall low-EWQI background. The findings highlight the necessity for aquifer-specific and land-use-targeted groundwater protection strategies in this hydrogeologically complex region. Full article

Foundation pit pumping induces groundwater drawdown both inside and outside the pit, consequently causing surrounding land subsidence. Based on actual engineering cases, this study established a three-dimensional numerical model using ABAQUS software (version 6.14-4) to systematically investigate the temporal evolution of groundwater drawdown and land subsidence during pit pumping, while quantifying the relationship between drawdown and subsidence stabilization time under different parameters. The key findings are as follows: (1) land subsidence stabilization time (50 days) is governed by external phreatic layer response, reaching 2.3 times longer than isolated aquifer conditions (22 days); (2) medium-permeability strata (0.01–10 K_0,AdII) showed peak sensitivity to drawdown–subsidence coupling; (3) pumping from a confined aquifer extends the subsidence stabilization time by a factor of 1.1 compared to phreatic aquifer conditions. These findings provide valuable insights for the design and risk assessment of dewatering strategies in foundation pits within multi-aquifer systems. Full article

The hydrochemical characteristics and evolution mechanisms of groundwater are critical for accurately understanding the input–output budget of hydrochemical constituents in pristine groundwater. However, few studies have analyzed the changes in mineral precipitation and dissolution equilibrium along the groundwater flow path, especially in arid regions. This study integrated hydrochemical analysis, stable isotopes, and inverse hydrochemical modeling to identify groundwater recharge sources, hydrochemical evolution, and controlling mechanisms in an arid endorheic watershed, northwestern China. A stable isotope signature indicated that groundwater is primarily recharged by high-altitude meteoric precipitation and glacial snowmelt. The regional hydrochemical type evolved from HCO₃·Cl-Ca·Mg·Na types in phreatic aquifers to more complex HCO₃·Cl-Ca·Mg Na and HCO₃·Cl-Na Mg types in confined aquifers and a Cl-Mg·Na type in high-salinity groundwater. The dissolution of halite, gypsum, calcite, K-feldspar, and albite was identified as the primary source of dissolved substances and a key factor controlling the hydrochemical characteristics. Meanwhile, hydrochemical evolution is influenced by cation exchange, mineral dissolution–precipitation, and carbonate equilibrium mechanisms. Inverse hydrochemical modeling demonstrated that high-salinity groundwater has experienced intensive evaporation and quantified the transfer amounts of associated minerals. This study offers deeper insight into hydrochemical evolution in the Golmud River watershed and elucidates mineral transport and enrichment mechanisms, providing a theoretical basis for investigating hydrochemical metallogenic processes. Full article

Efficient management of groundwater resources is essential for environmental sustainability. This study introduces the development and application of a digital twin (DT) for confined aquifers to optimise water extraction and ensure long-term sustainability. A resilience-based control model was implemented to manage the Morroa Aquifer (Colombia). This model integrated historical, hydrogeological, and climatic data acquired from in-situ sensors and satellite remote sensing. Several heuristic methods were employed to optimise the parameters of the objective function, which focused on managing water extraction in aquifer wells: grid search, genetic algorithms (GA), and particle swarm optimisation (PSO). The results indicated that the PSO algorithm yielded the lowest root mean square error (RMSE), achieving an optimal extraction rate of 8.3 l/s to maintain a target dynamic water level of 58.5 m. Furthermore, the model demonstrated the unsustainability of current extraction rates, even under high-rainfall conditions, highlighting the necessity for revising existing water extraction strategies to safeguard aquifer sustainability. To showcase its practical functionality, a DT prototype was deployed in a well within the Morroa piezometric network (Sucre, Colombia). This prototype utilised an ESP32 microcontroller and various sensors (DS18B20, SKU-SEN0161, SKU-DFR0300, SEN0237-A) to monitor water level, pH, dissolved oxygen, and temperature. The implementation of this DT proved to be a crucial tool for the efficient management of water resources. The proposed methodology provided key information to support decision-making by environmental management entities, thereby optimising monitoring and control processes. Full article

Globally, groundwater resources are experiencing a decline in hydraulic heads resulting from the dual effects of urbanization and climate change, highlighting the need for integrated and sustainable water resources management. Urban development in the cities of Kansai region, western Japan, presents a significant challenge to the sustainability of groundwater resources. This study aims to assess the combined influence of urbanization and climate change on the groundwater resources of the Nara Basin using MODFLOW 6 for two distinct periods: The Pre-Urbanization Period (PreUP: 1980–1988), and the Post-Urbanization Period (PostUP, 2000–2008) with an emphasis on spatiotemporal distribution of recharge in a multi-layer aquifer system. Simulated hydraulic heads were evaluated under three different recharge scenarios: uniformly, spatiotemporally and spatially distributed. The uniform recharge scenario both overestimates and underestimates hydraulic heads, while the spatially distributed scenario produced a simulated heads distribution similar to the spatiotemporally distributed recharge scenario, underscoring the importance of incorporating spatiotemporal variability in recharge input for accurate groundwater flow simulation. Moreover, our results highlight the relevance of spatial distribution of recharge input than temporal distribution. Our findings indicate a significant decrease in hydraulic heads of approximately 5 m from the PreUP to PostUP in the unconfined aquifer, primarily driven by changes in land use and climate. In contrast, the average head decline in deep confined aquifers is about 4 m and is mainly influenced by long-term climatic variations. The impervious land use types experienced more decline in hydraulic heads than the permeable areas under changing climate because of the impedance to infiltration and percolation exacerbating the climate variability effect. These changes in hydraulic heads were particularly evident in the interactions between surface and groundwater. The cumulative volume of groundwater discharge to the river decreased by 27%, while the river seepage into the aquifer increased by 16%. Sustainable groundwater resources management under conditions of urbanization and climate change necessitates a holistic and integrated approach. Full article

A vital step for any hydrochemical assessment is properly carrying out quality assurance and quality control (QA/QC) techniques to evaluate data confidence before performing the assessment. Understanding the processes governing groundwater evolution in coastal aquifers is critical for managing freshwater resources under increasing anthropogenic and climatic pressures. This study reassesses the hydrochemical and isotopic data from the Deep Confined Aquifer System (DCAS) in the Jiangsu Coastal Plain, China, by firstly applying QA/QC protocols. Anomalously high Fe and Mn concentrations in several samples were identified and excluded, yielding a refined dataset that enabled a more accurate interpretation of hydrogeochemical processes. Using hierarchical cluster analysis (HCA), principal component analysis (PCA), and stable and radioactive isotope data (δ²H, δ¹⁸O, ³H, and ¹⁴C), we identify three dominant drivers of groundwater evolution: water–rock interaction, evaporation, and seawater intrusion. In contrast to earlier interpretations, we present clear evidence of active seawater intrusion into the DCAS, supported by salinity patterns, isotopic signatures, and local hydrodynamics. Furthermore, inconsistencies between tritium- and radiocarbon-derived residence times—modern recharge indicated by ³H versus Pleistocene ages from ¹⁴C—highlight the unreliability of previous paleoclimatic reconstructions based on unvalidated datasets. These findings underscore the crucial role of robust QA/QC and integrated tracer analysis in groundwater studies. Full article

In-situ chemical oxidation (ISCO) is a common method to remediate chlorinated ethene contaminants in groundwater. Monitoring the effectiveness of ISCO can be hindered because of insufficient observations to assess oxidant delivery. Advantageously, potassium permanganate, one type of oxidant, provides the opportunity to use its strong electrical signal as a surrogate to track oxidant delivery using time-series borehole geophysical methods, like electromagnetic (EM) induction logging. Here we report a passive ISCO (P-ISCO) experiment, using potassium permanganate cylinders emplaced in boreholes, at a chlorinated ethene contamination site, Naval Air Station Pensacola, Florida. The contaminants are found primarily at the base of a shallow sandy aquifer in contact with an underlying silty-clay confining bed. We used results of the time-series borehole logging collected between 2017 and 2022 in 4 monitoring wells to track oxidant delivery. The EM-induction logs from the monitoring wells showed an increase in EM response primarily along the contact, likely from pooling of the oxidant, during P-ISCO treatment in 2021. Interestingly, concurrent natural gamma-ray (NGR) logging showed a decrease in NGR response at 3 of the 4 wells possibly from the formation of manganese precipitates coating sediments. The coupling of time-series logging and well-chemistry data allowed for an improved assessment of passive ISCO treatment effectiveness. Full article

The earthquake-induced water level responses in the fault zone may be distinctly different, even when the underground wells are very close. How to qualitatively and quantitatively analyze the differences and controlling factors of the groundwater response to earthquakes in the fracture zone is a hot topic in seismic hydrogeology. This study utilizes three adjacent groundwater monitoring wells, located across distinct structural domains of the Dachuan-Shuangshi Fault, to systematically investigate the different sensitivities of earthquake-induced water level responses and their main influencing factors. The statistical results reveal that monitoring wells located on opposing fault blocks demonstrate higher co-seismic sensitivity compared to the well situated within the fault fracture zone. The water level co-seismic responses are governed by multiple controlling factors, rather than being dominated by individual parameters. Therefore, we employed random forest to quantitatively assess the importance of influencing factors related to hydraulic parameters, aquifer confinement, fault architecture, tidal characteristics, and barometric efficiency. The results showed that hydraulic properties and aquifer confinement are the primary factors influencing the differential sensitivity of water level co-seismic responses. In contrast, the influence of barometric efficiency on water level co-seismic responses is relatively minor. These findings provide critical insights into the understanding of the mechanism and characteristics of seismic hydrological responses in fault zones and provide support for optimizing the placement of groundwater monitoring in seismotectonic environments. Full article

Uncovering the characteristics of groundwater pollution and its driving mechanisms are crucial for maintaining its ecological functions. This study focuses on hydrochemical changes and their driving factors in groundwater from different aquifers in industrial zones, taking Zibo City, Shandong Province, China, as the research area. During the dry and flood seasons of 2022, samples of phreatic water in pore media (17 sites) and karst confined water (23 sites) were collected and monitored. Piper trilinear diagrams, Gibbs diagrams, ion ratio diagrams, and a principal component analysis (PCA) were used for in-depth analyses. Pore phreatic water had higher excess rates of Na⁺, Cl⁻, and NO₃⁻ than karst confined water, which indicated a greater degree of human impact compared with karst confined water. The main hydrochemical type was HCO₃·SO₄-Ca, but in the dry season, pore phreatic water shifted to HCO₃·SO₄·Cl-Ca. The ion ratios and PCA indicated that the groundwater quality was mainly controlled by water–rock interactions and industrial activities. In the flood season, pore phreatic water was influenced by evaporite dissolution, industrial activities, and domestic sewage, while in the dry season, it was affected by halite and carbonate weathering dissolution and domestic sewage. Karst confined water was controlled by water–rock interactions and industrial activities in both seasons. The findings reveal that the key drivers of groundwater quality displayed significant differences depending on the aquifer type and seasonal variations. As such, customized approaches are essential to efficiently address and counteract the decline in groundwater quality. Full article

Groundwater resources in the Kou sub-basin of southwestern Burkina Faso play a critical role in supporting domestic water supply, agriculture, and industry in and around Bobo-Dioulasso, the second-largest city in Burkina Faso. This study synthesizes over three decades of research on groundwater vulnerability, recharge mechanisms, hydrochemistry, and residence time across the region’s sedimentary aquifers. The Kou basin hosts a complex stratified system of confined and unconfined aquifers, where hydrochemical analyses reveal predominantly Ca–Mg–HCO₃ facies, alongside local nitrate (0–860 mg/L), iron (0–2 mg/L) and potassium (<6.5 mg/L–190 mg/L) contamination. Vulnerability assessments—using parametric (DRASTIC, GOD, APSU) and numerical (MODFLOW/MT3D) models—consistently indicate moderate to high vulnerability, especially in alluvial and urban/peri-urban areas. Isotopic results show a deep recharge for a residence time greater than 50 years with deep groundwater dating from 25,000 to 42,000 years. Isotopic data confirm a vertically stratified system, with deep aquifers holding fossil water and shallow units showing recent recharge. Recharge estimates vary significantly (0–354 mm/year) depending on methodology, reflecting uncertainties in climatic, geological, and anthropogenic parameters. This review highlights major methodological limitations, including inconsistent data quality, limited spatial coverage, and insufficient integration of socio-economic drivers. To ensure long-term sustainability, future work must prioritize high-resolution hydrogeological mapping, multi-method recharge modeling, dynamic vulnerability assessments, and strengthened groundwater governance. This synthesis provides a critical foundation for improving water resource management in one of Burkina Faso’s most strategic aquifer systems. Full article

This study presents a novel approach that integrates the Kalman filter and genetic algorithms to obtain the hydraulic parameters of a confined aquifer with precision, eliminating noise that is not normally considered in traditional procedures; these parameters are necessary for the design of wells, the calculation of water balances and the numerical modeling of aquifers. The Theis solution for horizontal radial groundwater flow to an extraction well within a confined aquifer is implemented in the Kalman filter to calibrate the hydraulic transmissivity and the storage coefficient, minimizing the differences between drawdown estimates and the Theis solution by means of genetic algorithms. The estimate error variances provided by the method allowed for the quantification of an approximate average drawdown measurement error of 0.12 m and 0.02 m, respectively, during the execution of two pumping tests. Full article

To ensure the stability of deep foundation pits in confined aquifers, dewatering is often required. However, pumping from confined aquifers in large deep foundation pit groups may lead to significant environmental deformations. Therefore, field pumping and recharge tests are required to guide design of groundwater and environmental deformation control scheme. Focusing on a super-large deep foundation pit group in Shanghai, single-well pumping, multi-well pumping, and recharge tests were conducted in distinct geological zones (normally consolidated area and paleochannel zone). The hydraulic connectivity and spatiotemporal patterns of groundwater drawdown and soil settlement were systematically analyzed. The results show that: (1) There exists a certain hydraulic connection between the first and second confined aquifers. In the paleochannel area, the aquitard between the micro-confined and the first confined aquifer is insufficient to completely block hydraulic connectivity. (2) The ratio of ground surface settlement to groundwater drawdown is about 3.4 mm/m, and the deep soil settlement is significantly or even greater than the surface settlement, so it is necessary to strengthen the monitoring of deep settlement. (3) Recharge can elevate the groundwater and reduce settlement; however, it is difficult to eliminate the variation in settlement along the vertical direction. Full article

Groundwater drought, a significant natural disaster in arid and semi-arid regions, contributes to numerous consecutive issues. Due to the inherent complexity of groundwater flow systems, accurately quantifying and describing this phenomenon remains a challenging task. As a result of excessive agricultural development, the Marand Plain in northwestern Iran is experiencing both groundwater drought and land subsidence. The present study provides the first in-depth investigation into the intricate link between groundwater drought and subsidence. For this purpose, the open-source package LiCSBAS, integrated with the automated Sentinel-1 InSAR processor (COMET-LiCSAR), was utilized to assess land subsidence. The Standard Groundwater Index (SGI) was computed to quantify groundwater drought, aquifer characteristics, and human-induced disturbances in the hydrological system, using data collected from piezometric wells in a confined aquifer. The results revealed a negative deformation of 65 cm over a 75-month period, affecting an area of 57,412 hectares within the study area. The analysis showed that drought duration and severity significantly influence land subsidence, with longer and more severe droughts leading to greater subsidence, while more frequent drought periods are primarily associated with subsidence magnitude. Multi-resolution Wavelet Transform Coherence (WTC) analysis revealed significant correlations between groundwater drought and InSAR-derived land deformation in the 8–16-month period. Full article

In order to exploit the deep underground space, the construction of ultra-deep excavation in Shanghai is growing rapidly. In multi-aquifer strata, deep excavations typically require dewatering of confined aquifers to ensure engineering safety. However, existing studies have seldom conducted in-depth analysis on the influence of the soil parameters and construction measures on the deformation of retaining structures. In this study, a three-dimensional hydro-mechanical numerical model was developed to evaluate the performances of excavation and dewatering of the foundation pit. The model was validated by comparing the calculated and measured wall deflections and groundwater drawdowns of a 45 m ultra-deep double-wall excavation in Shanghai. According to the characteristics of soil stratification and construction activities, three parameters were selected for subsequent analysis, including the hydraulic conductivity of aquitard below the bottom of the pit, the pumping rate in the second confined aquifer and the construction of TRD wall. The stress distributions on both sides of the diaphragm wall were examined to elucidate the deformation mechanism. The results indicate that the aquitard hydraulic conductivity directly affects the effective stress of the overlying aquifer, which plays a crucial role in resisting wall deflection. An increase in the hydraulic conductivity leads to smaller effective stress, greater wall deflection and larger ground settlement. While an appropriately increased pumping rate enhances effective stress, over-pumping may induce excessive wall deflection at depth and disproportionate ground settlement. The TRD wall is quite useful in terms of waterproofing but the effect on deformation control is limited. The findings of this study provide valuable insights for engineering practices and the optimization of deep excavation construction measures in multi-aquifer strata. Full article

In order to ensure the smooth progress of foundation pit engineering, it is necessary to identify and control the seepage risk. At present, there are few research studies and applications on the seepage risk assessment of foundation pits, and the optimization of curtain depth and the interrelation and optimal combination of design variables are rarely considered in the optimization design of foundation pit dewatering scheme based on the objective function method. According to the geological and hydrogeological conditions of the research area, a mathematical model for optimizing foundation pit dewatering was established. The model takes the minimum total dewatering cost as the objective function and comprehensively considers decision-making variables. Additionally, it also takes into account constraints such as the drawdown depth of the water level in a single well and the pumping flow rate of a single well. The calculation results indicate that the errors between the measured water levels and the simulated water levels are within ±3.5%, suggesting that the parameter inversion results are effective. The horizontal and vertical permeability coefficients of the phreatic aquifer are 3.0 m/d and 0.45 m/d, respectively, and the horizontal and vertical permeability coefficients of confined aquifer are 10.28 m/d and 1.25 m/d, respectively. The horizontal and vertical permeability coefficients of the confined aquifer are 10.28 m/d and 1.25 m/d, respectively. Nine different excavation dewatering schemes that curtain depths of 66 m, 61 m, and 56 m were designed, and the optimal excavation dewatering scheme was determined by comparing the total dewatering cost. This scheme has the advantages of shortening the dewatering time, reducing the impact of foundation pit dewatering on the surrounding environment, and saving the total cost of dewatering. The research results provide a relevant decision-making basis for managers. Full article