Protection Of Groundwater Resources Research Articles

Compliance of Legal Restrictions in Potable Water Abstraction in Rajshahi WASA Area: An Overview

The ground water level in Barind area Rajshahi rise and falls continuously with the advance of wet and dry season. A growing population, urbanization, increasing pressure on land and water resources by different competing usage and degradation of scarce resources challenge the extraction, management and protection of the water resources of Rajshahi as well as all over the Bangladesh. Agriculture is the major water using sector for ground water irrigation with rice cultivation, the single most important activity in the economy. Industry is also liable for large scale water withdrawal. Due to water level depletion ‘deep tube well’ especially submersible pump is randomly used in many of the houses in Rajsahi WASA area. Apart from agriculture, presently uncontrolled water abstraction for domestic or household purposes causes serious threats to sustainable ground water management. Due to this excessive stress upon the ground water resource, the yield capacity is being reduced and the need to conserve them is now generally recognized. Some of the legislations have clear guidelines and restrictions on personal source of ground water abstractions. National water policy, 1999 stressed the need for the protection of surface water and groundwater resources. WASA Act, 1996; Water Act, 2013; Local Govt. Act 2009 are the major instruments in this respect. This study has been an attempt to review the relevant laws regarding restrictions on domestic water abstraction and to examine through field survey the real scenario how far these are being complied with.

Providing predictive models for quality parameters of groundwater resources in arid areas of central Iran: A case study of kashan plain

Groundwater pollution can occur due to both anthropogenic and natural causes, leading to a decline in water quality and posing a threat to human health and the environment. The pollution of ground water resources with chemical pollutants is often considered. To manage water resources sustainably, ensuring their quality and quantity is crucial. Yet, testing groundwater can be expensive and time-consuming. So, using modeling to predict the chemical parameters of groundwater resources is considered to be an efficient and economical method. In this study, we examined three models to predict groundwater quality in dry regions by using R programming language. The random forest (RF) outperformed the other models in developing predictive models for water quality. Also, the multiple linear regression (MLR) model demonstrated strong performance, particularly in predicting total hardness (TH) in Aran Va Bidgol groundwater resources. The decision tree (DT) model did well but had lower performance than the RF model in predicting quality parameters. This approach can be efficacious in the field of effective management and protection of groundwater resources and enables the assessment of risks related to water resources.

Hydrogeochemical process and coal mining-motivated effect on the hydrochemistry for the groundwater system in mining area of Western China

The Jurassic coalfield in the mining area of western China exhibits a multi-layered groundwater system. However, it is subject to an arid and semi-arid climate with limited water resources. Consequently, the ecological environment is highly vulnerable, and the chemistry and quality of groundwater may be influenced by multiple factors. This study systematically the coal mining-motivated effect on the hydrochemistry and water quality of the groundwater system, using the Caojiatan Coal Mine as a case study. The analysis incorporates a combination of the self-organizing maps (SOM), entropy-weighted water quality index (EWQI), and traditional hydrochemical analysis methods. After coal mining, there was an increase in the proportion of HCO3-Ca and HCO3-Mg in the groundwater samples of J2z, J2y4, and J2y5. The groundwater is controlled by cation exchange as a whole. The J2y4 and above groundwater is influenced by both the dissolution of carbonate and silicate rocks before coal mining. After coal mining, the Quaternary and J2a groundwater in the western wing is primarily influenced by the dissolution of carbonate rocks; the J2z, J2y4 and J2y5 groundwater is primarily governed by the dissolution of silicate rocks and the oxidation of FeS2; the J2y3 and below groundwater is primarily controlled by the dissolution of evaporate rocks. The resulting dilution effect after coal mining and the implementation of measures for the discharge of treated mine water make the groundwater quality of the J2y4 and higher aquifers tend to be better. The research findings serve as a valuable reference for promoting the sustainable development and protection of groundwater resources not only in the study area but also in other coal mines.

Groundwater vulnerability to pollution in Africa’s Sahel region

Protection of groundwater resources is essential to ensure quality and sustainable use. However, predicting vulnerability to anthropogenic pollution can be difficult where data are limited. This is particularly true in the Sahel region of Africa, which has a rapidly growing population and increasing water demands. Here we use groundwater measurements of tritium (3H) with machine learning to create an aquifer vulnerability map (of the western Sahel), which forms an important basis for sustainable groundwater management. Modelling shows that arid areas with greater precipitation seasonality, higher permeability and deeper wells or water table generally have older groundwater and less vulnerability to pollution. About half of the modelled area was classified as vulnerable. Groundwater vulnerability is based on recent recharge, implying a sensitivity also to a changing climate, for example, through altered precipitation or evapotranspiration. This study showcases the efficacy of using tritium to assess aquifer vulnerability and the value of tritium analyses in groundwater, particularly towards improving the spatial and temporal resolution.

Evaluation of the Offsets of Artificial Recharge on the Extra Run-Off Induced by Urbanization and Extreme Storms Based on an Enhanced Semi-Distributed Hydrologic Model with an Infiltration Basin Module

Urbanization and climate change exacerbate groundwater overexploitation and urban flooding. The infiltration basin plays a significant role in protecting groundwater resources because it is a prevalent technology of managed aquifer recharge. It could also be utilized as a retention pond to mitigate city waterlogging. The goal of this study was to explore the offsets of artificial recharge on the extra runoff induced by urbanization and extreme storms via infiltration basins. To achieve this objective, a lumped infiltration basin module was developed and integrated into a semi-distributed hydrologic model. Then, the enhanced model was applied to an agriculture watershed with urban areas. Finally, the functionalities of the infiltration basins were evaluated under the scenarios of the predicted urbanization and extreme storms. The results demonstrated the capability of the infiltration basins to influence both artificial recharge and flood mitigation. To mitigate floods, especially peak flows, larger areas are needed for infiltration basins than for artificial recharge purposes only. Based on different demands, the intermittent regulation of infiltration basins according to different hydrologic periods is recommended. The offsets of artificial recharge on the extra surface runoff provide insight into the comprehensive preservation and management of surface water resources and groundwater resources.

Mapping of Groundwater Potential Zones in the Kuzhithuraiyar Sub Basin of Kodayar River, Kanniyakumari District, Tamilnadu: Using Analytic Hierarchy Process (AHP) and GIS


 
 
 Groundwater plays a very important role for all living beings. It is decisive to have a scientific understanding of groundwater management since, with careful use and replenishment, groundwater may help solve issues. The distribution of groundwater tables, slope, land-form, drainage pattern, lithology, topography, geological structure, fracturing density, opening and connectivity of fractures, secondary porosity, and landuse landcover all affect the occurrence and efficiency of groundwater in an aquifer system. An essential tool for assessing, tracking and protecting groundwater resources is the integration of geospatial techniques such as Remote Sensing and Geographic Information System for the identification of groundwater potential zones. This study aims to find the groundwater potential zones using Analytical Hierarchy Process (AHP) and managing the resources by creating different thematic layers such as rainfall, geology, geomorphology, drainage density, soil, slope, lineament and landuse landcover (LULC) of the Kuzhithuraiyar sub basin of the Kodayar river in Tamilnadu using the application of geospatial technologies. The thematic maps for all the thematic layers have been prepared using tools such as Interpolation, contour lines, Classification in ArcGIS 10.8. Theme weight and class rank were assigned to different thematic layers in weighed overlay analysis. The results were validated through field work and groundwater potential map was created. The groundwater potential zonation mapping was done by the overlay analysis in ArcGIS 10.8 software. The obtained map was classified into four categories namely very high groundwater potential zone, high groundwater potential zone, medium groundwater potential zone and low groundwater potential zone. The North Eastern part of the basin is considered as low groundwater potential zone while the Southern portion has high groundwater potentiality. The low groundwater potential zone covers an area of 10.58 sq.km and high groundwater potential zone covers an area of about 388.37sq.km.This study will be helpful for useful groundwater management for different tenacities.
 
 

Temporal and spatial variations of groundwater quantity and quality for drinking and irrigation purposes in the arid and hot weather of Southern Iran

Groundwater provides a reliable water supply of fresh water worldwide for drinking, agricultural, and industrial purposes, especially in areas where surface water is scarce or unreliable, making it an essential resource for human and economic development. Proper management and protection of groundwater resources are crucial to ensure their sustainability and continued contribution to fulfilling the growing water demand worldwide. This study focused on the quantitative and qualitative changes in groundwater in the Kahoorestan Plain, located northwest of the Persian Gulf in southern Iran. The zoning maps produced by Arc GIS revealed a declining trend in the aquifer level and a drop in the groundwater level of 5.24 m over 20 years. The maps of the flow directions also indicated a general trend from the western highlands to the south and southeast regions of the plain. The Piper diagram showed that the predominant hydrochemical facies of the plain area is NaCl. Temporal changes analysis by the Mann-Kendall test revealed that EC, TDS, TH, Na, Mg, Ca, SO4, and Cl parameters have a rising trend in the majority of wells, which attributes to groundwater over-withdrawal, drought, excessive well drilling, and insufficient aquifer recharge. The study’s analysis of the temporal and spatial changes of the water quality index, Schoeller diagram, and Wilcox diagram revealed that the aquifer’s water quality is unsuitable for drinking and irrigation use due to its high salinity and sodium content. The findings underscore the urgency of adopting effective management strategies to ensure the sustainable management of groundwater resources in the region.

Analysis of the spatiotemporal variation of groundwater storage in Ordos Basin based on GRACE gravity satellite data

Groundwater is the primary source for drinking, agriculture, irrigation, industrial, and municipal uses in Ordos Basin, a regional energy and heavy chemical industrial base in China. In recent decades, groundwater levels in the basin have declined due to climate change and anthropogenic activity. Analyses of the spatiotemporal variation of groundwater storage are crucial to regional sustainability. This study conducts the analysis utilizing GRACE gravity satellite data and GLDAS model data, employing methods that include the generalized three-cornered hat, Augmented Dickey-Fuller (ADF) test, and wavelet analysis to investigate the spatiotemporal variation of groundwater storage in the basin. The analysis results indicate that (1) before 2008, the climate had a significant influence on groundwater storage, with minimal impact from human activities, while after 2008, human activities have caused a noticeable decline in groundwater storage, particularly in the eastern region. (2) The eastern region of the basin experienced a decline in groundwater storage with a rate of −1.86 cm/yr, the middle region with a rate of −1.24 cm/yr, and the western region with a rate of −0.63 cm/yr. The extensive extraction of petroleum, natural gas, coal, and mineral resources in the basin has contributed to this pattern. (3) Human activities have altered the hydrological processes from precipitation infiltration, groundwater propagation, and groundwater distribution, leading to an increasingly complex groundwater system. (4) Human activities affect groundwater in the saturated zone more extensively than in the unsaturated zone. The research findings highlight that human activities are the main factor driving the variation in groundwater storage in the basin and provide crucial scientific evidence for protecting groundwater resources.

Hydrogeochemistry and Water Quality Index for Groundwater Sustainability in the Komadugu-Yobe Basin, Sahel Region

The assessment of hydrochemical characteristics and groundwater quality is crucial for environmental sustainability in developing economies. This study employed hydrogeochemical analysis, geospatial analysis, and groundwater quality index to assess hydrogeochemical processes and quality of groundwater in the Komadugu-Yobe basin. The pH, total dissolved solids (TDS), and electrical conductivity (EC) were assessed in situ using a handheld portable electrical conductivity meter. The concentrations of the major cations (Na+, Ca2+, Mg2+, and K+), were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). The major anions (chloride, fluoride, sulfate, and nitrate) were analyzed via ion chromatography (IC). Total alkalinity and bicarbonate were measured in situ using a HACH digital alkalinity kit by the titrimetric method. Hydrochemical results indicate some physicochemical properties of the groundwater samples exceeded the maximum permissible limits as recommended by the World Health Organization guidelines for drinking water. Gibbs diagrams indicate rock–water interaction/rock weathering processes are the dominant mechanisms influencing the groundwater chemistry. Groundwater is predominantly Ca2+-Mg2+-HCO−3 water type, constituting 59% of the groundwater samples analyzed. The groundwater quality index (GWQI) depicted 63 and 27% of the groundwater samples as excellent and good water types for drinking purposes, respectively. This study further relates the interaction between geology, hydrochemical characteristics, and groundwater quality parameters. The results are essential to inform a sustainable management strategy and protection of groundwater resources.

Formation processes of groundwater in a non-ferrous metal mining city of China: Insights from hydrochemical and strontium isotope analyses.

Tongling is a significant non-ferrous metal mining city in China, which produces waste that negatively impacts the area's water environment. It is essential to comprehend the hydrochemical properties and formation processes of groundwater to safeguard and utilize it efficiently. We explored major ions, strontium, and its isotopes in water and river-bottom samples from the northern (i.e., A-A' section) and southern (i.e., B-B' section) areas. The hydrochemical facies show the mining activities have a greater impact on surface water than on groundwater. Groundwater hydrochemical formation results from several factors, with water-rock interaction and ion exchange being primary. Additionally, the dissolution of calcite, dolomite, and feldspar, oxidation of pyrite, and hydrolysis of carbonate minerals also impact the formation of groundwater chemistry. Our analysis of strontium and its isotopes indicates that carbonate dissolution primarily occurred in the recharge area; the runoff from the recharge to the discharge area results in the dissolution of certain silicate rocks; calcite dissolution sources account for > 70% contribution in both surface water and groundwater water-rock interactions, whereas silicate rock dissolution sources and dolomite dissolution sources account for < 30%. Due to changed order of dissolved carbonate and silicate minerals during groundwater flow, the distribution of strontium and its isotopes in the A-A' section is opposite to that in the B-B' section. The findings provide a basis for developing, utilizing, managing, and protecting groundwater resources, especially in similar mining areas.

Insights into biogeochemistry and hot spots distribution characteristics of redox-sensitive elements in the hyporheic zone: Transformation mechanisms and contributing factors

Biogeochemical hot spots play a crucial role in the cycling and transport of redox-sensitive elements (RSEs) in the hyporheic zone (HZ). However, the transformation mechanisms of RSEs and patterns of RSEs hot spots in the HZ remain poorly understood. In this study, hydrochemistry and multi-isotope (N/C/S/O) datasets were collected to investigate the transformation mechanisms of RSEs, and explore the distribution characteristics of RSEs transformation hot spots. The results showed that spatial variability in key drivers was evident, while temporal change in RSEs concentration was not significant, except for dissolved organic carbon. Bacterial sulfate reduction (BSR) was the primary biogeochemical process for sulfate and occurred throughout the area. Ammonium enrichment was mainly caused by the mineralization of nitrogenous organic matter and anthropogenic inputs, with adsorption serving as the primary attenuation mechanism. Carbon dynamics were influenced by various biogeochemical processes, with dissolved organic carbon mainly derived from C3 plants and dissolved inorganic carbon from weathering of carbonate rocks and decomposition of organic matter. The peak contribution of dissolved organic carbon decomposition to the DIC pool was 46.44 %. The concentration thresholds for the ammonium enrichment and BSR hot spots were identified as 1.5 mg/L and 8.84 mg/L, respectively. The distribution pattern of RSEs hot spots was closely related to the hydrogeological conditions. Our findings reveal the complex evolution mechanisms and hot spots distribution characteristics of RSEs in the HZ, providing a basis for the safe utilization and protection of groundwater resources.

An efficient wastewater collection model for groundwater resource protection in smart cities

Efficient wastewater collection is a critical concern in the development of smart cities, where sustainable urban infrastructure is paramount. In the context of smart city wastewater optimization, this study highlights the need for a comprehensive approach that considers both surface water and groundwater dynamics. Existing methods often fall short in addressing groundwater-related concerns, with limitations in accounting for potential contamination and aquifer vulnerability. The proposed method integrates a nuanced understanding of groundwater aspects, providing a more robust and sustainable solution for urban water resource management. This research introduces a new approach that harnesses the power of Divide-And-Conquer (DAC) and Variable Neighborhood Search (VNS) to optimize wastewater collection systems in smart cities. The DAC strategy divides the city into manageable zones, simplifying the optimization problem for parallel processing in large-scale urban environments. VNS fine-tunes wastewater collection networks within each zone by exploring diverse neighborhood solutions. The DAC and VNS offers several benefits, including improved efficiency in wastewater transport, reduced energy consumption, and minimized environmental impact. Zoning the urban landscape is a strategic approach to optimize wastewater collection in smart cities. It involves dividing the city into manageable zones based on specific criteria such as geographical features, population density, and infrastructure layout. Each zone is treated as an independent unit for focused analysis and optimization. The optimization process employs a scoring function that combines weighted criteria, yielding a composite score for each geographical location. Applying a threshold or clustering algorithm group's locations into zones, facilitating tailored wastewater management strategies. By optimizing collection routes and infrastructure design, this approach assists smart cities in achieving sustainability goals while efficiently managing wastewater. The study showcases the potential of DAC and VNS as a robust and adaptable solution for wastewater collection in smart cities, contributing to the development of greener, more resource-efficient urban areas.

Experimental study and numerical simulation of water-sand two-phase flow in fracture network

ABSTRACT The flow characteristics of water-sand two-phase in fractured rock mass has an important influence on underground engineering. A series of laboratory experiments are carried out by using a self-made fracture network test system. Based on the Euler-Lagrange method, a numerical simulation study of water-sand two-phase flow is conducted. The effects of sand mass fraction w, sand particle size Φ and combination of inlet and outlet on the flow characteristics of water-sand are systematically analyzed. The results show that the water-sand outflow is directly proportional to the fracture openings, and the growth rate of water-sand outflow is significantly different under multiple inlet-outlets configurations. The final volume proportions of water-sand are 14.1%, 35.9% and 50% respectively. Fluidity I exhibits an inverse correlation with fracture opening, w and Φ. Under the condition of the single inlet and outlet, the minimum fluidity I for 0.6 mm opening is 3.28E–7 m2+ns2- n/kg, the maximum fluidity I for 2.0 mm opening, reaching 3.88E–6 m2+ns2- n/kg. Based on the response surface regression method, a multivariate regression model for three fracture openings was established, boasting exceptional predictive accuracy and reliability. Particle residence time correlates positively with w and Φ. The turbulent kinetic energy k is significantly affected by the fracture opening and decreases with the increase of w and Φ. The variation range of k is 0.38 m2/s2 ~0.63 m2/s2. The results deepen our understanding of the migration behavior of water-sand in the fracture network, and provide a theoretical guidance for groundwater resource protection and other underground engineering.

Balancing urban growth and the sustainability of groundwater and agricultural land: Case of the berrechid-settat area

Urbanization is an inevitable global phenomenon characterized by the exponential growth of urban areas in terms of both population and infrastructure. However, this rapid urban expansion often comes at a significant environmental cost. This article explores the multifaceted consequences of urbanization, shedding light on its role in contributing to desertification, compromising water quality, and depleting groundwater resources. To assess the scale of urbanization’s impact, comprehensive landuse studies are crucial. Geographic Information Systems (GIS) and remote sensing techniques offer valuable tools for mapping and monitoring land-use changes over time. These methods enable the quantification of the conversion of agricultural land into urban areas and identify trends in urban sprawl, providing essential data for understanding the scale of the issue. Water quality assessments are equally vital; we can employ water sampling and laboratory analyses to quantify pollutant concentrations in urban runoff and groundwater. Monitoring the presence of contaminants such as oil, chemicals, and litter, as well as their effects on water quality; helps measure the environmental impact of urbanization. Groundwater studies can utilize hydrogeological investigations, including the use of monitoring wells and geophysical methods, to evaluate changes in groundwater levels and quality. These data are instrumental in gauging the depletion of groundwater reserves and their potential contribution to water scarcity issues. In conclusion, the consequences of urbanization extend far beyond the confines of urban areas, affecting agriculture, ecosystems, and water resources. As urbanization continues to advance, it is imperative to develop sustainable urban planning and management strategies that mitigate its environmental impact, preserve agricultural land, protect groundwater resources, and ensure the long-term health of the planet.

Groundwater Quality Monitoring in Response to Marine Intrusion: A Case Study in Northern Morocco

Water stress, resulting from a demand for water exceeding the available quantity, is a major global challenge. Groundwater usage is a commonly adopted strategy to address this situation, but it often leads to marine intrusion, threatening the quality of water in coastal aquifers. This phenomenon typically stems from overexploitation of aquifers, declining water table levels, and rising sea levels due to climate change. Our study aims to monitor the quality of groundwater intended for human consumption and provide a detailed assessment of its current state. We identified several physicochemical parameters, such as temperature, pH, and bicarbonates, with maximum electrical conductivity values reaching 2810 µs/cm, a total hardness of 21 meq/L, sulfate levels of 689 mg/L, and chloride levels of 628 mg/L, from six boreholes and one well located along the coastal area of the Al Hoceima region. These samples were also subjected to Principal component analysis (PCA) of the chemical parameters, revealing two factors that represent approximately 62.15% of the total variance in the groundwater quality dataset. Simulation results indicate signs of seawater intrusion in several areas, particularly near the coast, emphasizing the urgency of protecting groundwater resources and developing sustainable management strategies to ensure a safe and reliable supply of drinking water in the region.

Hydrochemical characterization and water quality perspectives for groundwater management for urban development

The present study was conducted to assess groundwater quality for drinking and industrial water purposes, evaluate the driving mechanisms of groundwater chemistry, and suggest appropriate management measures to protect groundwater resources for sustainable urban development in a part of Odisha, India. Overall Water Quality Index (OWQI) and Industrial Water Quality Index (IWQI), geochemical ratios and chemometric analyses were used to identify the causes of ionic sources of natural and anthropogenic inputs. Groundwater samples were collected and analysed for chemical parameters. The OWQI indicated that 95.93% of the study region is unfit for drinking water purposes due to high concentrations of Mg2+, Na+, Cl−, SO42−, NO3−, and F− ions supported by the ANOVA test. The IWQI found corrosion and incrustation activities in 80.05% and 94.33% of the study region, respectively, which hinders urban development. The trilinear diagram illustrated that the freshwater type changes completely to mixed water type, and then to reverse ion exchange water and saline water types due to the influence of anthropogenic sources. Gibbs diagrams explaining the mechanisms responsible for groundwater chemistry that groundwater quality moves from the rock domain to the evaporation domain due to human-induced activities. Saturation indices showed that fluoride, gypsum, and halite are in a dissolved state, and calcite is in a precipitated state. Different ionic ratios clearly illustrated that groundwater quality is mainly modified by anthropogenic sources from lithological origin. Principal component analysis (PCA) classified the chemical parameters into salinity, alkalinity, and soil-controlled factors of groundwater chemistry based on their high-positive loadings. High positive scores of PCA, and Clusters 1 and 2 of the hierarchical cluster analysis clearly differentiated polluted and unpolluted affected groundwater samples. Therefore, it is suggested to take appropriate preventive measures to improve the groundwater resources. Otherwise, there will be adverse conditions for urban activities.

Assessing the impact of artisanal gold mining on the environmental sustainability of groundwater resource for water security in southwestern Ghana

The increase in illegal gold mining (galamsey) activities that harm the environment by polluting water sources necessitates the need to take meaningful steps towards protecting the environment.The Jacobu water system in the Amansie Central district was selected as a case study. The purpose of the work is to assess the environmental sustainability of groundwater resource and whether surface water pollution has seeped into the water table to pollute groundwater resource. Methodologically, the study employed groundwater sustainability assessment framework, involving both linear and non-linear sustainability index functions, as well as analytical hierarchy process (AHP). Four groundwater sustainability aspects of quantity, quality, ecosystem and management were assessed. Also, thirteen groundwater sustainability indicators were created for the study. Using the linear sustainability index function, the environmental sustainability index was 0.845, which indicates an excellent level. For the assessment to properly reflect the reality in the study area, the combined linear and non-linear sustainability index function revealed a good level, 0.765, showing an environmentally good overview of Jacobu groundwater resource. This, therefore, suggests the need to ensure continuous protection of groundwater resource. Generally, the study area has not yet experience hydromorphic dispersion of polluted surface water into groundwater resources. For a sustainable groundwater in the future, strict control measures by enforcing environmental laws and regulations to prevent possible pollution of groundwater resource due to ‘‘galamsey’’ activities is critical to protect the invisible resource. This can be done through community engagement, and innovative approaches to monitoring and controlling illegal mining activities. This is to help sustain future generation's security of the ‘invisible’ groundwater resource in Ghana and contributes to Goal 6 (Ensuring Access to Clean Water and Sanitation) of the Sustainable Development Goals set by the United Nations.

Spatial predictions of groundwater potential using automated machine learning (AutoML): a comparative study of feature selection and training sample size in Qinghai Province, China.

Predicting groundwater potential is crucial for identifying the spatial distribution of groundwater in a region. It serves as an essential guide for the development, utilization, and protection of groundwater resources. Previous studies have primarily emphasized finding the most accurate prediction model for groundwater potential while giving less attention to the selection of training features and sample sizes. This study aims to predict groundwater potential within Qinghai Province using automated machine learning technology and assess the influence of sample sizes and feature selection on prediction accuracy. Sixteen groundwater conditioning factors were categorized into categorical and numerical variables. Four feature selection modes were utilized as input in training the model. The results indicated that, except for correlations between evaporation and landforms (- 0.8) and precipitation and normalized difference vegetation index (0.8), the Pearson correlation coefficients among the remaining sixteen factors were ≤ 0.5 or ≥ - 0.5. The models XGB-ALL, RF-Entropy, ET-CRITIC, and XGB-PCA yielded accuracy scores of 0.783, 0.685, 0.745, and 0.703, and area under curve (AUC) of 0.819, 0.724, 0.779, and 0.747, respectively. If enough samples are available with the tree model, an increased number of features can improve prediction accuracy. The principal component analysis method showed difficulty in reducing the dimensionality of the input space, while the Entropy method proved efficient. The accuracy and AUC value of the prediction model improved with an increasing number of samples. Training with 8 features and 200 data points achieved an accuracy of 0.745, sufficient to evaluate regional groundwater potential. As for training with 600 samples, the model's performance accuracy rose to 0.9, enabling precise groundwater potential prediction. The outputs of this research can provide decision-makers in groundwater resource management in Qinghai Province with crucial theoretical and practical support. The lessons learned can have future applications in similar situations.

Identification of groundwater hydrogeochemistry and the hydraulic connections of aquifers in a complex coal mine

It is important to understand the changes in the chemical composition and connectivity of each aquifer in the arid-semi-arid riverine mines under the driving force of coal mining and to establish a rapid identification of water sources in the riverine mines, which is important for the protection of groundwater resources and safe production in the study area. By analyzing the numerical characteristics of conventional elements, cluster analysis and the deuterium–oxygen and tritium isotopes of different aquifers, the groundwater chemical characteristics and hydraulic connections of each aquifer were determined. Three identification charts (Piper and Durov identification charts of conventional hydrochemical components and deuterium–tritium isotope identification charts) were established to enable the rapid identification of each aquifer water source. The results showed that the main recharge source of groundwater in the study area was atmospheric precipitation. There was a significant indigenous connection between the Quaternary aquifer and the Zhiluo Formation aquifer but a limited indigenous connection between the Zhiluo Formation aquifer and the Yan'an Formation aquifer, creating local groundwater systems that altered the local groundwater circulation patterns, driven by coal mining. Three identification charts were established to determine the water inrush sources and propose targeted solutions for water inrush from different aquifers in the Shendong mining area based on the differences in hydrochemical ion characteristics as well as deuterium–oxygen and tritium isotopes.

Chemical composition of groundwater and its controlling factors in the Liuzhuang coal mine, northern Anhui Province, China

Abstract Identification of the hydrochemical characteristics of the groundwater system in the mining area and the controlling factors of the water's chemical components is necessary to protect groundwater resources. In this study, 80 sets of groundwater samples were collected from three aquifers of the Liuzhuang coal mine (northern Anhui Province, China), and a total of eight indicators were selected for quantitative analysis of the chemical components of water. Conventional mathematical and statistical methods and Piper trilinear diagrams show that the cations in the groundwater samples of the mine area are mainly K+ + Na+ (92.4%), while the anions in the Cenozoic and Carboniferous aquifers are mainly Cl−, reaching 57.2% and 55.2%, respectively, and the anions in the Permian aquifer are mainly HCO3- (52.6%). Most of the water chemistry types are Cl-Na, HCO3-Na, and HCO3-Cl-Na. Analysis on the basis of Gibbs plots showed that the aquifer system in the mine area is primarily controlled by the water–rock interaction. The results of ion ratio analysis, principal component analysis, and cluster analysis showed that the dissolution of hydrochloric acid and alternating cation adsorption is more prominent in the Cenozoic and Carboniferous aquifers, while desulfurization is more significant in the Permian aquifer.