Variation Of Groundwater Quality Research Articles

GIS based geostatistical modelling and trends analysis of groundwater quality for suitable uses in Dhaka division

Preserving the quality of groundwater has become Bangladesh’s primary challenge in recent years. This study explores temporal trend variations in groundwater quality on a broader scale across 18 stations within the Dhaka division over 35 years. The data set encompasses an analysis of 15 distinct water quality parameters. Modified Mann-Kendal, Sens Slope and Mann-Kendal tests were performed to determine the trend’s variation and slope. In addition, the spatial–temporal changes in the quality of groundwater are studied through Geographic Information System (GIS) mapping and Piper diagram was applied to identify the unique hydrochemical properties. This is the first study conducted on this area using various trends analysis and no in-depth study is available highlighting the trends analysis of groundwater quality on a larger magnitude. In contrast, the correlation matrix reveals a high association between Mg2+ and SO42−, Na+ and Cl− that affects salinity and overall hardness at the majority of sites. The Piper diagram also demonstrates that the groundwater in Madaripur Sadar has major salinity issues. The analysis reveals a distinctive dominance of bicarbonate (HCO3−) ions across all sampling stations, with (HCO3−) equivalent fractions consistently ranging from 0.70 to 0.99 which can cause a significant impact on groundwater uses. This extensive analysis of long-term groundwater quality trends in the Dhaka Division enables researchers to comprehend the overall transition of groundwater quality for hardness related complications in future. Moreover, it can be a baseline study considering the valuable implications and future steps for sustainable water resource management in this region.

Anthropogenic Drivers of Spatial Trends in Groundwater Quality in the Upper Athi River Basin of Kenya, East Africa

Rapid urbanization and population growth in the upper Athi River basin in Kenya have increased the strain on the sub catchments water supply and sanitation situation. Due to increasing demand, inadequate supply of drinking water and lack of sanitation facilities, people in the sub-catchment are increasingly reliant on groundwater as a primary or supplementary water source. However, the use of on-site wastewater systems and agricultural pollution, mainly from runoff containing fertilizers, pesticides, herbicides, and faeces, pose a threat to groundwater in the sub catchment. Subsequently, the current study was conducted in the Thiririka sub catchment, Kiambu County, Kenya, to determine the safety of groundwater sources and to examine the factors influencing groundwater quality in the catchment area. This study assessed the influence of anthropogenic activities on the physical, chemical, and bacteriological quality of groundwater in the Upper Athi River basin of Kenya between April and June 2022. Twenty variables were analyzed and compared with water quality standards to determine hydro chemical characteristics, evidence of contamination, and suitability of groundwater. Shallow wells (SW) had higher concentrations of major ions and key parameters than boreholes (BH), such as alkalinity (7%), turbidity (96%), nitrates (92%), sulfates (48%), phosphates (93%), chlorides (77%), potassium (84%), sodium (30%) and fecal coliforms (99%) significant at p < 0.01. Concentrations of eleven water quality variables however were comparable in both systems. Farming, animal husbandry, and pit latrines were negatively but significantly correlated with the water quality of SW explaining substantial amounts of variation (≤ 45%) in concentrations of water quality variables. Ionic and coliform levels increased with decreasing distance and vice versa. IDW interpolation maps were generated in ArcGIS software to determine the spatial variability of groundwater quality in the basin. Anthropogenic activities such as pit latrines and animal husbandry impaired the quality of groundwater which in most cases was not potable.

Early Warning of Regional Groundwater Pollution： A Case Study for Plain Area of Barkol-Yiwu Basin

Groundwater pollution early warning is an effective means for regional groundwater pollution prevention. The groundwater pollution early warning model coupled with the current situation of groundwater quality, groundwater quality variation trend, and groundwater pollution risk were applied to the plain area of Barkol-Yiwu Basin, and the regional scale groundwater pollution early warning was realized by combining the early warning of groundwater quality status and trend. The TOPSIS method based on comprehensive weight was used to evaluate the current situation of groundwater quality. The variation trend of groundwater quality was analyzed by calculating the trend interpolation results of 18 in-situ groundwater quality monitoring wells. The groundwater vulnerability map, groundwater pollution load map, and groundwater function value map were superimposed using the superposition index method to evaluate groundwater pollution risk. The results showed that the groundwater quality was good and relatively good, and the poor groundwater quality in some areas was mainly affected by the shallow groundwater depth and the large porosity of the vadose zone. Groundwater quality was stable from 2011 to 2022, mainly due to the leakage of wastewater generated by industries and agriculture into groundwater, resulting in the deterioration of groundwater quality in some areas. Groundwater pollution risk was generally low, and the dual effects of high vulnerability and high pollution load of groundwater led to local areas with high pollution risk. The early warning level of groundwater pollution was generally low, and the heavy and highly heavy warning areas accounted for 16.4% and 17.5% of the study area, respectively, mainly distributed in Xiamaya Township of Yiwu County and northern Santanghu Town, Dahongliuxia Township, and Dahe Town of Barkol County. The quaternary sediments exposed were mainly sandy pebbles, with developed pores and strong water permeability. The interception and adsorption capacity of pollutants were weak. Pollutants produced by industries, agriculture, and life easily leaked into groundwater aquifers, resulting in poor groundwater quality and high risk of groundwater pollution, which ultimately led to a high early warning level of groundwater pollution in some areas. The research on early warning of groundwater pollution provided an important theoretical basis for the development of groundwater pollution remediation.

Hydrogeochemical processes, and health risk assessment of groundwater, in Santa María del rio aquifer: A case study of San Luis Potosí valley, Mexico

The main objectives of this research were to the hydrogeochemical processes that control the groundwater chemistry, groundwater quality, and assessment of health risks of water. The drinking water that supplies the community of Santa María del Rio, S.L.P., comes from groundwater, in some municipality localities, groundwater Fluorine and arsenic are reported. Twenty-one representative groundwater samples were taken. Physicochemical parameters in situ: pH, OD, ORP, Alkalinity, STD, EC, Salinity, Total Coliforms, and E-coli, were analyzed, and in the laboratory, the heavy metals, metalloids and major constituents, cations: calcium, sodium, magnesium, and potassium, were determined by the ICP, and anions: chlorides, and sulfates, by colorimetry techniques. The results of the analyses were compared with the Mexican and EPA drinking water standards to verify their suitability and ensure that they do not exceed the permitted limit values. The results of the chemistry of the principal groundwater ions in the study area suggest that the main hydrogeochemical process that controls the variation of groundwater quality is the rock–water interaction. Groundwater has been classified into two hydrochemical facies, CaMgHCO3 and NaHCO3, consistent with the type of rock. The samples with the CaMg–HCO3 facie are associated with less evolved waters located in areas with local recharge. The dominant reactions in the aquifer are calcite, dolomite, and gypsum solutions. The presence of the N–NO3- ion is associated with agricultural and urban zone influence, which indicates that this activity has impacted the water quality. The risk index (HI) results show that values > 0.1 < 1 of HI, for Pb present low chronic risks for adults and children. In contrast, HI values > 4 for both population groups represent high chronic risk. Excessive use of fertilizers should be controlled in the study area to prevent groundwater contamination by heavy metals and metalloids and be measured regularly to check drinking water quality.

Seasonal Variation of Groundwater Quality in Bonny Island, Rivers State Nigeria

This study investigated the seasonal variations in physicochemical parameters, heavy metals, and petroleum hydrocarbons in groundwater samples collected in nine locations in Bonny Island, Rivers State Nigeria. The water samples for the dry season were collected in December and January while for the wet season, water samples were collected in July and October. A quantitative approach was employed, involving the collection of quantitative data through field sampling and laboratory analysis. Physicochemical parameters, including pH, electrical conductivity, dissolved oxygen, and nutrient levels, were measured using standard analytical techniques. Heavy metal concentrations (Fe, Cd, etc.) were determined using atomic absorption spectrophotometry, while petroleum hydrocarbons (total hydrocarbons and polycyclic aromatic hydrocarbons) were analyzed through solvent extraction and gas chromatography techniques. The study revealed significant seasonal variations in several parameters, with notable significant decreases in phosphate during the wet season and significant increases in chromium and cadmium levels during the dry season (p-value &lt; 0.05). Petroleum hydrocarbon concentrations also exhibited seasonal fluctuations, potentially influenced by precipitation patterns, oil and gas activities, and accidental spills or leaks which were observed during the dry season.

Analysis on the spatiotemporal evolutions of groundwater hydrochemistry and water quality caused by over-extraction and seawater intrusion in eastern coastal China

The over-extraction of groundwater has resulted in seawater intrusion and the southward migration of the saltwater interface, gradually deteriorating the groundwater quality in the Weibei Plain. In this research, groundwater samples were gathered from 46 monitoring wells for shallow groundwater during the years 2006, 2011, 2016, and 2021. The hydrochemical features of regional groundwater and the factors influencing the issue were subjected to statistical analysis. Additionally, the assessment of spatiotemporal variations in groundwater quality was conducted using the customized entropy-weighted water quality index (EWQI) method. The relationship between groundwater over-extraction and the southward intrusion of the saltwater interface was compared and analyzed. The results of this paper revealed that the Weibei Plain has been in a state of long-term over-extraction of groundwater from 2000 to 2021, with an average annual over-extraction of 118.49 million m3. The groundwater depression cone areas in the northern part of the study area increased from 3,247.37 to 4,581.34 km2 from 2006 to 2021, with the center of the cone experiencing a drop in groundwater level from −22 to −85 m. The saltwater interface shifted southward by 711.71 km2 from 2006 to 2021. In groundwater, the high concentrations of TH, TDS, and Cl− were primarily related to the seawater intrusion, while higher concentrations of NO3− were mainly determined by frequent agricultural production, industrial wastewater, and domestic sewage discharges. The groundwater hydrochemical types in the study area transitioned from predominantly HCO3·Ca-Mg type in 2006 to HCO3-Na type and SO4·Cl-Ca·Mg type in 2021 due to seawater intrusion. The results of PCA and HCA show the effects of seawater intrusion, human activities, and rock weathering on groundwater hydrochemistry. The evaluation results based on the EWQI revealed that the average value of the samples in 2021 was 101.36, which belonged to Class IV water quality standards, representing the poorest water quality among the 4 years. The southward migration of the saltwater interface led to the deterioration of groundwater quality in the groundwater depression cone areas, which gradually worsened from 2006 to 2021. The maximum increase in EWQI value was 174.68 during the period, shifting from Class III water quality to Class V water quality. Groundwater quality remained relatively better in the western and southern regions which were less affected or unaffected by seawater intrusion. The results of the study can provide a certain reference value for the sustainable management of groundwater resources and the management of groundwater pollution and seawater intrusion in the Weifang City area in the future.

Assessing groundwater quality dynamics in Madhya Pradesh: Chemical contaminants and their temporal patterns

Groundwater is essential for maintaining ecosystem health and overall well-being as a pivotal resource for plants and animals. The increasing public consciousness of the deterioration of groundwater quality has emphasized the significance of undertaking extended evaluations of groundwater water quality, particularly in regions undergoing substantial hydrological alterations. This study primarily aims to investigate the spatio-temporal variations in groundwater quality and evaluate its suitability for potable purposes in the region of Madhya Pradesh. The study combines the Mann-Kendall (MK) test and Sen's Slope (SS) to analyze the changes in groundwater quality of all 51 districts of Madhya Pradesh, India, utilizing 12 water quality indices using MATLAB. Data was sourced from the Central Ground Water Board (CGWB) in India from the year 2001–2021. The data was then tested for homogeneity at all 1154 sampling stations using the software XLSTAT. Piper plot clustering characterized the state's groundwater as bicarbonate-calcium-magnesium (HCO3−-Ca2+-Mg2+) type. The study found that the groundwater in the area is heavily impacted by high levels of nitrate and hardness, which is caused by an increase in multivalent cations. The water was classified as ranging from hard to extremely hard, and approximately 25.49% of the state's groundwater has nitrate levels that exceed the acceptable limits. The MK test showed a significant increasing correlation in trends for parameters such as nitrate, sulfate, fluoride, chloride, bicarbonate, total hardness, and electrical conductivity. It also showed a significant decreasing correlation for calcium, magnesium, potassium, and sodium. These results were observed at a confidence level of 95%. The analysis of trends has shown that human-related factors have a considerable effect on the characteristics of groundwater quality. It is therefore recommended that such human-related factors be taken into consideration when developing policies for managing groundwater resources. Consequently, these policies should emphasize the strict enforcement of rules and standards that limit the overuse of fertilizers, ensure the appropriate disposal of municipal solid and liquid wastes, and regulate industrial pollutants.

Prediction of ground water quality in western regions of Tamilnadu using LSTM network

Assessing and safeguarding groundwater quality is critical for sustaining life in water-scarce regions like western Tamil Nadu. The motivation behind this study stems from the pressing need to address water quality challenges in a region grappling with scarcity. Despite existing efforts, a notable research gap exists in predictive tools that comprehensively capture the nuanced temporal variations and trends in groundwater quality. This is where the LSTM network steps in, showcasing exceptional accuracy in short-term predictions and discerning long-term trends. This research uses Long Short-Term Memory (LSTM) networks, a variant of recurrent neural networks, to predict groundwater quality in South Indian Regions, especially in Tamil Nadu. Extensive data, encompassing parameters such as pH, dissolved oxygen, turbidity, and various chemical constituents, were gathered over an extended timeframe. The LSTM model was then trained on this historical dataset, factoring in temporal dependencies and seasonality inherent in groundwater quality data. The validation process rigorously tests the LSTM model against actual groundwater quality measurements. The results were impressive, as the model demonstrated a remarkable ability to unravel the complex variations in groundwater quality.

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.

Evaluating Groundwater Quality Using Multivariate Statistical Analysis and Groundwater Quality Index

Under pressure from surface water pollution and climate change, groundwater becomes a critical water source. Information on groundwater quality could contribute to effective groundwater management. This study was carried out to utilize multivariate statistical analysis and the groundwater quality index (GWQI) to evaluate groundwater quality in Ca Mau Province, Vietnam. Twenty-five groundwater samples from residential-urban areas, cemetery areas, landfill areas, and saline intrusion areas were collected for this study. Groundwater quality was evaluated using the National Technical Regulation on Groundwater Quality (QCVN 09-MT:2015/BTNMT) and GWQI. Principal component analysis (PCA) was used to identify potential polluting sources and key variables influencing groundwater quality. Cluster analysis (CA) was applied to cluster groundwater quality, and the sites were recommended for future monitoring. The results revealed that NH4+-N contaminated groundwater in the landfill area, while the saline intrusion area was polluted by TDS and NH4+-N. The groundwater quality classified as excellent, good, poor, and very poor accounted for 44, 40%, 12%, and 4%, respectively. Cluster analysis divided groundwater quality into four groups, mainly based on the presence of NH4+-N and TDS. Nine groundwater sampling locations could be removed from the current groundwater quality program but still ensuring representativeness as a result of CA. PCA proposed two main sources of variation in groundwater quality at each residential-urban area: the cemetery area, the landfilling area, and the saline intrusion area. The groundwater parameters (i.e., pH, TDS, permanganate index, NH4+-N, NO3--N, and Fe) should be continued to monitor. Domestic and industrial wastewater discharge, leachate from cemeteries and landfills, the nature of groundwater aquifers, and seawater intrusion could be potential sources of groundwater variation. The current findings provide scientific information for local environmental authorities to manage and monitor groundwater quality in the study area. Doi: 10.28991/CEJ-2024-010-03-03 Full Text: PDF

The monsoon-groundwater nexus, impacts and adaptation strategies in the northern part of Chennai region, South India

The variations in groundwater quality and their influence on hydrochemical and microbial properties in the metropolitan cities of North Chennai have been scientifically examined in an attempt to comprehend the effects of urbanization. For this ongoing investigation, 50 groundwater samples from surface bore wells were collected in and around north Chennai, South India, during the pre-monsoon (PRm) season in June 2022 and 50 samples during post-monsoon (POm) in January 2023. Southeast of the desired extent, where urban enclaves predominate, has elevated salinity (12,500 mg/L) and electrical conductivity (EC) of 21,200 μS/cm. The predominant types shown in the Piper and Chadha models were sodium-chloride (Na-Cl). Additionally, the Gibbs diagram revealed the observation of evaporation dominance. The interaction between freshwater and seawater has been shown using ionic ratio analysis. A majority of the sample locations indicated the levels of standard plate count (SPC) and total coliforms (TC) contamination in the groundwater were above allowable limits (WHO). There was a slight improvement in groundwater quality during the post-monsoon session suggesting to a possible effect from recently recharged groundwater. In general, the groundwater quality of the research area is impacted by lithological changes, land use, and urban development. Water quality study may be useful in identifying potential health concerns and notify decisions about water management and treatment policies.

Water Quality Assessment of Groundwater Using Multivariate Statistical Techniques: A Case Study of Mogadishu, Banadir Region, Somalia

This study was carried out to assess the groundwater quality around the Mogadishu area, Banadir region, Somalia. Multivariate statistical techniques such as factor analysis (FA), principal component analysis (PCA) and cluster analysis (CA)were applied to 22 groundwater samples collected from boreholes and dug wells in the coastal line districts namely: Wadajir, Kaxda and Dharkinley districts of Banadir region, Somalia. Correlations among 14 hydrochemical parameters were statistically examined. A two-factor model is suggested and explains over 82.4% of the total groundwater quality variation. Factor Analysis (FA) revealed significant variables including electrical conductivity (EC), pH value and other parameters such as K&amp;lt;sup&amp;gt;+&amp;lt;/sup&amp;gt;, Ca&amp;lt;sup&amp;gt;2+&amp;lt;/sup&amp;gt;, Mg&amp;lt;sup&amp;gt;2+&amp;lt;/sup&amp;gt;, Na&amp;lt;sup&amp;gt;+&amp;lt;/sup&amp;gt;, SO&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;2-&amp;lt;/sup&amp;gt; and hardness expressed as CaCO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;, Chlorine, Fluoride, B, S, Si, and NO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; which are responsible for variations in groundwater quality and affect water chemistry. The results were compared with the World Health Organization (WHO) standard guidelines. Geographic Information System (GIS) was used to create the spatial distribution maps of water quality parameters. Cluster Analysis (CA) grouped all sites into three zones based on spatial similarities and dissimilarities of physiochemical properties. The pH value and Boron, fluoride calcium, magnesium, sulfide, potassium, and Silica are well within the desirable limit at all locations. However, the concentration of conductivity chloride, hardness as CaCO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;, sulfate, nitrate, and Sodium in all samples exceeded the desirable WHO maximum permissible limit. The study reveals that the groundwater quality changed due to anthropogenic and natural influences such as natural weathering processes. As a result of this the qualities of the boreholes and dug well water samples were therefore not suitable for human consumption without adequate treatment. Regular monitoring of groundwater quality, abolishing unhealthy waste disposal practices, and introducing modern techniques are recommended.

Assessment of Spatial Variability in Groundwater Quality of Kurnool Region for Irrigation Purpose and Management Options

Assessment of Spatial variability in Groundwater quality of Kurnool region for irrigation purpose and management options was conducted by collecting groundwater samples using GPS locations at various farming situations in different mandals of Kurnool district. The irrigation water quality indices were assessed to classify the ground water for its suitability based on ionic properties viz., pH, EC, Ca+2, Mg+2, Na+ and K+; CO3-2, HCO3-, Cl-and SO4-2.The pH, EC, SAR, RSC, Kellys ratio, Saturated sodium per centage and Permeability index in groundwater ranged from 6.5-8.4, 0.4-15.6 (dSm-1), 0.44-28.77 (mmol l-1)1/2, -66.8-15.4 (me l-1), 0.15-24.61, 11.04-94.89 and 17.22-111. The concentration of cations viz., Ca+2, Mg+2, Na+ and K+ varied from 0.8-24.4, 0.4-34.8, 0.5-108 and 0.003-27.6 me l-1 with mean values of 6.71, 6.19, 12.24 and 0.59 me l-1 respectively. Concentration of anions viz.,CO3-2, HCO3-, Cl-and SO4-2varied from 0-1.2, 0.4-18.2, 0.8-77.2 and 0.001-8.39 me l-1 with an average values of 0.04, 6.59, 8.78 and 1.78 me l-1 respectively. The relative abundance of ions for most of the water samples were Na+&gt; Ca+2&gt; Mg+2&gt; K+ for cations and Cl-&gt;HCO3-&gt;SO4-2&gt; CO3- for anions. Based on physico-chemical properties the groundwater is classified into good, marginally saline, saline, high SAR saline, marginally alkali, alkali, high SAR alkali for irrigation. Thematic maps representing spatial variability in groundwater quality in respect to pH, EC, SAR, RSC and irrigation water class were prepared by inverse distance weightage interpolation method using geographical information system. This will give the information of the irrigation water quality for management options in crop production.

Spatio-temporal variations in groundwater quality in the parts of South-western Punjab, India

Spatio-temporal variations in groundwater quality for drinking and irrigation purposes were assessed in the parts of Bathinda district in Punjab (India). A total of 800 geotagged water samples (400 samples in each season) were collected from running tubewells during pre-monsoon (June 2020) and post-monsoon (October 2020) seasons. These water samples were analyzed for pH, electrical conductivity (EC), major cations (Ca2+, Mg2+, Na+ and K+) and anions (CO32−, HCO3−, Cl−, SO42− and NO3−) using standard methods. The water samples were categorized into drinking and irrigation purposes based on water quality index (WQI). Results showed that electrical conductivity, total dissolved solids, total hardness (including Ca2+, Mg2+), Cl−, and NO3− concentration in groundwater samples were significantly (p < 0.05) higher during post-monsoon than pre-monsoon season. Total alkalinity (including CO32− and HCO3− concentration in groundwater), pH, Na+, K+ and SO42− concentration in groundwater was significantly (p < 0.05) higher during pre-monsoon than post-monsoon season. The water quality for drinking purposes deteriorated from pre- to post-monsoon season, but water quality for irrigation purposes improved from pre- to post-monsoon season. The Gibbs diagram showed that direct and reverse exchange reactions occurred in groundwater samples. Spatio-temporal variations in groundwater based on various indices and WQI showed the specific locations for water management. Multivariate analysis showed that three diverse sets of constraints (salinity, carbonates hardness, and pollution processes) influence the groundwater chemistry of the study area.

Application of geochemical tracers for the investigations of groundwater resources in semi‐arid region (Central‐East Tunisia)

AbstractGroundwater resources in Mahdia‐Ksour Essef region, located in the central‐eastern part of Tunisia, suffer from intensive exploitation and degradation of water quality. The assessment of groundwater vulnerability, the well‐understanding of geochemical processes and the investigation of groundwater quality variations are of particular importance for water resources management in this semi‐arid region. The results of this multi‐disciplinary investigation show that groundwaters of Mahdia‐Ksour Essef region are flowing from El Jem and Boumerdes regions in the South, towards the Mediterranean Sea and the sebkha of Moknine in the North. The groundwaters are classified as either Na‐Cl or Ca‐SO4. Stable oxygen and hydrogen isotope compositions (δ18O and δ2H) confirm a recharge by rapid water infiltration, evaporate surface water and water‐rock interaction processes in the salinity increase. The rock‐water interaction processes of the mineralization of groundwaters include the cation‐exchange reactions and the dissolution of carbonates and evaporate. The high values of the water quality index (WQI) and of the total dissolved solids (TDS) (3.7–11 g/L) of these groundwaters indicate their unsuitability for drinking purpose. Moreover, the combination of the WQI, TDS and nitrate results prove the vulnerability of the studied groundwater to the anthropogenic pollution linked to agriculture and domestic activities and to the salt water contamination.

Machine learning empowered prediction of geolocation using groundwater quality variables over YSR district of India

Machine Learning (ML) has been used in the prediction of geolocation with improved accuracies in this work. The pre-processed data was subjected to prediction analytics using 22 machine learning algorithms over regression mode. It was observed that Extra Trees Regressor performed well with better accuracies in predicting latitude, longitude, and Haversine distance, respectively. Regression models like CatBoost, Extreme Gradient boosting, Light Gradient boosting machine, and Gradient boosting regressor were also tested. The R2 values were computed for each case, and we obtained 0.96 (Longitude), 0.98 (Latitude), and 0.96 (Haversine), respectively. The evaluation of models was done using metrics like MAE, MASE, RMSE, R2, RMSLE, and MAPE and R2 is considered most important than others. The effect of data point was calculated using Cooks’ distance, and the variable fluoride has a significant impact on the prediction accuracy of Longitude followed by RSC, Cl, SO4, SAR, NO3, NA, Ca, EC and pH variables. In the prediction of latitude, the SAR variable played a significant role, followed by Na and TH. According to the t-SNE manifold, three longitude values were quite different from the others. This work is supported by some of the manifests like Cooks’ distance outlier detection, feature importance plot, t-SNE manifold, prediction error plot, residuals plot, RFECV plot, and validation curve. This work is done to report that the challenge of predicting both latitude and longitude on a common ground is solved partially, if not completely, and machine learning tools can be used for this purpose. Haversine distance can be obtained from latitude and longitude and can be used in the prediction of geolocation.

Groundwater Assessment in Udham Singh Nagar, Uttarakhand, India Using Multivariate Statistical Techniques, WQI, and HPI

We conducted a study to assess the variations in groundwater quality and metal pollution and identify the sources in the U S Nagar district of Uttarakhand state of India using multivariate statistical techniques. The two essential indicators of any developed society are Safe drinking water and decontamination. This research aims to undertake drinking water quality analyses of the groundwater and the sources of contamination in Udham Singh Nagar district, Uttarakhand. We produced results of 250 samples collected from hand pumps (Govt. and Private) and artesian wells. We measured 19 parameters which nine physicochemical parameters (pH, electrical conductivity, total dissolved solids, dissolved oxygen, oxidation and reduction potential, salinity, fluoride, chloride, nitrate), 7 Heavy metals (Lead, nickel, chromium, copper, iron, manganese, zinc) along with three metals (potassium, magnesium, sodium). Water quality index, Heavy metal pollution index, PCA (Principal component analysis)/FA (factor analysis), and CA (Cluster analysis) methods were applied. WQI index shows five samples (2 %) comes under the excellent, 211 samples (84.4 %) fall under good quality, and 34 samples (13.6 %) have poor water quality wqi status as per Yadav index. Further, referring to the Ramakrishnaiah index, 216 samples (86.4 %) fall under excellent quality and only 13 samples (13.6 %) come under good water quality. For HPI, as per Indian Standard, nearly 40.4% of samples show a low degree of pollution, 33.2% of samples show a medium degree of pollution, and 26.4% show a High degree of pollution. According to the International HPI standard, 46% of samples show a low degree of pollution, 38% have a medium degree, and 16% show a high-grade degree of pollution. The results of PCA show that groundwater has mainly geogenic (geochemical alteration and weathering of source rock like carbonate, dolomite, quartzite, etc.) followed by anthropogenic sources (agrogenic, domestic sewage and industrial wastes etc.). The results obtained through the PCA are also moderately supported by Cluster analysis. The cations which were over the limit in groundwater samples are presented in chronological order Fe &gt; Pb &gt; Ni &gt; Mg &gt; Mn &gt; Zn &gt; Cu, and significant anions were over the limit F¯ &gt; Cl¯, and the rest was under the limit. The highly heavy metal-contaminated drinking groundwater sample, being used for drinking purpose, is deteriorating and need a proper treatment strategy before domestic water supply.

Spatial Assessment and Variation of Soil Physicochemical Properties and Water Quality in the Tungi Watershed of Maharashtra, India

Aims: To thoroughly evaluate the spatial variability of soil physicochemical properties and groundwater quality of the study area by systematic collection and analysis of geo-referenced soil and groundwater samples to quantify the physical, chemical and biological attributes of the soil. The objective is to gain a comprehensive understanding of soil and water quality in the Tungi watershed, providing valuable insights to guide sustainable land and water management practices in the region.&#x0D; Place and Duration of Study: Department of Soil Science and Agricultural Chemistry, College of Agriculture, Latur between 2020 and 2021.&#x0D; Methodology: A total of one hundred geo-referenced surface soil samples (0-30 cm) and ten groundwater samples were methodically collected from the surrounding area of soil profiles in the Tungi watershed, situated in Latur, Maharashtra. Physical, chemical and biological properties of soil evaluated using recommended standard methods.&#x0D; Results: Bulk density varied from 1.13 to 1.93 Mg m-3, particle density from 2.48 to 2.94 Mg m-3 and porosity from 22 to 58 percent. Soil pH ranged from 7.05 to 8.96 and electrical conductivity was within the permissible range. Organic carbon content of soils ranged from 0.15 to 1.05 percent, with some soils having a calcareous character (0.6 to 22.2 percent). The analysis of nutrient content revealed variable quantities with available nitrogen ranging from 53.31 to 250.88 kg ha-1, available phosphorus from 12.51 to 27.49 kg ha-1, available potassium from 106.9 to 851.5 kg ha-1 and available sulphur from 4.37 to 66.65 mg kg-1. Exchangeable calcium and magnesium quantities revealed ranges of 14.60 to 42.40 cmol(p+) kg-1 and 5.40 to 21.60 cmol(p+) kg-1, respectively. Furthermore, DTPA extractable iron varied from 4.24 to 16.38 mg kg-1, manganese from 4.76 to 25.84 mg kg-1, zinc and copper from 0.5 to 6.56 mg kg-1 and 0.72 to 15.56 mg kg-1, respectively and boron from 0.1 to 3.56 mg kg-1. Microbial population estimates revealed the dominance of bacteria over fungi and actinomycetes in the studied area. Groundwater carbonate and bicarbonate ranged from 0.01 to 0.62 m mol-1 and 6.35 to 10.24 mmol-1 respectively. The dug well, bore well and tube well water RSC ranged from 0.70 to 1.25 mmol-1.&#x0D; Conclusion: This extensive study provides helpful insights into the regional variability of physical and chemical properties in both soil and water with help of soil fertility maps, providing better understanding of soil fertilizer input and environmental conditions in the Tungi watershed.

Impact of different land use types on groundwater quality in Ibadan, Nigeria

Studies of comparative analysis of groundwater quality under different land use types are scarce, and such studies remain critical in achieving sustainable water resource management. This study used suitable multi-statistical techniques alongside the Water Quality Index (WQI) to assess and compare the effects of residential, industrial, and agricultural land use types on groundwater quality in a region of Ibadan, Nigeria, primarily underlain by banded gneisses. The study also established the appropriateness of the water samples for human consumption. Thirty water samples, consisting of 10 samples each from three different land use types, were randomly collected and subjected to established methods of analysis for nine physicochemical parameters. The results from the Kruskal-Wallis test and Dunn's test showed that average concentration levels of pH, total hardness, calcium, magnesium, chloride, bicarbonate, nitrate, and sulfate in the tested water samples were significantly different (p-value ≤ 0.05) among the three land use types investigated. The results also suggested that where poor environmental conditions are common, residential land use type could pose a greater risk to groundwater quality than either agricultural land use or industrial land use. At least, a three-factor model was suggested and explained 63.4 %, 70.2 %, and 91.6 % of the total groundwater quality variation under the residential, agricultural, and industrial land uses respectively using Kaiser's varimax rotation method. In addition, the WQI results showed that 100 % of the water samples from industrial and agricultural land uses were appropriate for drinking but only 20 % of the water samples from residential land use were. The findings indicated that differing land use types affect groundwater quality in different ways. It was thus recommended that an improved sanitation system should be provided by the authorities to help reduce groundwater pollution in the residential area. This can help toward achieving water security mentioned in the African Union's Agenda 2063.

Seasonal recharge mechanism of the upper shallow groundwater in a long-term wastewater leakage and irrigation region of an alluvial aquifer

Understanding the mechanisms that control seasonal groundwater recharge at local and intermediate scales is critical for understanding contaminant transport. The recharge mechanism of seasonal precipitation and irrigation, companied with legacy wastewater in porewater in alluvial aquifer were complicated due to the seasonal variation of multiple recharge sources. In this study, a long-term wastewater leakage and irrigation region along the Tanghe Wastewater Reservoir (TWR) in the alluvial plain area of North China Plain to investigate the recharge mechanism from unsaturated zone to the upper shallow groundwater affected by multiple water sources. Water chemical ions and stable isotopes of water (2H and 18O) of 30 m deep sediment profiles and groundwater boreholes were used to trace the recharge processes. The porewater stable isotopes of the sediment profiles revealed vertical recharge rates ranging from 0.63 to 1.09 m/year for the layered unsaturated zone with silt and silty clay. Due to the matrix flow through unsaturated zone, the legacy wastewater in the unsaturated zone affected the variation of groundwater quality in long term. However, fast flow (i.e., preferential or lateral flow) occurred in sand layers of alluvial aquifers lead to significant precipitation contributions (44 to 61 %) to the upper shallow groundwater (USGW) recharge, resulting in the seasonal variation of stable isotopes and water chemical ions. Affected by the fast flow with seasonal variations and matrix flow with legacy wastewater in the unsaturated zone, the δ2H and δ18O relationship of the USGW showed two types of hysteresis loops in the dual isotope space: 1) groundwater in regions affected by the TWR wastewater leakage shows narrow loops and a nearly straight line with end-members of precipitation that recharged to groundwater by fast flow, and evaporated porewater plotting along the TWR evaporation line; and 2) groundwater in irrigated farmlands with low and high irrigation amounts and intense evaporation shows stronger hysteresis with loops overlapping with shallow porewater, suggesting the impact of legacy wastewater of the unsaturated zone on groundwater. The residual pollutants in soil and the type of fast flow determine the different seasonal variation of groundwater quality. Preferential flow in alluvial aquifer regions can increase the proportion of seasonal recharge from precipitation, resulting in the rapid introduction of contaminants from surface or shallow soils into the alluvial aquifer.