Investigation of Groundwater Quality with Borehole Depth in the Basin Granitoids of the Ashanti Region of Ghana

The dependence of groundwater quality on borehole depth is usually debatable in groundwater studies, especially in complex geological formations where aquifer characteristics vary spatially with depth. This study therefore seeks to investigate the relationship between borehole depth and groundwater quality across the granitoid aquifers within the Birimian Supergroup in the Ashanti Region. Physicochemical analysis records of groundwater quality data were collected from 23 boreholes of public and private institutions in the Ashanti Region of Ghana, and the parametric values of iron, fluoride, total hardness, pH, nitrate, and nitrite were used to study the groundwater quality-depth relationship. The results showed that the depth-to-groundwater quality indicated a marginal increase in water quality in the range of 30 to 50 m, which is mathematically represented by the low-value correlation coefficient (r2 = 0.026). A relatively significant increase occurs in the depth range of 50 to 80 m, which is given by a correlation coefficient of r2 = 0.298. The mean percent parameter compatibility was 74%, 82%, 89%, and 97% at 50, 60, 70, and 80 m depths, respectively. The variations in groundwater quality per depth ratio ranged from 1.48, 1.37, 1.27, and 1.21 for 50, 60, 70, and 80 m depth, respectively. The recommended minimum borehole depth for excellent groundwater quality is suggested with a compatibility per meter depth ratio of 1.37. This results in a range between 50 and 70 m as the most desirable drilling depth for excellent groundwater quality within the granitoids of the Birimian Supergroup of the Ashanti Region in Ghana.

Geogenic Pollution of Groundwater Quality in Gampaha District, Sri Lanka: A Case Study of Groundwater Acidification from Rathupaswala

Over recent decades, Gampaha district, Sri Lanka, has experienced significant urbanisation and industrial growth, increasing groundwater demand due to limited and polluted surface water resources. In 2013, a community uprising in Rathupaswala, a village in Gampaha district, accused a latex glove manufacturing factory of causing groundwater acidity (pH < 4). This study evaluates the spatial and temporal changes in geochemical parameters across three transects in the southern part of Gampaha district to 1) assess the impact of geological formations on groundwater;2) compare temporal variations in groundwater;and 3) explain acidification via a geochemical model. Seventy-two sample locations were tested for pH, electrical conductivity (EC), and anion concentrations (sulphate, nitrate, chloride and fluoride). Depth to the water table and distance from the sea were measured to study variations across sandy, peaty, lateritic, and crystalline aquifers. Results showed pH readings around 7 for sandy and crystalline aquifers, below 7 for peaty aquifers, and below 5 for lateritic aquifers, with significant water table fluctuations near Rathupaswala area. Principal component analysis revealed three principal components (PCs) explaining 86.0% of the variance. PC1 (40.6%) correlated with pH, EC, and sulphate (saltwater intrusion), while PC2 (32.0%) correlated with nitrates and depth to the water table (anthropogenic nutrient pollution). A geochemical transport model indicated a cone of depression recharged by acidic groundwater from peat-soil aquifers, leading to acidic groundwater in Rathupaswala area. Previous attributions of acidic pH to the over-exploitation of groundwater by the latex factory have been reevaluated;the results suggest natural acidification from prolonged water-rock interactions with iron-rich lateritic aquifers. Groundwater pH is influenced by local climate, geology, topography, and drainage systems. It is recommended that similar water-rock interaction conditions may be present throughout the wet zone of Sri Lanka, warranting detailed studies to confirm this hypothesis.

Groundwater quality in the vicinity of a dumpsite in Lagos metropolis,Nigeria

Inappropriate management of municipal solid waste dumpsites is a major cause of groundwater contamination in developing countries,but the extent of the problem is not known.This study investigated groundwater quality in the vicinity of Olusosun dumpsite in Lagos,Nigeria,the most populous city in sub-Saharan Africa.During 2020,monthly groundwater samples were collected in 17 wells and boreholes used as drinking water sources,and analysed for 20 physico-chemical parameters.Differences between sites and seasons were statistically assessed,together with changes in water quality index(WQI).The results indicated that heavy metals(Pb^(2+),Ni^(+),Mn^(2+),Fe^(2+),Cr^(6+)),cations(Ca^(2+),Mg^(2+),K^(+)),total hardness and pH were the main parameters impairing water quality.Drinking water quality standards from both the World Health Organization and Nigeria government were exceeded more often in the wet season than in the dry season.Some groundwater properties were negatively correlated with distance to dumpsite(e.g.,Fe^(2+),Pb^(2+),NO_(3)^(−)).Significant differences between sites were identified,but with no clear spatial trend.WQI varied from excellent(6%-24%of the sites over the study period)to unsuitable for drinking water purposes(12%-18%),with good quality prevailing at most sites(35%-47%).Although groundwater quality declined at 24%of the sites over 2020,the results indicated improvements compared with previous decades.Remediation strategies must be implemented to safeguard public health and the sustainability of water resources.

Groundwater Quality Surroundings Mining Activities Areas in Arlit Region(Tim MersoïBasin,North Niger)

The study area is a semi-arid area located in the Arlit region.This area contains significant uranium deposits that have been mined by two mining companies since 1968.The objective of this study is to determine the impact of these activities on existing aquifers,in particular Izegouande aquifer.A methodological approach based on hydrochemical methods focusing on the analysis of nitrates and sulfates showed that waters of Izegouande aquifer have high nitrate concentrations ranging from 16 mg/L to 60 mg/L,higher than WHO(World Health Organization)standards drinking water.In addition,these waters show elevated sulfate levels ranging from 16 mg/L to 57 mg/L,therefore acceptable.These high concentrations of nitrates and sulfates are located mainly near wastewater treatment of Arlit city and near industrial zone,which are potential areas for transfer of these elements such as nitrates and sulfates.It is therefore urgent to carry out periodic and regular checks on groundwater in these areas.

GROUNDWATER QUALITY AND CONTAMINATION INDEX MAPPING IN CHANGCHUN CITY,CHINA

Groundwater in Changchun City, Jilin Province of China tends to be influenced by human activities. Chemical types of groundwater were detected in both shallow and deep groundwater were: HCO3--Ca2+ and HCO3--Ca2+·Mg2+ or HCO3--Mg2+·Ca2+; SO42--Ca2+ and SO42--Ca2+·Mg2+; Cl--Ca2+; and CO32--Na+. The deteriorations of groundwater quality due to the increase of TDS, NO3-+ NO2-(as Nitrogen) and TH contents have been observed from 1991 to 1998. Scatter analyses showed strong positive correlations between Ca2+, Cl-and NO3-ions and weak negative correlations between the depth of water table and Ca2+, SO42-, Cl-and NO3-ions. A mapping of contaminant index based on Chinese standard of groundwater showed that a large proportion of the groundwater in 1998 was deteriorated by human process. Despite their low values of sodium adsorption ratio (SAR), the most of the sampled wells were not suitable for drinking and agriculture purposes due to higher contents of NO3-, NO2-and Mn2+ ions.

Groundwater quality and land use change in a typical karst agricultural region:a case study of Xiaojiang watershed,Yunnan

Taking the typical karst agricultural region, Xiaojiang watershed in Luxi of Yurman Province as a research unit, utilizing the groundwater quality data in 1982 and 2004, the aerial photos in 1982 and TM images in 2004, supported by the GIS, we probe into the law and the reason of its space-time change of the groundwater quality over the past 22 years in the paper. The results show： （1） There were obvious temporal and spatial changes of groundwater quality during the past 22 years. （2） Concentrations of NH4^＋, SO4^2- , NO3, NO2^-, Cl^- and the pH value, total hardness, total alkalinity increased significantly, in which NH4^2-, NO3, and NO2^- of groundwater exceeded the drinking water standards as a result of non-point pollution caused by the expansion of cultivated land and mass use of the fertilizer and pesticide. （3） Oppositely, Ca^2＋ and HCO3^- showed an obvious decline trend due to forest reduction and degradation and stony desertification. Meantime, there was a dynamic relation between the groundwater quality change and the land use change.

Groundwater quality modeling using self-organizing map(SOM) and geographic information system(GIS) on the Caspian southern coasts

Groundwater is the main source for water provision in the arid and semi-arid areas such as Iran.The groundwater quality was simulated by using a hybrid model integrating a Self-Organizing Map(SOM)and geographic information system(GIS).SOM and GIS were used as pre-processing and postprocessing tools in the Mazandaran Plain.Further,the Ground Water Quality Index(GWQI)and its effective factors were estimated by using digital maps and the secondary data.Neuro Solutions software was used for simulating the groundwater quality.To do this,a model was trained and optimized in the SOM and then the optimized model was tested.In the next step,the performance of SOM in groundwater quality simulation was confirmed(test stage,Rsqr=0.8,and MSE=0.008).Then,the digital maps of the SOM inputs were converted to raster format in GIS.In the last step,a raster layer was generated by combining the model input layers which comprised the model inputs values.The tested SOM was used to simulate GWQI in the sites without the secondary data of the groundwater quality.Finally,the groundwater quality map was generated by coupling the results of SOM estimations and GIS capabilities.The results revealed that the coupling of SOM and GIS has high performance in the simulation of the groundwater quality.According to the results,a limited area of the studied plain has groundwater resources with low quality(GWQI>0.04).Therefore,that will be a threat to the life of humans,animals,and vegetative species.Therefore,it is necessary to plan for managing the groundwater quality in the Mazandaran plain.

Compilation of Groundwater Quality Map and study of hydrogeochemical characteristics of groundwater in Asia

The groundwater quality map is among a series of Asian groundwater environment maps, which has been compiled and is about to be published. The article introduces the central theme and main content of the map, evaluates the method applied for groundwater quality gradation, and discusses hydrogeochemical characteristics of Asian groundwater. The distribution of water quality is investigated through the data collection of selected elements; hydrogeochemical characteristics are demonstrated via the analysis of elements’ allocation in horizontal and vertical zones; whilst the groundwater quality is evaluated by the Analytic Hierarchy Process(AHP).

Hydrogeochemical processes and multivariate analysis for groundwater quality in the arid Maadher region of Hodna,northern Algeria

This study focused on water quality and hydrogeochemical processes(evolution,origin)in the Maadher region,central Hodna in Algeria.In recent decades,the excessive exploitation of this resource due to urbanization,irrigation,and the effect of climate change reaching the countries of northern Africa have caused a decline in water levels and hydrochemical changes in the aquifer.The sampling campaign in 2019 based on 13 physicochemical parameters was carried out on the water from 32 boreholes in the study area,compared to data archives of both sampling campaigns in 1967 and 1996.The result revealed that the groundwater as a whole has moderate freshwater quality,due to its total dissolved solids(TDS)content and other dissolved ions of concern(nitrate NO),which exceed WHO standards.In addition,Piper diagram indicates that the hydrochemical facies of sulfate–chloride–nitrate–calcium(SO–Cl–NO–Catype),which globally characterizes the study area and these elements are the dominant dissolved ions.Principal component analysis and hierarchical cluster analysis(HCA)methodologies are applied in order to define the major control factors that affect the hydrochemistry of Maadher plain.Three distinct water groups were found,illustrating a different evolution of salinity(EC and TDS).The HCA indicated an interesting cluster with a distinct contamination signature and most likely with significantly higher sulfate,chloride,and nitrate concentrations.Anthropogenic processes also play an important role in the study area.The water resource comes from Bousaada Wadi,the exchange at the aquifer depth and the agricultural practices contribute to the deterioration of the quality.

Assessment of Groundwater Quality for Domestic and Irrigation Purposes in Northern Bamenda (Cameroon)

Safe and reliable drinking water availability constitutes a nightmare in many towns of developing countries and is usually appreciated from its physical appearance without prior knowledge of its chemical and biological properties. This study investigates the suitability of groundwater for domestic and irrigational purposes through physico-chemical and bacteriological analyses in the Northern part of Bamenda Town (Cameroon). Thus, 20 groundwater samples were collected from hand-dug wells and spring sources in September 2018 (rainy season) and February 2019 (dry season) and physico-chemical and bacteriological characteristics were determined. The results revealed that pH ranged from 5.5 to 6.6, thus enabling the classification of the water as slightly acidic. Electrical conductivity varied between 0.01 - 0.06 μS/cm. The relative abundance of ions was such that Ca2+ > K+ > Mg2+ > Na+ for cations and HCO-3 > Cl- > NO-3 > SO-4 for anions. The water types were Ca-Mg-NO3 in both dry and rainy seasons. The results revealed that the mechanisms controlling groundwater chemistry are rock weathering and atmospheric precipitation. Indicator bacteria such as E. coli, Shigella, Enterobacteria, Vibrio, Streptococcus and Staphylococcus were detected in the studied groundwater samples, thus the water sources may pose a threat to public health.

Groundwater Quality and Arsenic Contamination in Amphoe Khemmarat, Ubon Ratchathani, Thailand

Arsenic （As） is one of the most important elemental pollutants in groundwater and drinking water because it causes health problem of arsenicosis after consumption of drinking arsenic-rich water more than 5-10 years. Arsenic contamination of groundwater is an emerging issue in Mekong Basin including Cambodia, Vietnam, and Thailand. In Thailand, information about arsenic contamination in drinking water resources are quite rare due to that arsenic is not the main element in water qualification assay. The objective of this study is to determine groundwater quality and arsenic contamination in rural Mekong Basin, Ubon Ratchathani. Groundwater samples were collected from 20 different sampling points, between August 2009 and February 2010 in Amphoe Khemmarat, Ubon Ratchathani, Thailand. Physical and chemical characteristics of groundwater were determined. It was observed that the groundwater was 27.9-30.3 ~C, pH 5.7-6.9. The conductivity was 707-767 p.S.cm＂. Dissolved oxygen was 2.04-5.12 mg.L-1 and TDS was 352-384 mg.L~. The samples showed soft- to very hardness-water properties. In some area, few parameters like CI, Fe, Mn, and As exceeded the WHO guideline limits. This result represents basic information for quality of groundwater and the arsenic contamination in rural Mekong Basin, Ubon Ratchathani. Thus, it is probably useful for arsenic standard level assignment and public health authorities. Moreover, it also leads to establish research activity in treatment of arsenic-contaminated groundwater for different purposes

Evaluation of Groundwater Quality in the Deep Maastrichtian Aquifer of Senegal Using Multivariate Statistics and Water Quality Index-Based GIS

A regional groundwater quality evaluation was conducted in the deep Maastrichtian aquifer of Senegal through multivariate statistical analysis and a GIS-based water quality index using physicochemical data from 232 boreholes distributed over the whole country. The aim was to 1) identify the water types and likely factors influencing the hydrochemistry, and 2) determine the suitability of groundwater for drinking and irrigation. Results showed that sodium, chloride, and fluoride are highly correlated with electrical conductivity (EC) reflecting the significant contribution of these elements to groundwater mineralization. The principal component analysis evidenced: 1) salinization processes (loaded by Na+, K+, EC, Cl-, F- and HCO3-) controlled by water/rock interaction, seawater intrusion and cation exchange reactions;2) dolomite dissolution loaded by the couple Ca2+ and Mg2+ and 3) localized mixing with upper aquifers and gypsum dissolution respectively loaded by NO3- and SO42-. The hierarchical clustering analysis distinguished four clusters: 1) freshwater (EC = 594 μs/cm) with mixed-HCO3 water type and ionic contents below WHO standard;2) brackish (Na-mixed) water type with moderate mineralization content (1310 μs/cm), 3) brackish (Na-Cl) water type depicted by high EC values (3292 μs/cm) and ionic contents above WHO and 4) saline water with Na-Cl water type and very high mineralization contents (5953 μs/cm). The mapping of the groundwater quality index indicated suitable zones for drinking accounting for 54% of the entire area. The occurrence of a central brackish band and its vicinity, which were characterized by high mineralization, yielded unsuitable groundwater for drinking and agricultural uses. The approach used in this study was valuable for assessing groundwater quality for drinking and irrigation, and it can be used for regional studies in other locations, particularly in shallow and vulnerable aquifers.

Groundwater Quality Index Mapping for Gulbarga City, Karnataka State, India

The present work is aimed at assessing the water quality index （WQI） for the groundwater for Gulbarga city. The water quality index （WQI） is a mathematical instrument used to transform large quantities of water quality data into a single number which represents the water quality level. In fact, developing WQI in an area is a fundamental process in the planning of land use and water resources management. One can then compare different samples for quality on the basis of the index value of each sample. The present work relates to the development of water quality index for the study area based on the experimental results of physicochemical analysis of water samples. For calculating the WQI, the following 11 parameters have been considered, pH, TH, Ca, Mg, NO3, SO4, TDS, F, CI, K and Na. The WQI for these samples ranges from 10.40 to 155. Using developed indices, groundwater isopleth map has been prepared for study area. In the case study, the WQI map reveals that groundwater quality in two areas is extremely near to mineral water quality. Created index map provides a comprehensive picture that is easily interpretable for regional decision makers for better planning and management. The results of analysis have been used to suggest models for predicting water quality. The analysis reveals that the groundwater of the area needs some degree of treatment before consumption, and it also needs to be protected from the perils of contamination.

Groundwater Quality for Irrigation Purposes and Classification for Hydrochemical Facies in Parts of Southern Ijaw Local Government Area, Bayelsa State, Nigeria

As a result of economic development and rapid growth of the population in Southern Ijaw Local Government Area of Bayelsa State, Nigeria, there have been clear changes in the use of land, resulting in increased demand for water for various uses including agricultural activities. This study examined groundwater quality and classification of hydrochemical facies of communities in the study area. Fifteen (15) communities within the LGA were selected and groundwater from hand-dug well (HDW-15 samples) and borehole (BH-15 samples) was sourced during the wet season (July) and dry season (March) and analyzed for seasonal variation, irrigation purposes and hydrochemical facies classification using a standard method. Based on Sodium Adsorption Ratio (SAR) classification scheme, all groundwater sources in the area are excellent for irrigation purposes because they all have SAR values <3. This implies that SAR values of <3 will not threaten vegetation. The value of sodium percentage (Na%) ranges from 29.81% to 66.13% and 23.30% to 71.89% for hand dug wells in both wet and dry seasons. Similarly, the value of Na% ranged from 3.57% to 16.32% and 3.38% to 19.60% for borehole water in both wet and dry seasons. The groundwater hydrochemistry facies analysis indicated that there was an adjustment in groundwater chemistry during dry season while HDW and BH are linked to different sources. Groundwater in the communities are contaminated for both sources and season;however, showed potential for irrigational purpose. There is a need for continuous monitoring of the water quality, improvement in environmental and sanitation practices while treatment of water is strongly advised.

Sustainability Assessment of the Groundwater Quality in the Khoyrasole Block, Birbhum District, West Bengal to Achieve Rural Water Security

In order to attain the water security goal, specifically in highly developingareas, delineation of pure and sustainable water resources is of utmostpriority. In the present study, a preliminary investigation of the groundwaterchemistry was carried out. This was followed by assessing the suitabilityof groundwater to be used as an alternative and reliable resource for publicuse in the Khoyrasole block, Birbhum district, India. Altogether 15(fifteen)samples of groundwater, were collected from bore wells spread well overthe Khoyrasole block have been considered. After completing the chemicalanalysis of the groundwater samples, the study revealed the quality ofgroundwater. The spatial distribution of groundwater quality parameterssuch as pH, Total Dissolved solids (TDS), Hardness, Calcium, Magnesium,Sodium, Potassium, Iron, Chloride, Carbonate, Bicarbonate, Sulphate,Nitrate and Fluoride have also been studied. High to very high levels ofiron and fluoride have been observed to be present in 67% and53% of thesamples respectively. Based upon the calculated parameters like SAR,MAR, PI and Chloro Alkaline Indices, groundwater of Khoyrasole blockis majorly suitable for the purpose of agriculture and irrigation. Plotting ofionic scatter plots and geochemical facies also indicate the water samplesto be of “fresh water” category, with no dominant cation or anion playing aselectively dominant role in influencing the groundwater chemistry in thestudy area.

Application of machine learning models in groundwater quality assessment and prediction:progress and challenges

Groundwater quality assessment and prediction(GQAP)is vital for protecting groundwater resources.Traditional GQAP methods can not adequately capture the complex relationships among attributes and have the disadvantage of being computationally demanding.Recently,the application of machine learning(ML)in GAQP(GQAPxML)has been widely studied due to ML’s reliability and efficiency.While many GQAPxML publications exist,a thorough review is missing.This review provides a comprehensive summary of the development of ML applications in the field of GQAP.First,the workflow of ML modeling is briefly introduced,as are data preparation,model development,model evaluation,and model application.Second,299 publications related to the topic are filtered,mainly through ML modeling.Subsequently,many aspects of GQAPxML,such as publication trends,the spatial distribution of study areas,the size of data sets,and ML algorithms,are discussed from a bibliometric perspective.In addition,we review in detail the well-established applications and recent findings for several subtopics,including groundwater quality assessment,groundwater quality modeling using groundwater quality parameters,groundwater quality spatial mapping,probability estimation of exceeding the groundwater quality threshold,groundwater quality temporal prediction,and the hybrid use of ML and physics-based models.Finally,the development of GQAPxML is explored from three perspectives:data collection and preprocessing,model building and evaluation,and the broadening of model applications.This review provides a reference for environmental scientists to better understand GQAPxML and promotes the development of innovative methods and improvements in modeling quality.