Different Types Of Groundwater Research Articles

Hydrochemical Characteristics, Controlling Factors and Strontium Enrichment Sources of Groundwater in the Northwest Plain of Shandong Province, China

To elucidate the hydrochemical characteristics, controlling factors, sources and mechanisms of strontium ion enrichment in groundwater in the northwest plain of Shandong Province, China, 88 groundwater samples were collected, including 51 shallow pore groundwater samples, 29 deep pore groundwater samples and 8 karst groundwater samples. The hydrochemical characteristics of the different types of groundwater were quite different. The karst groundwater samples were all fresh water with a single hydrochemical type, either HCO3-Ca or HCO3-Ca·Mg. The deep pore groundwater samples were mainly brackish water, and the shallow pore groundwater samples were brackish water–salt water, which has complex hydrochemical types. The hydrochemical characteristics of all the types of groundwater were controlled by mineral dissolution and active positive cation exchange. In shallow pore groundwater, deep pore groundwater and karst groundwater, the dissolution of silicate, evaporite and carbonate minerals dominated the hydrogeochemical process. The strontium in groundwater was derived from the dissolution of minerals with strontium isomorphism. The average contents of strontium in shallow, deep and karst groundwater were 1.59 mg/L, 0.58 mg/L and 0.50 mg/L, respectively. The strontium in shallow pore groundwater was mainly derived from the enrichment of groundwater runoff, and its sources are abundant, with silicic rock being the main source. The deep pore groundwater mainly derived from the evaporative minerals containing strontium, and the karst water mainly derived from carbonate rock dissolution with similar characteristics.

Climate-related risk assessment in water safety plans: the case study of Acque Bresciane (Italy).

Acque Bresciane is a public company that manages the integrated water cycle for more than 580,000 inhabitants in the Province of Brescia, in the north of Italy, providing drinking water, waste water treatment, and sewer systems. Drinking water systems are supplied with different types of groundwater, springs, and surface water sources (from lakes and rivers) whose availability and quality can be affected by climate change events. A multidisciplinary team, in collaboration with the University of Milano Bicocca, developed a specific Water Safety Plan (WSP) risk matrix focusing on the evaluation of climate-related hazardous events and calculation of their likelihood of occurrence, also using thematic maps. Moreover, to reduce the residual risks, in the risk matrix, possible control measures are suggested, such as the activation of an emergency plan, the use of other water sources, storage tanks, and interconnection with other water distribution networks. This work shows a simple and effective tool that can be applied by drinking water utilities to evaluate climate-related catchment risks, using a WSP risk matrix, thematic maps, and possible control measures to reduce risks in terms of water quality and availability and to respond with resilience to changes.

Groundwater Hydrogeochemical Processes and Potential Threats to Human Health in Fengfeng Coal Mining Area, China

The Fengfeng mining area is in the transition zone between the North China Plain and the Taihang Mountains, and groundwater is the main source of water supply in the district. Under the combined influence of human activities and natural geological conditions, the quality of different types of groundwater varies greatly, posing a potential threat to the safety of drinking water. In this study, hydrogeochemical processes in different types of groundwater were analyzed using multivariate statistical analysis methods with ion–ratio relationships, and a groundwater quality and health risk assessment model was developed. The research findings show that the main chemical components and TDS in the groundwater have obvious spatial distribution characteristics, i.e., the content of deep karst water (DKW) in the west is significantly lower than that of shallow pore water (SPW) in the east, and the hydrochemical type has changed from HCO3–Ca to SO4–Ca. The chemical components of SPW and DKW are mainly derived from silicates and carbonates, accompanied by weathering dissolution of sulphidic minerals, especially SPW. The chemical components of the groundwater was also influenced by the cation exchange reaction and human activities. The quality of the SPW was significantly worse than that of the DKW, and the nitrates in SPW carry a high non-carcinogenic risk, especially to children. The shallow pore water is not suitable for drinking water. This study can provide guidance on the safety of drinking water in the Fengfeng coal mining area and other areas with intensive industrial, mining, and agricultural activities.

Study on Estimation of Inhalation and Ingestion Dose due to <sup>222</sup>Rn Concentration in Different Types of Ground Water of Some Taluks of Uttara Kannada District, Karnataka, India

The primary goal of this study was to determine the risk due to radon concentration in drinking water. Water is essential for most of the life on the Earth, and the quality of drinking water is a key criterion for one's health. Radon (222Rn) and radium (226Ra) are the radioactive elements that can be found in water. Thirty samples of drinking water were collected in Haliyal, Joida, and Mundgod taluks of Uttara Kannada district. Emanometry technique was used to determine the concentration of 222Rn activity. The activity concentration of 222Rn in water varies between 3.78 ± 0.38 Bq l-1. and 135.96 ± 1.72 Bq l-1 with a mean value of 26.23 ± 0.65 Bq l-1. The cumulative average annual effective doses for all of the samples under investigation are well below the safe limit of 100 µSv y-1 suggested by WHO.

Effectiveness and mechanisms of electromagnetic field on reverse osmosis membrane scaling control during brackish groundwater desalination

This study investigated the effectiveness and mechanisms of electromagnetic field (EMF) on reverse osmosis (RO) membrane scaling control during brackish groundwater desalination. Pilot-scale experiments were conducted with different types of groundwater and two configurations of RO skid operated each for 30 days and 55 days without any other pretreatment. The testing results demonstrated EMF was effective for scaling control under typical RO operating conditions. The EMF significantly enhanced the performance of the RO system by reducing membrane scaling, changing the nature of the formed scales, and decreasing the decline rate of the normalized water permeability. In addition, EMF treatment effectively removed the pre-formed scales and precipitates in water pipelines and tanks but had limited efficacy on removing the pre-formed scales on the RO membranes. Membrane autopsy showed that the scales formed on the membrane surface under the influence of EMF were soft and powdery, being easily removed by water rinsing. The mechanisms of the EMF on RO membrane were discussed, and the dominant mechanism was the magnetohydrodynamic effect. This is the first study that demonstrated the EMF as a chemical-free and effective alternative to control membrane scaling and maintain RO performance during brackish groundwater desalination with discussions on detailed mechanisms and perspectives.

Distribution Characteristics and Health Risk Assessment of Metal Elements in Groundwater of Longzici Spring Area

Longzici Spring is an important water source for industry, agriculture, and urban life in Linfen City. With the improvements in public environmental health awareness, it is particularly necessary to study the health risk of posed by metal elements in groundwater. In this study, 43 groundwater samples from Longzici Spring area were analyzed for ten metal elements (As, Cd, Hg, Al, Pb, Co, Mn, Fe, Cu, and Ni). The distribution and health risk of these metal elements in the groundwater were studied using multivariate statistical analysis and a health risk assessment model. The results show that metal elements can be ranked, from high to low, by their average concentrations in groundwater in the following order: Fe, Al, Mn, Ni, As, Cu, Co, Pb, Hg, and Cd. The concentration of Al, Mn, Fe, and As exceed the limit for class Ⅲ water, as defined in the quality standard for groundwater (GB/T 14848-2017). Different types of groundwater in the spring area showed different metal contents. The quality of karst spring water was good, reaching the standard for drinking water, while mine drainage water exceeded the standard for drinking water, with the highest metal concentration (60%) and the worst water quality. Multivariate statistical results show that Pb, Ni, Co, Cd, Mn, and Cu concentrations were mainly affected by the geochemical background, while Al, Fe, Hg, and As concentrations were closely related to human mining activities under the unique geological background of Shanxi Province. The health risk assessment showed that the different types of groundwater could be ranked by the annual total health risks, posed by metal elements to adults and children through drinking water and skin infiltration, as follows: karst well > non-karst spring > non-karst well > karst spring. The health risks mainly came from drinking water, while health risks through skin infiltration would not cause obvious harm to the human body. The metal element causing the greatest health risk in spring groundwater was As, which should therefore be controlled in the utilization of water resources, especially in children's drinking water.

Hydrogeochemistry Evidence for Impacts of Chemical Acidic Wastewater on Karst Aquifer in Dawu Water Source Area, Northern China.

The study of the hydrochemical characteristics and the water–rock interaction of karst groundwater is very important for the rational exploitation of karst groundwater and its pollution control. In this paper, the systematic clustering method was used to analyze the hydrochemical characteristics of different types of groundwater, combined with hydrochemical graphic analysis and correlation analysis to explore the impact of chemical acidic wastewater on the evolution of karst aquifer in the Dawu water source area, northern China. The results show that the chemical acid wastewater, sourcing from discharges/spillages from the local chemical industries, has different degrees of pollution impact on karst groundwater, causing the total hardness of all karst groundwater and the total dissolved solids, Cl− and SO42− in nearly half of the karst groundwater to exceed the quality indexes of class III water in China’s standard for groundwater quality (GB/T 14848-2017). Hydrochloric acid and sulfuric acid in the wastewater can be buffered by the dissolution of carbonate rocks, resulting in a nearly neutral pH (pH-buffering effect) and an increase in Ca2+, Mg2+, Sr, Cl− and SO42− concentrations in karst groundwater.

Water Quality Analysis and Health Risk Assessment for Groundwater at Xiangshui, Chongzuo

To investigate the environmental quality and human health risks of different types of groundwater at Xiangshui, Chongzuo, several regular water quality indexes and concentrations of metals in 60 groundwater samples were measured and analyzed. The environmental quality of groundwater was analyzed by means of the Nemerow index. The health risks were assessed by using a human health risk assessment model. The regular water quality indexes and concentrations of metals of the well water, spring water, and underground river water exceeded the standards to different degrees. The environmental quality of groundwater was at a poor grade. The comprehensive evaluation score of underground river water (F=4.26) was the lowest. The well water had the same score as spring water (F=7.10). The high hardness and salinity were conducive to enrichment of Cr, and the reducing environment was of great advantage for the enrichment of As. The environmental geochemistry of Zn, Pb, Cd, and Cu was similar. The sources of Fe, Al, and Mn were similar. The results of the health risk assessment indicated that the health risks of well water, spring water, and underground river water were relatively high. The health risks decreased in the order of well water > underground river water > spring water. The health risks mainly came from the carcinogenic metallic element Cr. Carcinogenic risks were 4-6 orders of magnitude higher than non-carcinogenic risks. Carcinogenic risks were higher than the maximum allowance levels (5.0×10-5 a-1). Non-carcinogenic risks were lower than the allowance levels (10-6 a-1). Children had greater health risks than adults. The health risks of metals through the drinking pathway were 2-3 orders of magnitude higher than the values caused by the dermal contact pathway. For the sake of drinking water safety, the well water, underground river water, and spring water should be properly treated and the concentration of Cr in groundwater should be controlled before drinking.

An experimental examination of the effect of the salt type on the chemo-osmotic, diffusive, and hydraulic parameters of Wakkanai mudstones

To better understand the groundwater flow and chemistry in argillaceous formations, the dependency of transport parameters such as permeability, diffusion coefficient, and chemical osmotic efficiency on each of the chemical species dominant in groundwater must also be understood. Despite its importance, however, little is known about the dependence of transport parameters on different types of groundwater. Thus, we investigated transport parameters of Wakkanai mudstones using three different types of electrolyte solutions. Here, we report the relationship among the solution salt type, solute concentration, transport parameters, and pore structure characteristics. Wide ranges in osmotic efficiency and intrinsic permeability, 0.0035–0.14 and 1.19 × 10–19 to 4.75 × 10–18 m2, respectively, reflect the difference in the solution composition based on the salt type, difference in solute concentration, and variation in the pore size distributions of Wakkanai mudstones. The effective diffusion coefficients with filtration effects, at 2.98 × 10–11 to 5.92 × 10–11 m2 s–1, vary depending on salt type, but remain invariant among samples, indicating no difference in fluid flow path associated with small values of osmotic efficiency. In contrast, the osmotic efficiencies are related to differences in salt concentrations. Our findings indicate that salt concentration and pore structure characteristics determine not only the semipermeability of the Wakkanai mudstones but also the diffusivity and permeability.

Occurrence of hypersaline groundwater along the coastal aquifers of Kuwait

To understand the process and the source of origin of the hypersaline/brines along the selected locations in Kuwait's, groundwater and sea water samples were collected. The analysis of the samples reveals that a few groundwater samples had Electricity Conductivity higher than that of the seawater. The study was carried out by calculating the ratio of ions to halides such as NO3/Cl, Mg/Cl, Br/Cl, Sr/Cl, Mn/Cl, Li/Cl and V/Cl. The ratios reveal that there were three different types of groundwater: a) groundwater less contaminated with seawater, b) groundwater equally contaminated by seawater and c) groundwater with ionic concentration greater than the seawater. It was inferred that most of the groundwater samples collected near the bay were having higher EC than those that were collected near the open sea. The hypersalinity of the groundwater samples was inferred due to the influence of the effluents of the desalination plants and H2S enriched waters, though there were other processes in operation governed by the pH, anthropogenic sources and infiltration of metal from oil ash near the thermal power plants. The statistical analysis reveals that in certain locations, multiple processes are active to make it more salt enriched.

CO2 Leakage-Induced Contamination in Shallow Potable Aquifer and Associated Health Risk Assessment

Leakage of stored CO2 from a designated deep reservoir could contaminate overlying shallow potable aquifers by dissolution of arsenic-bearing minerals. To elucidate CO2 leakage-induced arsenic contamination, 2D multispecies reactive transport models were developed and CO2 leakage processes were simulated in the shallow groundwater aquifer. Throughout a series of numerical simulations, it was revealed that the movement of leaked CO2 was primarily governed by local flow fields within the shallow potable aquifer. The induced low-pH plume caused dissolution of aquifer minerals and sequentially increased permeabilities of the aquifer; in particular, the most drastic increase in permeability appeared at the rear margin of CO2 plume where two different types of groundwater mixed. The distribution of total arsenic (∑As) plume was similar to the one for the arsenopyrite dissolution. The breakthrough curve of ∑As monitored at the municipal well was utilized to quantify the human health risk. In addition, sensitivity studies were conducted with different sorption rates of arsenic species, CO2 leakage rates, and horizontal permeability in the aquifer. In conclusion, the human health risk was influenced by the shape of ∑As plume, which was, in turn, affected by the characteristics of CO2 plume behavior such as horizontal permeability and CO2 leakage rate.

Influence of leachate composition on the leaching behaviour of concrete

In this work the leaching of heavy metals from concrete in contact with different leachates was investigated to quantify the influence of the leachate composition. Four different types of ground water, two synthetic waters as well as deionised water were selected and tank leaching tests were carried out using the standardised horizontal dynamic surface leaching test (DSLT). Four concrete mixtures with varying binder compositions and water/binder ratios were tested. The results show that the leachability of trace elements and heavy metals strongly depends on the water hardness respectively the calcium concentration and the availability of hydro carbonate in the leachate. The impact of these parameters is presented. It is pointed out, that the use of deionised water delivers overrated element releases and that by the use of ground water as leachate more realistic evaluations of the environmental compatibility of concrete are achievable.

The Fate of Rare Earth Elements and Yttrium in Groundwater and Bedrocks from Sikhote-Alin Ridge, Primorye

A 10-year monitoring period of rare earth element and yttrium (REY) contents and REY pattern shapes was carried in four different types of groundwater (fresh, rich-CO2, low thermal and brackish) from Sikhote Alin ridge. Obtained data reveals that REY concentrations and behavior strongly vary in different chemical groundwater types and depend on many factors, including the pH–Eh parameters, TDS and the composition of the bedrocks. Speciation calculations of REY were carried out using the computer program SELECTOR-Windows with the SPRONGS88 database of thermodynamic parameters.

Landscape‐scale ecohydrological mapping demonstrating how flood inundation water quality types relate to floodplain vegetation communities

AbstractLandscape‐scale ecohydrological mapping is commonly restrained to one‐dimensional ecohydrological transect studies or two‐dimensional vegetation distributions lacking adequate spatial coverage of explanatory hydrological data. The objective of this paper is to construct a two‐dimensional (semi‐3D) landscape‐scale ecohydrological map based on vegetation distribution maps and detailed spatial, multi‐year, floodplain inundation water quality data. The dataset comes from the near‐natural Biebrza floodplain mire in Poland encompassing 658 inundation water quality analyses over the period 2002–2012, covering 17 different vegetation communities of freshwater marshes and rich fens. The data represent the main hydrological gradients from valley edge to river encompassing groundwater seepage, local stagnant precipitation influences and river flooding and drainage. We used chi‐squared Haberman residuals analysis to correlate communities to inundation water quality types, resembling river water and three different types of groundwater. Out of 17 communities, six showed a preference for river water, three showed a preference for clean groundwater, four for diluted groundwater and one for polluted groundwater. For three communities, no significant preference was found. Spatial patterns in vegetation and attributed water quality preference can be linked to three dominant hydrological processes at the landscape scale, i.e. discharge of clean and polluted groundwater near the valley edges, dilution of exfiltrated groundwater with local snowmelt and precipitation water and flooding with river water along the river. The ecohydrological relations are depicted in two‐dimensional maps and a semi‐3D diagram with typical cross sections. Copyright © 2016 John Wiley & Sons, Ltd.

The groundwater-dwelling fauna of Southeast Asia

Groundwater fauna consists of organisms that are adapted to live their whole life-time in different types of groundwater (=aquifers): with fissured (karstic) and porous (alluvium) types as the most common. About 3800 species of obligate groundwater species (stygobionts) have been recorded worldwide and 2000 of them from groundwater in Europe. Before 1970, 19 species of stygobionts were known from Southeast Asia. After 1980, the number of stygobionts from this region started to increase, and, at present, 122 stygobionts are known here. Most of them are crustaceans, with the Copepoda, Isopoda, Amphipoda and Decapoda as the most abundant groups. Intensification of research on groundwater fauna can considerably increase the total number of stygobionts known from the region, which could rises up to several times the current tally if the intensity of research was comparable with that in Europe.

Lead isotopes in groundwater as an indicator of water–rock interaction (Masheshwaram catchment, Andhra Pradesh, India)

This study reports on the lead geochemistry and Pb-isotope ratios of ground waters along a small (53 km 2) endoreic granitic catchment in India (Masheshwaram, Andhra Pradesh). The main focus is on granitic parent rock composition, water chemistry and isotope tracing, through the determination of lead isotopes in water by Multi-Collector ICP-MS using an improved new procedure. This method is efficient to give reliable Pb-isotope ratios with uncertainties (i.e. lower than 0.3% on each 206Pb, 207Pb, 208Pb ratios normalized to 204Pb) low enough to allow the different types of groundwater to be discriminated. Lead concentrations span over one or two orders of magnitude up to approximately 20 µg L − 1 . Pb isotopes fluctuate largely as exemplified by the 206Pb/ 204Pb ratio, ranging from 17.01 up to 25.35. Most of the lead in the ground waters is of geogenic origin, and through the lead isotopic signature in groundwater, we have traced and fingerprinted the processes of water–rock interaction considering the granite matrix. Combining a weathering model and field observations, we were able to define a two step weathering process that includes a control on the Pb-isotope ratios by accessory phases and by the main mineral from the granite in a second step of weathering.

Multivariate statistical analysis of geochemical data of groundwater in Veeranam catchment area, Tamil Nadu

The study of hydrogeochemistry of the Mio-Pliocene sedimentary rock aquifer system in Veeranam catchment area produced a large geochemical dataset. Groundwater samples were collected at 52 sites over 963.86 km2 area and analyzed for major ions. The large number of data can lead to difficulties in the integration, interpretation and representation of the results. Two multivariate statistical methods, Hierarchical cluster analysis (HCA) and Factor analysis (FA), were applied to a subgroup of the dataset to evaluate their usefulness to classify the groundwater samples, and to identify geochemical processes controlling groundwater geochemistry. Hydrochemical data for 52 groundwater samples were subjected to Q- and R- mode factor and cluster analysis. R-mode analysis reveals the inter-relations among the variables studied and the Q-mode analysis reveals the inter-relations among the samples studied. The R-mode factor analysis shows that Ca, Mg and Cl with HCO3 account for most of the electrical conductivity, total dissolved solids and total hardness of groundwater. The ‘single dominance’ nature of the majority of the factors in the R-mode analysis indicates non-mixing or partial mixing of different types of groundwater. Both Q-mode factor and Q-mode cluster analyses indicate an exchange between the river water and the groundwater in the vicinity. The rock water interaction like flood basin back swamp deposits of silty clayey formation is the major cause for the cluster II classification. Cluster classification map reveals that 58% of the study area comes under cluster II classification.

Iron oxidation in different types of groundwater of Western Siberia

The groundwaters of Western Siberia contain high concentrations of iron, manganese, silicon, ammonium, and, in several cases, hydrogen sulfide, carbonic acids, and dissolved organic substances. Generally, the groundwaters of Western Siberia can be divided into two major types: one type with a relatively low concentration of humic substances and high hardness (water of A type) and a second type with a relatively low hardness and high concentration of humic substances (water of B type). For drinking water production, the waters of A type are mostly treated in the classical way by aeration followed by sand bed filtration. The waters of B type often show problems when treated for iron removal. A part of iron practically does not form the flocs or particles suitable for filtration or sedimentation. The aim of this work was to determine the oxidizability of Fe(II), to characterize the iron colloids, and to investigate the complexation of the iron ions with humic substances and the coagulation of the iron colloids in the presence of dissolved organic matter. Water samples of the A and B types were taken from bore holes in Western Siberia (A type: in Tomsk and Tomsk region, B type: in Beliy Yar and Kargasok). Depth of sampling was about 200 m below surface. The oxidation of the groundwater samples by air oxygen and ozone was done in a bubble reactor consisting of a glass cylinder with a gas-inlet tube. To produce ozone, a compact ozone generator developed by Tomsk Polytechnic University was used. For the characterization of the colloids in the water of B type, the particle size distribution and the zeta potential were measured. To investigate the formation of complexes between iron and humic substances in the water of B type, size exclusion chromatography was used. The coagulation behavior of iron in the presence of dissolved organic substances was investigated at different pH values. The agglomerates were detected by measuring the optical density using a UV-Vis spectrometer. Ozone showed, as expected, a faster oxidation of Fe(II) than air oxygen. The rate constants for Fe(II) oxidation were not much different for the waters of A and B types when the same oxidation process was used. However, the removal of iron after oxidation and filtration was higher in the water of A type than in the water of B type. No evidence for the formation of soluble complexes between iron and humic substances were found. In the water of A type, the coagulation process started at pH = 4.5 and accelerated with increasing pH value. In the water of B type, the coagulation of colloids occurred only at pH = 11 and higher. The oxidation experiments indicated no major effect of dissolved organic carbon concentration on the kinetics of Fe(II) oxidation. In contrast to this, the humic substances showed a significant influence on the aggregation behavior of the iron hydroxide colloids. Due to the sorption of humic substances on the iron hydroxide colloids, they were highly stable in the pH range between 4.5 and 10. The particle size measurements confirmed the presence of small colloids in the water of B type. In contrast to this, the iron hydroxide colloids aggregated rapidly at pH = 11. The results showed a great influence of humic substances on the iron removal from groundwaters of Western Siberia with high organic content. The sorption of humic substances on the iron colloids does not obviously allow their coagulation and formation of flocs suitable for filtration or sedimentation. By treatment of groundwaters containing high amounts of humic substances, some problems with the removal of iron are likely to occur. To increase the effectiveness of iron removal, the surface coating and pH-dependent charge effects should be taken into account by the selection and optimization of water treatment processes. The iron colloids coated by humic substances should be separated from the water phase by membrane filtration or by flocculation followed by filtration through different solid materials.

Groundwater investigation in Kuala Selangor using vertical electrical sounding (VES) surveys

Integrated geoelectrical and hydrochemical surveys were used to investigate and delineate different types of groundwater in the Kuala Selangor alluvial aquifer. Previous hydrogeological borehole investigation showed that this aquifer contains several types of groundwater in relation to its salinity. The high salinity of the groundwater in some areas is believed to be due to either saltwater intrusion from the nearby sea or river infiltration during high tide season. The vertical electrical sounding (VES) method was employed to study and map the subsurface variation of resistivity in the area. For each sounding measurement, a total spread length of 300 m was obtained with a vertical depth penetration of about 60 to 75 m. Chemical analysis of the groundwater samples taken from both shallow and deep boreholes was carried out for the water quality determination. A total of 45 VES stations were succesfully established along three parallel roads with a direction almost perpendicular to the coastal line. The distance between stations varies from 1 to 2 km with a maximum length of about 60 km surveyed line. Results of the vertical electrical soundings as well as the hydrochemistry of the groundwater samples show that the soil and groundwater in the study area can be grouped into fresh and brackish water zones. The subsurface resisitivity sections derived from the VES study suggest that the area is dominated by brackish soil and groundwater zones, especially in the area towards the coast. This result appears to agree well with the groundwater pumped from boreholes scattered around in the area. Water drawn from boreholes near the coast showed higher salinity compared to the water pumped from inland boreholes. Chloride values greater than 250 mg/L are considered to represent the brackish zones whilst values less than 250 mg/L represents zones of fresh soil and groundwater.

The utility of multivariate statistical techniques in hydrogeochemical studies: an example from Karnataka, India

Quality of groundwater is controlled by many factors amongst which the interaction of river water with adjacent groundwater and mixing/non-mixing of different types of groundwater may be important. An attempt has been made to study these processes using multivariate statistical techniques such as factor and cluster analyses. The Nethravathi catchment (India) which is a tropical river basin draining the Precambrian crystalline province of peninsular India, has been selected for this study. Hydrogeochemical data for 56 groundwater samples were subjected to Q- and R- mode factor and cluster analysis. R-mode analysis reveals the inter-relations among the variables studied and the Q-mode analysis reveals the inter-relations among the samples studied. The R-mode factor analysis shows that Na and CI with HCO 3 account for most of the electrical conductivity and total dissolved solids of the groundwater. The ‘single dominance’ nature of the majority of the factors in the R-mode analysis indicates non-mixing or partial mixing of different types of groundwater. Both Q-mode factor and Q-mode cluster analyses shows that there is an exchange between the river water and the adjacent groundwater.