Hydrogeochemical variability and appraisal of water quality of groundwater in Mahoba district, Uttar Pradesh, India

Mahoba district comes under the state of Uttar Pradesh (U.P.), India which is a part of mighty Bundelkhand Granitic Terrain known for its water debt condition. The region is hard rock terrain having recent alluvium cover of variable thickness relating to slope and level of erosion. Secondary porosity i.e. in the fractures and cracks present hosts the groundwater in the study area. The high-water scarcity and poor drinking quality led us to carry out our research work in the study area. The water facies analysed shows Ca–Mg–HCO3 and Na–HCO3 water types which indicated their compositional source from rock and anthropogenic inputs. Majority of the samples showed the dominance of alkaline earths over alkalies and weak acids over stronger counterparts. The correlation coefficients calculated between hydrochemical parameters projects a strong positive correlation of EC and TDS with most of the major ions, including SO42−, NO3−. The hierarchical cluster analysis of all samples was classified into five clusters (C1A, C1B, C2A, C2B1 and C2B2). The sites of cluster C1 water samples were found located closer to drainage streams than C2 cluster water samples. The excessive fertilizers, unplanned municipal wastes and agricultural wastes resulted in high SO42− and NO3−. High F− showed concentration in various samples may have geogenic sources due to flour-apatite in granitic terrain and Fe found in excess gives an unpleasant taste on drinking. The analysed irrigation parameters (%Na, MR, TDS, RSC, SAR, TH, and KI) revealed perfect under permissible quality. Various negative human health issues like indigestion, bone problems, alimentary canal problems have been seen due to excess of SO42−, NO3− and F−). The study reflects the need for immediate preventive measures to improve drinking quality from health alarming ion concentrations and also would help for further management programs.


Introduction
It is a common fact that groundwater is a freshwater source which can be consumed readily and directly without processing. Globally, the increasing harsh effects of multi-contamination in drinking water became an alarming condition and above 300 million of the world's population are suffering consequences of fluoride contamination Singh et al. 2021). In different parts of China, the level of groundwater is sharply decreasing as can be related to India in terms of high population Chen et al. 2020). Various studies done globally include groundwater pollutants in the majority as an excess of inorganic salts, toxic heavy metals, cations (sodium, calcium, potassium and magnesium), and anions (chloride, bicarbonate, carbonate, fluoride, nitrate and sulphate) . Therefore, major studies in the quality of groundwater have become a trend along with health evaluation in countries like the USA, India, China, etc. In India, the daily consumption of water for various purposes of human and associated necessities is ever increasing (CGWB 1995(CGWB , 1997(CGWB , 2006(CGWB , 2008(CGWB , 2009(CGWB , 2013(CGWB , 2014ab). The country faces high depletion of groundwater as noticed by Niti Ayog in 2018 in its composite water management index (CWMI) report where they predicted the probable depletion of groundwater in various wells upto 54% by 2020 in major 21 metropolitan cities. The indiscriminate development in consumption of groundwater reflects a worse effect of groundwater decline especially in the case of hard rock terrains in respect to alluvial plains.

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A long term decline in groundwater has been observed in various states including Rajasthan, Gujarat, Haryana, Punjab, Tamil Nadu, Parts of U.P. and M.P. especially in the Bundelkhand region (Gupta et al. 2014;Krishnamurthy et al. 1996;Krishna Kumar et al. 2012;Shankar and Mohan 2006;Abhay et al. 2012;Paul et al. 2020). The groundwater usage among people increased many folds and unmannered huge consumption of groundwater lead to over exploitation of groundwater, aquifer depletion and increase of groundwater pollution (Raju et al. 1994;Chowdhury et al. 2009Chowdhury et al. , 2010Pradhan 2009;Pratap et al 2000;World Bank Deep Wells and Prudence 2010;World Bank Report India Groundwater 2012;Paul et al. 2020). The high dependence on groundwater for irrigation purposes has also resulted in high depletion in terms of quality and quantity (Mohanthy and Behera 2010;Shahid and Nath 1999;Shahid et al. 2000;Ibrahim-Bathis and Ahmed 2014).
India hosts various types of groundwater and surface water pollutions of different elements. Some pollution is geogenic and rest are anthropogenic pollution. The presence of arsenic, fluoride, iron, chromite, chloride, etc. are a few important elements which are useful as constituents of water in different use up to a limit but their excessive presence (above permissible limit) causes harmful effects combinedly known as pollution. The endemic water problem of fluorosis (Choubisa 2001;Susheela et al. 1993;Susheela 1999;Teotia and Teotia 1984;Rao and Devadas 2003;Sreedevi et al. 2006;Raju et al. 2009) has been found in many parts. The Bundelkhand region along with water depletion faces multi-contamination in drinking water (Pant et al. 2021). The aquifers in Bundelkhand region are mostly unconfined and shallow in nature whereas the major population residing are below the poverty line which makes them totally dependent on the water present in surface or sub-surface (CGWB 2017).
The quality and quantity of groundwater in hard rock terrains are threatening and, in this context, authors have selected a neglected area, Mahoba district, with little previous published work but facing huge issues of groundwater which is a part of Bundelkhand region. Mahoba suffers an acute shortage of groundwater and excess of SO 4 2− , NO 3 − and F − in quality parameters along with high water hardness making drinking water tougher to sustain.

Study area
The district Mahoba, covering 2884 km 2 , is situated in the southwestern part of Uttar Pradesh lying between 25° 01′ 30″ and 25° 39′ 40″ North latitude and 79° 15′ 00″ and 80° 10′ 30″ East longitude. The district is bordered by four districts of two states. In Uttar Pradesh district Hamirpur at the north, district Jhansi at the west, district Banda at east and only district Chhatarpur at the south of Madhya Pradesh.
Agriculture is a major occupation of the study area. Wheat can be seen as a staple food of the district which requires intensive water irrigation for proper cultivation which is however not fulfilled throughout the year. The Kharif crops are paddy, jowar, maize, pulses (tur, moong, urad, etc.) and Rabi crops are wheat, gram, barley and mustard. The region receives an average annual rainfall of 790 mm where 87% of it during the middle of June to September from south-west monsoon. May receives shooting temperature upto 49 °C being the hottest month and January is the coldest month receiving a temperature of about 4 °C.

Geology and hydrogeology
Mahoba is an integral part of Bundelkhand region mostly comprising of Bundelkhand Gneissic Complex (BGC) and Alluvium of Archaean Age and Recent Age respectively (Fig. 1). The alluvium thickness is highly variable ranging from 7 to 38 m having an average value of 10 m so the cover is very less to hold water as a groundwater reservoir. BGC consists mostly of non-foliated granitic rocks of older age (2500-26-Ma) with the intermittent presence of ultramafics, gneiss as enclaves, calc-silicates, proper banded magnetite (Basu 1986). In some regions presence of elongated quartz reefs, tuffaceous serpentines, basic dykes have been noted. The dolerite dykes of various lengths are characterised by dark greyish colour and moderate grains found intruding granite and quartz reefs. Along with felsites, porphyry dykes were also reported (Basu 1986). The region has quartz and plagioclase feldspar as leucocratic minerals and ferromagesium minerals as hornblende, chlorite, pyroxene and olivine forming the major mineral assemblages whereas muscovite, apatite, zircon, magnetite and sphene as minor minerals (Mishra and Sharma 1975).
Physiographically the total area is divided into two parts as hillocks with high relief constitute the southern portion whereas the northern portion is showing low altitude hillocks with low relief. The major rivers present in the district are Arjun, Birma, Dhasan and Urmil which are the district's natural drainage system. The well discharge has been found varying from 5 to 30 L/s (lps) and water level recorded between 1 and 3 m bgl of shallow aquifers in patches present the district (CGWB 2017). The deep tube wells give yield up to 150 m bgl showing 15-100 lpm at normal drawdown in the fractured granitic regions. The transmissivity observed to vary from 10 to 150 m 2 /day (CGWB 2017). The net groundwater recharge was reported around 37,000 hectare meters and net groundwater draft around 30,000 hectare metres for the year 2016 showing higher stage of groundwater development of about 85%. The surface drainage systems are groundwater fed so during summers they almost get dried. Wide seasonal rainfall fluctuations result in poor infiltration and poor water content availability in the perennial and seasonal rivers. In a major part of the district, groundwater serves as a drinking water source. Waterborne disease and unhygienic sanitation practices are some common problems among villagers. The improper solid and liquid waste management leads to contamination of nearby surface water and shallow groundwater.

Methodology
The study area was divided into 60 grids for sampling purpose and some modifications were made during sampling in the field based on population and water availability. One litre and 100 mL of each sample were collected from handpumps and tube wells according to availability in 60 pre-washed thick polyethylene bottles. The 100 mL of each 60 samples collected were treated with ultra-pure nitric acid to analyze heavy metals in the laboratory. The pH and electrical conductivity (EC) were analysed in the field using a movable hand handling (portable) conductivity and pH meter (Consort C831).
The samples in the laboratory were filtered using 0.20 µm Millipore membrane syringe filters and the major cations (Ca 2+ , K + , Mg 2+ , Na + ) and anions (NO 3 − , F − , Cl − , SO 4 2− ) were analysed in Ion Chromatograph (model: Dual channel 930 Compact IC Flex ChS/PP). The bicarbonate (HCO 3 − ) and carbonate (CO 3 2− ) were detected using the acid titration method (APHA 1998). The heavy metal analysis was done by ICP-MS (model: iCAP6200 Duo). Instruments were calibrated, prior to analysis, with diverse standard solutions and the results were crosschecked using ion balance error equation which was within ± 5%. The chemicals used during analysis and preservation were of the standard grade analytical reagent (Merck/BDH). In Ion Chromatograph, NIST-certified standards were utilized for calibration purpose.
The Hierarchical cluster analysis (HCA) has been incorporated to have proper correlation among the samples to understand the factors (geogenic or anthropogenic) controlling the groundwater hydro-geochemistry. In HCA, squared Euclidean distance (Ward 1963) used to understand the multivariate dissimilarities or similarities in the data sets which was done using the variance approach (ANOVA) to understand the clusters in Ward's method (Sajil Kumar 2020). Piper's plot and Gibb's plot were done to interpret the hydro-geochemical behaviour of the groundwater. The groundwater suitability for drinking purposes has been assessed using (Table 6) drinking water quality standards (BIS 2012;WHO 2017). The groundwater for irrigation purpose suitability has been analysed using proper indices (Table 8) and diagrams in the United States Salinity Laboratory (Wilcox 1955).

Results
The various physical and chemical data have been analysed for 60 groundwater samples of the Mahoba district. Major ions in milligram per litre (Table 2) were used to calculate chloroalkaline indices (CAI) (Table 5), sodium adsorption ratio (SAR), % Na, residual sodium carbonate (RSC), Kelly index (KI), magnesium ratio (MR) and total hardness (TH) ( Table 7). Minor elements or trace metals in µg/L (Table 3) element have been analysed. The ionic dominance has been shown by Scholler's plot (Fig. 7l).

Hierarchical cluster analysis (HCA)
HCA has been done to understand the hydro-geochemical behaviour of the water samples. This was done using Ward's method (Ward 1963) (Teng et al. 2018;Kumar 2018) (Table 1). The phenon line was drawn across the dendrogram at a linkage distance of 10 which resulted in five clusters (Fig. 2) reflecting the most satisfactory results for understanding hydro-geochemical behaviour. Two major cluster groups C 1 (29 samples) and C 2 (31 samples) classified were further sub-divided as C 1 A (14 samples), C 1 B (15 samples), C 2 A (7 samples), C 2 B 1 (17 samples) and C 2 B 2 (7 samples).

Physical parameter
The pH value ranges from 6.74 to 8.89 (7.69 as average) which suggests the acidic to alkaline nature of the groundwater samples. The electrical conductance (EC) is the measure of salt concentrations of water and it also gives indications of the presence of ionic concentration. The EC value of the samples ranges from 628 to 1247 µS/cm (908.30 µS/cm as average) at 25 °C. EC values of C 1 cluster of the HCA were found to have higher values (average of 1000 µS/cm) than C 2 cluster (average of 800 µS/cm). The total dissolved solid (TDS) in the water samples of the study area varies from 415 to 802 mg/L (597.98 mg/L as average). According to Freeze and Cherry (1979) water has been classified into fresh (TDS ≤ 1000 mg/L), brackish (TDS ≥ 1000 mg/L), saline (TDS ≥ 10,000 mg/ L) and brine (TDS ≥ 100,000 mg/L) based on the total dissolved solids. According to the TDS values, 100% of samples belong to freshwater type. Excessive hardness causes cardio-vascular disorder, urolithiasis, parental mortality (Durvey et al. 1991;Agrawal and Jagetia 1997) (Table 2).

Chemical parameters
Cations The cation chemistry shows Na + and Ca 2+ form the major cationic concentration of the groundwater in The alkaline earth (Ca 2+ + Mg 2+ ) account for 57% and it dominates over alkaline (Na + + K + ) of the groundwater. At many places, Mg 2+ value exceeds Ca 2+ concentration owes to the fact that the supply of ions is from the weathering of ferromagnesian minerals having an association with basic and ultrabasic/mafic rocks. Concentration of Na + is 37.476 to 97.77 mg/L (70.60 mg/L as average) whereas concentration of K + is 0.042-2.768 mg/L (1.23 mg/L as average) and, Na + and K + together contribute 41% of total cationic charge balance.
Anions In general concentration of Cl − is less in any common rock type compared to other constituents of ions in natural water. Higher concentration of Cl − resembles either lithological source examples from halite and evaporates weathering and atmospheric source or from seawater. The Cl − concentration varies from 19.712 to 215.024 mg/L (95.19 mg/L as average). The study area is situated far away from the coastal region thus a Na + / Cl − higher concentration ratio shows a non-lithogenic and non-atmospheric source of chloride (Jalali 2007;Singh et al. 2011). At some places, a higher concentration of Cl − suggests local contaminations due to agricultural runoff, domestic, anthropogenic or animal waste. The measured concentration of HCO 3 − in the study area varies from 97-386 mg/L (218.71 mg/L as average).
Nitrate being an important pollutant in the atmosphere is mostly contributed to groundwater from atmospheric precipitation, human faunal excreta, and biological fixation of nitrogen, nitrification process of N and NH 4 and agricultural fertilizer (Appelo and Postma 1999). The nitrate concentration has ranging values from 1.134-98.094 mg/L (36.97 mg/L as average) so the enhancement of NO 3 − in the groundwater are mostly due to anthropogenic activities, and uses of fertilizer (e.g., urea (NH 2 ) 2 CO, ammonium nitrate (NH 4 NO 3 ), superphosphate and livestock manure) proving to be the important source of contamination and its excess causes methaemoglobinaemia, cancer, etc.
The sulphate concentration varies from 10.002 to 131.034 mg/L (59.60 mg/L as average) showing a higher value than the normal concentration at some locations is a strong indication of agricultural activities and anthropogenic factors (Berner and Berner 1987). The correlation matrix showed strong positive correlations between SO 4 − , NO 3 − , Cl − indicating the anthropogenic source of contamination (Alemayehu et al. 2010;Demlie et al. 2007).
The fluoride concentration in the study area varies from 0.09 to 2.573 mg/L (0.98 mg/L as average) where in many locations concentration exceeds the desirable limits of drinking water is due to the geogenic source i.e., from muscovite, biotite, fluorite, flouro-apatite, etc. The weathering of apatite, biotite, sphene contributes F − ions in groundwater found   as accessory minerals in granites and granitic gneisses of the area (Mishra and Sharma 1975;Chen et al. 2016Chen et al. , 2017. The general trend of anionic abundance has been found HCO 3 − > Cl − > SO 4 2− > NO 3 − > CO 3 2− > F − . The presence of HCO 3 − and SO 4 2− in the groundwater and, moreover, in higher value signifies two major reactions for their contribution. The two major reactions are carbonation and sulphide oxidation that are the cause of two proton producers which can be shown on the basis of HCO 3 − /(HCO 3 − + SO 4 2− ) equivalent ratio called C ratio (Brown et al. 1996;Singh 2002). The C value 1 shows carbonic acid weathering and acid hydrolysis having atmospheric proton source whereas 0.5 value shows coupled reaction involving weathering of carbonates by proton derived from sulphide oxidation. The formation of HCO 3 − and SO 4 2− also suggests a continuous process having fluctuation Eh-pH conditions and resulting to relative concentration (Table 3).
Trace elements Trace metals are very important to understand specially the quality aspect of drinking water of any area. Mahoba groundwater has been analysed and are discussed below (Table 2): Iron Aquifer naturally contains iron but the levels of iron increased in groundwater because of dissolution of ferrous component of the borehole. The iron contains groundwater generally looks orange or light red and has an unpleasant smell. Iron occurs in two forms ferrous and ferric in water. According to WHO, iron is recommended ≤ 0.3 mg/L for drinking purpose or 300 µg/L as desirable whereas 1000 µg/L as a permissible limit. The Fe concentrations ranged from 86 to 1082 µg/L (average 400.39 µg/L) showing 58.33% of the total samples exceeding the desirable limit. The region is dominated by agricultural practice, stone mining and stone crushing having no such industrial practice so the higher Fe content in the groundwater resembles geogenic origin i.e., rock-water interaction. This shares the highest trace element concentration among all other trace elements tested (Fig. 3).
Copper Copper play a very important role in animal and plant metabolism. In earth, crust occur as a free native metal, Cu 0 or, as Cu + or Cu 2+ in minerals. In solution it occurs as either Cu + or Cu 2+ oxidation states and Cu + ions have tendency to break into more oxidize form (Cu + = Cu 0 + Cu 2+ ). Modern industrialization uses copper extensively, which results in its dispersal in the environment. Sometime, to suppress the growth of algae small amount of copper salt is added to water supply reservoirs. In agriculture, many organic and inorganic form of copper is used as pesticide sprays. It has been found that copper deficiency is linked with anaemia, diarrhoea, demineralization of bone, etc. Lead The free ion Pb 2+ , hydroxide complexes and probably the sulphate and carbonate ions pairs are dissolved inorganic forms of lead. Due to the large amount used in automobiles, it is widely dispersed in the environment. In the study, it ranges from 0.04 to 9.86 µg/L. Its increased quantity is poisonous and may cause nervous, heart, skin, gastrointestinal and respiratory disorder.
Aluminium Aluminium occurs as Al 3+ under acidic conditions and as Al(OH) 4 − under neutral to alkali conditions. Other forms of aluminium include AlOH 2 + and Al(OH) 3 . The dissolved form of aluminium Al 3+ affect the roots and decrease their phosphate intake, it is also toxic to plants. Aluminium has a negative effect on terrestrial and aquatic life in a different life. The solubility of aluminium from the soil is increasing in acidic condition. So, the aluminium concentration in river and lakes rises during the minimal rainy season because of acid rain.
The other measured toxic metals like As, Se, Cd, Cr, Cu were found well within the specified limit of Indian drinking standards (BIS 2012). The national (BIS 2012) and international (WHO 2017) standards for drinking water have been used to understand the drinking water conditions i.e., are under permissible limits or not. The drinking water part has been discussed below in the water quality part.

Hydro-geochemistry and hydro-geochemical facies
The proper relationship between the dissolved ions helping to understand the geochemical evolution of groundwater can be done by Piper (2007) trilinear diagram plots. There are three diamond-shaped fields where the central one indicates the combination of anions and cations concentrations together whereas the other two diamond-shaped fields at right and left indicate the concentration of cations and anions separately showing their intra-dominance. The central diamond field plot has been categorised into different numbers based on their classification. The plot values reveal the dominance of area number 1, 3, 5 and 8 (Fig. 4) i.e., most of the plot falls in these numbered areas. The plots indicate the dominance of alkaline earth (Ca 2+ and Mg 2+ ) over alkalies (Na + and K + ) and weak acids (HCO 3 − ) over strong acids (SO 4 2− , Cl − ). Although the central plot classification shows the majority of points in 5 number area indicates secondary alkalinity and carbonate hardness. Lesser samples fall under 8 area showing primary alkalinity and carbonate alkali water.
The trilinear diagram mostly suggests the groundwater of the area consists of alkaline earths and weak acidic chemistry having Ca-HCO 3, Ca-Mg-HCO 3 and Na-HCO 3 as dominant facies in hydrochemical analysis. The major Fig. 4 Piper's trilinear diagram dominance of Ca-Mg-HCO 3 and Ca-Na-HCO 3 type water mainly indicates the water-rock relationship where the dissolution of plagioclase-feldspar, ferromagnesian minerals and carbonates takes place of country rock by the recharging water (that may bear other reactive ions) to groundwater from different sources i.e. from irrigation, rainfall, or other surface inputs. This reaction process of cation exchange may have given the Ca-Na-HCO 3 water type.

Water rock interaction and solute acquisition process
The groundwater chemistry depends on various factors that may be having different sources of types-geogenic, anthropogenic, natural borne, etc.
Rainwater, geological setting, country rock's mineral composition and other anthropogenic sources are responsible for water chemical composition (Datta and Tyagi 1996;Andre et al. 2005;Singh et al. 2007).
The important and higher contribution of (Ca 2+ + Mg 2+ ) to the total cations, relatively high (Na + + K + )/TZ + ratio (0.35) and low equivalent ratio of (Ca 2+ + Mg 2+ )/(Na + + K + ) i.e. 2.29 suggest that the chemical composition of the water controlled mostly by silicate weathering along with limited carbonate weathering.
The level of atmospheric inputs to the dissolved salts present in the water can be understood by assessment of local rainwater chemical composition or by the ions/element's ratio to Cl − (Sarin et al. 1989;Singh et al. 2005;Zhang et al. 1995). The average ratios of Na + /Cl − and K + /Cl − for subsurface water in the study area (Na + /Cl − = ̴ 6.34 and K + / Cl − = ̴ 0.04) was found to be more than marine aerosol (Na + / Cl − = 0.85 and K + /Cl − = 0.0176) suggesting limited contribution of these ions from the atmosphere and mostly from hosting rock i.e., weathering of the hosting minerals forming rock.
In the Gibbs diagram (Gibbs 1970) plot (Fig. 5) showing ratio between (Na + + K + )/ (Na + + K + + Ca 2+ ) and (Cl − + NO 3 − )/(Cl − + NO 3 − + HCO 3 − ) as a function of TDS describes the plots under rock dominance region indicative of the ionic source from weathering of rock rather than atmospheric and anthropogenic sources (Hounslow 1995;Rose 2002). The major lithogenic sources of ions in groundwater are weathering of carbonate, silicate and sulphide minerals, and also the dissolution of evaporates. The plot between (Ca 2+ + Mg 2+ ) versus (HCO 3 − + SO 4 2− ) (Fig. 6a) has most of its samples falling at and nearest to 1:1 line showing the dissolution of calcite, dolomite and gypsum acting crucial reactants (Cerling et al. 1989;Fisher and Mullican 1997). The part of the samples of the study area falls below the equiline plotted between (Ca 2+ + Mg 2+ ) and (HCO 3 − + SO 4 2− ) suggests a significant contribution from various non-carbonate sources and the excess HCO 3 − /SO 4 2− would be balanced by alkalies (Na + + K + ). Similarly, the samples falling above equiline show more cations that would be balanced out by Cl − or other anions in the system. According to stoichiometric balance of carbonate derived from (Ca 2+ + Mg 2+ ) must be more or less equal to (HCO 3 − ) derived carbonates. The chemical plot between (Ca 2+ + Mg 2+ ) and HCO 3 − (Fig. 6e) shows most plots have more HCO 3 − value than (Ca 2+ + Mg 2+ ), so this cation deficiency should be balanced by alkalies (Na + + K + ) to balance excess negative charge of HCO 3 − and this alkali ions (Na + + K + ) are mostly derived from silicate weathering. Samples having excess (Ca 2+ + Mg 2+ ) in comparison to  (Fig. 6c) major contribution of Ca 2+ and Mg 2+ in the total cation count which further cleared by (Ca 2+ + Mg 2+ ) versus (Na + + K + ) (Fig. 6d) plot. Na + and K + together constitute 36% of total cations which shows a significant amount shown by plot between (Na + + K + ) and total cations (Fig. 6b) having their sources from atmosphere or weathering of alkaline silicates richer in K + and Na + . The plot between (Na + + K + ) versus Cl − shows average samples are dominating in Na + and K + with respect to Cl − (Fig. 6f) suggesting the origin of alkalies from various sources other than precipitation process and sources may be from weathering of silicates enriched with Na + and K + which can be understood by reaction mentioned below. The chemical composition of the solution (water) mostly controlled by weathering of silicates and a few by carbonate weathering. According to Gaillardet et al. (1999) lithology having carbonate dominance shows higher ratios of Ca 2+ /Na + (around 50), Mg 2+ /Na + (around 10), HCO 3 − /Na + (around 120) and same values abruptly decreases in case of silicates end member as Ca 2+ /Na + = 1.26 ± 0.95, Mg 2+ /Na + = 0.81 ± 0.52 and HCO 3 − /Na + = 0.6 ± 0.5 in the study area. The ratio of Ca 2+ / Na + in molar terms is around 1.26 showing more solubility of Na + with respect to Ca 2+ results to lower (Ca 2+ /Na + ) molar ratio in the dissolved ions of water drained silicate terrain compared to carbonate terrain (Taylor and MacLennan 1985). Thus, the expected chemical reaction responsible for silicate weathering for source of various solutes under presence of carbonic acid ( Chloro-alkaline indices It describes the exchange of ions under a suitable environment between groundwater and the host rock/ soil while residue or movement of water in host medium. It is understood by the base exchange reaction (Schoeller 1967(Schoeller , 1977. The water-rich in salt experiences positive CAI whereas low saltwater suffers negative CAI value. During the exchange, reaction host plays the primary source for the dissolved salts in water. If CAI (I and II) values are positive then an exchange of Na + and K + (from water) and Ca 2+ and Mg 2+ (from soil or rock), and if negative then an exchange of Ca 2+ and Mg 2+ (from water) and Na + and K + (from soil or rock) takes place. The positive is termed as base exchange reaction and the negative is termed as disequilibrium (Table 5).
Base exchange types-if HCO 3 − < (Ca 2+ and Mg 2+ ) then Na + ion is exchanged for alkaline earths, and is referred as base exchange hardened water. If HCO 3 − > (Ca 2+ and Mg 2+ ) then alkaline earths were exchanged for Na + ion, and is referred as base exchange softened water. Alkali metals/ ions as Na + and K + , and alkaline earth metal/ ion as Mg 2+ and Ca 2+ are involved.

Water quality assessment
The data acquired from different laboratory analysis were calculated for their efficiency in drinking and irrigation purposes.

For drinking purpose
The quality assessment was done by various previous leading authors (Szabolcs and Darab 1964;Davis and De Wiest 1966;Back 1966;Sawyer and McCarty 1967;Schoeller 1977;Todd 1980;Todd and Mays 2013;Dhang et al. 1984;2KMg 3 Table 4 Correlation coefficient matrix of physicochemical parameters of groundwater (all the parameters are in mg/L except EC, pH)   Ayers and Westcot 1985;Stuyfzand 1989;Gogai et al. 1991;Eawari and Ramanibai 2000;Raju 2006) which were considered as reference purpose for the present study and the present study parameters were strictly classified under standards prescribed by World Health Organisation (WHO 2017) and Bureau of Indian Standards (BIS 2012). The pH condition of the samples examined is well under the drinking range (around 6-8.5). Among all the ions, variable concentrations mentioned in concentration distribution maps (Fig. 7a-k), some have been found exceeding their permissible and desirable limits (Ca 2+ , Mg 2+ , Na + , NO 3 − , Cl − , F − ) in various samples (Table 6). NO 3 − and F − have been detected exceeding permissible limits in significant spatial distribution and have been reported first time in the study area by the authors.
Most of the metal concentrations found to be within desirable limits as specified by the World Health Organisation (WHO 2017) and Indian drinking standards (BIS 2012). There are some exceptions which crossed the desirable and permissible limits. The Fe concentrations ranged from 86 to 1082 µg/L (average 400.39 µg/L) showing an exceeding desirable limit.

For irrigation purpose
Water quality in combination with associated soil types is very much linked with different cropping practices which can be understood as different parameters governing the suitability of water for irrigation.
Percent sodium (%Na)-it is a parameter used to understand the water quality suitable for irrigation purpose. %Na = Na + + K + ∕ Ca 2+ + Mg 2+ + Na + + K + × 100 The Wilcox diagram shows status of the sample based on percent sodium with respect to total concentration (meq/L) either suitable or permissible or doubtful or unsuitable (Fig. 8).
Kelley index is a ratio showing suitability of water for irrigation purpose (Kelley 1946). If the ratio is more than one (> 1) then the water quality is unsuitable for irrigation which is due to the fact that excess Na content leads to a reduction of soil fertility (Table 7).
Higher total hardness and salt concentration in water lead to an increase in salinity in the soil whereas high Na concentration makes a soil more alkaline. The increase in sodium or amount of sodium or alkali in terms of hazard can be expressed as SAR (sodium adsorption ratio), magnesium hazard expressed as magnesium ratio (Szabolcs and Darab 1964;Schoeller 1977) and total hardness calculated based on the concentration of Ca and Mg which are calculated as:

Discussion
In groundwater chemistry the total hardness calculated was very well under the freshwater category. In major ion chemistry Ca 2+ is the dominant one in cations and HCO 3 − is dominant in anions so the major facies is Ca-HCO 3 but TH (mgCaCO 3 ∕L) = (2.5 × Ca) + (4.1 × Mg). other ions in abundant in the water forms Na-HCO 3 , Ca-Mg-HCO 3 , Na-Mg-HCO 3 , Ca-Cl types. The HCA revealed the majority of the C 2 cluster samples have higher F − concentration exceeding the permissible limit but major samples of C 1 cluster have F − concentrations below the permissible limit. C 2 B 1 and C 2 B 2 sub-clusters of C 2 B cluster are differentiated by higher Mg 2+ and NO 3 − concentrations in the samples of C 2 B 1 than C 2 B 2 . Moreover, the samples of Fig. 7 a-k Spatial variability map of different physical parameters and major ions; l Scholler's plot for ionic dominance C 2 A have lower Cl − , SO 4 2− and NO 3 − concentrations than C 2 B samples. The C 1 A cluster is differentiated from C 1 B cluster by higher total hardness (TH) of C 1 A than C 1 B. In the HCA, C 1 cluster is dominated by Na-HCO 3 facies (65%) of its samples followed by Ca-HCO 3 facies (35%) whereas C 2 cluster describes Ca-HCO 3 as dominating facies (80%) followed by Na-HCO 3 , Ca-Mg-HCO 3 , Ca-Mg-Cl-HCO 3 , Ca-Cl-HCO 3 and Ca-Cl types of water. The second highest anion, Cl − , in most of the sample exhibits lower concentration in C 1 cluster than C 2 cluster as C 2 has Ca-Cl-HCO 3 and Ca-Cl types of water.
In the chemical reaction, shown above in the result section, responsible for silicate weathering showed the formation of HCO 3 − which indicates the interaction of CO 2 gases from the atmosphere with the weathering of carbonate and aluminosilicate rocks, hence the soil zone in its subsurface region has elevated CO 2 pressure with in turn combines with water dripping down from different source specially rainwater and leads to the formation of HCO 3 − in groundwater. The presence of HCO 3 − concentration relative to other anions in groundwater shows weathering of primary silicate mineral i.e., dominated by alkaline earth (Rose 2002). The correlation between major ions and physical parameters in Table 4 showed the EC and TDS have a good and mostly positive correlation including NO 3 − , SO 4 2− and K + which suggests the chemical composition of water have their origin from geogenic as well as anthropogenic causes. The correlations (> 0.5) suggest that the concentration of respective parameter increased in groundwater with more and more rock-water interaction. Nitrate is showing a strong correlation with Cl − and SO 4 2− suggesting the nitrate sources from urban, animal wastes and return flow from irrigation. Fluoride has a moderate correlation with Na + and HCO 3 − suggesting an increase of fluoride in groundwater shows more alkaline conditions and other studies (Li et al. 2015;Ali et al. 2018;Adimalla et al. 2019) showed alkaline water helps in the release of fluoride from F − bearing minerals.
The drinking parameters were calculated and results have been mentioned above. According to the Census 2011, the population of the study area is about 875,958 which is not dense in nature. The water quality in many places is many places is not suitable for drinking purpose so the respective localites are compelled to borrow drinking water from other places. The poor sections in such regions suffers waterborne diseases. Summers in the study area are very harsh as a major part of the study area faces an acute shortage of drinking water. High NO 3 − concentration in drinking water has lots of drawbacks in form of harmful diseases as goiter, gastro-intestinal complications, methaemoglobinaemia in infants, hypertensions, etc. (Majumdar and Gupta 2000). Fluoride being a crucial element has various drawbacks when found in excess and results to ortho/bones-related diseases like bending of backbones. Teeth along with bones are also highly affected as mottling of teeth on excess intake of fluoride. Excess of Na + causes nervous imbalance, heart diseases, kidney disorders whereas Ca 2+ and Mg 2+ excessive intake causes stone problems in alimentary canal and kidney (Maragella et al. 1996). The Fe concentrations at some places show exceeding the desirable limit.
In irrigation water quality if Na + ion is more/excess in water then an exchange of Na + takes place between water and soil, and Ca 2+ and Mg 2+ in the soil is replaced by Na +   i.e., exchange of Na + ion is exchanged for Ca 2+ and Mg 2+ in rock/soil. This decreases the permeability of soil (Na + affinity is more than Ca 2+ and Mg 2+ for replacement) leading to a decrease in internal flow/drainage of water in soil (Collins and Jenkins 1996). The recommended standard for irrigation of Na% is 60% according to Indian Standard (BIS 2012). Thus, in Fig. 8 proper categorization of the values can be seen. The parameters indicating suitability for irrigation purpose show under suitable categories except for the total hardness (TH) at few sites. Few small surface water reservoirs, small streams and groundwater help in the irrigation practice of the district. During summers most of the streams get dried up and groundwater proves only a source of irrigation but due to poor or no groundwater at some locations a no-agriculture period is observed at those locations. The people during summers residing in such parts faces acute shortage for drinking purpose (Table 8).

Conclusion
The hard rock area, Mahoba, has a higher concentration of various parameters namely Ca 2+ , Mg 2+ , Na + , NO 3 − , Cl − , F − at various locations. The water samples exhibited Ca-HCO 3 , Na-HCO 3 and Ca-Mg-HCO 3 as major water types owing to their source from rock and anthropogenic inputs. The statistical analysis, HCA, of water samples in five clusters reveals Ca-HCO 3 , Na-HCO 3 and Ca-Mg-HCO 3 as major facies and Ca-Mg-Cl-HCO 3 , Ca-Cl-HCO 3 and Ca-Cl as minor facies types of water. The sites of cluster C 1 water samples were found located closer to drainage streams than C 2 cluster water samples. The calculated correlation coefficients among hydrochemical parameters indicate a strong positive correlation of EC and TDS with most of the major ions, including SO 4 2− , NO 3 − . NO 3 − and F − detected exceeding desirable limits of about 28.33 and 50% respectively in significant spatial distribution have been reported first time in the study area by the authors. The potential sources of hardness and nitrate found in higher amount have their contamination from fertilizers and, other inputs from urban and animal wastes. High F − showed concentration in various samples may have geogenic sources due to flour-apatite in granitic terrain and Fe found in excess gives an unpleasant taste on drinking. The various evaluations of drinking and irrigation parameters reflected their contribution from anthropogenic and geogenic processes at different locations based on their respective exposures.
The excess of various components at different sites due to local effects strongly requires treatment before groundwater utilization. The general water purification processes like demineralization, ion exchange and water softening can be used to minimize the concentration of impurities. It is high time to carry out immediate and legitimate measures to control long-term human health issues and agricultural production in the hard rock terrains in and around Mahoba district.  -9, 12-15, 17, 34-37, 47, 53, 54, 60 36.67