Introduction

Groundwater chemistry based on hydrochemical parameters presents preliminary information on water types, classification of water for various purposes, as well as study of different chemical processes (Saxena et al. 2003; Jalali 2007; Sarwade et al. 2007; Mondal and Singh 2011; Mondal et al. 2011). Groundwater quality changes due to geogenic interaction or any type of anthropogenic influence (Kelley 1940; Wilcox 1948). Different hydrogeochemical processes like dissolution, precipitation, ion-exchange processes, etc. control the chemical composition of the ground water in the shallow alluvial aquifers (Apodaca et al. 2002).

Groundwater forms the major source of water supply for irrigation as well as drinking and domestic purposes in most parts of the India (Sridhar et al. 2013). A total of 90% of rural and 30% of urban Indian population still depend completely on untreated surface or groundwater resources (Kumar et al. 2005). Though recent years, microbiological problems in rural India are controlled to a certain extent by changing in usage from surface water to groundwater, but the same has led to sources of newer problems like fluorosis, arsenicosis, and salinity due to overexploitation of groundwater (Singh et al. 2013). However, a number of studies on groundwater quality with respect to drinking and irrigation purposes have been reported to be carried out in different river basins of India (Majumdar and Gupta 2000; Dasgupta and Purohit 2001; Khurshid et al. 2002; Sujatha and Reddy 2003; Pulle et al. 2005; Hussain et al. 2005; Sunitha et al. 2005; Subba Rao 2006; Mondal et al. 2008, 2016; Sundaray et al. 2009; Mondal and Singh 2010; Tiwari et al. 2016; Kaur et al. 2017; Kumar et al. 2017).

The river Jia Bharali, a major north bank tributary of Brahmaputra plain, originates from higher Himalayan ranges and travels through geologically younger Himalayan ranges which contain unconsolidated sedimentary rocks. The north Brahmaputra plain of NE India is an actively subsiding foreland river basin with subtle neotectonic changes and catchment area tectonics. The people in the Jia Bharali river basin widely use the groundwater for drinking as well as for their daily household purposes including irrigation of crops, rearing of poultry and fish, etc. The ground water quality of the basin is thus intimately connected with public health and is very important for sustaining aquatic life in the area. Although the drinking water quality of the aquifers of this area was analysed with respect to a few water quality parameters (Khound et al. 2012), the irrigational and drinking aspects of the groundwater sources are yet to be taken up. In this context, the major objectives of this study were to evaluate the suitability of groundwater regime of Jia Bharali river basin for drinking and agricultural purposes by comparing with WHO and Indian Standards (ISI) guidelines, respectively.

Materials and methods

Study area

The Jia Bharali catchment is bound by longitudes 92°00′–93°25′E and latitudes 26°39′–28°00′N. The river Jia Bharali is one of the major south flowing tributaries of the river Brahmaputra with a major part of its catchment within the Himalayan range of the Arunachal province of India. In the piedmont zone where it debouches from the Himalayas, the river is flowing along a northwest–southeast course and follows a straight braided course to enter the Brahmaputra river plain near Tezpur (92°53′53″E, 26°39′15″N), Assam. The northern part along the foothills of Arunachal Himalaya is made up of Reserve Forests of evergreen deciduous forestry and sparsely populated forest-villages. The study area falls in the subtropical climatic region and enjoys monsoon type of climate (Jain et al. 2007). The southwest monsoon causes widespread rainfall in the basin during June–September. About 65–80% of the average annual rainfall takes place in this period. Rainfall during July and August is the highest and amounts to more than 33% of the annual rainfall (Jain et al. 2007). The quantity of water utilized for irrigation in the studied basin was observed quite large, particularly in comparison to the quantity used for municipal, industrial, and other household purposes.

Geology

The Jia Bharali river basin is a heart-shaped basin covering an area of 11,300 sq km (Goswami 1985). The river covers 9950 sq km in Arunachal Pradesh and in Assam 1000 sq km. The groundwater potential in this zone is because of fracture system within the crystalline rocks as well as valley fills interspersed with the inselberg (Khound et al. 2012). Older alluvium is found to be composed of partially indurated and oxidized sand, silt, and clay which form higher topographic levels within an overall younger alluvial terrane of the present-day river deposits (Fig. 1). The geomorphic mapping of the alluvial catchment has revealed the presence of a number of river terraces at different topographic levels with extensive tea plantations and paddy fields. The basin is dotted with numerous meander scars, remnant channels, misfit streams, inactive floodplains, and natural levee. The aquifers of the lower Jia Bharali catchment and adjoining areas in central part of North Brahmaputra Plain (NBP), India, are unconfined and shallow alluvial with a general southward flow, which are largely tapped for domestic use through numerous dug wells attached with almost every household. Aquifer materials are generally fine-coarse sand which may be occasionally pebbly.

Fig. 1
figure 1

Alluvial pattern of Jia Bharali river basin

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Water sampling and chemical analysis

Water samples were collected from 50 shallow hand dug wells spread over the lower Jia Bharali basin and adjoining areas (Fig. 2) for 3 hydrological years 2008–2011. The sampling and analysis programme was conducted for six seasons in these 3 consecutive years as (1) W1: wet season (July 2008), (2) D1: dry season (February 2009), (3) W2: wet season (July 2009), (4) D2: Dry season (February 2010), (5) W3: wet season (July 2010), and (6) D3: dry season (February 2011). The standard methods were followed in collection, storage, and analysis of the water samples (APHA 1998), and represented in Table 1.

Fig. 2
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Location map of groundwater sampling points

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Table 1 Abbreviations, units, and analytical methods used for water quality parameters
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Data treatment and classification methods

The parameters such as sodium adsorption ratio (SAR), percent sodium (% Na), residual sodium carbonate (RSC), Kelly’s index (KI), and magnesium ratio were calculated to evaluate the suitability of the groundwater quality for agricultural purposes (Mondal et al. 2016). The standard techniques and methods (APHA 1998; Ayers and Westcot 1994; Tiwari and Manzoor 1988a, b; ISI 1974; Durfer and Backer 1964; USSL 1954; Kelly 1940; Paliwal 1967) were followed for analysis, calculation, and interpretation of the generated database.

Results and discussion

The hydrochemical parameters at 50 wells from shallow alluvial aquifers in the Jia Bharali river basin system with minimum, maximum, mean, and standard deviation values in each wet and dry season from 2008 to 2011 are incorporated in Tables 2, 3, and 4.

Table 2 Descriptive characteristic of shallow aquifers with respect to physico–chemical parameters and major cations
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Table 3 Descriptive characteristics of shallow aquifers with respect to major anions
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Table 4 Descriptive characteristics of surface water sources with respect to trace metals
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The pH of water samples were found in the range of 5.8–8.1 (mean 6.9) in W1, 5.7–8.0 (mean 6.6) in W2, 5.1–7.3 in W3 (mean 6.6), 5.6–7.7 (mean 6.7) in D1, 5.4–7.4 (mean 6.6) in D2, and 5.7–7.2 (mean 6.7) in D3. A number of samples in the wet seasons (16% in W1, 40% in W2, and 32% in W3) as well as in dry seasons (26% in D1and D2, 14% in D3) showed high acidic pH (< 6.5) implying their unsuitability for drinking and irrigation purposes. The pH values in the wet seasons were recorded below 6.0, and in the dry seasons, they were found below 8.0, while average pH values in all the wet and dry seasons were found in between 6.0 and 7.0. The low pH of water samples may be due to (1) eutrophication (Garcia et al. 2001), (2) wide distribution of lateritic soil in the basin or extensive use of acid producing fertilizers like ammonium sulphates and super phosphates of lime (Raghunath et al. 2001) during cultivation. However, the studied ground water regime was found in ‘no problem’ (6.5–8.4) and ‘moderate’ category (5.1–6.4) under Ayers and Westcot (1994) pH classification for irrigation of soils in all the wet and dry seasons.

The EC of the selected shallow wells were found in the range of 80–1010 µS/cm (mean 307 µS/cm) in W1, 60–1070 µS/cm (mean 383 µS/cm) in W2, 60–1350 µS/cm (mean 320 µS/cm) in W3, 50–1130 µS/cm (mean 233 µS/cm) in D1, 50–510 µS/cm (mean 191 µS/cm), and 60–1010 µS/cm (mean 245 µS/cm) in D3, respectively. These values were lower than WHO (1984) permissible limit (1400 µS/cm) for drinking water and indicated their suitability for household purposes. However, mean EC values of the shallow wells were found in the range of 200–400 µS/cm in all the wet and the dry seasons. The low EC values indicated the effect of (1) dilution due to high rainfall, (2) insoluble geologic rock and mineral types, (3) very little solute dissolution, and (4) rapid ion exchange between the soil and water. The higher EC values indicated the input of alkali and alkaline earth metal ions through agricultural and domestic sewage (Bernard et al. 2004). EC variation pattern was not uniform and this may be due to non-uniform influence of various local factors on ionic contents of the water. Human activities and inflows from surrounding agricultural fields are likely to be significant influences on the salt contents of the groundwater. Considering US Salinity Laboratory (1954) classification, it was found that all the aquifers could be categorized under low salinity (< 2500 µS/cm) regime, and therefore, the water was highly suitable for the irrigation of crops. Moreover, the studied water samples were found in ‘Low Class’ (< 1500 µS/cm) category under Indian Standard guidelines (1985) which implied their suitability for irrigation uses. Except a few wells, all the studied shallow wells were found in ‘excellent’ (< 250 µS/cm) to ‘permissible’ (250–500 µS/cm) category for the irrigation of crops (Ayers and Westcot 1994) in all the wet and dry seasons.

Total Hardness (TH) of the groundwater regime varied from 24 to 260 mg/L (mean 109 mg/L) in W1, 59–268 mg/L (mean 132 mg/L) in W2, 46–220 mg/L (mean 114 mg/L) in W3, 20–168 mg/L (mean 71 mg/L) in D1, 30–220 mg/L (mean 79 mg/L) in D2, and 50–154 mg/L (mean 85 mg/L) in D3, respectively. According to WHO (1984) classification (Table 5), the studied shallow wells were found in different categories from ‘Soft’(0–50 mg/L) to ‘Very hard’ (> 200 mg/L) in all the wet and dry seasons with majority of the wells in ‘moderately soft’ category (50–100 mg/L) for drinking uses. Using Durfer and Backer (1964) TH classification, most of the samples were found in the ‘Moderately soft’ category (60–120 mg/L), while a few wells in ‘very hard’ category (> 180 mg/L) found doubtful for irrigation purposes (Table 5). The sources of hardness in the groundwater regime might be due to discharge of sewage, detergents, and large-scale human use (Jain and Sharma 2002). However, all water bodies had hardness (CaCO3/L) well below the WHO (1984) permissible limit of 500 mg/L implying their suitability for household purposes.

Table 5 Drinking and irrigation quality of 50 aquifers based on hardness
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Major cations

Calcium (Ca) content of the shallow wells varied in the range 6.4–68.9 mg/L (mean 27.0 mg/L) in W1, 5.8–51.0 mg/L (mean 21.2 mg/L) in W2, 10.2–46.4 mg/L (mean 23.5 mg/L) in W3, 4.2–47.1 mg/L (mean 16.0 mg/L) in D1, 7.5–46.5 mg/L (mean 19.3 mg/L) in D2, and 6.4–38.5 mg/L (mean 18.7 mg/L) in D3, respectively. Corresponding magnesium contents were found in the range of 1.0–29.2 mg/L (mean 9.2 mg/L) in W1, 2.4–27.5 mg/L (mean 9.6 mg/L) in W2, 2.8–28.9 mg/L (mean 9.7 mg/L) in W3, 1.9–19.5 mg/L (mean 6.8 mg/L) in D1, 2.6–26.5 mg/L (mean 9.0 mg/L) in D2, and 2.4–17.8 mg/L (mean 8.1 mg/L) in D3, respectively. The calcium and magnesium concentration of the study area could be attributed to rock weathering. Calcium and magnesium contents of all water samples were found well below the guideline value of WHO (1984) (Ca: 100 mg/L, Mg: 150 mg/L) and ISI (1991) (Ca: 75 mg/L, Mg: 30 mg/L), respectively, and indicated their suitability for drinking purposes in both the rainy and dry seasons. Moreover, Ca and Mg contents of all the wells were found well below the tolerance limits (Ca: 80 mg/L, Mg: 24 mg/L) of irrigation (ISI 1974) for both the wet and dry seasons in the study area.

Magnesium hazard (MH)

Harmful effect of magnesium could be presented with the help of an important ratio called index of MH or magnesium ratio (MR) (Paliwal 1972). Magnesium ratios of more than 50% would adversely affect the crop yield as the soils become more alkaline (Paliwal 1972; Sundaray et al. 2009). MR of the studied shallow wells were observed to be in the range of 9–55% (mean 35%) in W1, 25–63% (mean 43%) in W2, 20–61% (mean 40%) in W3, 24–63% (mean 42%) in D1, 28–65% (mean 43%) in D2, and 29–64% (mean 42%) in D3, respectively, during the sampling periods. Only a few wells (≤ 16%) in all the wet and dry seasons showed MR more than 50% indicating their unsuitability for irrigation purposes. High Mg ratio in these wells may be due to high interaction between surface–subsurface water and passage through the limestone, and kankar and granitic rock formation in the study area (Pandian and Sankar 2007). The published reports also favour this result. Assessing the quality for domestic and agricultural uses in the Tiruvallur District of Tamil Nadu state of India, Kumar and co-workers (2017) found MH values of majority of the groundwater samples below 50% and suggested their suitability for irrigational uses.

Na and K

Sodium (Na) contents of the shallow wells were in the range of 5.6–46.7 mg/L (mean 17.4 mg/L) in W1, 4.2–42.0 mg/L (mean 10.8 mg/L) in W2, 4.2–62.5 mg/L (mean 15.3 mg/L) in W3, 1.9–30.1 mg/L (mean 10.8 mg/L) in D1, 5.1–28.4 mg/L (mean 10.2 mg/L) in D2, and 3.5–32.8 mg/L (mean 11.5 mg/L) in D3, respectively. Similarly, wet season potassium (K) contents varied from 2.7 to 26.1 mg/L (mean 10.2 mg/L) in W1, 2.6–24.5 mg/L (mean 6.6 mg/L) in W2, 2.2–25.6 mg/L (mean 8.4 mg/L) in W3, while dry season values ranged from 1.3 to 16.7 mg/L (mean 5.3 mg/L) in D1, 1.9–18.5 mg/L (mean 5.4 mg/L) in D2, and 1.9–14.9 mg/L (mean 5.5 mg/L) in D3, respectively. However, all the wells were found to have Na content below WHO (1984) permissible limit (200 mg/L), while a few number of wells (< 20% in wet seasons and 4% in the dry seasons) showed K content more than recommended limit (12 mg/L) of WHO (1984) for drinking water. The sodium hazard of irrigation water is usually specified with the help of two sodium-related indices named as (1) sodium adsorption ratio (SAR) and (2) sodium percentage (Na %) (Mondal et al. 2016; Tiwari et al. 2016; Kaur et al. 2017).

Sodium absorption ratio (SAR)

SAR defined irrigation quality of water sources with respect to sodium hazard, since it is more closely related to exchangeable sodium percentages in the soil (Tiwari and Manzoor 1988a). In the present work, wet season SAR values of the shallow aquifers ranged from 0.21 to 2.90 (mean 0.77) in W1, 0.18 to 1.58 (mean 0.51) in W2, and 0.14 to 1.94 (mean 0.68) in W3, while, in case of dry seasons, SAR values varied from 0.11 to 1.99 (mean 0.59) in D1, 0.22 to 1.32 (mean 0.51) in D2, and 0.19 to 1.40 (mean 0.57) in D3 during sampling periods. According to Richards’ (1954) and ISI (1991) classification, all the samples could be classified under excellent (< 10) category for irrigation in all the seasons. Similar SAR values (< 10) have also been reported in the Malwa region of Punjab (Kaur et al. 2017) bounded by river Sutlej indicating the absence of alkali hazards in ground water samples. Tiwari and co-workers (2016) also measured similar groundwater SAR values which range from 0.40 to 1.90 (avg. 1.00) in the West Bokaro coalfield area of Jharkhand State of India.

Sodium percentage (Na %)

The Na% of the studied groundwater samples varied from 12 to 73% (mean 34%) in W1, 9–52% (mean 27%) in W2, 6–59% (mean 31%) in W3, 12–66% (mean 31%) in D1, 8–55% (mean 27%) in D2, and 12–59% (mean 29%) in D3, respectively. Na% values presented that most of the water sources (≥ 78%) under “excellent” (< 20%) to “good” (20–40 Na%) category except a few sources for irrigation of soils. As per ISI (1974) guidelines, the maximum tolerance limit of Na% for inland water used for irrigation is 60%, and hence, except two wells, all the other studied wells of Jia Bharali river basin were found suitable for irrigation purposes. Similar results have also been found in several published research works. In the Sutlej river basin of Punjab, Kaur and co-workers (2017) found most of the groundwater samples in excellent (< 20%) and good (20%–40%) categories which could be safely used for irrigation purposes.

Kelly’s index

Water quality towards irrigation could also be classified based on Kelly’s index (KI). It is the ratio of sodium ion to calcium and magnesium ions in meq/L (Kelly 1940). A Kelly’s index of more than one indicates an excess level of sodium in waters (Kelly 1940; Paliwal 1967). Kelly’s index in the present study varied from 0.15 to 2.05 (mean 0.54) in W1, 0.13 to 1.12 (mean 0.36) in W2, 0.10 to 1.37 (mean 0.48) in W3, 0.08 to 1.41 (mean 0.42) in D1, 0.15 to 0.94 (mean 0.36) in D2, and 0.14 to 0.99 (mean 0.40) in D3, respectively. Waters with a Kelly’s index less than one are considered as suitable for irrigation, and except a few wells (3% wells in W1, 4% wells in W2, 12% wells in W3, and 2% wells in D1), all the wells showed their suitability for agricultural purposes in both the wet and dry seasons. Published reports are in conformity with the results of the present work. The groundwater regime of Markandeya River basin of India (Ravikumar et al. 2010) showed Kelly’s index in the range from 0.057 to 1.12, and all the water samples are suitable for irrigation according to Kelly’s index, except for one sample with a KI value of 1.12.

Major anions

In the present study, the groundwater samples had pH lower than 8.3, and hence, no carbonate (CO3) alkalinity could be found in the studied wells (Narain et al. 2000). The total alkalinity was, therefore, almost entirely due to the presence of bicarbonate, which was found at slightly higher levels in the post-monsoon period, indicating that some contribution might have come from the carbonate weathering process due to heavy downpour in the catchment. Bicarbonate content (as CaCO3) of the groundwater samples varied from 20 to 114 mg/L (mean 75 mg/L) in W1, 27 to 118 mg/L (mean 67 mg/L) in W2, and 34 to 118 mg/L (mean 69 mg/L) in W3 season, while, for dry seasons, its values varied from 16 to 92 mg/L (mean 47 mg/L) in D1, 20 to 70 mg/L (mean 38 mg/L) in D2, and 17 to 88 mg/L (mean 44 mg/L) in D3, respectively. High values of bicarbonate indicated the contribution from silicate and carbonate chemical weathering into the shallow aquifers (Sridhar et al. 2013). All the water samples showed the bicarbonate alkalinity higher in the dry seasons than that of the wet seasons, and the values were well within the WHO permissible limit (120 mg/L) for drinking water. The hazardous effect of carbonate and bicarbonate on the quality of water for agricultural uses could be explained in terms of RSC (residual sodium carbonate) indices (Eaton 1950).

The most common toxicity in the irrigation water originates from chloride (Sundaray et al. 2009). Cl showed a wide range of values as 2.8–116.4 mg/L (mean 37.0 mg/L) in W1, 4.9–112.5 mg/L (mean 29.6 mg/L) in W2, 5.9–129.5 mg/L (mean 50.9 mg/L) in W3, 2.8–99.4 mg/L (mean 31.1 mg/L) in D1, 8.2–110.2 mg/L (mean 30.3 mg/L) in D2, and 8.5–138.3 mg/L (mean 48.9 mg/L) in D3. High concentration of chloride makes water unpalatable and unfit for drinking and livestock watering. However, all the shallow wells showed Cl content below the permissible limit of 250 mg/L (WHO 1984) for drinking water. The Cl content of the ground water sources of the basin was also within the tolerance limit for irrigation (ISI 1974, 600 mg/L). The groundwater sources of Jia Bharali river basin were also free from chloride hazard and they are classified under ‘no problem’ category (< 4 meq/L) for irrigation uses (Sundary et al. 2009). The sulphate contents were much below the permissible limit for drinking water (400 mg/L, WHO 1984) with the wide range of values in different seasons as W1: 5.8–99.5 mg/L (mean 23.9 mg/L), W2: 2.6–80.5 mg/L (mean 19.2 mg/L), W3: 6.9–69.3 mg/L (mean 21.2 mg/L), D1: 1.2–43.0 mg/L (mean 10.9 mg/L), D2: 1.2–30.0 mg/L (mean 11.9 mg/L), and D3: 5.5–71.7 mg/L (mean 31.7 mg/L). However, the ground water sulphate content of the Jia Bharali river basin was within the tolerance limit (1000 mg/L) for irrigation purposes (ISI 1974). The shallow wells of the investigated area were found to contain only small amounts of NO3 in both wet and dry seasons as from BDL to 1.20 mg/L (mean 0.17 mg/L) in W1, BDL to 0.45 mg/L (mean 0.07 mg/L) in W2, BDL to 0.64 mg/L (mean 0.08 mg/L) in W3, BDL to 0.30 mg/L (mean 0.04 mg/L) in D1, BDL to 0.28 mg/L (mean 0.05 mg/L) in D2, and BDL to 0.32 mg/L (mean 0.02 mg/L) in D3, respectively. Smaller values of nitrate in the study area indicate that the nitrifying bacteria are not much active due to the presence of anaerobic conditions (the area having a water cover for most of the time) for the large part of the year. The occurrences of nitrate in the wells are likely to be the application of fertilizers like ammonium sulphate, [(NH4)2SO4] in the agricultural fields of the locality. However, all the groundwater sources in all the seasons showed nitrate content below the WHO (1984) permissible limit (50 mg/L) for drinking water. Ayers and Westcot (1994) classification showed that all the aquifers were fall under ‘no problem’ category (< 5 mg/L) for irrigation water, and hence, they were free from NO3 hazards. The wet and dry season PO4 contents of the shallow wells were recorded as 0.04–1.50 mg/L (mean 0.26 mg/L) in W1, BDL to 1.45 mg/L (mean 0.13 mg/L) in W2, BDL to 0.88 mg/L (mean 0.08 mg/L) in W3, BDL to 1.15 mg/L (mean 0.06 mg/L) in D1, BDL to 1.04 mg/L (mean 0.09 mg/L) in D2, and BDL to 0.83 (mean 0.06 mg/L) in D3, respectively. The presence of vast paddy rice cultivation in the study area obviously points to agricultural runoff being the main source.

The nutrient boron showed its presence in most of the water samples ranging from BDL to 0.20 mg/L (mean 0.08 mg/L) in W1, BDL—0.24 mg/L (mean 0.10 mg/L) in W2, BDL to 0.25 mg/L (mean 0.12 mg/L) in W3, BDL—0.39 mg/L (mean 0.17 mg/L) in D1, BDL to 0.41 mg/L (mean 0.19 mg/L) in D2, and BDL—0.40 mg/L (mean 0.21 mg/L) in D3, respectively. All the sources in all six seasons were found to have B content well below the WHO (1984) permissible limit (0.50 mg/L) for drinking water. Boron affects plant growth and yield, and an overdose or an underdose of boron can result in toxicity or deficiency symptoms in plants. All the wells showed B content below the tolerance level for semi tolerant (< 0.67 mg/L) and tolerant (1.00 mg/L) crops (ISI 1991) in all the wet and dry seasons. However, in dry seasons, a few wells (≤ 12%) showed B content above the tolerance limit (0.33 mg/L) for sensitive crops (ISI 1991) in the studied basin.

Residual sodium carbonate (RSC)

The ground water samples showed RSC values in the range of − 2.47 to 0.23 meq/L (mean − 0.60 meq/L) in W1, − 3.63 to − 0.04 meq/L (mean − 1.09 meq/L) in W2, and − 2.40 to 0.04 meq/L (mean − 0.89 meq/L) in W3, whereas, in dry season, RSC values were observed in the range of − 3.84 to 0.23 meq/L (mean − 0.92 meq/L) in D1, − 4.13 to 0.43 meq/L (mean − 0.80 meq/L) in D2, and − 3.38 to 0.18 meq/L (mean − 0.84 meq/L) in D3, respectively. All the samples had RSC values much less than 1.25 meq/L, and hence, groundwater regime is ‘safe’ (1.25 meq/L) as well as ‘excellent’ quality for irrigation (USSL 1954, ISI 1991) in all the wet and dry seasons. Furthermore, more than 80% wells in all the six seasons showed negative RSC values which implied the absence of complete precipitation of calcium and magnesium (Tiwari and Manzoor 1988b) in the studied basin. Except a few sources, groundwater regime of Tiruvallur District of Tamil Nadu State of India showed RSC values which range from − 12.29 to 2.51 meq/L indicating their suitability for agricultural purposes.

Trace metals

The As concentration of the ground water samples was observed in the range of BDL to 0.009 mg/L (mean 0.002 mg/L) in W1, BDL to 0.007 mg/L (mean 0.001 mg/L) in W2, and BDL to 0.009 mg/L (mean 0.002 mg/L) in W3, while dry season As were observed as BDL to 0.019 mg/L (mean 0.003 mg/L) in D1, BDL to 0.011 mg/L (mean 0.003 mg/L) in D2, and BDL to 0.012 mg/L (mean 0.003 mg/L) in D3, respectively. Dry season arsenic concentration was found higher than that of wet seasons mainly due to reduction in water volume. Except one source in foothills of Arunachal Himalaya, all the groundwater sources were found to have As content well below the recommended maximum permissible limit (0.01 mg/L) of drinking water (WHO 1984) in both wet and dry seasons. Similarly, all the wells showed As content well below tolerance limit (0.10 mg/L) for irrigational uses (ISI 1991). Arsenic poisoning causes cancers, melanosis, hypertension, and heart disease (Guha et al. 2000; Morales et al. 2000; Rahman 2002). Arsenic inhibits plant growth by interfering the plant metabolism and nutrient uptake by competing directly with nutrients or altering metabolic processes (Farnese et al. 2014).

Cadmium is one of the most toxic elements with reported carcinogenic effects in humans (Goering et al. 1994). Cd content of the present samples varied from BDL to 0.025 mg/L (mean 0.002 mg/L) in W1, BDL to 0.040 mg/L (mean 0.003 mg/L) in W2, BDL to 0.013 mg/L (mean 0.002 mg/L) in W3, BDL to 0.038 mg/L (mean 0.004 mg/L) in D1, BDL to 0.070 mg/L (mean 0.008 mg/L) in D2, and BDL to 0.022 mg/L (mean 0.008 mg/L) in D3, respectively. The relatively consistent distribution of Cd throughout the study area (Fig. 3) implied that it could have been derived from non-point sources such as agricultural runoff in the absence of industrial activities. There is, however, Cd concentration in a number of groundwater samples (10% samples in W1, 18% samples in W2 and W3, 30% samples in D1, 50% samples in D3, and 66% samples in D3) which were found to exceed the desirable limit of 0.005 mg/L (WHO 1984) for drinking water. Similarly, in the wet seasons, 4% samples in W1, 10 samples % in W2, 6% samples in W3, and, in the dry seasons, 2% samples in D1, 22% samples in D2, and 40% samples in D3 had cadmium content above the tolerance limit (0.01 mg/L) for irrigational water (ISI 1991). Excess cadmium affects plants growth by disturbing structure and functional activity of the photosynthetic processes (Vassilev et al. 1995).

Fig. 3
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Distribution contours of cadmium (mg/L) of the shallow wells in the dry season D2

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WHO (1984) has not proposed any drinking water guideline value for Co, but the shallow wells showed Co content in the considerable ranges from 0.017 to 0.055 mg/L (mean 0.039 mg/L) in W1, BDL to 0.064 mg/L (mean 0.035 mg/L) in W2, BDL to 0.054 mg/L (mean 0.023 mg/L) in W3, 0.004 to 0.109 mg/L (mean 0.053 mg/L) in D1, BDL to 0.112 mg/L (mean 0.058 mg/L) in D2, and 0.009 to 0.099 mg/L (mean 0.042 mg/L) in D3, respectively. However, most of the groundwater samples (20% in W1, 22% in W2, 4% in W3, 56% in D1, 62% in D2, and 26% in D3) showed Co content exceeding permissible limit (0.05 mg/L) for irrigational water (ISI 1991) in both the wet and dry seasons. Co is an essential element for humans and plants, but, at higher concentration, it can cause anorexia, nausea, vomiting, and diarrhea in human beings (Bhagure and Migaue 2010) and irreversible damage to plant cell and cell membrane (Jayakumar et al. 2008). Cu is an essential nutrient, but overdoses of Cu cause hypertension, liver, and kidney dysfunctions (USEPA 1999; Stenhammar 1999). In the present study, the Cu concentration [W1: 0.03 to 0.83 mg/L (mean 0.21 mg/L), W2: BDL to 0.31 mg/L (mean 0.06 mg/L), W3: BDL to 0.19 mg/L (mean 0.05 mg/L), D1: 0.03 to 1.10 mg/L (mean 0.26 mg/L), D2: 0.05 to 1.43 mg/L (mean 0.24 mg/L), and D3: 0.01 to 0.21 mg/L (mean 0.07 mg/L)] of the water samples was found far below the desirable value of 2 mg/L (WHO 1984) for drinking water. However, a large number of groundwater samples in some seasons (62% in W1, 46% in D1 and D2) showed Cu content above the tolerance limit (0.20 mg/L) for irrigational water (ISI 1991), and these sources could be considered as unsafe for agriculture use with respect to copper content. Copper may be toxic to plants, affecting mainly the growth of the roots (Owen 1981) of plants like cauliflower, potato, carrot, lettuce seedling, and rice seedling which are widely cultivated in the study area.

Cr (III) is considered as an essential trace element for the maintenance of an effective glucose, lipidd, and protein metabolism in humans, animals, plants, and microorganism (Nielsen 1998), while Cr(VI) is regarded as serious toxic pollutant due to its carcinogenic and mutagenic properties (Mondal and Singh 2010; Cohen et al. 1993; Cieslak-Golonka 1995). In the present work, the total Cr concentration [both Cr(III) and Cr(VI)] was measured, and it varied from low to sufficiently high values, i.e., in the range of BDL − 0.15 mg/L (mean 0.05 mg/L) in W1, BDL − 0.14 mg/L (mean 0.06 mg/L) in W2, BDL − 0.17 mg/L (mean 0.06 mg/L) in W3, BDL − 0.24 mg/L (mean 0.08 mg/L) in D1, BDL − 0.22 mg/L (mean 0.09 mg/L) in D2, and BDL − 0.17 mg/L (mean 0.08 mg/L) in D3, respectively. However, 40% wells in W1, 64% wells in W2, 54% wells in W3, as well as 46% wells in D1, 70% wells in D2, and 72% wells in D3 of the studied basin showed very high Cr concentration exceeding the permissible limit (0.05 mg/L) for drinking water (WHO 1984). Spatial distribution contours in the Fig. 4 showed that the regions having higher Cr content are far away from the river. Cr-rich situation in the basin needs to be investigated further. The Cr enrichment of the water samples could be attributed to the transportation from the Cr-rich rocks and soils of the basin as well as to the human activities like agricultural cultivation and fertilization of the studied area. However, all the studied wells were found to have chromium content far below the maximum permissible limit (1.0 mg/L) for irrigational water (ISI 1991), and hence, they could be used as potential source for agricultural purposes. Consumption of Cr-contaminated plants and their foodstuffs may pose a serious health hazard to human beings through food-chain biomagnifications (Nriagu and Pacyna 1988).

Fig. 4
figure 4

Distribution contours of Chromium (mg/L) of the shallow wells in the dry season D1

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In the present work, iron contents of the groundwater samples varied from 0.10 to 5.64 mg/L (mean 1.03 mg/L) in W1, 0.10 to 3.86 mg/L (mean 0.96 mg/L) in W2, 0.14 to 4.15 mg/L (mean 0.92 mg/L) in W3, 0.14 to 9.15 mg/L (mean 1.09 mg/L) in D1, 0.10 to 11.76 mg/L (mean 1.32 mg/L) in D2, and 0.13 to 3.68 mg/L (mean 0.64 mg/L) in D3, respectively, with majority of the sources exceeding WHO (1984) limit (0.3 mg/L) for drinking water. Fe, along with Mn, can affect the organoleptic quality of water as well as coloration of the water, thus initiating sedimentation in the system. It was observed that, in case of wet seasons, 40% wells in W1, 70% wells in W2, and 92% wells in W2, while, in case of dry season, 54% wells in D1, 78% wells in D2, and 58% wells in D3 had Fe content above the maximum permissible limit (0.30 mg/L) for drinking water (WHO 1984). The enrichment of iron in these shallow wells was mainly due to soil leaching and chemical weathering linking particular geology of the plain (Puttaiah and Kiran 2008; Zorer et al. 2008). The high iron content of the studied wells may also be, plausibly, due to interaction with highly oxidized partially indurate older alluvium with limonitic layers of the study area (Fig. 5). The lowering of iron content in the monsoon season had been attributed to the dilution effect of the rainfall and consequent increased flow of water into the water sources (Sharma and Subramanian 2010). However, iron contents of all the shallow wells were found far below the permissible limit (5.0 mg/L) of ISI (1991) showing their suitability for agricultural purposes in all the seasons.

Fig. 5
figure 5

Distribution contours of iron (mg/L) of the shallow wells in the dry season D1

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Mn plays an essential micronutrient in the plant metabolic processes and becomes toxic when it is in excess (Kochian et al. 2004; Pulle et al. 2005). In human beings, overdoses of Mn can cause kidney, pancreas, and liver damages (Underwood 1977). The shallow wells of the study area showed Mn content in the range of BDL − 0.99 mg/L (mean 0.18 mg/L) in W1, BDL − 0.88 mg/L (mean 0.15 mg/L) in W2, and BDL − 0.90 mg/L (mean 0.13 mg/L) in W3, while the dry season manganese contents were observed as 0.10–1.26 mg/L (mean 0.35 mg/L) in D1, BDL − 1.37 mg/L (mean 0.42 mg/L) in D2, and BDL − 1.29 mg/L (mean 0.22 mg/L) in D2 season, respectively. In the wet seasons, 40% wells in W1, 34% wells in W2, and 17% wells, while, for dry seasons, all wells in D1, 90% in D2, and 66% in D3 were found to have Mn content above the permissible limit of 0.10 mg/L (WHO 1984) for drinking water. Similarly, 30% wells in W1, 24% wells in W2, 14% wells in W3, 56% in D1, 68% in D2, and 26% in D3 showed Mn content above the maximum tolerance limit (0.20 mg/L) for irrigational water (ISI 1991).

In this work, Ni contents ranged from BDL to 0.07 mg/L (mean 0.02 mg/L) in W1, BDL to 0.09 mg/L (mean 0.04 mg/L) in W2, BDL to 0.10 mg/L (mean 0.04 mg/L) in W3, 0.01 to 0.18 mg/L (mean 0.04 mg/L) in D1, BDL to 0.16 mg/L (mean 0.03 mg/L) in D2, and BDL to 0.12 mg/L (mean 0.04 mg/L) in D3, respectively. 64% samples in W1, 72% samples in W2, 82% samples in W3, 98% samples in D1, 60% samples in D2, and 88% samples in D3 were found to have Ni content above the permissible limit (0.02 mg/L) for drinking water (WHO 1984). Excess Ni could cause laryngeal and lung cancer in human being (Lessard et al. 1978). The nickel toxicity in plants appears as chlorosis or yellowing of leaves usually followed by necrosis (Rathor et al. 2014). However, all the selected shallow wells showed Ni content below the permissible limit (0.20 mg/L) of irrigational water (ISI 1991) in both the wet and dry seasons.

Long-term exposure to lead or its salts can affect the kidney and nervous system of human beings adversely (Mugica et al. 2002). In this work, the concentration of Pb was in the range of BDL − 0.18 mg/L (mean 0.09 mg/L) in W1, BDL − 0.15 mg/L (mean 0.09 mg/L) in W2, BDL − 0.19 mg/L (mean 0.09 mg/L) in W3, 0.03–0.20 mg/L (mean 0.11 mg/L) in D1, 0.04–0.22 mg/L (mean 0.11 mg/L) in D2, and 0.03–0.21 mg/L (mean 0.11 mg/L) in D3, respectively. In the present study, almost all the wells had higher Pb-content in the dry season than in the wet season. Contours in the Fig. 6 showed that lead was present in all the aquifers in both the seasons, and it was likely that its adsorption on organic and inorganic sediment surfaces (Hem 1976) may have enhanced its concentration in the ground water. Majority of the wells (≥ 88%) in both the seasons had Pb concentration above the permissible limit of 0.05 mg/L (WHO 1984) for drinking water. The low concentration of Pb in natural waters is normally ascribed to less solubility of Pb-containing minerals in water, while high concentration of lead in natural water occurs mainly contributed by geological and anthropogenic sources (Mondal et al. 2010; Singh et al. 2006). Pb concentration of the studied wells was found very low in compared to permissible limit (5 mg/L) for irrigational water (ISI 1991). High level of Pb in irrigational water may reduce the plant growth and other metabolic activities (John et al. 2009).

Fig. 6
figure 6

Distribution contours of lead (mg/L) of the shallow wells in the dry season D1

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Zn, an essential trace element, plays an important role in the physiological and metabolic processes of many organisms and plants and becomes toxic in high concentrations (Pillai and Paul 1983). Zinc showed a significant presence in the wells from BDL − 0.11 mg/L (mean 0.03 mg/L) in W1, BDL − 0.12 mg/L (mean 0.04 mg/L) in W2, BDL − 0.14 mg/L (mean 0.03 mg/L) in W3, BDL − 0.19 mg/L (mean 0.05 mg/L) in D1, BDL − 0.20 mg/L (mean 0.04 mg/L) in D2, and BDL − 0.16 mg/L (mean 0.03 mg/L) in D3, respectively. Zn content of the water sam may be attributed to leaching from the overlying soil layers by the runoff. The values were very low compared to WHO (1984) permissible limit (3 mg/L) for drinking water as well as permissible limit (2 mg/L) for irrigational water (ISI 1991). Hence, due to enrichment of the micronutrient Zn, the groundwater sources of the study area are suitable for agricultural purposes.

Piper classification

In the present study, Piper (1944) classification showed that the 50 alluvial shallow wells could be grouped into two categories in all the wet and dry seasons (Table 6). Thus, Piper’s classification revealed that alkaline earths (Ca, Mg) and weak acids (HCO3) are preponderance over alkalis (Na, K) and strong acids (SO4, Cl) in majority of the selected aquifers of the study area, thereby indicating calcium and magnesium bicarbonate type of water. Piper diagrams for the wet season W1 and the dry season D1 are presented in Figs. 7 and 8, respectively.

Table 6 Piper classification of 50 alluvial aquifers
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Fig. 7
figure 7

Piper diagram of the shallow wells in the wet season W1

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Fig. 8
figure 8

Piper diagram of the shallow wells in the dry season D1

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Correlation analysis

The correlation matrices for 23 variables were prepared for both wet (Table 7) and dry seasons (Table 8) using SPSS 16.0. If the correlation coefficient is nearer to + 1 or − 1, it shows the perfect linear relationship between the two variables (Tiwari et al. 2016). A correlation coefficient of < 0.50 exhibits poor correlation, 0.50 indicates good correlation and > 0.50 represents strong correlation (Kumar et al. 2017). Thus, correlation analysis reveals the nature of the relationship between the water quality parameters. A good correlation between EC–TH [r = 0.61(wet) and 0.51 (dry)], EC–Ca [r = 0.56 (wet) and 0.59 (dry)], EC–Mg [r = 0.66 (wet) and 0.64 (dry)], EC–Na [r = 0.75 (wet) and 0.55 (dry)], EC– Cl [r = 0.65 (wet) and 0.62 (dry)], and EC–SO4 [r = 0.65 (wet) and 0.60 (dry)] was observed in all the groundwater samples. This suggested that the presence of TH, calcium, sodium, chloride, and sulphate greatly influences the EC of the studied wells (Kaur et al. 2017). Besides this, the correlation matrices also showed significant positive correlations between different physicochemical parameters such as TH–Ca [r = 0.70 (wet) and 0.83 (dry)], TH–Mg [r = 0.69 (wet) and 0.67 (dry)], TH–Cl [r = 0.51(wet) and 0.58 (dry)], TH–HCO3 [r = 0.64(wet) and 0.59 (dry)], and TH–SO4 [r = 0.59(wet) and 0.50 (dry)]. This showed that there was great dependence of hardness on calcium, magnesium, bicarbonate, chloride, and sulphate. Chloride content was significantly and positively correlated with Ca [r = 0.62 (wet) and 0.70 (dry)], Mg [r = 0.70 (wet) and 0.68 (dry)], Na [r = 0.67 (wet) and 0.62 (dry)], and sulphate [r = 0.63 (wet) and 0.60 (dry)]. Good correlations were also observed in between HCO3–Ca [0.71 (wet) and 0.55 (dry)], TH – Ca [r = 0.70 (wet) and 0.83 (dry)], and TH – Mg [r = 0.69 (wet) and 0.67(dry)] which indicated similar sources and/or geochemical behaviour during ionic mobilization (Tiwari et al. 2015). The positive correlations between Cl – Na [r = 0.67 (wet) and 0.62 (dry)] indicated that Cl and part of the Na were derived from anthropogenic sources (Tiwari and Singh 2014). The good correlation between Ca – SO4 [0.61 (wet) and 0.62 (dry)] indicated that gypsum dissolution could be the major contributor for the dissolved ions in the water of study area.

Table 7 Correlation matrix of the chemical constituents of the ground water samples in the wet season (taking average of all wet seasons)
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Table 8 Correlation matrix of the chemical constituents of the ground water samples in the dry season (taking average of all dry seasons)
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However, no such significant relationships were observed in between the other constituents of the ground water samples.

Conclusion

Hydrochemical analysis in and around Jia Bharali river basin showed that majority of the shallow wells had preponderance of alkaline earths (Ca, Mg) and weak acids (HCO3) over alkalis (Na, K) and strong acids (SO4, Cl), thereby indicating calcium and magnesium bicarbonate type of water. Major cations Ca, Mg, Na, and K as well as major anions HCO3, Cl, SO4, and NO3 were found well within maximum permissible limits for drinking and irrigational purposes. Majority of the wells were found to come under the ‘excellent’-to-‘good’ category for irrigation purposes with respect to Electrical Conductivity values. The ground water regime was also free from alkalinity, chloride, and nitrate-nitrogen hazard. Low RSC (1.25 meq/L) and SAR (< 10) implied suitability of shallow wells for irrigation purposes, while a few wells found unfit for agricultural uses due to high Na% (> 60%) and Kelly’s Index (> 1). The results also revealed that a number of water sources are not suitable for drinking and agricultural uses due to the presence of excess trace metals like Cd, Cr, Fe, Mn, Ni, and Pb. Hence, this study suggests some limitations in the use of the shallow alluvial hand dug wells for drinking and irrigational purposes with respect to health hazard in the localities.