HYDROCHEMICAL APPRAISAL OF GROUND WATER QUALITY AND ITS WATER QUALITY INDEX: A CASE STUDY IN MATHURA DISTRICT, INDIA

Salman ahmed 1 , shadab khurshid 1 , ali p. Yunus 2 and sanjay kumar koli 3 . 1. Department of geology, Aligarh Muslim university, Aligarh 202 002, India. 2. Department of Remote Sensing and GIS Applications, Aligarh Muslim University, Aligarh 202 002, India. 3. Ch. Brahm Prakash Government Engineering College. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Because freshwater sustains life, a large number of studies have focused on groundwater quality research that has been impacted by natural causes as well as human intervention. Contemporary studies on water quality research relies extensively on analytical techniques, isotopic measurements, numerical modelling and remote sensing techniques coupled with GIS models (Li, 2016). Several studies have found that contaminated groundwater can harm humans and plants (Bhutiani et al. 2016; El-Salam and Abu-Zuid, 2015). Arsenic contamination in groundwater has been well documented in IGB and other parts of India and Bangladesh (Chakraborti et al. 2009 ). Physio-chemical characteristics of groundwater such as pH, total dissolved solids (TDS), magnesium (Mg), sodium (Na), iron (Fe), calcium (Ca), manganese (Mn), lead (Pb), nitrate (NO 2 ) and nitrite (NO 3 ), and bicarbonate levels (HCO 3 ) have been intensively studied for measuring and understanding the quality of water. The concentrations of salts are related to the specific conductivity of water along with the related proportion of bicarbonates to calcium and magnesium. When salts are present beyond a certain limit in water and used for drinking or irrigation, such water harms human health and plant growth (Purushotham et al., 2011).
A water crisis in Mathura district, Uttar Pradesh, India has aggravated recently due to the drying of surface water and depletion of groundwater levels. The over abstracting of groundwater for irrigation and improper fertilizer practices leads to salt intrusion, soil salinization and importantly contamination. This study attempts to identify potential groundwater prospect zones that are safe for drinking and irrigation in Mathura district by employing analytical techniques and GIS.
Study Area:-Mathura, one of the most populated district (2.5 bn) in Uttar Pradesh, India is a sacred place for believers of Hindu faith. The investigated area lies between latitudes 27° 14′ and 27° 17′ N and longitudes 77° 17′ and 78° 12′ E and covers about 3339 sq. Km. The average monthly maximum temperature varying between about 36 º C and 47 º C in summer and 25 º C and 32 º C in winter, and annual rainfall is 826 mm. The study region falls in the Survey of India toposheet no 54E and 54I. The only drainage in the area is the Yamuna river which enters the area from the north and after following a meandering course is passed out of the area in the SSE direction into the Agra distract. The persistent problem of high salinity and concentrations of other chemicals in groundwater is reported in previous studies (CGWB, 2012). Physiographically the region is divided into older and newer alluvial plains. The older alluvial plains are flat to gently undulating alluvial tracts. In the marginal tracts of Yamuna in the southern part, badlands and ravenous tracts are developed. Major soil types are silty, sandy and loamy soils. According to Central Ground Water Board, India, there are 61456 tube wells and borewells reported in this region. During pre-monsoon periods the water is 2.65 to 14.34 m below ground level (bgl)and during post-monsoon, the levels are between 1.33 to 14.0 m bgl (CGWB, 2012).
The geology of the study area is covered with the homogenous formation and does not show any significant structural complications. The litho-unit met within the area has been tentatively grouped under Kaimur Formation and is delivered at a lower place: Quaternary alluvium consisting of mainly sands of various grade silt, clay and kankar except for a few NE-SW trending ridges, which expose the Delhi Super Group of rocks in the west (Table  1).
1132  Oxidised, Khaki to brownish yellow silt, clay with kankar disseminations, and grey to brown fine to medium grained sand Upper Bhander sandstone, Quartzite, Phyllite and shale Group.

Methodology:-
Groundwater samples for 65 locations were collected from government hand pumps from different parts of Mathura district. Analysis of ions was carried out on the basis of methods given by APHA (American Public Health Association, 2005). Calcium (Ca 2+ ), total hardness (TH), bicarbonate (HCO 3 -) and chloride (Cl -) were analysed by volumetric titration method. Sodium (Na + ) level is analyzed by Systronic flame photometer (UV-VIS) model. Nitrate (NO 3 -) and sulphate (SO 4 2-) were analysed by UV spectrophotometer. The concentration of EC is expressed in microsiemens/cm at 25ºC whereas TDS, TH, Ca +2 , Mg +2 ,Na + , Cl -, SO 4 , NO 3 , HCO 3 and Fare expressed in mg /l. The piper trilinear plot and USSL (sodium adsorption ratio vs conductance) diagram were plotted based on the hydrochemical results to assess the quality controlling mechanism and dominated hydro-geochemical facies of the study area. Statistical analysis was performed using the SPSS software package (SPSS, 2001). The physio-chemical parameters analysed for groundwater were compared with standard values recommended by the WHO, BIS and WQA.
ArcGIS and Surfer software were used to represent the spatial distribution maps of physio-chemical parameters. To prepare the integrated water quality map, the individual physico-chemical parameters rasters were added in the raster calculator according to the relative importance of each parameter in the overall quality of water for drinking and irrigation water purposes. The integrated water quality map is then interpreted in a GIS environment to determine the suitable ground water sites.
A land use and cover (LULC) map for the study area is generated with the help of Landsat 8 OLI image acquired on 30 th January 2016. Four classes of LULC are identified from the imagery and they are classified based on the supervised classification techniques in ENVI. The four classes identified are :i) agriculture land, ii) built-up area, iii) waterbodies and iv) wasteland/barren land.
Water Quality Index:-WQI is one of the most effective tools to monitor the surface as well as groundwater pollution and can be used efficiently in the implementation of water quality upgrading programmes. WQI provide information on a rating scale from zero to hundred. Eleven parameters have been selected for developing the water quality index.
In the present study, the WQI has been calculated in three steps. In the first step, each of the 11 parameters (PH, TDS, HCO 3 , Cl, SO 4 , NO 3 , F, Ca, Mg, Na and K) has been assigned a weight (w i ) according to its relative importance in the overall quality of water for drinking purposes in Table 1. The maximum weight of five has been assigned to the parameter nitrate due to its major importance in water quality assessment. Bicarbonate is given the minimum weight of 1 as it plays an insignificant role in the water quality assessment. Other parameters like calcium, magnesium, sodium and potassium were assigned a weight between 1 and 5 depending on their importance in water quality determination. In the second step, the relative weight (W i ) is computed from the following equations Wi and wi is the relative weight and weight of each parameter, respectively, and n is the number of parameters.
In the third step, a quality rating scale (Qi) for each parameter is assigned by dividing its concentration in each water sample by its respective standard according to the guidelines laid down in the BIS and the result for the same is multiplied by 100 (Equation 2) 1134 where, Qi is the quality rating, Ci is the concentration of each chemical parameter in each water sample in mg/L. Also Si is the Indian drinking water standard for each chemical parameter in mg/L according to the guidelines of the BIS.
For computing the WQI, the SI is first determined for each chemical parameter, which is then used to determine the WQI as per the following Equations (3 and 4)  where SI i is the sub-index of the ith parameter, Q i is the rating based on the concentration of i th parameter, n is the number of parameters.
The computed WQI values are categorized into five types as "excellent water" to "water, unsuitable for drinking". The range for WQI for drinking purpose is tabulated in Table 2.

Total Dissolved Solids (TDS):-
Total dissolved solids, the concentration of total inorganic salts and a small amount of organic salts dissolved in the water is another important physio-chemical parameter determining the water quality. TDS in groundwater samples ranges from 848 mg/l to 17172 mg/l with a mean of 4963 mg/l in 65 samples. However, the desirable limit of TDS 1135 in water for drinking as prescribed by WHO (2006) and BIS (2012) is 500mg/l. All the 65 samples collected in this study area are higher than the permissible limit indicating severe contamination and health threat. Based on Todd (1980), about 87 percent of groundwater is classified as brackish (TDS between 1000 to 10000 mg/), about 12 percent is saline (10,000 to 1,000,000 mg/l) and less than 1 percent fresh water (TDS < 1000 mg/) Sodium, Calcium and Magnesium:-Sodium, the dominant substances in general water has a permissible limit of 200 mg/l according to the WHO standards. The concentration of Na+ in the collected samples ranges from 45 mg/l to 2200 mg/l with a mean value of 562 mg/l. More than 86 per cent of samples lies above the prescribed limit. The high concentrations may be due to the deposition of salts from silicate bearing minerals as well as from fertilizers. The values of calcium range from 4.8 mg/l to 881.2 mg/l with a mean value of 82.5 mg/l ( Table 2) The TH in the study area varies between 180 to 4700 with a mean value of 1306 mg/l. The WHO standards for TH is 500 mg/l suggesting 80 per cent of water samples collected are undesirable for drinking.

Bicarbonate, Sulphate, Nitrate and Chloride:-
In general, bicarbonate ion concentration in water are due to chemical dissolution of carbonate rocks and some parts dissolved CO 2 in rain water. The concentration of HCO 3 is observed from 39 mg/l to 1027 mg/l, with a mean value of 465.5 mg/l that exceeds the maximum permissible limit (200 mg/l). Sulphate is derived mainly from the sulphide minerals present in igneous and metamorphic rocks. Anhydrites in sedimentary rocks also contribute to sulphate ion. The value of sulphate in the study area varies from 5.1 mg/l to 2237 mg/l, with more than half (61%) of the analyzed samples exceeding the permissible limit (200 mg/l). Nitrate in groundwater is mainly contributed from the decay of organic matter, sewage waste and application of fertilizers. The value ranges from 0 mg/l to 149.32 mg/l. Chloride salts are highly soluble and free from a chemical reaction with the mineral of reservoir rock and remain in the form of sodium chloride. High concentration of chloride indicates a higher degree of organic pollutant. The maximum permissible limit given by WHO (2006) is 250 mg/l. The value ranges from114 mg/l to 3905 mg/l.   1138

Piper trilinear diagram:-
Piper plots (also known as Piper trilinear diagrams) are robust tools for visualizing the relative abundance of common ions present in groundwater (Piper A.M., 1953). The piper plots are explained using the facies classification of Back and Hanshaw (1965). It has been extensively used in groundwater hydrology in order to determine whether water is suitable for human consumption. Differences and similarities within groundwater samples can be identified from the trilinear plot, because the water of similar qualities will the occupy same space as groups. For plotting the diagram, sample concentrations are normalized to 100 (sum of cations = 100; and the sum of anions = 100), for calculations to be made on a percentage basis. The plots in figure 2 show that the alkali concentrations are abundant constituting 71% of cations; whereas 10% of samples exhibit no dominant character. Calcium represents 3% of the samples; and 16% are comprised of magnesium type. About 75% of the samples exhibit chloride, 21% of the total samples shows no dominant character and 4% of the sample are rich in sulphate anions. Interpretation of diamond plots indicates sodium chloride waters and calcium sulfate waters dominate the study region followed by a small percent of sodium bicarbonate waters.

USSL Diagram:-
The quality of water for irrigation purpose can be tested using the sodium adsorption ratio (SAR). It is an indicator of the suitability of the water for agricultural irrigation, as it quantifies the amount of sodium relative to calcium and magnesium in the water. The US Salinity Laboratory classification for classification of ground water is shown in Figure 3. This diagram plots SAR against the conductance. The data plotted on the USSL Diagram in Figure 3 illustrates that most of the groundwater samples fall in the field of C3S1, C4S3 and C4S2 indicating high to very high salinity and low to high sodium water type which can be unsuitable for irrigation purposes. LULC Map:- Figure 4 shows the land use and cover prepared from Landsat 8 OLI image using a supervised classification technique. More than 78 % of the study area falls under the agriculture land category. Wasteland (barren) accounts for 6 % of the Mathura district. Surface water bodies occupies about 1 % of the total area. The settlements (built-up area) which accounts for more than 14% are located largely on the banks and flood plains of Yamuna River. As seen from the LULC map and field observations, the agricultural land extracts large amounts of water for irrigation. This causes the depletion of water resources and saline intrusion. Apart from this issue, fertilizers added to these cultivated lands leach into the groundwater and pollute the aquifers. Figure 4:-Satellite imagery and land use/land cover map for the study area. Note that 78% of the area is covered with agricultural land. Figure 5 shows the iso-concentration contour lines for various physio-chemical parameters analysed using inverse distance weight (IDW) interpolation in a GIS environment. Red contours show the areas above permissible limits. Large variations in nitrate concentrations are observed in Figure 5a,. The highest concentrations are noticed at the central and north Mathura blocks. Permissible limits of NO 2 concentrations are observed as patches in southern and north eastern regions. Figure 4b shows the spatial distribution of sulphate concentrations. Similar to NO 2 , sulphate are also highest at the central region with patches of permissible limits at the margins of the district boundary. The bicarbonate concentration map shown in Figure 5c suggests that except for some patches in central and sothern Mathura, most of the regions are covered under the permissible category. TH is found highest for the whole of Mathura district (Figure 5d); whereas calcium concentration is highest only in the western Mathura (Figure 5e). Similar to the TH map, sodium and magnesium are also found in the non-permissible category for the entire Mathura suggesting a severe threat to human health for those consuming these waters (Figure 5f and 5g). Chloride is found in higher concentrations in the western part of the City of Mathura (Figure 5h). Except for minor patches in the eastern part, electrical conductivity and TDS are found highest for large parts of Mathura district (Figure 5i and 5j).

Spatial distribution characteristics:-
The integrated groundwater quality map (Figure 5k) has categorized the region into five classes on the basis of the overlay analysis applied to different features of the thematic maps. The classes are namely i) desirable for drinking and irrigation, ii) desirable for irrigation, iii) moderately desirable for irrigation, iv) low desirability for irrigation, 1140 and iv) undesirable. Based on the overlay analysis for desirable groundwater sources, it is found that only 2% of the area in Mathura district is desirable for extracting drinking water according to the WHO standards, 18% of area is desirable for extracting water for irrigation, 45% under moderate category, 29% occupies low desirability category and 4% in the undesirable category for the study area.
It can be observed from our study that most parts of the Mathura district in

Conclusion:-
Analytical techniques coupled with GIS and remote sensing approaches have been used to identify suitable groundwater sites in Mathura district for drinking and irrigation purposes. The results show that water quality in most parts of the study area is unsuitable for drinking and irrigation. The suitable sites identified based on the spatial distribution characteristics are located at north-east and southern parts of Mathura district. The major cause of the high concentration of different water quality parameters is geogenic. The suitable groundwater zonation map generated through analytical analysis, remote sensing and GIS ascertains the applicability of coupled models and necessity of regional-scale analysis. It is suggested that proper treatment methods and measures should be implemented before consumption of the water for drinking and irrigation. Furthermore, to tackle the ground water depletion in the region, it is recommended to adapt sprinkling irrigation for proper utilization of water resources and to overcome the shortage of water faced in future.