Assessment of seasonal variations in surface water quality

Proc. Natl. Acad. Sci., India, Sect. A Phys. Sci. DOI 10.1007/s40010-014-0195-8 RESEARCH ARTICLE Assessment of Seasonal Variations in Surface Water Quality of Bageshwar District, Uttarakhand, India for Drinking and Irrigation Purposes Richa Seth • Manindra Mohan • Prashant Singh • Rakesh Singh • Vinod K. Gupta • Rajendra Dobhal • Devi P. Uniyal • Sanjay Gupta Received: 16 August 2013 / Revised: 18 September 2014 / Accepted: 22 November 2014 Ó The National Academy of Sciences, India 2015 Abstract The seasonal variation in surface water quality of district Bageshwar, Uttarakhand (India) has been evaluated for 3 years from 2010 to 2012 for determining the suitability of water for drinking and irrigation needs. Water samples collected from different drinking water sources during pre-monsoon and post-monsoon seasons in each year were analysed for 23 water quality parameters including physico-chemical and metal analyses. The analysed water quality parameters show seasonal variation and low concentration in post-monsoon season compared to pre-monsoon season due to dilution effects. The Box and Whisker plots indicated the dominance of major cations and anions in order of Ca2? [ Mg2? [ Na? [ K? and HCO3- [ SO42- [ Cl- in both seasons, respectively. Piper trilinear diagram showed that most of the water samples fall in Ca–Mg–HCO3 hydrogeochemical facies. The water quality index revealed deteriorated water quality R. Seth  M. Mohan  P. Singh (&) Department of Chemistry, DAV (PG) College, Dehradun 248001, Uttarakhand, India e-mail: prashant.ucost@gmail.com R. Singh Department of Chemistry, DBS (PG) College, Dehradun 248001, Uttarakhand, India V. K. Gupta Department of Chemistry, Indian Institute of Technology, Roorkee 247667, Uttarakhand, India R. Dobhal  D. P. Uniyal Uttarakhand State Council for Science and Technology (UCOST), Dehradun 248007, Uttrakhand, India S. Gupta Department of Biotechnology and Biochemistry, SBSPGI, Balawala, Dehradun 248161, Uttarakhand, India at some of the sources during pre- and post-monsoon seasons. The Wilcox diagram and calculated sodium adsorption ratio, residual sodium carbonate and sodium percent values indicate that the water was suitable for irrigation purposes in both the seasons. The results concluded that water quality at some of the locations is deteriorating and needs proper monitoring to preserve and maintain its quality to reduce hazards to local population. Keywords Water quality  Box and Whisker plot  Wilcox classification  Seasonal variation  Piper trilinear diagram 1 Introduction Over exploitation of surface water sources during last decade in different parts of the world has resulted into water pollution and scarcity. Water pollution not only affects the water quality but also threats human health, economic development and social prosperity [1]. Availability of safe and reliable surface water resources for drinking purpose is essential for the sustainable ecosystem. The quality and quantity of surface water within the region is governed by its chemical compositions, therefore monitoring of physico-chemical properties of surface water is used to assess the water reliability for various purposes [2, 3]. Surface water, one of the most important sources of water for human need, is unfortunately under sever environmental stress and being threatened as consequences of developmental activities. High risk of pollution due to easy accessibility for disposal of wastewater highlights significance to control water pollution and monitor water quality of surface water sources [4]. 123 R. Seth et al. Natural as well as anthropogenic activities are controlling the surface water chemistry. Variety of anthropogenic activities such as municipal and industrial waste discharge, agricultural activities are deteriorating the surface water quality and impair its use for drinking, industrial, agricultural, recreational and other purposes [5]. The anthropogenic discharge constitutes a constant polluting source whereas, surface runoff, a seasonal phenomenon, is largely affected by climate within the region [6–8]. Quality of water changes with respect to their spatial distribution and time. Temporal variation in precipitation, surface run-off, interflow and groundwater flow strongly affects the surface water quality [9, 10]. For controlling the deterioration of surface water quality, it is important to develop a monitoring program, for assessing the pollution sources and understanding the environmental conditions of site and provide overall reliable estimation for proper management of water resources [11, 12]. Therefore, evaluation of the quality and quantity of water and establishing the data base are important for future water resources development strategies. Traditionally, assessing of surface water quality is based on the comparison of experimentally determined parameter values with existing local normatives. In many cases, the use of this methodology allows for a proper identification of contamination sources and may be essential for checking legal compliance and give a proper vision on the spatial and temporal trends in the overall water quality in a watershed [13–15]. With the above background and in the continuation of our previous studies [16–18] of different districts of Kumaun region, the present work has been designed to evaluate the surface water quality of district Bageshwar, Uttarakhand, India for drinking and irrigation purposes by analysing the physico-chemical parameters and heavy metal contents in water. The effects of seasonal variation and proximity to pollution source on the concentration of the parameters are also evaluated. The major cations and anions are plotted on Piper trilinear diagram using AquaChem software version 2011.1 to assess the hydrochemical facies. The surface water quality for drinking purpose has been classified on the basis of water quality index (WQI) and irrigation purpose by Wilcox classification, sodium adsorption ratio (SAR), residual sodium carbonate (RSC) and sodium percent [Na %]. The results of the analyses highlight the importance for proper management and regular monitoring of water quality. 2 Study Area Bageshwar is one of the mountainous district of Uttarakhand state of India. Prior to its formation as a separate 123 district, Bageshwar constituted a part of Almora district. The district lies between latitudes 298400 and 308200 N and longitudes 798250 and 808100 E. Bageshwar district is bounded by Almora district in south, Chamoli district in North and Northwest and Pithoragarh district in the East. The geographical area of the district is 1,687.8 km2 and the population is about 259,840 according to Census 2011. Physiographically, the area can be divided into central Himalayan zone and lesser Himalayan zone. The general slope is towards south and in the northern parts, the elevation of the land surface ranges from about 3,000–6,861 m above mean sea level, whereas, in the valleys of southern part, the altitude is as low as 795 m [19]. The study area experiences temperate to sub-humid climate. The mean annual temperature in summer ranges from 15 to 25 °C and in winter varies from 2 to 10 °C. The total annual rainfall is 1,611 mm. Rainfall begins in June and continues up to the end of September. 3 Materials and Methods 3.1 Sample Collection Procedure The water samples were collected from six locations of Bageshwar district during pre-monsoon (PRM) and postmonsoon (POM) seasons in the years 2010–2012 during the months of April to June and October to December, respectively. The detail of sampling sites with GPS coordinates and elevation is given in Table 1 and illustrated in Fig. 1. The water samples were sampled in cleaned, rinsed and sterilized Tarson bottles separately for physico-chemical and metal analyses. For metal analysis, the water samples were preserved by adding ultra pure nitric acid [3 ml/l diluted (1 ? 1)]. These samples were brought to laboratory by maintaining temperature below 4 °C. 3.2 Analytical Method The physico-chemical parameters like pH and turbidity were analysed on site. The other parameters such as electrical conductivity (EC), alkalinity, bicarbonate, hardness, total dissolved solids, nitrate, chloride, fluoride, sulfate, aluminum, calcium, manganese, cadmium, chromium, copper, iron, sodium, potassium, magnesium, lead and zinc were analysed in laboratory as per Bureau of Indian Standards [20] and American Public Health Association specifications [21]. The colorimetric analyses such as fluoride, nitrate and sulphate were measured using Pharo 300 Spectrophotometer (Merck). The metal ions analyses were performed on Varian-AA240 Atomic Absorption Spectrophotometer (AAS). Assessment of Seasonal Variations in Surface Water Quality Fig. 1 Sampling sites of Bageshwar district of Uttarakhand, India 123 R. Seth et al. Table 1 The detail of sampling sites of Bageshwar district of Uttarakhand, India Site no. Source Location Longitude 1 Saryu river Bageshwar N29°510 04.300 0 Latitude Elevation (m) E79°460 59.800 876 00 2 Balen gadhera Kafkot N29°58 05.7 E79°520 35.800 1,280 3 Gadera gadhera Bhayon N29°550 50.500 E79°540 23.900 1,210 0 00 0 00 4 Group nala Gadera N29°51 43.0 E79°56 10.5 1,347 5 Garud ganga Anna-Bamna N29°530 47.200 E79°340 25.600 1,247 6 Tikta gadhera Bijori Jhal N29°530 34.700 E79°420 22.500 1,115 4 Results and Discussion The statistics of surface water chemistry for samples collected from Bageshwar district during PRM and POM seasons from years 2010 to 2012 are given in Table 2 and shown in Fig. 2a–j for parameters having values more than the limits as per BIS (1991). Turbidity measures the water clarity and depends upon the nature of water bodies. Turbidity values ranged from 0.6 to 22 NTU during PRM season and 3.5 to 115 NTU during POM season. Turbidity values were found higher in POM season compared to PRM season and exceeded the permissible limit of 10 NTU. The pH of the water samples fluctuated in limited range from 7.89 to 8.49 in PRM season and 7.55 to 8.47 during POM season, which indicate water is slightly alkaline in nature. EC is directly related to concentration of ions dissolved in water. EC varies between 179 to 1,409 lS/cm in PRM season and 119 to 958 lS/cm in POM season. The relativity higher values of EC in the present study area can be attributed due to higher amount of TDS in water samples. TDS mainly consists of inorganic salts and it has been seen that water containing TDS more Table 2 Statistics of water quality parameters of Bageshwar district in PRM and POM seasons Parameters Turbidity, NTU BIS:10500 Pre-monsoon Post-monsoon Desirable limit Permissible limit Min. Max. Average 5 10 0.6 22 8.93 SD 5.78 Min. Max. Average 3.5 115 25.52 SD 32.00 pH 6.5 8.5 7.89 8.49 8.33 0.19 7.55 8.47 8.01 0.31 EC, lS/cm – – 179 1,409 663 407.79 119 958 431 258.72 TDS, mg/l 500 2,000 119 932 438 272.52 78 633 268.39 172.58 Total hardness, mg/l 300 600 55 589 265 167.66 37 288 143.65 85.02 Alkalinity, mg/l 200 600 54 412 205 122.47 28 276 129.67 83.74 Fluoride, mg/l 1.0 1.5 0.27 0.95 0.56 0.20 0.17 0.54 0.32 0.09 Nitrate, mg/l Calcium, mg/l 45 75 No relax 200 0.60 15 4.20 132 2.62 60.36 1.01 39.05 ND 8.81 2.80 82 1.26 36.81 0.89 23.26 Magnesium, mg/l 30 100 4.37 55 24.65 14.43 2.28 36 15.06 9.81 Sodium, mg/l 20a No relax 3.72 8.29 5.89 1.28 2.93 6.77 4.74 1.11 Potassium, mg/l – – 1.44 4.56 2.93 1.00 1.09 4.05 2.48 0.90 Bicarbonate, mg/l – – 66 503 250 149.41 34 337 158.19 Sulphate, mg/l 200 400 ND 140 32.71 39.48 ND 56 6.89 14.17 Chloride, mg/l 250 1,000 8.1 42 22.01 9.33 7.3 31 16.84 6.74 Iron, mg/l 0.3 1.0 0.032 3.480 0.456 0.798 0.021 0.190 0.069 0.039 Copper, mg/l 0.05 1.5 0.001 0.034 0.009 0.007 0.001 0.006 0.003 0.002 Manganese, mg/l 0.1 0.3 0.003 0.231 0.058 0.062 0.002 0.102 0.023 0.024 Cadmium, mg/l 0.01 No relax 0.000 0.009 0.004 0.002 0.001 0.005 0.002 0.001 Chromium, mg/l 0.05 No relax 0.004 0.046 0.015 0.011 0.001 0.021 0.004 0.005 Lead, mg/l 0.05 No relax 0.005 0.044 0.027 0.016 0.003 0.032 0.015 0.011 Aluminum, mg/l 0.03 0.2 0.009 0.038 0.022 0.009 0.003 0.180 0.020 0.040 Zinc, mg/l 5 15 0.054 1.586 0.639 0.555 0.012 0.932 0.305 0.351 ND not detected, SD standard deviation a As per WHO guidelines 123 102.17 Assessment of Seasonal Variations in Surface Water Quality than 500 mg/l causes gastrointestinal irritation. During the monitoring, TDS values varied from 119 t o 932 mg/l in PRM season and 78–633 mg/l in POM season and exceeded the desirable limit of 500 mg/l in both the seasons but found within permissible limit of 2,000 mg/l. The values of hardness ranged from 55 to 589 mg/l and 37 to 288 mg/l in PRM and POM seasons, respectively. The values were found higher in PRM season and exceeded the desirable limit of 300 mg/l but within permissible limit of 600 mg/l as per BIS. The concentration of alkalinity in surface water is measured by the ability of water to neutralize acid. The values during PRM and POM seasons ranged from 54 to 412 mg/l and 28 to 276 mg/l, respectively. All the samples were found within permissible limit of 600 mg/l in both the seasons but more than the desirable limit of 200 mg/l, which may be ascribed due to the action of carbonates upon basic material in the soil. Fluoride and nitrate concentration in all the water samples were found quite low and values ranged from 0.27 to 0.95 mg/l and 0.60 to 4.20 mg/l in PRM season and 0.17 to 0.54 mg/l and ND to 2.80 mg/l in POM season, respectively. The concentration of major cations such as [Ca2?] and [Mg2?] were found higher in PRM season and varied from 15 to 132 mg/l and 4.37 to 55 mg/l than POM season concentration which varied from 8.81 to 82 mg/l and 2.28 to 36 mg/l, respectively. [Ca2?] and [Mg2?] values in PRM and POM seasons were found more than desirable limits of 75 and 30 mg/l at some of the sites but within permissible limits of 200 and 100 mg/l, respectively. The concentration of sodium and potassium ranged from 3.72 to 8.29 mg/l and 1.44 to 4.56 mg/l, respectively in PRM season, whereas in POM season, the values varied from 2.93 to 6.77 mg/l and 1.09 to 4.05 mg/l, respectively. The concentration of major anion such as [HCO3-] was found higher in PRM season and values varied from 66 to 503 mg/l compared to the values of POM season which ranged from 34 to 337 mg/l. The concentration of [SO42-] and [Cl-] in PRM seasons ranged from ND to 140 mg/l and 8.1 to 42 mg/l, respectively while, in POM season, ND to 56 mg/l and 7.3 to 31 mg/l, respectively. In both seasons, the concentration of [SO42-] and [Cl-] were found within desirable limits of 200 and 250 mg/l and permissible limits of 400 and 1,000 mg/l, respectively as per BIS. The concentration of various heavy metals in PRM and POM seasons during the years of study were also determined and are presented in Table 2. Fe concentration oscillated from 0.032 to 3.480 mg/l in PRM season and 0.021 to 0.190 mg/l in POM season. Fe values in water samples during PRM season were found higher than desirable limit of 0.3 mg/l and permissible limit of 1.0 mg/l of BIS. The concentration of Cu and Mn in PRM season ranged from 0.001 to 0.034 mg/l and 0.003 to 0.231 mg/l, respectively whereas; in POM season the values were 0.001 to 0.006 mg/l and 0.002 to 0.102 mg/l, respectively. Concentration of Cu in all water samples were found within desirable limit of 0.05 mg/l whereas, the Mn concentration exceeded the desirable limit of 0.10 mg/l but within the permissible limit of 0.3 mg/l. The value of Cd and Cr in PRM season varied from ND to 0.009 mg/l and 0.004 to 0.046 mg/l and in POM season 0.001 to 0.005 mg/l and 0.001 to 0.021 mg/l, respectively. The values of Cd and Cr were analysed in trace amount and were found within prescribed desirable limit of 0.01 and 0.05 mg/l, respectively as per BIS. Similarly, Al and Zn metal concentration were also found quite low in water samples compared to desirable limits of 0.03 and 5.0 mg/l and permissible limits of 0.2 and 15 mg/l, respectively. The concentrations of Pb in water samples during PRM season ranged from 0.005 to 0.044 mg/l and 0.003 to 0.032 mg/l in POM season and were within desirable limit of 0.05 mg/l of BIS. Box and Whisker plots represent the seasonal trends of the major cations and anions as shown in Fig. 3. The top and the bottom of a rectangle box represent upper quartile and lower quartile of the data. The line inside the box represents the median value and the size of the box represents the spread of the central value. The trend of major cations and anions were in the order of Ca2? [ Mg2? [ Na? [ K? and HCO3- [ SO42- [ Cl-, respectively in both PRM and POM seasons. Major cations [Ca2?], [Mg2?] and major anions [HCO3-] and [SO42-] showed increasing trend in PRM season compared to POM season, which may be ascribed due to dilution effects [22, 23]. 4.1 Hydrochemical Facies The hydrochemical facies of water can be obtained through Piper trilinear diagram [24]. Geometrical combination of two triangles (outer) and one diamond shaped quadrilateral (middle or inner) constitute Piper diagram. This diagram effectively classifies the water quality by the distribution of major cations like [Na?], [K?, Ca2?] and [Mg2?] and some major anions like [Cl-], [SO42-], [CO32-] and [HCO3-]. The diagram represents the cations and anions composition of water samples on a single graph in which major groupings or trends in the data can be distinguish visually [25]. The distribution of major cations and anions in meq/l are shown by the left and right and these plotted points in the triangular fields are projected further into the central diamond-like quadrilateral structure, which provides the overall characters of the water samples. Piper diagrams of water samples of PRM and POM seasons presented in Fig. 4. The plots revealed that in all the water sample, alkali earth metals elements [Ca2? ? Mg2?] are higher than alkali elements [Na? ? K?] and weak acids are [CO32- ? HCO3-] are 123 R. Seth et al. a 140 Site 1 Site 2 Site 3 Site 4 Site 5 Site 6 b pH Turbidity, NTU 80 60 7.4 20 7.2 7 Pre-2011 Post-2011 Pre-2012 Post-2012 1600 1200 1000 800 600 400 200 Pre-2010 d 700 Total Hardness, mg/l Post-2010 1400 ,EC,µ/.cm 8 7.8 7.6 40 Pre-2010 600 0 300 TDS, mg/l Alkalinity, mg/l 350 250 200 150 100 50 0 120 300 200 100 1000 900 800 700 600 500 400 300 200 100 0 60 50 Mg, mg/l 100 Ca, mg/l Post-2012 Pre-2010 Post-2010 Pre-2011 Post-2011 Pre-2012 Post-2012 h 140 80 60 40 40 30 20 10 20 0 0 Pre-2010 Post-2010 Pre-2011 Post-2011 Pre-2012 Post-2012 Pre-2010 Post-2010 Pre-2011 Post-2011 Pre-2012 Post-2012 Bicarbonate, mg/l Pre-2012 400 Pre-2010 Post-2010 Pre-2011 Post-2011 Pre-2012 Post-2012 500 Post-2011 Pre-2010 Post-2010 Pre-2011 Post-2011 Pre-2012 Post-2012 f 400 600 Pre-2011 0 450 i Post-2010 500 Pre-2010 Post-2010 Pre-2011 Post-2011 Pre-2012 Post-2012 g Site 3 Site 6 8.2 100 0 e Site 2 Site 5 8.4 120 c Site 1 Site 4 8.6 j 4 3.5 3 Iron, mg/l 400 300 200 2.5 2 1.5 1 100 0.5 0 0 Pre-2010 Post-2010 Pre-2011 Post-2011 Pre-2012 Post-2012 Pre-2010 Post-2010 Yearl y seasonal varartion Pre-2011 Post-2011 Pre-2012 Post-2012 Yearl y seasonal varartion Fig. 2 a–j Yearly seasonal variation (time series) plots for various water quality parameters higher than the strong acids [Cl- ? SO42-]. The diagrams showed that the entire water samples during the study fall in the field Ca–Mg–HCO3 type except water sample of Saryu 123 which was dominated in of Ca–Mg–HCO3–SO4 during PRM season and Gadera sample which was dominated with Ca–Mg–HCO3–Cl in POM season. Assessment of Seasonal Variations in Surface Water Quality Fig. 3 Box and Whisker plots for seasonal variation of major ions in water samples in PRM and POM seasons 550 500 450 400 350 300 250 200 150 100 50 0 550 500 450 400 350 300 250 200 150 100 50 0 PRM Season Ca Mg Na K HCO3 Cl SO4 POM Season Ca Mg Na K HCO3 Cl SO4 4.2 Water Quality Parameters for Drinking and Irrigation Purposes steps are followed. In first step weightage of each parameter is computed by using following equation:The weightage of ith parameter 4.2.1 Drinking Water Quality Characterization Wi ¼ k=Si Use of WQI is an important technique for demarcating surface water quality and its suitability for drinking purpose [26–29]. WQI is a criterion of rating the water quality in terms of index number that provides composite influence of individual water quality parameters on the overall water quality at certain area. The concept of WQI represents the grading of water quality and is calculated from the point of view of human consumption. It is simple and easy to understand by decision makers about quality and possible uses [30]. The weighted arithmetic index method is commonly used for calculation of WQI using 11 water quality characteristics namely, turbidity, pH, total hardness, alkalinity, chloride, total dissolved solids, calcium, magnesium, sulphate, nitrate and iron. For computing the WQI, three where, Wi = unit weightage, Si = standard permissible values ith parameter, k = proportionally constant. Calculated unit weightage (Wi) of each of the 11 water quality parameters considered are given in Table 3. In second step, quality rating of each parameter is assigned by dividing its concentration in each water sample by its respective standards i.e. permissible limit according to the guidelines of BIS then individual quality rating is given by the expression Qi ¼ ðCi = Si Þ  100 ð1Þ ð2Þ where, Qi = quality rating, Ci = concentration of each parameter in each water sample in mg/l, Si = standard for each parameter in mg/l according to the guidelines of the BIS. Fig. 4 Piper trilinear diagram during PRM and POM seasons 123 R. Seth et al. Table 3 Unit weight of each of the physico-chemical parameters used for WQI Standard value (Permissible limit) (BIS 10500:1991) Unit weight (Wi) Turbidity, NTU 10 0.07923 pH 8.5 0.09321 Total hardness, mg/l 600 0.00132 Alkalinity, mg/l 600 0.00132 Chloride, mg/l 1,000 0.00079 Total dissolved solids, mg/l 2,000 0.00040 Water quality parameter ½Naþ  SAR ¼ qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ½Ca2þ þMg2þ  2 Calcium, mg/l 200 0.00396 Magnesium, mg/l 100 0.00792 Sulphate, mg/l 400 0.00198 Nitrate, mg/l 45 0.01761 Iron, mg/l 1 0.79227 ð4Þ where all the concentrations of ions in meq/l. In general, higher the SAR value, the water is less suitable for irrigation. The high SAR level increases the Na level in soil, which in turn can adversely affect soil infiltration and percolation rates. During monitoring, the mean value of SAR in PRM season ranged from 0.04 to 0.08 meq/l and in POM season from 0.05 to 0.07 meq/l as given in Table 9. According to classification given in Table 6, SAR value was found below 10 in both PRM and POM seasons, which indicate water is suitable for irrigation during the period of study. In the third step, the summation of these sub-indices gives the overall index. The WQI is therefore, calculated by using the following equation: . Xn Xn WQI ¼ ðWi Þ ð3Þ ð Q W Þ i i i¼1 i¼1 where, Qi = quality rating of ith parameter, Wi = unit weightage of ith parameter, n = number of parameters considered. The status of water quality for determining suitability for drinking purposes according to the WQI scale has been defined on the basis of criteria given in Table 4. The WQI values of the water sources have been determined by considering the average of respective PRM and POM seasons of the years and are provided in Table 5. During the study, the quality of water sample in PRM season ranged from excellent to unsuitable with grade A to E while in POM season excellent to very poor with grade A to D. The unsuitable and very poor water quality at site no. 1 (Saryu River) in PRM and POM seasons while poor water quality at site no. 6 (Tikta Gadhera) in PRM season is ascribe due to higher concentrations of iron and turbidity at that sites. 4.2.2 Irrigation Water Quality Characterization 4.2.2.1 Sodium Adsorption Ratio (SAR) SAR is generally used as an index for evaluating the sodium hazard Table 4 Drinking water quality rating according to WQI values WQI scale Water quality rating (WQR) 0–25 Excellent water quality A 26–50 Good water quality B 51–75 Poor water quality C 76–100 Very poor water quality D [100 Unsuitable water quality E 123 associated with an irrigation water supply. The value of SAR is calculated by using following equation [31] Grading 4.2.2.2 Wilcox Classification Wilcox classification [32] uses SAR (meq/l) and EC (mg/l) mean values for categorizing the water quality for irrigation purposes. Wilcox classification showed that the water samples in PRM season showed low sodium hazards and low to high salinity hazard, while the POM season revealed low sodium hazard and low to medium salinity hazard as shown in Fig. 5 and it is concluded that water is suitable for irrigation purposes. 4.2.2.3 Residual Sodium Carbonate (RSC) RSC is used to indicate the sodium permeability hazard and takes into account the bicarbonate/carbonate and calcium/magnesium concentration in irrigation water quality. RSC can be calculated using the following equation:   2þ  RSC ¼ CO2 þ Mg2þ ð5Þ 3 þ HCO3   ½Ca where all the concentrations of ions are in meq/l. RSC value [2.5 meq/l is unsuitable for irrigation purposes according to classification given in Table 7. During the monitoring from 2010 to 2012, the RSC mean values in PRM season ranged from -0.38 to -2.19 meq/l and from -0.28 to 0.86 meq/l in POM seasons as given in Table 9. Overall, the values of RSC lie within the scale of \1.25 meq/l showing safe/good water quality for irrigation. 4.2.2.4 Sodium Percent [Na %] Na % in water is considered vital for determining the suitability of water for irrigation purpose. Excess of sodium in water reacts with soil and reduces the soil permeability and which is not good for plant growth. Evaluation of sodium concentration in terms of [Na %] is necessary for considering the suitability of water for irrigation. Na % can be calculated by using following equation: Assessment of Seasonal Variations in Surface Water Quality Table 5 Calculated WQI values during PRM and POM seasons Site no. PRM POM Calculated WQI WQR Calculated WQI 1 144.21 Unsuitable 85.86 Very poor 2 20.79 Excellent 33.86 Good 3 27.35 Good 17.32 Excellent 4 37.85 Good 19.42 Excellent 5 28.05 Good 20.57 Excellent 6 54.13 Poor 16.45 Excellent WQR Table 6 Irrigation water quality as per SAR values SAR value Water quality Suitability for irrigation 0–10 Excellent Suitable for all types of crops and soils, except those crop, which are sensitive 10–18 Good Suitable for coarse and organic soil, unsuitable for fine textured soil 18–26 Fair Harmful for all types of soil; requires good drainage, high addition of gypsum [26 Poor Unsuitable for irrigation Fig. 5 Wilcox classification according to EC and SAR values for PRM and POM seasons Table 7 Irrigation water quality rating as per RSC values Table 8 Irrigation water quality as per Na % scale RSC value Class Na % Water class \1.25 Safe/good \20 Excellent 1.25–2.50 Marginal/doubtful 20–40 Good [2.50 Unsuitable 40–60 Permissible 60–80 Doubtful [80 Unsuitable þ ½Na % ¼ ½Ca 2þ þ ½Na þ K   100 þ Mg2þ þ Kþ þ Naþ  where all the concentrations of ions are in meq/l. ð6Þ Based on the classification given in Table 8, [Na %] in water should not be exceeded to 40–60 % in order to avoid deleterious effects on soil. During the monitoring, the mean 123 R. Seth et al. Table 9 Summary of irrigation water quality parameters during PRM and POM seasons Site no. SAR (meq/l) RSC (meq/l) Na % (meq/l) PRM POM PRM POM PRM POM 1 0.04 0.05 -2.19 -0.76 2.99 4.08 2 0.05 0.05 -1.14 -0.29 3.46 4.73 3 0.06 0.07 -0.99 -0.28 4.98 7.22 4 0.06 0.06 -0.38 -0.29 6.00 7.98 5 0.07 0.07 -0.52 -0.86 7.34 7.98 6 0.08 0.06 -0.38 -0.41 7.48 7.47 values of Na % in PRM seasons ranged from 2.99 to 7.48 meq/l while, 4.08 to 7.98 meq/l in POM seasons as shown in Table 9. In both the seasons, Na % was found less than 20 % showing excellent quality of water for irrigation. 5 Conclusion The water quality assessment revealed that water sources of Bageshwar district during 2010–2012 at some locations are influenced by various activities. The result showed higher concentration of the values of turbidity, EC, total dissolved solids, hardness, alkalinity, bicarbonate, calcium and magnesium but chloride, nitrate, fluoride and sulphate content were found within desirable limit in all the samples. All the metals were found within the desirable except the concentration of iron, which exceeded the permissible limit. The hydrochemical facies indicated that most of the water samples were of Ca–Mg–HCO3 type. The Box and Whisker plots showed that Ca2?, [Mg2?], [HCO3-], [Cl-] and [SO42-] were higher during PRM season compared to POM season. The calculated WQI revealed that few sites had very poor and unsuitable water which may be ascribed due to the presence of high concentration of turbidity and iron. Wilcox diagram and values of SAR, RSC and Na % of water samples inferred that the water is suitable for irrigation purposes. The water quality in PRM seasons of the 3 years exhibited poor water quality compared to POM seasons and this may be due to dilution due to rain in POM season. Some of the drinking water sources studied were not found suitable for drinking purposes but were suitable for irrigation purposes. The study has helped to improve understanding about the water quality of the area, which needs proper attention and management. A regular monitoring program along with determination of the cause of contamination will avoid further deterioration of water quality in the region. Acknowledgments Authors are thankful to Uttarakhand State Council for Science and Technology (UCOST), Dehradun and Uttarakhand Jal Sansthan (UJS) for financial assistance and laboratory support provided for this work. 123 References 1. Milovanovic M (2007) Water quality assessment and determination of pollution sources along the Axios/Vardar River, Southeastern Europe. Desalination 213:159–173 2. 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