determination of water quality index and suitability of an urban ...

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a district head quarter, which lies in the foothills of. Westernghats ..... in a polluted urban reservoir. Hussain Sagar, Hyderabad: Impact on water quality and.
Sengupta, M. and Dalwani, R. (Editors). 2008. Proceedings of Taal2007: The 12th World Lake Conference: 342-346

Determination of Water Quality Index and Suitability of an Urban Waterbody in Shimoga Town, Karnataka K. Yogendra* and E.T. Puttaiah Department of P.G. Studies and Research in Environmental science, ‘Jnana Sahyadri’, Kuvempu University, Shankaraghatta-577451, Shimoga, Karnataka,India. *Corresponding author: Email: [email protected] ABSTRACT The present study was intended to calculate Water Quality Index (WQI) of an urban waterbody, Gopishettykere, in Shimoga town, Karnataka in order to ascertain the quality of water for public consumption, recreation and other purposes. This paper deals with the study on the influence of environmental parameters on the water quality of waterbody. There are several ways to assess the quality of water as deemed fit for drinking, irrigation and industrial use. Water Quality Index, indicating the water quality in terms of index number, offers a useful representation of overall quality of water for public or for any intended use as well as in the pollution abatement programmes and in water quality management. A number of parameters affect the usability of water for a particular purpose. In this study Water Quality Index was determined on the basis of various physico-chemical parameters like pH, electrical conductivity, total dissolved solids, total alkalinity, total hardness, total suspended solids, calcium, magnesium, chloride, nitrate, sulphate, dissolved oxygen and biological oxygen demand.

Key words: Lentic waterbodies, Eutrophic, Physicochemical parameters and Drinking water quality

INTRODUCTION The fresh water is of vital concern for mankind, since it is directly linked to human welfare. The surface waterbodies, which are the most important sources of water for human activities are unfortunately under severe environmental stress and are being threatened as a consequence of developmental activities. Shimoga is a district head quarter, which lies in the foothills of Westernghats comprising numerous lentic waterbodies. These waterbodies are man made or artificially constructed reservoirs to provide water for irrigation purposes or domestic use. There is something very beautiful about these waterbodies not just aesthetically, but also intellectually. They do not just mirror their environment, they also reflect the society around them and accumulate all the ‘Sins’ of humanity. The condition of these waterbodies is rather pathetic. Most of the waterbodies disappeared due to encroachment and pollution. It is with this background, the present work was undertaken between April-2006 and March2007. Water quality index provides a single number that expresses overall water quality at a certain location and time, based on several water quality parameters. The objective of water quality index is to turn complex water quality data into information that is understandable and usable by the public. A single number cannot tell the whole story of water quality;

there are many other water quality parameters that are not included in the index. However, a water quality index based on some very important parameters can provide a simple indicator of water quality. In general, water quality indices incorporate data from multiple water quality parameters into a mathematical equation that rates the health of a waterbody with number. STUDY AREA Shimoga, the district head quarter is situated roughly in mid-south-western part of Karnataka state (Between 13° 27' and 14° 39' North latitude and between 74°38' and 76° 4' East longitude). It is rich in small waterbodies and most of the agricultural lands are dependent on these for water source. For the present study, an urban waterbody, Gopishettykere of Shimoga was selected. This waterbody located towards western part of Shimoga city at a distance of 3kms. The water is held by raised east-west running earthen bund, with a water spread area of about 14.99 hectares. The Karnataka Housing Board has already converted the catchment area of this waterbody into residential site. This waterbody practically receives domestic wastes and drainage water from this residential area throughout the year.

MATERIALS AND METHODS The water samples from the water body were collected at an interval of 30 days and analysed for 13 physicochemical parameters by following the established procedures. The parameters pH, electrical conductivity and dissolved oxygen were monitored at the sampling site and other parameters like total dissolved solids, total alkalinity, total hardness, total suspended solids, calcium, magnesium, chloride, nitrate, sulphate and biological oxygen demand were analysed in the laboratory as per the standard procedures of APHA (1995). In this study, for the calculation of water quality index, sixteen important parameters were chosen. The WQI has been calculated by using the standards of drinking water quality recommended by the World Health Organisation(WHO), Bureau of Indian Standards (BIS) and Indian Council for Medical Research (ICMR). The weighted arithmetic index method (Brown et. al.,) has been used for the calculation of WQI of the waterbody. Further, quality rating or sub index (qn ) was calculated using the following expression. q n = 100[V n -V io] / [S n -V io] (Let there be n water quality parameters and quality rating or subindex (qn) corresponding to nth parameter is a number reflecting the relative value of this parameter in the polluted water with respect to its standard permissible value.)

q n =Quality rating for the nth Water quality parameter Vn=Estimated value of the nth parameter at a given sampling station. Sn =Standard permissible value of the nth parameter. V io = Ideal value of nth parameter in pure water. (i.e., 0 for all other parameters except the parameter pH and Dissolved oxygen (7.0 and 14.6 mg/L respectively) Unit weight was calculated by a value inversely proportional to the recommended standard value Sn of the corresponding parameter. Wn =K/ Sn Wn= unit weight for the nth parameters. Sn= Standard value for nth parameters K= Constant for proportionality. The overall Water Quality Index was calculated by aggregating the quality rating with the unit weight linearly. WQI=∑ q n Wn/ ∑Wn Table 1. Water Quality Index (WQI) and status of water quality (Chatterji and Raziuddin 2002) Water quality Index Level 0-25 26-50 51-75 76-100 >100

Water quality status Excellent water quality Good water quality Poor water quality Very Poor water quality Unsuitable for drinking

Table 2. Drinking Water standards recommending Agencies and unit weights. (All values except pH and Electrical Conductivity are in mg/L) Sr.No.

Parameters

Standards

Recommended agency

Unit Weight

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

pH Electrical Conductivity Total Dissolved Solids Total alkalinity Total hardness Total suspended solids Calcium Magnesium Chlorides Nitrate Sulphate Dissolved oxygen Biological oxygen demand

6.5-8.5 300 500 120 300 500 75 30 250 45 150 5.00 5.00

ICMR/BIS ICMR ICMR/BIS ICMR ICMR/BIS WHO ICMR/BIS ICMR/BIS ICMR ICMR/BIS ICMR/BIS ICMR/BIS ICMR

0.2190 0.371 0.0037 0.0155 0.0062 0.0037 0.025 0.061 0.0074 0.0412 0.01236 0.3723 0.3723

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RESULTS Table 3. Seasonal variations of the physicochemical parameters of the Waterbody: Sr.No. Parameters 1. pH 2. Electrical Conductivity 3. Total Dissolved Solids 4. Total alkalinity 5. Total hardness 6. Total suspended solids 7. Calcium 8. Magnesium 9. Chlorides 10. Nitrate 11. Sulphate 12. Dissolved oxygen 13. Biological oxygen demand Water Quality Index

Rainy season 6.8 380 575 58 165 380 70 30 156 42 141 4 28 96.00

Winter Season 7.8 395 456 75 171 398 72 34 174 48 148 3.5 28 101.7

Summer season 6.2 401 590 78 175 412 75 36 178 52 151 3 33 106.3

Table 4. Calculation of Water Quality index in Rainy season Sr.No.

Parameters

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

pH Electrical Conductivity Total Dissolved Solids Total alkalinity Total hardness Total suspended solids Calcium Magnesium Chlorides Nitrate Sulphate Dissolved oxygen Biological oxygen demand

Observed values 6.8 380 575 58 165 380 70 30 156 42 141 4 28

Standard Values(Sn) 6.5-8.5 300 500 120 300 500 75 30 250 45 150 5.00 5.00

Unit Weight (Wn) 0.2190 0.371 0.0037 0.0155 0.0062 0.0037 0.025 0.061 0.0074 0.0412 0.01236 0.3723 0.3723 ∑Wn =1.51

Quality rating(qn) 13.33 126.67 115.00 48.33 55.00 76.00 93.33 100.00 62.33 93.33 94.00 80.00 133.33 ∑qn =1090.73

Wnqn 2.92 46.99 0.43 0.75 0.34 0.28 2.33 6.10 0.46 3.85 1.16 29.78 49.64 ∑Wnqn =145.04

Water Quality Index =∑ q n Wn/ ∑Wn = 96.00

Table 5. Calculation of Water Quality index in Winter season Sr.No.

Parameters

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

pH Electrical Conductivity Total Dissolved Solids Total alkalinity Total hardness Total suspended solids Calcium Magnesium Chlorides Nitrate Sulphate Dissolved oxygen Biological oxygen demand

Observed values 7.8 395 456 75 171 398 72 34 174 48 148 3.5 28

Water Quality Index =∑ q n Wn/ ∑Wn = 101.7

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Standard Values(Sn) 6.5-8.5 300 500 120 300 500 75 30 250 45 150 5.00 5.00

Unit Weight (Wn) 0.2190 0.371 0.0037 0.0155 0.0062 0.0037 0.025 0.061 0.0074 0.0412 0.01236 0.3723 0.3723 ∑Wn = 1.51

Quality rating(qn) 53.33 131.67 91.20 62.50 57.00 79.60 96.00 113.33 69.60 106.67 98.67 70.00 133.33 ∑qn= 1162.90

Wnqn 11.68 48.85 0.34 0.97 0.35 0.29 2.40 6.91 0.52 4.39 1.22 26.06 49.64 ∑Wnqn= 153.63

Table 6: Calculation of Water Quality index in summer season Sr.No.

Parameters

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

pH Electrical Conductivity Total Dissolved Solids Total alkalinity Total hardness Total suspended solids Calcium Magnesium Chlorides Nitrate Sulphate Dissolved oxygen Biological oxygen demand

Observed values 6.2 401 590 78 175 412 75 36 178 52 151 3 33

Standard Values(Sn) 6.5-8.5 300 500 120 300 500 75 30 250 45 150 5.00 5.00

Unit Weight (Wn) 0.2190 0.371 0.0037 0.0155 0.0062 0.0037 0.025 0.061 0.0074 0.0412 0.01236 0.3723 0.3723

Quality rating(qn) 53.33 133.67 118.00 65.00 58.33 82.40 100.00 120.00 71.20 115.56 100.67 60.00 157.14

∑Wn 1.51066

∑qn= 1235.30

=

Wnqn 11.68 49.59 0.44 1.01 0.36 0.30 2.50 7.32 0.53 4.76 1.24 22.34 58.50 ∑Wnqn= 160.58

Water Quality Index =∑ q n Wn/ ∑Wn = 106.3

DISCUSSION Water quality Index of the present waterbody is established from important various physicochemical parameters in different seasons. The values of various physicochemical parameters for calculation of Water quality index are presented in Table 3. Season wise Water Quality Index calculations are depicted in the Table 4, 5 and 6. The Water Quality Index obtained for the waterbody in different seasons of study period i.e., rainy season, winter season and summer season are 96, 101.7and 106.3 respectively, which indicate the poor quality of water (Chatterji and Raziuddin 2002). This water quality rating study clearly shows that, the status of the waterbody is eutrophic and it is unsuitable for the human uses. It is also observed that the pollution load is relatively high during summer season when compared to the winter and rainy seasons. The above water quality is also supported by the following physicochemical parameters variations observed during the different seasons of the study. Among all the physicochemical parameters selected for the Water Quality Index calculations, pH is an important parameter which determines the suitability of water for various purposes. In the present study pH ranged between 6.2 & 7.8. In many of the collections the pH remained exactly neutral. However, when the average values for three seasons are taken into account the waterbody was found to be slightly alkaline. Ambasht (1971), Petre (1975), Shardendu and Ambasht (1988), Swarnalatha and Narasingarao (1993) and Sinha (1995) have also made similar observations in their studies on different waterbodies. Electrical

Conductivity and total dissolved solids were also found to be very high. Seasonwise it is found to be high during summer season. Chloride is one of the most important parameter in assessing the water quality. Munawar (1970) is of the opinion that higher concentrations of chlorides indicate higher degree of organic pollution. In the present study the concentration of chloride fluctuated between 156 mg/1 and 178 mg/1. Seasonally, chloride was found to be high during summer season and low during rainy season. A similar observation has been made by Shastry et.al.,(1970) and Sinha (1995). The concentration of dissolved oxygen regulates the distribution of flora and fauna. The present investigation indicated that the concentration of dissolved oxygen fluctuated between 3mg/1 and 4mg/1. Seasonally, the concentration of dissolved oxygen was more during monsoon and least during summer. This observation is in conformity with the observations of Reddy et.al., (1982)., Ghosh and George (1989)., Swarnalatha and Narasingarao (1993) and Venkateswarlu (1993). Bio-chemical oxygen demand is a parameter to assess the organic load in a waterbody. Many researchers have recorded higher BOD values in polluted water. The BOD concentration ranged between 28 mg/1 to 33 mg/1 indicating the fact that the waterbody is eutrophic. Seasonally, it was high during summer, being in conformity with the observation of Chatterjee (1992). From the foregoing observations of the physicochemical parameters, it can be concluded that the waterbody shows the characters of eutrophication.

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Low dissolved oxygen, high bio-chemical oxygen demand and high nitrate concentrations indicate the eutrophic status of the waterbody. A relatively higher concentration of chlorides and sulphates also indicate the unsuitability of water for domestic use. Hence, application of Water quality index technique for the overall assessment of the water quality of a waterbody is a useful tool. REFERENCES Ambasht, R.S., 1971. Ecosystem study of a tropical pond in relation to primary production of different vegetation zones. Hydrobiologia 12 : 57-61. APHA. 1995. AMPHA. Standard methods for the examination of water and waste water, 19th Edition, American Public Health Association, WashingtonDC. BIS 1993. Analysis of Water ad Waste water, Bureau of Indian Standards, New Delhi. BIS 1983. Standards for Water for Drinking and other purposes, Bureau of Indian Standards, New Delhi. Chatterjee, A.A., 1992. Water quality of Nandakanan lake. India., J. Environ. Hlth. 34(4): 329-333. Chaterjee,C. and Raziuddin, M.2002. Determination of water quality index (WQI) of a degraded river in Asanol Industrial area, Raniganj, Burdwan, West Bengal. Nature, Environment and pollution Technology,1(2):181-189. Ghosh, A. and J.P. George, 1989. Studies on the abiotic factors and zooplakton in a polluted urban reservoir Hussain Sagar, Hyderabad: Impact on water quality and Embryonic Development of Fishes. Indian J.Environ.Hlth. 31(1): 49-59. Horton,R.K., 1965. An index number system for rating water quality. Journal of Water Pollution.Cont.Fed.,3:300305

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Munawar, M., 1970. Limnological studies on fresh water ponds of Hyderabad, India-II, J. Hydrobiologia. 35:127-162. Naik,S. and Purohit,K.M.,1996. Physico-chemical analysis of some community ponds of Rourkela. Indian Journal of Environmental Protection, 16(9): 679-684. Naik,S. and Purohit,K.M.1998 Status of water quality at Bondamunda of Rourkela industrial complex-Part-I: Physico-Chemical Parameters, Indian Journal of Environmental Protection, 18 (5) : 346-353. Petre, T. 1975. Limnology and fisheries of Nyumba Yamung, a man made lake in Tanzania, J. Trop. Hydrobiol. Fish. 4: 39-50. Reddy, K.R.P.D. Sacco, D.A Graetz, K.L. Campbell and L.R. Sinclair. 1982. Water treatment by aquatic ecosystem: Nutrient removal by reservoirs and flooded fields. J. Environmental Management, 6(3): 261-271. Shastry, C.A.K.M., Aboo, H.L. Bhatia and A.V. Rao, 1970. Pollution of upper lake and its effect on Bhopal water supply. J. Environmental Health., 12: 218-238. Shardendu and R.S. Ambasht, 1988. Limnological studies of a rural pond and an urban tropical aquatic ecosystem: oxygen enforms and ionic strength. J.Tropical Ecology. 29 (2): 98-109. Sinha S.K., 1995. Potability of some rural ponds water at Muzaffarpur (Bihar)-A note on water quality index, J. Pollution Research, 14(1): 135-140. Swarnalatha, N. and A. Narasingrao, 1993. Ecological investigation of two lentic environments with reference to cyanobacteria and water pollution. Indian J. Microbial. Ecol., 3:41-48. Venkateswarlu, V., 1993. Ecological studies on the rivers of Andhra Pradesh with special reference to water quality and pollution. Proc. Indian. Acad. Sci. (Plant Sci). 96:495-508. WHO, 1992.International Standards for Drinking water. World Health Organization, Geneva, Switzerland.