Hydrogeochemical Studies of Dalvoy Lake Ecosystem of Mysore City, India

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1 Sengupta, M. and Dalwani, R. (Editors) Proceedings of Taal2007: The 12 th World Lake Conference: Hydrogeochemical Studies of Dalvoy Lake Ecosystem of Mysore City, India Mahesha 1, and A. Balasubramanian Department of Studies in Environmental Science, University of Mysore, Manasagangothri, Mysore India. 2 Department of Studies in Geology & Educational Multi-Media Research Centre, University of Mysore, Manasagangothri, Mysore India. ABSTRACT Lakes are beneficial to many urban and rural populations. They belong to the family of promising freshwater ecosystems. Lakes are supportive to several human activities and biological productivity. The survival of all life in and around lakes depends on the quantity and quality of water available and its dynamic changes in space and time. In the present study, the surface water of different localities in Dalvoy lake, Mysore city has been taken up on the basis of Hydrogeochemistry using Global Positioning System (GPS) in order to evaluate its suitability for domestic and irrigation purposes. The lake water is primarily used for agricultural purposes. To understand the water quality variations within the lake, samples were collected from the surface and also from depths ranging from 1 to 3 m feet from the existing water level. These water samples were analysed for major cations, anions and also for some of the trace elements. The water analysis data was processed using a computer program called HYCH. The result shows that, the water of this lake is well within the permissible limits of many environmental variables. According to USSL classifications, the lake water falls under C3S1 with moderately high salinity. The values of Sodium Adsorption Ratio (SAR) in the studied locations belong to the excellent type. According to Handa s classification, the study area is characterized by water having temporary and permanent hardness. Based on Schoellers (1965, 67) water type classification, most of the samples are found to be of type I, III and IV. Keywords: PI, SAR, Corrosivity Ratio, Handa s classification, USSL, HYCH, Mysore city. INTRODUCTION Urbanization, expansion of irrigation and increasing trend of industrialization has contributed towards the demand for water. Surface water is the principal source of Irrigation in rural areas. Most of the fresh water bodies all over the world are getting polluted waters, thus decreasing the potability of the water (Gupta et. al., 2005). Since the beginning of civilization, surface water bodies have been the centers of cultural development and anthropogenic activity. The causes of pollution in these water bodies are directly related to human activities. India, being essentially a rural and agrarian country, needs assured supply of water for a large rural population and even a larger agricultural area demanding assured input of water (Mukherjee et. al., 1993). This paper analyses the various chemical parameters of water in an urban lake to find out its usability for domestic, agriculture and industrial purposes. Meenakumari et al., (2004) studied the ground water classification of Mysore city using borewell waters based on salinity hazard and sodium adsorption ratio. There are only few reports on the classification of surface waters for irrigation. In recent years trace elements have received great attention because they provide a coded history of lakes's environment (Rippy et. al., 1982). Therefore in this paper an attempt has been made to evaluate the environmental quality of water in Dalvoy lake of Mysore city, Karnataka State, India. The investigated area Dalvoy Lake was constructed during the rule of Maharaja's of Mysore. This lake is located 5km south of Mysore city. This lake can be located in the toposheets No. 57 D/11/6 and 57 D/12/NE at ' latitude and ' E longitude (Fig.1).

2 Figure 1. Flow Chart of the Hydrochemical data processing Program HYCH Figure 2. Flow Chart of the Hydrochemical Data Processing Program HYCH MATERIALS AND METHODS The lake water samples (25) were collected in different locations from the study area. The samples collected were analyzed in the laboratory. All parameters were determined by employing standard methods (APHA, 1975; Trivedy & Goel, 1986). GPS receiver was used to record the exact location. Water temperature and dissolved oxygen were recorded on the site of sampling. The samples were preserved and further analyses including that for heavy metals were carried out. The trace element analysis was done using AAS. The data were subjected to processing using HYCH computer program (Balasubramanian, et. al., 1991). This program is capable of providing mostly the needed output using the major ion chemistry data. It gives the interpretation of water quality based on water chemistry, facies, 338

3 mechanisms of origin, type, suitability and usage factors like corrosivity and permeability. Fig. 2 shows the Flow chart of the Program. In this program, hydrochemical facies classification is attempted using the criteria of Handa (1964), Piper (1944), Stuyfzand (1989), and USSL (1955). The index of Base Exchange (IBE) and water types are also computed using Schoeller s procedure (1961). Schoeller also specified that the first and foremost waters are expected to have rco3>rso4 (Type I) as the total concentration increases, it becomes rsor (Type I) as the total concentration increases, it becomes rso 4 >rcl (Type II) and rcl>rso 4 >rco3 (Type III) and rna>rmg>rca (Type IV). The water types of this area have been identified using this procedure. Ryzner (1994), proposed the Corrosivity Ratio (CR) as an index to study the corrosive tendencies of flowing water in a metallic pipe. Corrosivity ratio was calculated using the formula, CR=[Cl (mg/l)+so 4 (mg/l)]/ [(HCO 3 +CO 3 ) mg/l/50] Gibbs (1970) proposed plots using the Chloroalkaline indices for inferring the mechanism controlling the Chemistry of groundwater. Sodium Absorption Ratio (SAR) was calculated using the formula, SAR=Na + /[(Ca ++ +Mg ++ )/2] 1/2. The output contains information pertaining to the ionic strength, Index of Base Exchange (IBE), NCH, total Hardness, water types of Schoeller and Stuyfzand, permeability Index of Doneen, Piper Hydrochemical Facies, USSL Classes of water quality and the mechanisms controlling water Chemistry. A comprehensive picture of the water quality criterion is obtained using this software. In this study, numerical steps have been included instead of making use of all these traditional graphical procedures, used earlier. RESULTS AND DISCUSSION The results of a water quality assessment from Dalvoy lake water are shown in Table 1. Standard methods (APHA, 1975) have been employed in the analysis of the water samples. Most of the Physicochemical parameters are within the permissible limits of BIS and WHO standards for water. Table 2 shows the different types of water in the study area according to hydrogeochemical classification. Table 1. Physico-chemical analysis Sl.No. Ca Mg Na+K Fe HCO 3 CO 3 Cl NO 3 SO 4 TDS EC ph S TRACES S TRACES 539 NIL S TRACES S TRACES S TRACES S TRACES S TRACES 564 NIL S TRACES S TRACES S TRACES S TRACES 583 NIL S TRACES S TRACES S TRACES S TRACES S TRACES S TRACES S TRACES S TRACES 553 NIL S TRACES 549 NIL S TRACES 587 NIL S TRACES 534 NIL S TRACES 562 NIL S TRACES 560 NIL S TRACES 576 NIL

4 Table 2. Hydrogeochemical Classification of water sample Na me SAR PI CR USSL Handa s Hardness Handa s Salinity SWT RSC IBE C3S1 A1 C3S1 III C3S1 B1 C3S1 III C3S1 A1 C3S1 I C3S1 A1 C3S1 I C3S1 A1 C3S1 III C3S1 A1 C3S1 I C3S1 A1 C3S1 IV C3S1 A1 C3S1 I C3S1 A1 C3S1 I C3S1 A1 C3S1 I C3S1 B1 C3S1 IV C3S1 B1 C3S1 I C3S1 B1 C3S1 I C3S1 A1 C3S1 I C3S1 A1 C3S1 I C3S1 B1 C3S1 I C3S1 B1 C3S1 I C3S1 A1 C3S1 I C3S1 B1 C3S1 IV C3S1 B1 C3S1 IV C3S1 B1 C3S1 IV C3S1 B1 C3S1 III C3S1 B1 C3S1 IV C3S1 B1 C3S1 IV C3S1 B1 C3S1 IV Corrosivity Ratio (CR) Corrosion is an electrolytic process that takes place on the surface of the metal, which severely attacks and corrodes away the metal surfaces. Most of the problems are associated with salinity and encrustation problems. Water samples having corrosivity ratio less than 1 is considered to be noncorrosive, while the value above 1 is corrosive. In the present study, all the water samples have less than 1 and within the permissible limits. Sodium Adsorption Ratio (SAR) It can be defined as the expression of the equilibrium between exchangeable positive ions (Cations) in the soil and cations in the irrigation water is known as Sodium Adsorption Ratio. It gives a measure of suitability of water for irrigation with respect to the sodium (alkali) hazards. High SAR values may cause damage to soil. Based on Table 2 all the samples are found to be of excellent types. Permeability Index (PI) The soil permeability is influenced by long term use of irrigation water containing Sodium and bicarbonate contents. Permeability index of study area varies from to epm. US Salinity Laboratory (USSL) Classification According to a method formulated by the US Salinity Laboratory (1954), water use for irrigation can be rated based on salinity hazards and sodium or alkali hazard. When the Sodium hazards ratio and Electrical conductivity of water are known, the classification of water for irrigation can be done by plotting these results on the graph. Low salinity water (Cl<250 μ mho /cm 250 mho /cm) can be used for irrigation of most crops on most of the soils with little likelihood that soil salinity will develop. According to USSL classification (Table 2), all the water samples fall under C 3 S 1 (High Salinity and low sodium hazard) category, which are highly suitable for irrigation to all crops. Modified Hill-Piper Diagram The modification of Hill-Piper method as proposed by Handa (1964) has been resorted to in the present work for the classification of water with regard to its suitability for not only domestic purpose but particularly for irrigation purposes. He has combined the trilinear plot of Piper and the US Salinity Research Lab diagram with some modifications. Based on Handa s classification and sodium salinity the lake water of the study area is coming under C 3 S 1 category. C 3 is suitable only for well drained soil with regard to sodium hazard, and S 1 is 340

5 suitable for all purposes. The hardness of study area could be delineated into two horizons A 1 (non carbonate/ permanent Hardness), and B 1 (carbonate/temporary hardness). The study area is characterized by water having temporary and permanent hardness (Table 2). Chloroalkaline Indices have been used for basin wise hydrogeological studies by Balasubramanian, A (1986) which have pointed out that the ratios are positive in the recharge areas and negative in the discharge areas. Based on this character, the study area can be divided into positive and negative zones, demarcating the recharge and discharge horizons respectively. Schoeller s concept of water types is related to the evaluation of lake water with respect to chemistry. Based on Schoellers (1965, 67) water type classifications most of the samples are falling under type I, III and IV. CONCLUSIONS On the basis of the present study, analysis of water in Dalvoy Lake, Mysore city in Karnataka state shows that in the study area water samples have physicochemical properties well within the permissible limits except Calcium, Magnesium, Copper, Nickel and Manganese. when compared to WHO. According to USSL, study area lake water fall under C 3 S 1 with moderately high salinity. The value of SAR in the study area was in excellent type and is non-corrosive. According to Handa s classification the study area is characterized by water having both temporary and permanent hardness. Based on Schoellr s (1965, 67) water type classification, most of the sample are falling under type I, III and IV. The overall quality of waters in Dalvoy Lake seems to be suitable for agriculture. Periodical monitoring of the water quality is thus required to assess the condition of surface water. This will be helpful in managing the lake from further degradation. ACKNOWLEDGEMENT The authors are indebted to their respective departments, University of Mysore, for the facilities provided to carryout this research work. Thanks are also due to Dr. M.S.Sethumadhav and Dr. Brijesh, V.K., Department of Geology, University of Mysore, Mysore for their valuable suggestions. REFERENCES APHA-AWWA-WPCE Standard Methods for the Examination of Water and wastewater. 14 th Edition. American Public Health Association, Washington D.C. Balasubramanian, A Hydrogeological Investigation of Tambraparani River Basin, Tamil Nadu, Unpublished Ph.D. Thesis, Mysore University, 349. Balasubramanian, A., Subramanian, S. and Sastri, J.C.V Hydrochemical Facies Classes Software, Basic Computer Programme for Hydrogeological Studies. Gibbs, R.J Mechanisms Controlling World s Water Chemistry, Sciences. 170: Gupta, S.K., Dixit, S., and Tiwari, S., Assessment of Heavy Metals in Surface water of lower Lake, Bhopal, India. Poll. Res. 24(4): Handa, B.K Modified Classification Procedure for Rating Irrigation Water. Soil Sci., 98: Meenakumari, H.R and Hosmani, S.P Studied the Ground Water Classification of Borewells of Mysore City Based on Salinity Hazard and Sodium Absorption Ration. Nat. Env. Poll. Tech. 3(3): Mukherjee, S., Gupta, K., and Tutul, R., Rural Surface Water Management: A Case Study of Birbhum District, West Bengal, India. Jour. Appl. Hydrology.1 to 4: Piper, A.M A Graphic Procedure in the Geochemical Interpretation of Water analysis. AM. Geology. Union. Trans., 25: Rippey, B., Murphy, R.J., and Kyle, S.W., Anthropogenically derived changes in the sedimentary flux of Mg, Cr, Ni, Cu, Zn, Hg, and P in Lough Neagh, Northern Ireland. Environ. Sbi. Technol. 16: Ryzner, J.W A New Index for Determining Amount of Calcum Carbonate Scale formed by Water. Jow.Amer. W.W.Assn., 36: Schoeller, H., Hydrodynamique dans lekarst (Ecoulement etemmagasinement), actes Colloques Doubronik. I, AIHS et UNESCO. Schoeller, H Qualitative Evaluation of Ground Water Resource. (Method and Techniques of Ground water Investigation and Development), Wat.Res.Series-33. UNESCO, Trivedy, R.K and Goel, P.K., Chemical and Biological Methods of Water Pollution Studies. Environmental Media Publications, Karad. USSL, Classification of Irrigation Waters. U.S.Department of Agriculture, Circu 969. Washington. WHO, Guidelines for Drinking-Water Quality, Third Edition (Recommendations), World Health Organization, Geneva. 341