East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 Groundwater quality evaluation and its suitability for domestic and irrigation use in the hard rock terrain of Olakkur block, Tamilnadu, India Vinodh. D1, Senthilkumar.S2, Gowtham.B1 , WegeneTalelign3and Jeevanandam M*3 1Department of Geology, Presidency College(Autonomous),Chennai – 600 005, India 2Department of Earth Sciences, Pondicherry University, Puducherry, India 3Department of Geology, College of Natural and Computational Sciences, Hawassa University, Hawassa, Ethiopia. KEYWORDS: Corrosion; Hydrogeochemical; Ollakur block; Irrigation quality; Groundwater quality INTRODUCTION In most parts of India ground water play a vital role and major source for drinking and agricultural purposes. The quality of groundwater is a function of physical and chemical parameters that are greatly influenced by anthropogenic activities and geological formations (Krishna Kumar et al., 2011). The chemistry of groundwater is not only related to lithology and rock water interaction but also reflects inputs from soil, atmosphere and pollutant sources such as saline intrusion, mining activities, industrial and domestic wastes (Babiker et al., 2007). Groundwater also gets polluted due to excessive irrigation practices (Sujatha and Reddy, 2003). Understanding Journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs Hawassa University College of Natural & Computational Sciences Year 2021 Volume xx No xx 34 East African Journal of Biophysical and Computational Sciences Research article *Corresponding author: Email: jeevam24@hu.edu.et ABSTRACT Ground water is the main source of water for agriculture and domestic use in the study area. This study was aimed to evaluate the groundwater quality for domestic and irrigational purposes. Groundwater samples were collected from twenty five locations in both pre-monsoon and post-monsoon months and examined for various physico-chemical parameters such as pH, total dissolved solids, total hardness, calcium, magnesium, sodium, potassium, bicarbonate, sulphate, Nitrate and chloride. To assess the domestic suitability of groundwater, all these parameters were compared with the standards of World Health Organization and Indian standards. Sodium Adsorption Ratio (SAR) and US salinity diagram were used to evaluate the groundwater for irrigation suitability. At some locations sodium and potassium values were higher than the prescribed limits. The SAR values were less than 10. Based on United States Salinity Laboratory Staff (USSL) diagram the dominant categories were C2-S1, C3-S1, C2-S1, C3-S1, C3-S2 in both pre and post-monsoon. Groundwater samples were classified as Na-HCO3 and Na-Cl water type in pre-monsoon and Ca-Na-HCO3 and Na-Cl types in post-monsoon. The geochemical analysis revealed that the groundwater samples were fit for domestic purpose. The irrigation quality assessment based on Sodium Adsorption ratio and US Salinity diagram suggested that, most of the groundwater samples were fit for irrigational activities except in certain locations where sodium and salinity values were high. Based on Piper water classification, mixing process and evaporation were the dominant geochemical process in the study area. mailto:jeevam24@hu.edu.et East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 geochemical evolution of groundwater in arid and semi-arid regions would be helpful for sustainable development, consumer protection from noxious substances/contaminants and proper management of water resources (Jalali, 2009; Furi et al., 2011). Geographic Information system (GIS) is an effective tool for assessing and mapping groundwater quality and its utilization for irrigation and drinking needs (Srinivasamoorthy et al., 2011; Ravikumar et al., 2013). The geological formations and anthropogenic activities are greatly influenced the groundwater quality in the study area. Agriculture practice is the major economic activity in the study area. Surface water resources are very scarce and groundwater resources represent water source for drinking and agricultural purposes for the people living in this area. It is widely accepted that the utilizations of groundwater resources are closely associated with their geochemical properties (Abderamane, 2013; Krishna Kumar et al., 2015). For effective and safe use of ground water for various agricultural and domestic uses, sufficient information should be available. However, there is no such study in the area. Therefore, the present study was attempted with the objective of assessing the groundwater quality and its suitability for drinking and irrigation purpose. MATERIALS AND METHODS Study area The study area, Olakkur Block, is located between latitudes 12°10’00” and 12°25’00” N and longitudes 79◦30’00” and 79◦50’00” E, in Villupuram District (Figure 1) and covers an area of about 277.64 Sq.km. The study area falls in the following Survey of India topographic sheets 57P/11, 57P/12, 57P/15 and 57P/16. The area is bounded by the Kancheepuram district in the north Tiruvannamalai district in west, Marakanam block and Mailam block of Villupuram district in the east and south, respectively. Agriculture is the main activity where paddy is the principal crop, and crops such as sorghum, maize, ragi, pulses, chillies, groundnut, cotton and sugarcane are also cultivated. Geology and Geomorphology 35 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 The Charnockite of Archaean age covers most part of the study area (Figure 2). Hornblende biotite gneiss and pink migmatite is seen along north western part of the study area. The rock shows typical granular texture with Quartzo- feldspathic composition. Conglomerate is exposed in north part near the Marakanam region. Thickness of weathering varies in different places and it depends on the mechanical and chemical action on the granitic rocks. Prominent vertical and oblique joints and fractures are observed from well inventories. The trend of the granitic gneiss is N60 °E and dipping towards S35°E which are noticed on the N-NE of Melmalayanur. The trend also varies from N35°E to N45°E on the northern and southern side of Gingee. This is due to the changes in tectonic disturbance, which also controls the movement of groundwater. Charnockite is seen in North-West and South- East which extends up to Melmalayanur and NE till Gingee around Perumpugai village. It is composed of blue quartz, feldspar and hypersthene. In some part of the study area charnockiteacts as intrusive rock (Senthilkumar et al., 2014). The weathering thickness is moderate and the joints and fractures are limited. The Geo-morphological study area is based on the fact that the specific characteristics of each of the landform vary greatly in terms of shape, dimension, and thickness of the overburden material, permeability, porosity etc, depending on the underlying rock type, structural control, climate and vegetative cover. Geomorphology of the area dominantly consists of the deep buried pediment, shallow buried pediments and pediments. Methodology Base boundary map was prepared using Survey of India topo-sheets of the study area, and data such as rainfall, geomorphology, geology and land use were collected from central and state government agencies. During field study, groundwater samples were collected from 25 locations from both bore well and dug wells during pre-monsoon and post monsoon seasons in 2020. The samples were analysed for major ions by employing the standard water quality analysis procedures (APHA, 1995). Physical parameters such as pH and EC were measured using potable meters in the field. Major ions such as Ca, Mg were analyzed titrimetrically using Standard EDTA (0.2N) solution. Sodium (Na) and potassium (K) were estimated, using a Flame photometer (model CL354). Carbonate (CO3) and bicarbonates (HCO3) were analysed by standard HCl titration method and Sulphate (SO4) was analyzed, using a spectrophotometer (model SL27). The Corrosivity ratio of water was calculated by using the formula of Ryznar (1944) Corrosivity Ratio (CR) =       + + 100 )/( 2 96 )/(2 5.35 )/( 33 4 lmgHCOCO lmgSOlmgCl Total Hardness denotes the concentration of Calcium and Magnesium in water and is usually expressed as the equivalents of CaCO3, calculated by the following formula Total Hardness (TH) = 2.497 Ca+4.115 Mg (Karanth, 1991). 36 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 The spatial analysis of various physico-chemical parameters was carried out using the ArcGIS®9.1 software. An inverse distance weighed (IDW) algorithm was used to interpolate data spatially and estimate values between measurements. This interpolation technique calculates a value for each grid node by examining surrounding data points that lie within a user-defined search radius (Burrough and McDonnell, 1998). All of the data points are used in the interpolation process and the node value is calculated by averaging the weighted sum of all the points. RESULTS AND DISCUSSION Assessment of groundwater quality The spatial distribution of total dissolved solids (TDS), total hardness (TH) and corrosivity ratio for pre and post-monsoon is shown in Figure 3. 37 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 80 The physico-chemical analysis of the groundwater samples for both seasons is presented in Table 1 & 2. 38 Figure 3: TDS, TH and Corrosivity ration for pre-monsoon and post-monsoon East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 81 Table 1: Physico-chemical characteristics of groundwater in the study area Pre- monsoon Sample locations pH TDS Ca Mg Na K HCO3 Cl SO4 NO3 SAR 1 7 756 31 18 153 18 393 126 27 1 6 2 7.2 399 29 5 48.6 5.4 207 22 10 3 2 3 7.2 1106 50 31 223.2 24.8 442 253 64 10 7 4 7.3 1533 77 55 217 25 613 250 81 9 5 5 6.8 1078 44 27 207 23 431 156 140 8 7 6 7.4 417 21 18 58 6 167 69 35 2 3 7 7.1 627 59 9 89 10 313 82 21 9 3 8 6.9 910 20 38 150 17 437 119 40 4 5 9 6.8 721 59 13 152 25 346 164 43 2 5 10 7.2 1155 71 40 225 30 462 336 43 4 6 11 7 483 48 8 60 10 242 46 42 2 2 12 7 1428 45 68 335 15 571 465 26 6 8 13 7.3 767 64 13 129 21 345 123 79 6 4 14 6.7 357 22 4 61 7 171 41 25 2 4 15 7.5 966 32 26 189 21 386 192 51 7 7 16 7.3 900 77 8 176 20 360 211 59 4 6 17 6.8 1229 99 33 224 24 491 260 148 5 6 18 6.9 1778 118 49 366 41 711 446 166 3 8 19 7.5 963 30 18 230 26 385 250 36 6 9 20 6.9 1736 107 27 462 51 694 577 103 10 12 21 7.4 350 25 6 67 7 140 76 27 5 3 22 7.2 956 58 11 260 29 382 307 67 6 9 23 7.3 595 44 13 87 10 238 100 35 6 3 24 6.6 403 27 8 59 7 161 69 18 4 3 25 6.9 606 48 10 183 20 297 58 53 7 4 pH: The pH value of groundwater samples ranging from 6.6-7.5 and 6.7-7.7 during pre and post-monsoon, respectively. WHO standards reveals that all the groundwater samples from the study area during both monsoons exceed the most desirable limit of 6.5 but under maximum allowable limit of 8.5. The pH values indicate slightly acidic nature in some locations which could be attributed to the weathering process of underlain geology. 39 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 Table 2: Physico-chemical characteristics of groundwater in the study area Post- monsoon Sample locations pH TDS Ca Mg Na K HCO3 Cl SO4 NO3 SAR 1 7.4 602 32 15 71 8 313 31 12 2 3 2 7.1 438 21 12 51 6 228 15 18 4 3 3 7 1302 92 8 331 37 521 442 11 3 10 4 7.1 1022 105 9 171 19 409 223 56 9 5 5 7.1 763 47 12 159 18 305 161 67 8 6 6 7.2 378 23 15 59 6 151 81 27 2 3 7 6.8 550 42 5 89 10 275 73 9 8 4 8 7.1 777 35 27 105 12 373 73 40 5 4 9 7.4 637 55 17 99 11 306 123 24 2 3 10 7.2 378 25 9 73 8 151 100 10 4 4 11 6.7 441 35 10 71 8 221 61 35 2 3 12 7.1 1358 50 22 377 42 543 461 31 5 12 13 6.9 693 57 13 113 13 312 131 28 6 4 14 6.7 315 25 7 39 4 151 38 12 3 2 15 7.5 945 36 24 182 20 378 188 50 8 6 16 6.7 1225 80 19 281 31 490 346 67 3 8 17 6.8 925 49 21 195 22 381 215 64 4 7 18 6.9 1372 119 36 286 32 549 413 103 3 7 19 7.7 900 30 19 211 23 360 242 21 6 8 20 7.4 1369 82 23 383 42 547 499 88 10 11 21 7.4 350 25 6 67 7 140 76 27 5 3 22 7.5 882 54 11 242 27 353 291 63 5 9 23 7.4 546 39 12 80 9 218 91 32 5 3 24 6.8 336 23 8 50 5 134 62 14 3 3 25 7 546 22 4 40 4 68 44 48 6 2 Total dissolved solids (TDS): Different geological regions influence the concentration of TDS due to differences in the solubility of minerals (WHO, 2004). As the residence time of groundwater in the geological formation increased, the TDS and major ion concentrations are also increased (Norris et al., 1992). Based on WHO standards, the highest desirable limit for TDS is 500mg/l and maximum permissible limit is 1500 mg/l. In the study area, during pre-monsoon the TDS values exceeds maximum permissible limit at locations 6, 22 and 24. The remaining locations fall under the category of highest desirable limit at Locations 3, 8, 12, 16, 20 and 25 and maximum permissible limit at Locations 1, 2, 4, 5, 7, 9, 10, 11, 13, 14, 15, 17 18, 19, 21 and 23. During post-monsoon the groundwater quality has been changed as evidenced by the locations 6, 22 and 24 which are changed in to maximum 40 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 permissible category from exceeding limit. The highest desirable limit category occurs at locations 3, 8, 12, 14, 16, 20 and 25 and maximum permissible limit category at 1, 2, 4, 5, 6 7, 9, 10, 11, 13, 15, 17 18, 19, 21, 22, 23 and 24. The classification of groundwater, according to Davis and De Wiest (1966), based on TDS is given in Table 3. Table -3: Classification of groundwater based on TDS (Davis and De Wiest, 1966) TDS (mg/l) Water type Samples (pre-monsoon) Samples (post-monsoon) <500 Desirable for drinking 3, 8, 12, 16, 20,25 3, 8, 12, 14,16, 20, 25 500-1000 Permissible for drinking 1, 2, 5, 9, 10, 11, 13, 15, 18, 19, 23 1, 2, 5, 7, 9, 10, 11, 13, 15, 19, 21, 23, <3000 Useful for irrigation 4, 6, 7, 14, 17, 21, 22, 24 4, 6, 17, 18, 22, 24 >3000 Unfit for drinking and irrigation ------ ------ Total Hardness (TH): The presence of carbonates and bicarbonates of calcium and magnesium, chlorides, nitrates and sulphates of calcium and magnesium cause total hardness in groundwater. According to Sawyer and McCarty (1967), based on TH, the groundwater is classified as soft (TH<75 mg/l), moderately hard (TH= 75-150 mg/l), hard (TH= 150-300 mg/l) and very hard (>300 mg/l). Spatial distribution of total hardness for pre and post- monsoon is shown in Figure 3. During pre- monsoon no soft water occurred in the study area but moderate hard water was found at location no. 20. Hard water mainly occurred in west and some eastern part of the study area at locations 1, 2, 3, 5, 8, 9, 10, 12, 13, 16, 23 and 25. Very hard water occurred at locations 4, 6, 7, 11, 14, 15, 17, 18, 19, 21, 22 and 24. In post- monsoon, the total hardness of the groundwater was remarkably changed. Except at locations 6 and 22, which showed very hard water, all other groundwater samples were observed as hard water. The drinking water quality was evaluated by comparing with the specifications of TH, TDS and other parameters set forth by the World Health Organization and Indian standards (Table 4). Calcium and magnesium: Calcium and magnesium are abundantly occurred elements in natural waters in the form of bicarbonates, sulfate and chloride. Ca concentrations were varying from 21 to 118 mg/l in pre-monsoon and 21 to 119 mg/l in post-monsoon. The desirable limit of calcium concentration for drinking water as per the standards of WHO (2004) is 75 mg/l. During pre-monsoon and post-monsoon, 84% of the groundwater samples were under desirable limit. Only 16 % of the groundwater samples have crossed the desirable limit. The higher concentration of Ca could cause abdominal ailments in humans and encrustation and scaling in pipes. Magnesium content varied from 4 to 68 mg/l in pre- monsoon and 4 to 36 mg/l in post-monsoon. According to WHO standards, the desirable limit for Mg is 50 mg/l which shows that 92% and 100% groundwater samples from the study 41 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 area fell under the desirable category during pre-monsoon and post-monsoon respectively. Table -4: Parameter range WHO (2004) and ISI (2009) standards for drinking purpose S.No Water quality parameters WHO Standards (2004) Indian standard (ISI 10500,2009) Pre- monsoon range in the study area Post- monsoon range in the study area Most desirable limit Max. allowable limit Highest desirable Max. permissible 1 pH 6.5 8.5 6.5-8.5 No relaxation 6.6-7.5 6.7-7.7 2 TDS 500 1500 500 2000 350-1778 315-1372 3 TH (as CaCO3) 100 500 200 600 71-495 71-445 4 Ca 75 200 75 200 21-118 21-119 5 Mg 50 150 30 No relaxation 4-68 4-36 6 Na - 200 - 200 48-462 39-383 7 K - 12 - - 5-51 4-42 8 SO4 200 400 200 400 18-166 9-103 9 Cl 200 600 250 1000 22-577 15-499 10 NO3 40 50 45 No relaxation 1-10 2-10 Sodium and potassium (Na and K): The concentration of Na in the study area varied from 48 to 462 mg/l in pre-monsoon and 39 to 383 mg/l in post-monsoon. According to WHO standards (200 mg/l) 40% and 28 % of the groundwater samples exceeded the maximum allowable limit during pre and post-monsoon respectively. Water with high sodium content can be easily absorbed by soil which in turn determines the irrigation soil quality. High sodium concentration in the soils leads to development of an alkaline soil which results in alkaline hazard. The maximum allowable limit for K is 12 mg/l as per WHO standard but in pre-monsoon 68% of the groundwater samples exceeded the limit and during post-monsoon only 48 % of the samples exceeded the limit. The high concentration of K could be attributed to the dissolution of potash feldspar associated with charnockite in the study area. Bicarbonate (HCO3): The value of bicarbonate was observed from 140 to 711 mg/l and 68 to 549 mg/l during pre and post-monsoon respectively. Mineral dissolution plays the key role for higher concentration of HCO3 in groundwater (Stumm and Morgan, 1996) Sulphate (SO4): The sources, residence time and different geochemical process influence the concentration of SO4. Dissolution or weathering of gypsum and anhydrite minerals is the important geochemical process responsible for high concentration of SO4 in groundwater. The SO4 concentration in groundwater samples from the study area varied from 18 to 166 mg/l and 9 to 103 mg/l during pre and post-monsoon respectively. As per WHO standards, all groundwater samples were well within desirable limit of 200 mg/l in both the seasons. Chloride (Cl): The chloride content in groundwater might be originated from different 42 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 sources such as intrusion of salt water, weathering, leaching of various rock types, domestic and industrial waste discharges (Karanth, 1987). In the study area, the concentration of chloride ranged between 22 and 577 mg/l and 15-499 mg/l in which 40% and 36% of total water samples exceeded the most desirable limit of 200 mg/l set by WHO during pre and post-monsoon respectively. The excess of chloride in the water is usually taken as an index of pollution and considered as tracer for groundwater contamination (Loizidou and Kapetanios,1993). Nitrate (NO3): According to WHO, nitrate concentration in groundwater samples from the study area was within the prescribed limit of 50 mg/l in both the seasons. The values vary from 1 to 10 mg/l and 2-10 mg/l during pre and post- monsoon respectively. Nitrate concentration in the study area could be attributed to discharges of sewage effluents and agriculture chemicals. Corrosivity ratio: Corrosion is basically an electrolytic process, which severely attacks and corrodes the metal surfaces. The rate at which corrosion proceeds depends upon a variety of chemical equilibrium reactions as well as upon certain physical factors like the temperature, pressure and velocity of flow (Ayers and Westcot, 1985). If the corrosivity ratio is less than 1, then the metal pipes can be used for transporting water, whereas PVC pipes must be used in areas where corrosivity ratio is more than 1. Out of total water samplestested, only few locations at 5, 9, 12, 14, 17, 21, 22, 23 and 24 were exceeded the limit of 1 in pre-monsoon. During post-monsoon the corrosivity ratio of the groundwater samples was more than 1 at locations 4, 5, 13, 14, 17, 18, 22, 23 and 24. Piper’s Trilinear Plot: The major cations and anions are plotted on Piper diagram (Piper, 1944) to assess the geochemical evolution of groundwater. This diagram is used to study the differences and similarities in the composition of groundwater and for classification of water types. The hydrochemical facies for the groundwater samples from the study area is shown in Figure 4. During pre-monsoon two major facies types are present which are Ca-Na- HCO3 water type and Na-Cl water type. These water types suggest that the groundwater chemistry was controlled by a mixing process and evaporation process. In post monsoon also the major water types are Ca-Na-HCO3 and Na- Cl types. A few samples however were mixed Ca-Mg-Cl type suggesting that same geochemical process was controlling the groundwater chemistry. 43 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 86 Figure- 4: US salinity and Piper plot for pre-monsoon and post-monsoon Suitability of groundwater for irrigation Sodium adsorption ratio (SAR): SAR ratio is a measure of alkali or sodium hazard to crops. More Na concentration in irrigation water can reduce permeability and free flow of air and water. This is due to exchange process by Na ions adsorbed by the clay particle replacing the Mg and Ca ions (Saleh et al., 1999; Yidana, 2010). The Sodium adsorption ratio is expressed as where all ionic concentrations are expressed in meq/L. 44 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 The SAR value varied from 2 to 12 (Table 1 and 2) in both pre-monsoon and post-monsoon. Table 5a and 5b illustrates SAR classification of groundwater samples from the study area for both the season. During pre-monsoon 96% of groundwater samples were suitable for all types of crops and soil except for those crops sensitive to sodium. The remaining 4% of the ground water sample was suitable for coarse textured or organic soil with permeability. During post- monsoon 92% of the groundwater samples were suitable for all types of crops and soils except for those crops which were sensitive to sodium, and 8 % were suitable for coarse textured or organic soil with permeability. Table- 5a: Suitability of water for irrigation with different value of SAR-Pre- monsoon SAR Suitability of Irrigation Samples 1-10 Suitable for all types of crops and soil except for those crops sensitive to sodium 96% 10-18 Suitable for coarsed textured or organic soil with permeability 4% 18-26 Harmful for almost all soil -- >26 Unsuitable for irrigation -- Table- 5b: Suitability of water for irrigation with different value of SAR-Post- monsoon SAR Suitability of Irrigation Samples 1-10 Suitable for all types of crops and soil except for those crops sensitive to sodium 92% 10-18 Suitable for coarse textured or organic soil with permeability 8% 18-26 Harmful for almost all soil -- >26 Unsuitable for irrigation -- US Salinity Diagram (1995): The analytical data was interpreted using USSL diagram to assess the groundwater quality for irrigation purpose. Figure 4 shows 60% samples were in C2-S1 and C3-S1 categories suggesting that the water can be used for irrigation activity in pre- monsoon. The remaining 40 % were in C3-S2 and C4-S2 indicating that groundwater is suitable for irrigational use with limited risk due to exchangeable sodium. In post-monsoon 56% of the samples belonged to C2-S1 and C3-S1 categories and 36 % samples were in C3-S2 category suggesting that the water can be used for irrigational purpose. The remaining 8% samples fell in C3-S3 category which shows high salinity and sodium hazard suggesting that water is not suitable for irrigation purpose. CONCLUSIONS The geology and geomorphology of the study area comprises of Charnockite of Archaean age and buried pediments respectively. In the present study, interpretation of geochemical analysis of groundwater samples revealed that, TH and TDS values were found to be suitable for drinking purposes. Based on TH values very hard water occurred at locations 4, 6, 7, 11, 14, 15, 17, 18, 19, 21, 22 and 24. Total dissolved solids in groundwater were less than 2000 mg/l in both the seasons. In some locations the sodium and potassium concentrations were 45 East Afr. J. Biophys. Comput. Sci., Vol. 2, Issue 1 higher than the prescribed limit Corrosivity ratio of the groundwater samples was more than 1 at some sampling points suggesting that PVC pipe must be used in those areas. Except for a very few locations SAR valuewas less than 10 signifying the suitability of groundwater for irrigation purpose. Based on USSL diagram, the dominant categories were C2-S1, C3-S1, C2-S1, C3-S1, C3-S2 in both pre and post-monsoon, suggesting that the groundwater is suitable for irrigational activities excepting a few locations which fall under the C3-S3 category indicating high sodium hazard. According to Piper diagram most of the samples were classified as Na-HCO3 water type and Na-Cl water type in pre-monsoon and Ca-Na-HCO3 and Na-Cl types in post-monsoon. The interpretation of these water types suggests that, mixing and evaporation processes are the two dominant geochemical processes in the study area. Acknowledgements The authors are grateful to the Head of the Department of Geology, Presidency College, Chennai, Tamilnadu, India for all the facilities provided to continue the research work. References Abderamane H., Razack M. and Vassolo S. 2013. Hydrogeochemical and isotopic characterization of the Ground water in the Chari-Baguirmi depression. Republic of Chad. Environ. Earth Sci. 69: 2337– 2350 APHA 1995. Standard method for the examination of water and waste water, 16thed, Washington D.C. Ayers R.S. and Westcot D.W. 1985. Water quality for Agriculture, Irrigation and Drainage, Paper No. 29, Rev.1, FAO, Rome, 174p. Babiker I.S. Mohamed M.A.A. and Hiyama T. 2007. 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Earth Sci. 57: 455–469. . 47 Cover V2.pdf (p.1) Cover.pdf (p.1-2) Slide Number 1 blank page.pdf (p.2) Table of contents Vo 2.pdf (p.3-5) all articles vol 2.pdf (p.6-81) Volume 2 Issue 1_ 6 articles_4_3.pdf (p.6-91) 4_Captive fish_Anna RESULTS AND DISCUSSION References 3_Reproductive Disorder 6_Diet bredth_Prof. Nat 8_Ground water_Jeeva Base boundary map was prepared using Survey of India topo-sheets of the study area, and data such as rainfall, geomorphology, geology and land use were collected from central and state government agencies. During field study, groundwater samples were ... 10_Ethnoveterinary Following comments Dagne et al_ Challenging students’ performance through Practical Skills Assessment.pdf (p.73-82) Guideline to Authors_ EAJBCs.pdf (p.82-90) Back cover.pdf (p.91) INTRODUCTION EXTENSION OF THE MODIFIED MODEL INTO AN OPTIMAL CONTROL Optimal protection and hospitalization using modified model Existence of an optimal control The Hamiltonian and optimality system Numerical simulations of optimal control problem Optimal control comparisons and strategies CONCLUSION INTRODUCTION INTRODUCTION