Imperial Journal of Interdisciplinary Research (IJIR) Vol-3, Issue-3, 2017 ISSN: 2454-1362, http://www.onlinejournal.in Aquifer Mapping Of Chennai City Using GIS Techniques K. Deepa1, A. Karthiga2 & K. Rehana V. Rayen3 1Professor, Department of Civil Engineering 2,3 Student Department of Civil Engineering, Panimalar Engineering college Abstract: Groundwater is an indispensable industrial and other sites (Xenixd et al. 2003; resource for survival on Earth. It is an important Gnanachandrasamy et al. 2012). Quality of component for domestic and agricultural purposes groundwater is equally important to its quantity as well as for industrial processes. Aquifer, an owing to the suitability of water for various underground saturated zone from which purposes. Variation of groundwater quality in an groundwater can be drawn out is rapidly depleting area is a function of physical and chemical due to human population and various other parameters that are generally influenced by activities .In order to protect this valuable resource geological formations and anthropogenic activities from exhaustion, aquifer mapping is done in (Subramani et al., 2005). Chennai using GIS techniques. Aquifer mapping is an approach for facilitating planning and decision Groundwater vulnerability deals only with the making processes in order to protect this valuable hydrogeological setting and does not include resource. It helps in determining the water quantity pollutant attenuation. The natural hydrogeologic and quality in Chennai. Pan European methodology factors affect the different pollutants in different for aquifers vulnerability has recently been ways depending on their interactions and chemical developed by assessing all the existing relevant properties. Many approaches have been developed techniques and emphasizing on karstic to evaluate aquifer vulnerability. They include environments. The water quality also needs to be processbased methods, statistical methods, and checked because of the environmental pollutants overlay and index methods (Tesoriero et al., 1998). present in groundwater. Water quality is checked by The remote sensing and Geographic information taking groundwater samples and the water is tested system (GIS) tool can open new path in water for the physico chemical parameters. resource studies. Analysis of remote sensing data along the survey of India (SOI) topographical sheets 1. Introduction and collateral information with necessary ground An aquifer is an underground layer of water-bearing truth verifications help in generating the baseline permeable rock, rock fractures or unconsolidated information for groundwater targeting (Yammani, materials (gravel,sand, or silt) from which 2007). groundwatercan be extracted using a water well. Groundwater is a valuable natural resource that is A GIS-based study was carried out by Barber et al. essential for human health, socio-economic (1996) to determine the impact of urbanization on development, and functioning of ecosystems groundwater quality in relation to landuse changes. (Zektser, 2000; Humphreys, 2009; Steube et al., Deuterium and oxygen concentrations in ground 2009). Spatial variations in groundwater quality in water, river water and precipitation were used to corporation area of Gulbarga city located in assess the origin of groundwater and to quantify northern part of Karnataka state, India have been amounts of bank filtrated water in the flood plain of studied using geographic information system upper rhinevalley.Using the dispersion model, technique. GIS a tool which is used for storing, residence times and dispersion parameters were analyzing and displaying spatial data is also used for estimated for three different ground water wells. investigating ground water information. (P.Koniger, S.Uhlenbrook& Ch.Leibundgut,1996). (P.Balakrishnan, Abdul saleem& N.D.Mallikarjun, Because of the long coastline of the India and the 2002). overexploitation of ground-water, saline water intrusion has also become an important problem The use of maps is common practice in earth-related (Daskalaki and Voudouris 2008; Mimikou 2005; sciences in order to evaluate the evolution of Sofios et al. 2008; Voudouris et al. 2004). physical phenomena and predict natural variables as well as assess the risk regarding surface and In this article, different maps and graphical groundwater contamination in waste disposal representations are used to classify and interpret the Imperial Journal of Interdisciplinary Research (IJIR) Page 165 Imperial Journal of Interdisciplinary Research (IJIR) Vol-3, Issue-3, 2017 ISSN: 2454-1362, http://www.onlinejournal.in geochemical data in terms of interpolation map of 4. Software used chemical parameters, Piper diagram and geochemical modelling. An appropriate assessment A Geographical Information System is a computer for the suitability of groundwater requires the system of capturing ,storing, checking and concentrations of some important parameters like displaying data related to positions on earth pH, electrical conductivity (EC), calcium, surface.GIS can show many different kinds of data magnesium, sodium, potassium, chloride, fluoride on one map.This enables people to more easily are compared with the guideline values set for see,analyze and understand patterns and potable water (WHO 1996). Poor quality of water relationships. adversely affects the human health and plant growth (WHO 2004; Nag and Ghosh 2013). Visual modflow 2.8 is the U.S geological survey modular finite difference flow model, which is a 2. Study Area computer code that solves groundwater flow Chennai is one of the fast growing urban city equation .The program is used by hydrogeologists to because of URBANSPRAWL water level decreased stimulate the flow of ground water through aquifers. so, this is mandatory to know the reason for the declination & save it from scarcity in future .Many Different thematic map layers such as soil countries are not able to manage their water map(fig:1),slope map(fig:2),landuse map(fig:3) are resources to sustainably meet current and future prepared using GIS software in arcinfo workstation demands because they lack a comprehensive 10.2 version. assessment of the quality and availability of their resources. The soil of Chennai mostly consists of clay, sedimentary rocks and sandstone. The city is classified into three regions based on geology, sandy areas, clayey areas and hard-rock areas. Sandy areas are found along the river banks and the coasts. 3. Methodology Fig 1.soil map Imperial Journal of Interdisciplinary Research (IJIR) Page 166 Imperial Journal of Interdisciplinary Research (IJIR) Vol-3, Issue-3, 2017 ISSN: 2454-1362, http://www.onlinejournal.in Fig 4.ground water sampling location Fig 2.Slope map 6. Results and discussions 6.1.Total dissolved solids(TDS) TDS comprises of inorganic salts and small amount of organic matter that are dissolved in water.WHO(World Health Organisation) has set the permissible limit for TDS as <500 mg/L.The level of TDS is unacceptable if it is beyond 1200 mg/L.It mainly arises due to runoff of water in urban area, use of pesticides and fertilizers.In Vepery(Perambur-Purasawakkam taluk),the total dissolved solids value is very high as 1823 mg/L.The lowest concentration is in Perambur(193 mg/L)(from table:1).The dark blue coloured zones in fig:5 indicates high concentration of TDS. In the years 1996-2000 the concentration of TDS in groundwater is lower when compared to the years 2010-2015. Fig 3.Landuse map 5. Location of ground water sampling station The groundwater sampling stations in Chennai are illustrated in fig:4 Fig 5.Variation of Total Dissolved Solids 6.2. pH The concentration of hydrogen ion in a solution determines the pH value. Pure water has pH value of 7 mg/L. pH fluctuations may affect aquatic organisms, affect solubility, toxicity of chemicals and heavy metals may occur in water. Major aquatic Imperial Journal of Interdisciplinary Research (IJIR) Page 167 Imperial Journal of Interdisciplinary Research (IJIR) Vol-3, Issue-3, 2017 ISSN: 2454-1362, http://www.onlinejournal.in animals prefer pH value of 6.5-9.0 mg/L. Humans have high tolerance to pH levels(drinking levels range from pH level 4-11 mg/L with minimal gastrointestinal irritation, skin and eye irritation).Acidity is caused mainly due to interactions with carbonate rocks and industrial pollutants. WHO permissible limit for drinking water is 6.5-8.5 mg/L. pH value of water in Vepery, Chennai is neutral and that of Velacherry is 8.8 mg/L which is acidic in nature .In Perambur- Purasawakkam taluk the pH of water is only 6.9 mg/L which is slightly alkaline(Table:1).The concentration of pH has increased from 2010 onwards when compared to the Table:1 Fig 6. Variation of pH WELL NO WELL NO TAHSIL/ TAHSIL/ TALUK VILLAGE LATITUDE LONGITUD E WATER (m) LEVEL TDS pH CALCIUM MAGNESIU M SODIUM POTASSIU M CHLORIDE FLUORIDE EC 13229 Mambalam- Velacheri 1205 8001 5 16 8.1 40 92 393 109 762 67 2950 Guindy 9’07 3’28 75 ” ” 13147 Mambalam- Adayar 1300 8001 3 48 7.9 76 27 62 12 113 34 900 Guindy 0’16 5’44 0 ” ” 13152 Perambur- Ayanavara 1300 8001 2 79 8.5 52 7 237 11 301 14 1370 Purasavakkam m 6’00 3’00 7 ” ” 13153 Perambur- Perambur 1300 8001 2.5 28 8 36 12 48 13 64 0 520 Purasavakkam 6’15 4’28 1 ” ” 13154 Perambur- Vepery 1300 8001 3 18 8.2 32 78 529 40 865 12 3210 Purasavakkam 5’13 6’05 23 0 ” ” 13455 Fort-Tondiarpet Tondiarpet 1300 8001 1.5 80 8 80 10 196 27 326 48 1400 8’00 7’00 0 ” ” 13156 Mylapore- Mylapore 1300 8001 2 50 7.8 60 24 90 7 103 19 900 Tiruvallikeni 2’19 5’30 5 ”