AN INTEGRATED APPROACH for GROUNDWATER POTENTIAL ZONING in PALAR BASIN in and AROUND WALAJABAD BLOCK Mathiazhagan M1, Madhavi G2 and Selvakumar T3
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Mathiazhagan M et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945 Research Paper AN INTEGRATED APPROACH FOR GROUNDWATER POTENTIAL ZONING IN PALAR BASIN IN AND AROUND WALAJABAD BLOCK 1 2 3 Mathiazhagan M , Madhavi G and Selvakumar T Address for Correspondence 1Research Scholar and 2,3Associate Professor, 1 & 2 Centre for Water Resources, Anna University, Chennai -600 025 3 KCG College of Technology, Karapakkam, Chennai – 600 097 ABSTRACT: In this study, an integrated approach for the identification of groundwater occurrence in Palar Basin in and around Walajabad Block, Kanchipuram District of Tamil Nadu using geophysical, geology and remote sensing data. It is predominantly underlain by hard rocks, sedimentary and alluvium deposits. Vertical Electrical Sounding data were collected from 110 locations using ABEM SAS 1000 Terrameter and it was interpreted qualitatively and quantitatively. The resistivity varying from 0.565 Ωm to 39174.4 Ωm and thickness from 0.105 m to 94.91 m. With an integrated approach on using Remote Sensing and Geographical Information System (GIS). Topographic map has been used to prepare base map and generate thematic maps like geology, geomorphology, lineament and lineament density, drainage, drainage density, and slope maps has been prepared. A composite groundwater potential map has been generated for the category of Good, Medium and Poor based on the groundwater availability. The outcome of the analysis suggests that 33.4 % of available ground water is good and 65.9 % of ground water falls under moderate category. The rest of 0.7 % of groundwater is Poor and serviceable. The data generated subjected to validate with limited field checks. The Groundwater Estimating Committee (GEC) announced in 2011, the groundwater had been over exploited in the Walajabad block. So, this is an alarming level for groundwater quality and quantity of Walajabad block. KEYWORDS: Palar Basin, Ground water, Vertical Electrical Sounding, Remote Sensing, GIS. 1. INTRODUCTION aquifers (K’Orowe, M.O. 2012). Resistivity value in In general, the occurrence and movement of sedimentary rocks are also controlled by parameters groundwater is controlling by lithology, geological such as water contents, salinity, texture, matrix structure, drainage pattern and climate condition. The conductivity and the presence of clay materials electrical resistivity technique involves the (Nwankwo C.N. 2012) and vulnerability of aquifer measurement of the apparent resistivity of soil and contamination (Opera A.I 2012). rock as a function of depth or position. The most In hard rock terrain availability of groundwater is common electrical technique needed in limited and is essentially confined to fractured and hydrogeologic and environmental investigations is weathered zones. There are several methods vertical electrical soundings (resistivity sounding). employed for delineating groundwater potential During resistivity survey, current is injected into the zones such as geological, hydrological, geophysical each through a pair of current electrodes, and the and remote sensing techniques. Integration of various potential difference is measured between a pair of data and thematic maps, such as terrain features current electrodes, and the potential electrodes. The derived from remote sensing images, bulk average resistivity of all soils and rock hydrogeomorphical details, depth to groundwater influencing the current. It is calculated by dividing table and geophysical resistivity sounding data help the measured potential difference by the input current in generation of groundwater potential zone maps and multiplying by a geometric factor specific to the which when supplemented with geophysical data i.e. array being used and electrode spacing (Zohdy AAR, VES data in GIS environment, facilitates effective 1974). evaluation of groundwater potential zones (Singh J In a resistivity sounding the distance between the and Jha, B.P, 1997; Yadav,G.S and Singh, S.K 2007). current electrodes and the potential electrodes is The sustainability and yield of the wells are mainly systematically increased, thereby yielding controlled by fracture density, aperture and information on subsurface resistivity from connectivity, secondary porosity, hydraulic properties successively greater depth. The variation of and the interrelationships among these factors resistivity with the depth is modeled using forward (Greenbaum, D., 1992; Mukherjee, S., 1996; Roy, and inverse modeling computer software. The A.K., 1996; Srinivasa Rao,Y., et al, 2000; Vijith, H., vertical sounding method was chosen for this study 2000; Jyoti Sarup et. al, 2011). Vertical electrical because the instrument is simple, field logistics are resistivity method can provide depth of occurrence of easy and straight forward while the analysis of data is groundwater zone, thickness of the aquifer system less tedious and economical (Ako and Olorunfemi, and the probable location for well sites (Srivastava, 1989). It also has capability to distinguish between P.K., and Bhattacharya, A.K., 2006; Israil, M., et al., saturated and unsaturated layers. The Schlumberger 2006). Remote-sensing and GIS techniques are being method has greater penetration than the Wenner routinely used to identify and map prospective configuration. In resistivity method, Wenner groundwater zones through qualitative assessment of configuration discriminates between resistivities of indicative, controlling parameters such as lithology, different geoelectric lateral layers while the geomorphology, regional structural features, and Schlumberger configuration is used for the depth drainage systems (Sander, P. et.al., 1997; Sander, P., sounding (Olowofela et al, 2005). Jessica Roe 2010, 2007; El Baz 1995; El Baz et al. 1998; Gheith, H., delineation of the groundwater potential aquifers and Sultan, M., 2002; Robinson, C.E., et al., 2006; (Joseph Olakunle Coker 2012). Geo-electrical Sultan, M., et al. 2008; Amer, R., et.al., 2010). techniques provide an alternative method for Integrated studies using remote sensing, GIS and acquiring hydraulic parameters and processes data in VES approaches has been applied successfully for order to adequately characterize flow in hard rock delineation of ground water potential zones by Int J Adv Engg Tech/Vol. VII/Issue III/July-Sept.,2016/76-82 Mathiazhagan M et al., International Journal of Advanced Engineering Technology E-ISSN 0976-3945 various researchers (Kukillaya,J.P., 2007; Semere Alluvial deposits are the youngest formation consists and Woldai, 2007; Mondal, N.C., et al, 2008; Hyun- of sands and clays and is deposited by the Vegavathy Jo Oh, et al., 2011; Balakrishna, S., et al., 2014; river and Palar rivers. The Palar alluvium comprises Venkateswaran, S., et al., 2014; Sahebrao, S., 2014). of coarse sands and gravels. The average thickness of In Palar Basin, there are number of studies related to alluvium is about 1 to 30 m. groundwater prospect. Central Groundwater Board (CGWB) has carried out a systematic hydrological survey on various issues in different physiographic region in Kanchipuram District, Tamilnadu. The study is an attempt to delineate the groundwater potential zone in Palar basin in and around Walajabad Block. 2. MATERIALS AND METHODS 2.1 Study Area In this research project the study area selected is Walajabad block of Kancheepuram District, Palar sub basin. As per Groundwater Estimating Committee (GEC), 2011 the Walajabad block has been categorized as overexploited block. The areal Figure 1. Geology map extent of the study area is 325 Km2 and it lies 2.3.2 Gondwana between the geographical co-ordinates of Latitude This formation comprise of clays, shales, sandstones 13˚14’12” to 12˚15’38”and Longitude 79˚30’37” to and conglomerates. The shale and clay of gondwana 80˚30’42”. Palar river is the major river draining occur on the bank of Palar river in Walajabad block, across the district from West to East, and the river is as clay and shale beds, are of upper gondwana age. a seasonal in nature. As the surface water drying on, The fine grained sand is observed at Walajabad the groundwater has become the main source for block. Sandstone is called Conjeevaram gravels irrigation and drinking water sectors. The study area which is equivalent to cuddalore and Rajmundry sand is predominantly underlain by hard rocks, stone of Tertiary age. sedimentary and alluvium deposits and hence 2.3.4 Archaean: Hard Rocks because of heterogeneity in geological formation a The hard rocks spread over an area of about 30 suitable methodology is required to identify percent of this block. These rocks are Granitic groundwater potential zones. gneisses in parts of Walajabad block. Groundwater 2.2 Methods occurs mostly under water table or pheratic Vertical Electrical Sounding data were collected conditions in weathered, fractured jointed and faulted using ABEM SAS 1000 Terrameter from 110 portions of granitic rocks and under artesian locations was interpreted qualitatively and conditions in fractured zones located below quantitatively to obtain layered resistivity parameters impervious hard rocks. The pore spaces developed in and to delineate potential fractured zones in the deep the weathered mantle acts as shallow granular aquifer. The apparent resistivity and AB/2 values aquifers and forms the potential water bearing zones. were plotted on double-log sheet in IX1D software. Water table is shallow in ayacut regions whereas it is The layered resistivity model obtained in IX1D was relatively