2nd CUTSE International Conference 2009 1 GR_08_curtin Hydrogeochemical studies of ground waters in Neyveli basin along the Cuddalore coast, SE coast of India G. Senthil Kumar and AL. Ramanathan School of Environmental Science Jawaharlal Nehru University New Delhi, India S. Chidambaram 1 and M.V.Prasanna 2 1. Department of Earth Sciences Annamalai University Annamalai Nagar, India. 2. School of Engineering and Science Curtin University of Technology, Sarawak Miri, Malaysia. Abstract— A detailed study had been carried out on groundwater in Neyveli basin along the Cuddalore coast to establish the hydrogeochemistry and identify the various sources of contaminants as well assess the physical and chemical quality of the groundwater. The groundwater was found to vary considerably in terms of chemical and physical properties. Generally the water was alkaline, high chemical constituents near the coastal region and undersaturated with respect to carbonate minerals. The majority of groundwater clustered towards Mg-Cl, Ca-Cl and Na-Cl facies. Interpretation of data reveals that weathering and ion exchange through which major ions enter the groundwater system. Anthropogenic activities were found to have greatly impacted negatively on the quality of the groundwater. Keywords- Groundwater quality; Anthropogenic activity; ion exchange; Weathering; Neyveli basin. I. INTRODUCTION Water is the elixir of life, life without water in unimaginable and impossible. It is the prime requirement of the world. Ground water plays an important role being the primary source of water. Ground water is a mixture of various contents since flows below ground and during passage it contact with different rocks and formation. The water quality depends on its time residence. Some time the quality of water deteriorates with variation in formation and residence time, which makes it for serving in to various purposes. With the changing environment the responsibility of the scientists must be (1) to develop and maintain information on the availability of water resources; (2) to assess, monitor and predict the resulting quality of water bodies and the water related environment; (3) to develop a better scientific understanding of those effects of man’s activities that influence the hydrological regimes: and (4) to provide the decision makers the importance of water management with necessary information in the succinct, properly constructed formats such that they will understand the problems and enable them to react appropriately. The present study mainly aims is to study the impact of entire pumpage from Neyveli mine area including the additional pumping operations (VEERANAM Project) for the drinking water supply to the people of Chennai city on the groundwater quality changes by distinguishing their types, genesis variations through hydro-geochemical studies. The study is intended to identify the movement of salt water migration including the interface through hydrogeochemical approach, which is reported moving presently towards the Neyveli basin from Cuddalore coast (Prasanna et al., 2008) and also the feasibility of artificial recharge to arrest the movement of the sea water. II. STUDY AREA Neyveli basin is located in 250 Km SW of Chennai. The area is located between the geographical coordinates, latitudes of 11 ◦ 36’ – 11 ◦ 70’ and between longitudes of 79 ◦ 51’ – 79 ◦ 86’. The region falls in the toposheet of 58 M/11 (Fig.1). Relative humidity of the area was recorded in the eastern part of the district i.e., at Cuddalore ranges between 60 and 83%, whereas in the western part of the district i.e., at Lekkur it ranges between 46.73 and 71.12%. Higher rates of relative humidity are observed during the months of northeast monsoon period i.e., from October-November-December, where as lower rates are observed during the summer months of April and May. The 70 years average annual rainfall of the district is 1160mm. More than 50% of the rainfall occurs during North – East Monsoon. About 30% of the rainfall during South – East monsoon and the balance from January to May. In the study area, from Veeranam to Panruti, the rainfall normally more than the district average. There are three types of aquifers in this region viz., Phreatic aquifers, aquifer under semi – confined to confined conditions and alluvial aquifers. Phreatic aquifers found in the areas with the top Cuddalore sand stone. Along the river, shallow aquifers are available