IJEP 26 (6) : 497-504 (2006) (Received on. April 10, 2006) Groundwater Quality Assessment in Tondiar Basin K. Ramesh and L. Elango Anna University, Department of Geology, Chennai - 600 025 Groundwater quality study was carried out in the Tondiar Basin, Tamil Nadu. THe objective of this study is to identify the quality of groundwater in the rural areas where groundwa- ter is used for domestic and agriculture purposes. Forty-five groundwater samples were col- lected in the month of September 2005 from different wells in the study area and were analysed for major ions. The groundwater quality depends upon geological, meteorological and topographical conditions. This study reveals that the agriculture activities, geological formation and local envi- ronmental conditions control the groundwater The groundwater in this area is mostly moderately hard to hard in nature. Groundwater suitability for domestic and irrigati,on pur- poses were examined using WHO, I.ndian standards USSL classification, which indicate that groundwater in a f·ew locations, were unsuitable for domestic purpose and irrigation. INTRODUCTION its chemical composition. Groundwater in. this area is the only source for irrigation and Groundwater, is used for domestic, agricul- domestic activities. ture and industrial purpose in most parts of the world. Rural population living in India Study a.rea depends on groundwater for domestic and Tonidar River basin is sityated about 130 km agriculture purpose. Groundwater quality is south of Channai city in the Tiruvannamalai degrading due to natural and human activi- and Villupuram district, Tamil Nadu (Figure ties. Once pollutants enter the subsurface 1). Tondiar River flows only for a few days it remains there for many years and gets receives water during" the Northeast mon- dispersed over wide regions. Over exploita- soon season (October to December). The tion of groundwater resources in many coun- study area experiences a maximum tempera- tries induces degradation of groundwater ture 42°C during the ITronth of Aprfl and quality. Thus water quality analysis is an May and the mini,mum temper'ature of about important issue in groundwater. studies. 26°C duri.ng the month of N'ovember and Variation of groundwater quality in an area December. The average annual rainfall of is mainly influenced by the geological for- this area is about 1 200 mm, which is mainly mation and. anthropog"enic activities., Many received during in North-East Monsoon from problems originate during inefficient man- October to December and during the South ageme.nt of water for agriculture, especially East Monsoon that is from June to Sep- when it carries high salts. The salts present tember and small amount during the sum- in water besides affecting the plants it also mer period. Precipitation is the main sources aftect the soils. Hence there is always a of groundwater recharge· in this area. This need for and concern over the protection basin has a number of lakes and ponds, and management of groundwater was af- which are major source o·f recharge of fected by the use of fertilizers. Subram.anian groundwater in this area (Figure 2). All the and Elango (2005) have studied groundwa- . lakes are con,nected and they drain into the ter quality and its suitability for drinking and Tonidar river. Groundwater is abstracted for agricultural use in Chithar basin, Tamil Nadu. irrigation and domestic purposes for m-ost the present study an attempt is made to of the year. Irrigation mainly de- ::haracterise the groundwater quality of pend on the groundwater during most of Tonidiar basin, Tamil Nadu with respect to the year and lake water for about 1 or 2 J. ENVIRONMENTAL PROTECTION, VOL. 26, NO.6, JUNE 2006 497 © 2005 - Kalpana Corporation