GIS based Groundwater Quality Mapping in Paravanar River Sub-Basin, Tamil Nadu, India

Water, the precious gift of nature to human being, polluted daybyday with increasing urbanization. Although threefourth of earth is being surrounded by sea only a little portion of it can be used for drinking purpose. The study area Paravanar basin lies in the Cuddalore District of Tamil Nadu. The area is located in the survey of india toposheets No's 58M/6, 58M/7, 58M/10&11, of the year 2003 in 1:50,000 scale lying between the longitude 11°18'to11°45' and latitude 79°18' to 79°45'. The Geographical extent of Paravanar subbasin is 880 sq km. It is bounded on the north by Gadilam river basin, in the south by Vellar basin, on the east by Bay of Bengal. The study area is typically covered by sedimentary rock types of Cretaceous to Recent age. Though the basin receives moderate to heavy rainfall, it frequently faces water scarcity problems as well as water quality problems in some specific areas. Hence, a GIS based groundwater quality mapping has been carried out in the region with the help of data generated from chemical analysis of water samples collected from the basin. An attempt has been made to study on the quality of ground water for the Villages falling in the Paravanar Sub Basin to interpolate major ions concentration in groundwater by using ARC/view GIS software. Major elements thematic maps on Calcium, Magnesium, Sodium, Potassium, bicarbonates, chlorides and sulphates were prepared from the Hydrochemistry data. Different classes in thematic maps were categorized as (i) good (ii) Moderate and (iii) poor. In the study area sulphates are found to be within prescribed limit for drinking purpose.