Spatial mapping for Groundwater Vulnerability to Pollution Risk Assessment Using DRASTIC Model in Ponnaiyar River Basin, South India

Groundwater is the principle source of drinking water and protection of groundwater quality is an important issue meets out the increasing population and agricultural practices. The present research an attempt made to develop DRASTIC model to understand the groundwater contamination risk in Ponnaiyar River Basin (PRB), Tamil Nadu, India using geographical information system (GIS). GIS have been shown to be useful tools for assessing groundwater pollution hazard. According to Central Ground Water Board reports the PRB categorized by semi-critical groundwater development. In view of the extensive reliance on this basin, contamination of PRB groundwater became an alarming issue. To assess groundwater contamination risk in the PRB the parameters such as Groundwater depth, Net recharge, Aquifer media, Soil media, Topography, Impact of vadose zone and Hydraulic conductivity were selected. Based on the importance of groundwater contamination all the parameters were assigned to rank and weights. Then all the themes were integrated and classified into five categories such as very low (9.33%), low (26.54%), moderate (34.77%), high (22.38%) and very high (6.98) risk. To validate the DRASTIC model, nitrate concentration was selected and found that it is 81.53% accurate which reflects that, DRASTIC model is appropriate to understand groundwater pollution risk assessment. In the GSB groundwater is contaminated mainly due to extensive use of groundwater extraction for agriculture purpose. Groundwater risk index assessment is an effective tool for groundwater management in the PRB.