Geospatial technology and modified DRASTIC model to assess the groundwater pollution vulnerability along a stretch of Cauvery River, South India

In the recent years, the vulnerability of groundwater aquifers to pollution is one of the major issues. The fast growth of industrialization, deforestation and agricultural activities are the potential sources for groundwater pollution. Assessment of groundwater vulnerability in a region is necessary for any groundwater management and developmental activities. The present study assess the aquifer vulnerability to contamination along a limited stretch of Cauvery River (Kumarapalayam to Kokkarayanpettai) in Namakkal and Erode district, in the state of Tamil Nadu, India, using modified DRASTIC model. The textile dyeing units and other small-scale industries are located along Kumarapalayam to Kokkarayanpettai stretch on the bank of the Cauvery River. The river course is highly polluted due to disposal of effluent from a number of dyeing industries. In the first step, the ranks and weights were assigned for the DRASTIC parameters including groundwater depth ( D ), net recharge ( R ), aquifer media ( A ), soil media ( S ), topography ( T ), impact of vadose zone ( I ) and hydraulic conductivity ( C ). These parameters were integrated and reclassified into five categories such as very low (1.88%), low (9.33%), moderate (24.23%), high (52.57%) and very high (11.99%) vulnerability zones. The results revealed that about 64% of the study area was affected by groundwater vulnerability as per DRASTIC index. Further, the lineament density and land use/land cover were incorporated in the DRASTIC model. The integrated results also show the major groundwater aquifer zone in the study area vulnerable to pollution. Finally, the modified DRASTIC model was validated with nitrate (NO 3 ) concentration in the groundwater samples and it shows 82.42% accuracy in the result. It confirms that the modified DRASTIC model is one of the essential tools to estimate the groundwater pollution risk. The overall results revealed that the groundwater aquifer in the study area is facing contamination due to sewage disposal and dyeing industry. Immediate attention is required for maintaining groundwater aquifer free from contaminations.