Groundwater vulnerability mapping using geophysical, geospatial technology and the SINTACS intrinsic vulnerability index (SIVI) model in the Kiliyar sub-basin of the Palar River Basin, South India

Groundwater is one of the most precious natural resources on the Earth. The increase in deforestation, agricultural activities and urbanization have inevitably led to pollution of the groundwater aquifers. The present study aims to develop the SINTACS model to assess the vulnerability of the aquifer to contamination in the Kiliyar sub-basin of the Palar River Basin, South India. The groundwater vulnerability conditioning factors of the SINTACS model, namely Depth to Aquifer Layer (S-Parameter), Net Recharge (I-parameter), Impact of Vadose Zone (N-parameter), Soil Media (T-parameter), Aquifer Media (A-Parameter), Hydraulic Conductivity (C-Parameter) and Topographic Slope (% slope) (S-parameter) were selected. These parameters were assigned a rank and weights as per the previous literature studies. Then all the SINTACS parameters were integrated and reclassified into five categories, very low (3.77%), low (14.67%), moderate (49.03%), high (30.53%) and very high (2.01%). The results revealed that about 38% of the study area is affected by high to very high groundwater vulnerability as per SINTACS index. The results revealed that a substantial groundwater aquifer zone in the study area is vulnerable to pollution. The SINTACS model was validated with nitrate (NO3) concentration and lineaments in the groundwater samples and it shows 82.24 % accuracy in the result. It confirms that the modified SINTACS model is one of the most important tools to calculate the risk of groundwater pollution. The risk map shows a high risk of groundwater contamination where agricultural and human activities are concentrated. The remaining areas are placed in moderate and low vulnerability categories due to the absence of agricultural and human activities. The overall result shows that the groundwater aquifer in the study area is facing contamination due to sewage disposal. Immediate attention is required for maintaining the groundwater aquifer free from contaminations.