Groundwater vulnerability and contamination risk assessment using GIS-based modifiedDRASTIC-LU model in hard rock aquifer system in India

Groundwater vulnerability and risk assessment is an essential step for preventing and controlling contamination in any area.DRASTICmodel with modification incorporating land use (LU) widely used for assessing groundwater vulnerability worldwide. The present study used this modified model termed asDRASTIC-LU considering LU as a significant parameter in addition to other conventionalDRASTICparameters. Geographic information system employed to prepare and integrate different parameter maps led to demarcate the risk zones in a catchment of Damodar River, Jharkhand, India. FinalDRASTIC-LU map was categorized as low (19.50%), moderate (34.02%), high (29.90%) and very high (16.58%) risk zones of groundwater contamination. Validation of models done through Spearman's rank correlation coefficient (rho) and receiver operating characteristic curve using nitrate concentration in groundwater, which indicatedDRASTIC-LU (rho = 0.893; AUC = 71.65%) had a better agreement thanDRASTICmodel (rho = 0.7818; AUC = 67.36%). Thus, such modification inDRASTICimproves the performance of the model.