Application of GIS-based DRASTIC model approaches in assessing groundwater vulnerability for shallow alluvial aquifer deposited

Groundwater can be contaminated by many sources, such as anthropogenic activities on the ground surface. To evaluate the vulnerability of groundwater to contamination, the present study was conducted in the shallow alluvial aquifer of Bachok, Kelantan, by embedding several hydrogeological parameters using the GIS-based DRASTIC model. Considering the importance of land use activities on groundwater vulnerability, the land use map of the study area was integrated with the DRASTIC model, known as the integrated land use DRASTIC model. Results of the DRASTIC model classified 58.36% of the area as high vulnerability, 14.40% as moderate vulnerability, and 27.14% as low vulnerability. Meanwhile, the integrated land use DRASTIC map showed that most parts of the study area have moderate vulnerability (61.03%). The depth to the water table and net recharge parameters have contributed to large variations in groundwater vulnerability indices. The models were validated using nitrate concentrations. Negative weak correlations were measured between nitrate concentrations with DRASTIC index (− 0.318; p