Intrinsic and Integrated Models for Groundwater Vulnerability Assessment in Tay Ninh Province, Vietnam

ABSTRACT This study assessed the vulnerability of upper–middle Pleistocene aquifers in Tay Ninh Province, Vietnam. This shallow aquifer is susceptible to contamination from natural geological, climatic and anthropogenic sources, particularly agricultural activities, in the context of rapid socio‐economic development in this study area. In this study, the GOD, DRASTIC and combined DRASTIC methods were used to identify vulnerable areas, particularly the susceptibility of aquifers to nitrate. The study indicates that the extended vulnerability index (DL) has low, medium and high levels of 1.4%, 72.1% and 26.5%, respectively. Moreover, the nitrate vulnerability index (DN) has low, medium and high levels of sensitivity: 29.4%, 47.8% and 22.8%, respectively. The DN index showed a strong correlation coefficient ( r = 0.746) for the spatial distribution of nitrate concentration in the aquifer, which was related to different land uses. The DN multiplicative model outperformed traditional methods in evaluating the vulnerability related to the impacts of land use types. The results of this study on the vulnerability of groundwater to nitrate provide a basis for sustainable groundwater protection and land use planning in the current study area.