Groundwater pollution vulnerability assessment using a modified DRASTIC model in Ho Chi Minh City, Vietnam

Abstract

The Pleistocene aquifer serves as a vital water source for various activities in Ho Chi Minh City, Vietnam, including concentrated and individual exploitation. In the present study, the DRASTIC (D, depth of water; R, net recharge; A, aquifer media; S, soil media; T, topography; I, impact of vadose zone; C, hydraulic conductivity) model was used to evaluate the groundwater sensitivity of the study area. To analyse Ho Chi Minh City's Upper-Middle Pleistocene aquifer vulnerability, the analytic hierarchy process (AHP) method was used to optimize the DRASTIC score and include land use (LU) characteristics. Four distinct weights were used: DRASTIC, modified DRASTIC-LU, AHP-DRASTIC and modified AHP-DRASTIC-LU. This study identified low, moderate and high vulnerability for 12%, 55% and 33% of the DRASTIC-LU index values, respectively. The AHP-DRASTIC index classifies 61%, 26% and 13% of sites as low, moderate and highly vulnerable, respectively. The study reveals that 52%, 30% and 18% of the area are vulnerable to the modified AHP-DRASTIC-LU index classes. The most sensitive factors are shallow aquifer roofs, recharge and LU. The real-world accuracy of the DRASTIC models was tested using 106 groundwater nitrate concentrations. The modified AHP-DRASTIC-LU is the most accurate and appropriate model for the current research region.