Assessment of Pleistocene Aquifer Vulnerability to Saline Intrusion in the Coastal Region of Ba Ria-Vung Tau Province Using GIS and Entropy-GALDIT

Abstract

Sea-level rise, in the context of climate change, increases the likelihood of seawater intruding into coastal aquifers. This study assesses the vulnerability of the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province, Vietnam. Data for calculation and analysis were collected from 99 boreholes in the study area. Using the vulnerability assessment index (GALDIT) with expanded weights, the vulnerability of the aquifer to the influence of coastlines was evaluated and visualized in a GIS environment. The set of Entropy weights used clearly shows the significance of the component parameters and indicates the characteristics of the risk partitioning of aquifer salinization. The Entropy-GALDIT results divided the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province into three levels of vulnerability: high vulnerability zones (3.88% of the area), medium vulnerability zones (55.47%), and low vulnerability zones (40.65%). According to the GALDIT susceptibility zoning map, the western area of Phu My town (along the Thi Vai River), the southwest region of Vung Tau City, and the southeast region of Dat Do District are highly sensitive and not recommended for any purpose. This result provides useful insights into the vulnerability of aquifers in the coastal area of Ba Ria-Vung Tau province, with respect to factors such as the height of the groundwater level above sea level, the distance from the shore to the wells, and the impact of existing seawater intrusion. Accordingly, it is necessary to establish monitoring systems to warn of saltwater intrusion and to develop integrated resource management strategies to ensure the sustainability of groundwater resources in the area.