Applying the Geographic information system (GIS) to create an vadose zone map of the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province

Abstract

The vadose zone is an important component in assessing the ability of the aquifer to be affected by surface contaminants, serving to assess the vulnerability of the aquifer. This study has initially applied spatial calculation and interpolation tools in a geographic information system (GIS) environment to create thematic maps to help visualize contamination assessment from surface activities, especially in areas with many groundwater exploitation activities through Pleistocene aquifer characteristics data in the coastal area of Ba Ria-Vung Tau (BR-VT) province. The vadose zone in the study area is relatively uniform in thickness, with 87.2% of the aquifer area ranging from 10 to 23 meters, distributed mainly in the West - Southwest of the area. The vadose zone with a thickness of over 23 m only account for 9.73% of the study area, mainly in the Southeast of the area (Dat Do district). At the same time, the silt and clay composition of 92.16% of the Pleistocene aquifer vadose zone is relatively thin, consisting primarily of sand and gravel. The vadose zone has less silt and clay in central area of Phu My town. Only 7.84% of the aquifer area has thick silt and clay components appearing in the vadose zone of the coastal areas of Dat Do district and Vung Tau city. The results show that the Pleistocene auifer distributed in the hinterland and almost the entire Xuyen Moc district is more sensitive to pollutants, susceptible to direct penetration by surface activities due to less protection from the silt and clay in the vadose zone.