Hydrogeochemical characteristics of shallow aquifers in Thanh Phu District, Ben Tre Province, Vietnam

Abstract

Shallow aquifers in the Thanh Phu coastal area in Ben Tre Province are increasingly withdrawn for domestic and irrigation purposes. However, groundwater resources here are declining in quality due to the effects of seawater intrusion and anthropogenic activities. It requires an understanding of the groundwater origin and changes in water quality to protect local groundwater resources. By applying the hydrogeochemical approach, the origin and quality of groundwater here have been clarified. A total of 35 water samples were collected during the 2023 dry season. The laboratory analysis included 16 ions. The results show that the groundwater water types are Ca-Cl, Ca-Mg-Cl and Na-Cl, with the domination of the third pattern. Hydrochemical characteristics have shown evaporation, silicate weathering, cation exchange and marine effects as the vital processes governing the mineralization of regional groundwater. Most of the water samples are of poor quality, not adapting to domestic water standards according to the National Technical Regulation on Domestic Water Quality and WHO 2011. It requires water treatment before being used for domestic purposes. However, the SAR, Na%, PI, KR and EC values displayed that groundwater here was still acceptable for irrigation purposes, demonstrating the prospect of using groundwater for agricultural purposes in the study area.