Spatio-temporal variability of seawater mixing in the coastal aquifers based on hydrogeochemical fingerprinting and statistical modeling

This study discusses monitoring and characterization of spatial and temporal variability to comprehend groundwater salinization based on hydrogeochemical fingerprinting and statistical modeling in the coastal belt of Digha-Shankarpur-Tajpur-Mandarmani, West Bengal, India. An integrated study of hydrogeochemical, bulk magnetic susceptibility, multivariate statistical, and geochemical modeling methods is implemented. The major cationic and anionic concentrations in groundwater are in the order Na+ > Ca2+ > Mg2+ > K(+ )and Cl- > HCO3> SO4- > NO3- > F- respectively. The major water types are dominated by (Ca2+ - HCO3- ) followed (Ca2+ - Mg2+ Cl-), (Ca2+ - Na+ - HCO3- ), (Na+ - HCO3- ), and (Na+ - Cl). The results showed that the groundwater quality continuously declined steadily from pre-monsoon 2020 to pre-monsoon 2022. The deterioration of groundwater is due to an interplay of multiple factors, i.e., water-rock interaction, including ion-exchange, seawater mixing, and anthropogenic actions. Furthermore, it is also found that the regions showing higher seawater mixing index and oversaturated with carbonate minerals are also areas where groundwater is unsuitable for irrigation. The findings are beneficial in assisting local communities and legislators in designing appropriate management and mitigation techniques to arrest seawater intrusion in coastal regions.

Automated summary

This study discusses the monitoring and characterization of groundwater salinization in the coastal belt of West Bengal, India using hydrogeochemical fingerprinting and statistical modeling. The results show a continuous decline in groundwater quality due to various factors such as water-rock interaction, ion-exchange, seawater mixing, and anthropogenic actions.