Hydrochemical Evaluation of Saltwater Intrusion in Some Coastal Areas in Rivers State, Nigeria

This study evaluates the hydrochemical characteristics and extent of saltwater intrusion in selected coastal communities of Rivers State, Niger Delta, Nigeria, with particular emphasis on groundwater vulnerability, salinity distribution and suitability for domestic and agricultural applications. Groundwater samples were collected from six (6) boreholes and six(6) hand-dug wells across Sama, Tema, Abalama, Buguma, Ido and Obuama communities and analysed for physicochemical parameters, major ions and selected heavy metals using standard laboratory procedures. The results revealed considerable spatial variability in groundwater quality, with electrical conductivity (EC) ranging from 77 to 7,490 µS/cm and total dissolved solids (TDS) varying between 40 and 3,750 mg/L. Salinity concentrations were exceptionally elevated at Tema (3,810 mg/L), Sama (3,310 mg/L) and Ido (2,712 mg/L), exceeding the recommended drinking water threshold. Sodium concentrations also exceeded permissible limits at selected sampling locations, while elevated sodium adsorption ratios indicated potential irrigation constraints. Chloride-bicarbonate ratios ranged from 0.229 to 1.552, suggesting variable saline influence and localized hydrochemical modification. Spatial distribution maps further revealed heterogeneous salinization, reflecting interactions between coastal hydrodynamics, aquifer characteristics and anthropogenic activities. The findings establish that saltwater intrusion constitutes a significant threat to groundwater sustainability, necessitating continuous hydrochemical monitoring, regulated groundwater abstraction and appropriate aquifer protection strategies to safeguard potable water resources in the coastal Niger Delta.