Re-evaluating coastal aquifer using graphical and geochemical approach. A case study of Niger Delta Region, Nigeria

The study was carried out in coastal region of Niger Delta, Nigeria. This study was aimed at evaluating the effect of seawater intrusion and corrosion tendency on coastal aquifer. In other to achieve this aim, 24 groundwater samples was measured and analyzed for various hydrochemical parameters. Results obtained from the study revealed that groundwater was considered to fresh water based on TDS value obtained. Findings from geochemical model showed that 71 % of groundwater samples showed trace of seawater intrusion, while the remaining 29 % showed no trace of seawater intrusion. The value obtained from corrosivity indices such as Chloride-Sulfate Mass Ratio (CSMR) revealed that 33% of groundwater showed no galvanic corrosion potential, 67% showed galvanic corrosion potential, findings obtained from Revelle Index (RI) showed that 2 % of groundwater was not influenced by salinization, 96 % was slightly influenced by salinization and 2% strongly influenced by salinization. Values obtained from Larson-Skold Index (LSI) showed that groundwater samples were classified to be high in corrosion expect for sample locations pH/07 and 23. The plot of Cl¯/HCO3¯ against Cl¯ revealed that 98% of groundwater were classified to be slightly/moderately influenced by sea water intrusion, 2 % was strongly influenced by seawater. Findings from Chadba plots suggested that 97 % of groundwater were of Ca2+ - Mg2+- ˗ Cl¯ water type, 2% were of Na+ ˗ Cl¯ water type and 1% is of Ca2+ - Mg2+ - HCO3¯ water type. On a general note, it was observed that seawater intrusion slightly influenced groundwater of the study area.