Aquifer Characteristics and Evidence of Saltwater Intrusion in Coastal Groundwater of Niger Delta (Nigeria) Based on Historical and Recent Data

Abstract

AbstractThe economic expansion of Niger Delta region depends on groundwater resource for various uses. Therefore, there is need for an understanding of the hydrogeological and hydrochemical characteristics as an integral for management of the resource. Hence, this study was aimed at delineating areas of saltwater intrusion in the area. Geological and hydrogeological data were used to delineate two aquifers: alluvial aquifer (upper designated as A and lower designated as B) and a coastal plain aquifer (designated as C). Groundwater in the area was classified as fresh (<1500 μS/cm), brackish (1500–3000 μS/cm), and saline (>3000 μS/cm). Among the groundwater samples (n = 105), 95% from A, B, and C were classified as fresh, while 2 and 3% of the samples from A were classified as brackish and saline, respectively. The main groundwater facies were Na–Cl, Mg–Cl, and Na–HCO3 respectively, for A, B, and C aquifers. The enrichment of Na+ and Cl−, freshwater–seawater mixing ratio, cross plots, and classifications by means of different schemes indicated that seawater intrusion was occurring in the A aquifer. In terms of drinking and irrigation use, the A aquifer water is of poor quality relative to the groundwater from B and C aquifers. The study highlights the potential danger of contaminated groundwater in the coastal areas occupied by low income dwellers. Hence, seawater intrusion should be continuously monitored for sustainable development and management of groundwater in coastal areas.KeywordsCoastal aquiferContaminationSaltwaterNiger DeltaNigeria