Hydraulic analysis and electrical resistivity for optimizing coastal groundwater management for irrigation under climate stress

A critical challenge in coastal aquifer management is the lack of integrated, multi-method studies that combine geophysical, hydrochemical, hydraulic, and climate modelling to provide a comprehensive understanding of groundwater dynamics, especially in data-sparse regions. In coastal West Africa, there is mounting pressure on coastal groundwater systems from climate variability, land-use change, and sea-level rise. However, limited information is available on full multi-method testing, which combines geophysical, hydrochemical, hydraulic, and climate modelling, especially in data-sparse environments. The paper presents a site-specific analysis of groundwater resources in the town of Abavo, Delta State, Nigeria, including Electrical Resistivity Tomography (ERT), Vertical Electrical Sounding (VES), hydrochemical profiling, pump-test hydraulic analysis, and climate scenario analysis using representative concentration pathways (RCP) 4.5 and 8.5. The resistivity surveys map the heterogeneous aquifer lithologies, whose interpretations are supported by the existing resistivity-lithology associations in the literature. Groundwater quality depends on depth, and the hydraulic conductivity suggests moderate aquifer productivity. Climate scenarios indicate that recharge can decrease by 25 per cent under RCP4.5 and 50 per cent under RCP8.5 by 2050, with considerable model uncertainty. Spatial analysis indicates potential contamination hotspots associated with land-use intensification, but these links are inferred and not directly verified. The comprehensive and transparent approach provides a generalisable framework for assessing groundwater in data-sparse coastal settings, emphasising uncertainty-conscious interpretation for sustainable management.