Saline intrusion in Niger Delta coastal aquifers, drivers, hydrogeological dynamics and mitigation strategies

Saline water intrusion poses a critical environmental challenge, affecting the Niger Delta's coastal aquifers and significantly jeopardising freshwater resources essential for drinking, agriculture, and industrial use. Approximately 30% of these aquifers are affected by salinisation. The drivers of saline intrusion are multifaceted, encompassing anthropogenic factors such as the overexploitation of groundwater, unregulated borehole drilling, and climatic impacts, including rising sea levels and increased tidal fluctuations. The hydrogeological dynamics within the region, particularly the geological complexity of the Benin Formation, exacerbate the vulnerability to saline intrusion by facilitating the movement of saline water inland through paleo-channels, faults, and fractures. This review synthesises current research findings and addresses the pressing need for efficient management techniques to tackle this issue. Proposed interventions include managed aquifer recharge (MAR) systems analogous to successful applications in global contexts, which aim to enhance freshwater retention and groundwater sustainability. Furthermore, the study advocates for comprehensive policy reforms, robust stakeholder engagement, and the implementation of Integrated Coastal Zone Management frameworks to coordinate land-use and water policies effectively. By leveraging community-based monitoring initiatives that incorporate both modern technology and indigenous knowledge, stakeholders can foster sustainable resource management. Ultimately, tackling the Niger Delta's saline incursion problem necessitates a concerted effort across scientific, political, and community spheres to ensure long-term water security for over 30 million residents while preserving crucial coastal ecosystems.