Sustainable Groundwater Management and Aquifer Recharge in Bayelsa State, Nigeria: A Review of Hydrogeological Characteristics, Threats, and Management Strategies

Bayelsa State, situated in the low-lying, hydrologically dynamic core of the Niger Delta, depends almost entirely on groundwater abstracted from the unconfined and semi-confined sands of the Benin Formation for domestic, agricultural, and industrial water supply, because surface water throughout the state is largely contaminated, saline, or otherwise unsuitable for direct use. This paper synthesises the published hydrogeological, hydrochemical, and disaster-risk literature on Bayelsa State to examine the sustainability of current groundwater use and to identify practicable aquifer-recharge and management interventions. Evidence is drawn from borehole hydrochemical surveys, geoelectrical aquifer investigations, coastal saline-intrusion studies, and disaster reports on the catastrophic 2022 flood event that submerged seven of the state's eight Local Government Areas. The review finds that, although the Benin Formation aquifer is generally prolific and recharges readily under the region's high (approximately 2,000-4,000 mm) annual rainfall, groundwater quality is compromised in many communities by acidity, elevated iron and manganese, and localised saline intrusion driven by unregulated borehole proliferation, tidal influence, and the geological complexity of paleo-channels within the Benin Formation. Escalating flood frequency, attributed to both extreme rainfall and inadequate land-use planning, further threatens aquifer integrity through recharge-zone disturbance and contaminant mobilisation. The paper proposes an integrated management framework combining managed aquifer recharge (MAR) techniques -- rainwater harvesting and infiltration, recharge ponds, coastal injection barriers, and wetland-buffer retention -- with regulatory reform, borehole-spacing controls, and community-based groundwater monitoring. It concludes that sustainable groundwater management in Bayelsa State requires coordinated action across hydrogeological science, disaster risk reduction, and water governance to secure long-term freshwater availability for the state's growing population.