Salinity Intrusion Dynamics in the Niger Delta During the Dry Season

Salinity intrusion into freshwater systems during the dry season poses significant threats to agricultural irrigation, domestic water supply, and freshwater biodiversity in the Niger Delta, South South Nigeria. This study examines the spatial extent, temporal dynamics, and controlling factors of salinity intrusion in selected creeks of the central Niger Delta, Bayelsa and Rivers States, during the November to March dry season of 2023 to 2024. A network of continuous conductivity-temperature-depth loggers deployed at ten stations along the Nun River and Ekole Creek records hourly salinity, temperature, and water level data throughout the study period. Complementary field surveys measure salinity profiles at spring and neap tides to characterise the salt wedge behaviour and tidal pumping mechanisms. Bathymetric surveys define channel morphology influencing intrusion dynamics. Statistical models correlate intrusion length with upstream freshwater discharge, tidal range, and wind forcing. Results are expected to demonstrate intrusion extending up to 45 kilometres upstream of the river mouth during peak dry season conditions, threatening freshwater abstraction points used by rural communities. The effects of reduced upstream discharge linked to reservoir impoundment and changing rainfall patterns are discussed. Recommendations include the designation of freshwater buffer zones and monitoring protocols for municipal water authorities in the Niger Delta. Keywords: salinity intrusion, Niger Delta, dry season hydrology, salt wedge, freshwater resources