Impact of Climate Variability on Hydropower Generation in the Niger River Basin, North Central Nigeria

Hydropower contributes approximately 20 to 25 percent of Nigeria's installed electricity generation capacity, with major facilities concentrated on the Niger and Kaduna Rivers, making the sector's performance sensitive to climate variability affecting river flow regimes, reservoir inflows, and evaporative losses. This study examines the impact of climate variability on hydropower generation in the Niger River Basin, focusing on the Kainji and Jebba hydropower stations in Niger State, North Central Nigeria. Observed climate data including rainfall, temperature, and river discharge spanning 1990 to 2023 were assembled from the Nigerian Meteorological Agency, Niger River Basin Development Authority, and national hydrological records. Statistical trend analysis using Mann-Kendall tests and Sen's slope estimator quantifies directional changes in climate and flow variables. Correlation and regression analyses link climate drivers to monthly hydropower generation records obtained from the Transmission Company of Nigeria. Reservoir water balance modelling evaluates the combined effects of reduced inflows and increased evaporation under observed warming trends. Results show a statistically significant decline in annual river discharge of 2.3 percent per decade since 2000, corresponding to a 1.8 percent per decade reduction in average annual hydropower generation. Projections using regional climate model outputs suggest further generation reductions of 8 to 15 percent by 2040. The study recommends incorporation of climate risk scenarios into hydropower dispatch planning and advocates for expanded run-of-river renewable energy diversification to compensate for declining hydro reliability. Keywords: hydropower, climate variability, Niger River Basin, generation impacts, climate risk.