Comparative trend analysis of hydroclimatic variables for sustainable water resource management in Jebba Dam in the Niger River Basin

Analyzing the trends of key hydroclimatic variables can enhance sustainable water resource management in the face of a changing climate, water availability, and their associated uncertainty. This is critical for hydropower generation, especially cascaded dams like Jebba Hydropower Station (JHS). In this study, we analyzed the trends of hydroclimatic variables – rainfall, temperature, and associated hydropower generation variables using satellite and observed data from 1981–2022. We employed statistical tests, the standardized precipitation index (SPI), Modified Mankendall (MMK) trend test, homogeneity tests, and Innovative Trend analysis (ITA). The study reveals that the annual mean rainfall in Niger River Basin (NRB) and Jebba hydropower station has been experiencing a normal variability with high, moderate, and normal variability detected for different seasons. Furthermore, the SPI reveals that the Ilorin and Bida rainfall station has the highest and the lowest negative anomaly, with 66% and 40%, respectively. The most prolonged dry period was 1981–1989 in the NRB, followed by 1992–1996 in the Ilorin station. The MMK and ITA reveal similar results, showing that Ilorin and Bida rainfall, Jebba dam’s inflow, outflow, turbine discharge, and energy generation have increased significantly; nevertheless, evaporation loss decreases while other variables show no trend. Likewise, the homogeneity test, notably the Pettit test, reveals that abrupt changes (change year) are detected in all variables in the JHS and neighboring rainfall stations except Bida, Minna, and Lokoja rainfall. The study concludes that the significant increase in the hydropower generation is attributed to the increase in the water availability (rainfall and reservoir inflow) in the hydropower station.