Temporal Variability in Rainfall Amount, River Stage and Discharge at Ibi Section of River Benue, Taraba State Nigeria

This study examined the temporal variability in rainfall, river stage, and discharge at the Ibi section of the Benue River in Taraba State, Nigeria, using data covering 1981 to 2020. Daily rainfall data, collected from the Nigerian Meteorological Agency, were aggregated to compute monthly and annual totals, and daily discharge and water levels were obtained from the Nigeria Hydrological Services Agency. The analysis utilized time series methods, including Least Square Regression and Pearson’s Product Moment Correlation, to assess trends and fluctuations. Results of monthly rainfall patterns revealed that the rainy season begins in April, peaks in September, and ends in October, with average monthly rainfall increasing from 65.47 mm in April to a peak of 205.93 mm in September before declining sharply to 111.20 mm in October. Annual rainfall shows a declining trend of 3.1226 mm per year with an R² value of 0.0416 and a correlation coefficient (r) of 0.2039, but this decline is not statistically significant (t = 1.2838 critical t = 1.684), with peak levels reaching 1109.00 cm in September. This increase in water levels despite declining rainfall suggests significant runoff contributions from the Ibi catchment, reflecting a complex interaction between rainfall and river dynamics.