Rainfall–Runoff in Conterminous Tropical River Basins of Southwestern Nigeria

Abstract

ABSTRACT Frequency analysis of extreme events is used to evaluate the probable maximum flood from runoff records using probability distribution functions. This study aims to understand rainfall-runoff relationships in four conterminous basins in Southwestern Nigeria using the runs test, Pearson correlation, and wavelet coherence. The study revealed that the highest Extreme Annual Rainfall in the series is expected to occur once every 31 years with 0.03 probability. Wavelet coherence shows a strong significant association with phases between Yewa – Ikeja and Yewa – Abeokuta. The observed extreme discharge values constitute the basis for establishing exceedance probabilities for the stations and their recurrence intervals.