Analysis of Rainfall Trend Using Mann– Kendall Test and Sen's Slope Estimator in Ikole Ekiti, Ekiti State, Nigeria

Abstract

Precipitation plays a crucial role in shaping the climate system, affecting temperature patterns, atmospheric circulation, and regional climate variations. Monitoring precipitation is essential for assessing the intensity and duration of rainfall events, enabling the prediction and mitigation of risks associated with excessive rainfall. This research aims to investigate long-term rainfall trends in Ikole Ekiti, positioned at latitude 7.805° and longitude 5.495°, southwestern Nigeria. The study utilizes extensive time series data to analyze precipitation patterns in the area. The study relies on daily precipitation data spanning from January 2013 to December 2022, obtained from the PDIR-Now system, a satellite-based product that employs Artificial Neural Networks and Dynamic Infrared Rain Rate Technology to provide high-resolution precipitation estimate in near real-time. The evaluation of rainfall trends was carried out by employing the Mann-Kendall Test in conjunction with Sen's Slope Estimator. The results reveal a distinctive two-peak pattern in the distribution of rainfall throughout the years. The first peak, occurring in September, exhibits an average value of 185.4 mm, while the second peak emerges in July, with an average value of 147.9 mm. Although, it was observed that there was a decrease in annual rainfall, it was not statistically significant. The findings of this research can provide valuable insights for developing future strategies aimed at adapting to and mitigating climate change, with the goal of ensuring the sustainable management of rainfall resources in the study region.