Assessment of Rainfall Trends, Variability, and Distribution under Climate Change in Southern Plateau State, Nigeria

Abstract

The effect of climate change on rainfall trends, variability, and distribution, which in turn affects agricultural activities and food security, is alarming. This study attempts to assess the rainfall trends, variability, and distribution in Southern Plateau State, Nigeria. The study utilized 42 years of monthly and annual rainfall data (1981-2022) derived through the NASA POWER archive. Seasonal patterns were analyzed using monthly rainfall, whereas annual totals were utilized to analyze long-term trends and spatial variability of rainfall in the area. Inferential statistics, including the Mann-Kendall (MK) trend test and Sen’s slope estimator, were used in conjunction with descriptive statistics. The findings show that the rainfall regime is unimodal with a start in April-May, a peak in July-August, and cessation in September-October, with a short growing season of 5-7 months. The trend analysis reveals that the rainfall has steadily decreased in all LGAs, with the Sen’s slope values varying between -7.6 mm/year and -11.9 mm/year. The MK test reveals statistically significant decreasing trends (p < 0.05) in all locations, which depict an upsurge in dryness and variability. Spatial analysis reveals that the distribution of rainfall is uneven, with the highest amounts in Langtang South and Qua’an Pan and the lowest values in Wase. These findings indicate growing climate instability, which is very problematic for rain-fed agriculture in the study area.