Analysis of rainfall trends and variabilities for three decades in Sub – Sahara Africa

Abstract

Rainfall trend is an important climatic factor that influences agricultural products, groundwater production, drainage planning, commercial and industrial activities. The research aims to determine the trends and variability of monthly, seasonal, and annual rainfall for 30 years (from 1980 to 2010) in Sokoto (13.0059° N, 5.2476° E) and Maiduguri (11. 8333° N, 13.1500° E) using archives data obtained from the Nigeria Meteorological Agency (NiMet), Oshodi Lagos Nigeria. Statistical models were used to analyze the data. The results reveal that the maximum rainfall recorded was 371.60 mm at Maiduguri station and 374.90 mm at Sokoto station which shows a higher rainfall peak in Sokoto than Maiduguri. The coefficient of variation in the Sokoto station (126.39%) was higher than that of Maiduguri station (61.78%) which indicates that there was more rainfall variability in Sokoto than in Maiduguri. Seasonally, the average rainfall recorded in both stations was 61.78% and 126.39% respectively. No rainfall was recorded in January, February, and November for Maiduguri station, more so, no rainfall was recorded in January, November, and December for Sokoto station. According to Man-Kendal trend analysis, significant trends (p<0.5) were observed in Maiduguri and Sokoto. Therefore, the modelled statistical approach on rainfall trends and variability revealed that the peak month of annual rainfall is between June and September for the two stations. It can be recommended that the government should make favourable policies to utilize the rainfall received during this period to store more water in reservoirs and construction of water channels across the country.