Analysis of the Monthly Rainfall Variation in Benue State

Awoji Edwin Idoko¹, Peter Nkashi Agan¹*, Adewale O Adeyefa¹ and Chioma Precious Oku^2
1Department of Geography, Faculty of Science, University of Ibadan, Ibadan, Nigeria
²Department of Urban and Regional Planning, School of Environmental Science, Federal University of Technology, Owerri
*Corresponding Author: Peter Nkashi Agan, Department of Geography, Faculty of Science, University of Ibadan, Ibadan, Nigeria.

Published: March 31, 2023

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Abstract  

This study looked at monthly rainfall variations in Benue State to see what trends and patterns there were during the rainy season in Makurdi, Otukpo, Gboko, Zaki-Biam, Igumale, Vandeikya, Katsina-Ala, and Bopo stations. The month of December had the least amount of rainfall, followed by January and February at all of the stations. Except at Makurdi station, where the highest rainfall amount was obtained in August, September was the month with the highest rainfall quantity. The maximum monthly rainfall was reported at Vandeikya and Igumale stations in the south, while the lowest monthly rainfall was recorded at Makurdi and Bopo stations in the north. From 1984 to 2017, total rainfall at all stations ranged from 672.11mm in 1999 at Bopo station to 3454.66mm in 2000 at Vandeikya station. The significance level of 0.05 in the analysis of variance (ANOVA) used to evaluate the variation in yearly rainfall amount across all stations indicated that F7,264=13.51, indicating that there is a substantial variation in rainfall amount across all stations in Benue State. Using the Mann-Kendal and Sen Slope, the rainfall trend and pattern in Benue State from 1984 to 2017 shows both increase and downward trends in yearly rainfall across all stations. From 1985 to 1989, yearly rainfall trends were on the rise. Makurdi Station's rainfall ranges from 1290mm to 1584mm (294mm); Otukpo Station's rainfall ranges from 1233mm to 1479mm (246mm); Gboko Station's rainfall ranges from 1413mm to 1675mm (262mm); Zakibiam Station's rainfall ranges from 1411mm to 1717mm (306mm); Igumale Station's rainfall ranges from 1307mm to 1665mm (358mm); Vandeikya Station's rainfall ranges from 1815mm to 2135mm (320mm); and Bopo Station's rainfall ranges from 1506mm to 1629mm (123mm). Only Katsina-Ala station recorded a negative trend from 1833mm to 1624mm (-320mm). The rainfall variation in Benue state is mostly on an upward trend, which can be utilised for aggressive forestation and reforestation in areas where deforestation is a concern, particularly in the state's southern and north-eastern regions. In the guinea savannah zone of the country, where Benue state is located, there is a need for continual cultivation of roots, tubers, and cereals, which are the most suited crops.

Keywords: Monthly Rainfall; Trends; Variation; Mann Kendal Test