Rainfall Trends and its Implication for Moisture Availability over the Kainji Dam Area, Nigeria

Abstract

The study analyzed thirty (30) years (1991-2020) rainfall data of Kainji dam area. The data was sourced from the Mainstream Energy Solution Office in New Bussa. The study examined the trend and variability of rainfall and its implication for moisture availability over the study area. Standard Deviation (SD), Coefficient of Variation (CV) and Standardized Precipitation Index (SPI) methods were used for the analysis. Generally, result shows irregular rainfall distribution over the study area during the period under review. The rainfall distribution across the study area shows that the lowest amount of rainfall was detected in 2002 at 735.33mm while the highest was in 2017 at 1537.59mm. Further result shows a decline in rainfall amount from 1285.29mm in 1991 to 753.63mm in 1992 with a sharp rise of 1015.48mm in 1993. The study revealed that there was a consistent rise in the rainfall amount from 1997 to 1999 at 1117.29mm, 1249.3mm and 1295.07 mm respectively. In contrast, the rainfall amount from 2000 to 2003 shows decreasing trend at 971mm, 982.47mm, 735.33mm and 846.93mm respectively. The SPI analysis for the first decade shows that 1992 was a severe dry year while 1991 and 1999 were moderate wet years. The SPI for the second decade shows that 2010 was a severe wet year while 2002 was a severe dry year in the study area. Further result shows that four years in the third decade, 2004, 2006, 2008 and 2009 depicted mild wet SPI value while 2013 shows severe dryness. The observed variations in the rainfall distribution is likely to have implication for moisture availability to support crop production in the study area especially in the second decade (2001-2010). The study recommends the mainstreaming of farming calendar into the changing climate regime to ensure improved agricultural production.