Analysis of rainfall and temperature trend and variability of the Tordzie Watershed in Ghana

Abstract

Climate change is universally occurring but probable fluctuations are not anticipated to be uniform worldwide; rather, there may be local differences. Thus, there is a need to investigate the trend and variations at the local and watershed levels to comprehend the magnitude of the change. This study was conducted to determine the trend of rainfall and temperature and assess their dependability. In this study, mean monthly and annual rainfall and temperature were analysed to determine the variability in magnitude over the period 1984-2014 at different stations. The non-parametric trend detector, Mann-Kendall test (MK) and trend magnitude detector, Sen’s Slope (SS) were used to reveal the trend and magnitude of rainfall and temperature, respectively. The largest increasing slope of significant annual precipitation occurred in November with a magnitude of 1.68 mm/y in Tordzinu. October recorded the most reliable rainfall at Kpetoe with a Coefficient of Variation (CV) of 0.3. The highest maximum monthly rainfall occurred in May, 2005 at Tordzinu with a magnitude of 522.2mm for the period under review. The minimum and maximum temperature increased by 0.2oC and 0.8oC respectively at Kpetoe and also 0.2oC and 0.5oC at Tordzinu per decade respectively.