Telesia M. Mutua*, Sebastian N. Runguma
The study investigated the rainfall variability for Nairobi, Nyeri, Thika, Meru, and Embu which are agriculturally potential zones located in the Kenya Highlands region. The rainfall data were retrieved from the archival documentaries and instrumental rainfall records for 112 years. Using the non-parametric Mann Kendal land regression analysis tests, the coefficient of variance and long-term trend analysis, revealed an insignificant trend in the annual rainfall for all areas under investigation. The study found out a significant deterioration in the long rains (MAM), while the short rains (OND) trend continued significantly increasing over most of the highlands, particularly in Embu and Nairobi since the 1970s. A significant decrease in the long rains was observed in Thika and Meru, which portrays a likely deterioration of agricultural outputs in these areas during the season. The study findings conclude that there are no major observed changes in the annual rainfall amounts in the Highland zones, except a slight increase attributable to the increase of the short rains in some areas. This is a useful record disclosing localized long-term rainfall trends, which can be utilized in simulating the future rainfall events for these areas.