Statistical Patterns of Rainfall Variability in the Great Rift Valley of Kenya

Most ecoMost economic activities like crop farming, livestock keeping, hydro-energy generation, transport, tourism, and other climate dependent sectors rely heavily on rainfall patterns in Kenya and the Great Rift Valley. In this study we examine rainfall patterns, long-term trends and variability in the Great Rift Valley of Kenya (06° 00'N to 03° 00’S and 38°.00-34.00’E) for the period ranging from 1950 to 2011. The study utilizes monthly rainfall data obtained from Kenya Meteorological Department for six synoptic stations in the region. The study examines the changing trends and variation of rainfall using statistical methods. Results indicate depressed rainfall in some stations while others showed increased rainfall activities. Difference between two means and comparison between two variances of equal sample data is carried out and shows changing trends in rainfall at seasonal and annual scales in all six stations of Great Rift Valley. Test for significance showed significant changes, thus showing climate change signals in rainfall patterns. Stations in arid and semi-arid areas had high percentage of variability with stations in the central rift having least percentage in variability. In conclusion, study observes a decreasing trend in annual rainfall during March-April-May season and high variability within seasons.