Rainfall Variability and Extreme Hydrological Events in Kenya Since 1845-2012 Driven from Documentary Evidence and SPI Analysis

Abstract

The study investigates the chronology of rainfall extremities in Kenya and their inter-relationship with the external climate factors since the years 1845-2012. It is the first study in Kenya to evaluate a long-term temporal evolution of the droughts and wet extremities using documentary evidences and Standardized Precipitation Index (SPI) analysis. The statistical procedures for this study involved the establishment of drought and wet events indices using MATLAB R 2009a and Instat Plus (Instat+ v3.36) statistical software programs. The study findings show that the 19th century was much drier than the 20th and 21st centuries, marked by great desiccation, especially towards the end of the century. In the 20th century, very severe long droughts were also experienced in 1940s and 1970s but there were also very wet years which moderated the situations in 1960s and 1990s. Based on the (SPI), results droughts were not uniformly severe in all areas of the country. The strongest impacted stations were those located in the arid and semi-arid lands, some parts of the highlands and the coastal region.