Analysis of past and future precipitation extremes in Uganda’s climate

Abstract

Analyzing long term changes in precipitation extremes is of great importance to the welfare of human beings as well as the entire ecosystem. Increase in maximum number of consecutive wet days can lead to more and worse floods while high maximum number of consecutive dry days can pose a threat to the drought problem that greatly affects water sources and soil moisture. The occurrence of dry spells (consecutive dry days) within a rainfall season greatly affect agriculture and other sectors such as tourism and fisheries. This study addressed the past and future changes in extreme rainfall over Uganda using the Coordinated Regional Downscaling Experiment model outputs for the two rainy seasons of March-May and September-November. The analysis was performed for two time periods: historical/past (1986-2015) and future(2021-2050). Downscaled data from CanESM for RCPs 4.5 and 8.5 was used. The significance in the time series trend was tested using Mann-Kendall test and the results were analyzed using python software. The results indicated that there was no significant trend in historical time series for both consecutive dry days and consecutive wet days.The future trends were non-significant with very mixed spatial patterns of positive and negative trends. There were no significant trends in historical time series for both consecutive dry days and consecutive wet days for both rain seasons with constant number of consecutive wet days over most parts of the country. For September-November season, maximum number of consecutive dry days increased while number of consecutive wet days decreased. Projections show that maximum number of consecutive dry days will increase while number of consecutive wet days will decrease for most parts of the country but with no significant trends for both rain seasons.