Examining the changes and trends in observed and projected intense rainfall events over Uganda’s Lake Victoria Basin

Abstract

Daily intense rainfall events have a profound impact on the environment and society often leading to agricultural, economic and human loss especially around the LVB of Uganda. Timely and reliable prediction of events is therefore important to the region’s development. Therefore, this study examined changes in observed (2000-2021) and projected (2021-2051) intense rainfall events during MAM and SOND seasons over Uganda’s L. Victoria basin using the Mann Kendall trend test and wavelet analysis. For observed changes results indicated an increasing trend for Mbarara by 13%, Entebbe by 18% and Kabale by 19% respectively during MAM season except for Jinja station and a downward trend in each of the stations during the SOND season for Mbarara by 17%, Jinja by 18%, Entebbe by 26% and Kabale by 12% respectively. Furthermore, projected changes demonstrated an increasing trend in both MAM and SOND seasons except for Mbarara, Entebbe and Kabale that did not have a significant trend during SOND for both scenarios (RCP 4.5 and 8.5) and this is attributed to the fact that the CORDEX Rcms underestimate the frequency of intense rainfall events especially during MAM season. In addition to this, the results also showed that there were more observed rainfall events during both MAM and SOND seasons especially for Jinja and Entebbe station and this could be attributed to El Nino episodes that enhance rainfall over a given season. however, this study recommends further analysis on daily intense rainfall events during the 21century associated with global warming.