Assessing the impacts of Indian Ocean Dipole on the seasonal rainfall patterns of Eastern Uganda.

Abstract

Eastern Uganda is characterized by a tropical savanna climate with distinct wet and dry seasons. Rainfall is a critical resource for agriculture and water security in the region, and its variability has significant socio-economic implications. The Indian Ocean Dipole (IOD) is a coupled ocean-atmosphere mode of climate variability that has been shown to influence rainfall patterns in East Africa. This dissertation investigates the impact of the IOD on the seasonal rainfall patterns of Eastern Uganda. The different data sets were subjected to several methods including graphical analysis for both the rainfall and IOD data sets to study the temporal trends within the data . The Man Kendell trend test was also used to establish the significance of the trends in the rainfall and IOD data. Then the rainfall and IOD data sets were subjected to a correlation analysis using Karl Pearson’s correlation to establish the correlation between the SON seasonal rainfall patterns and the IOD . A comprehensive analysis of rainfall data from meteorological stations across Eastern Uganda ie;Jinja, Soroti, Buginyanya and Tororo meteorological stations reveals significant temporal variability of rainfall across Eastern Uganda for the SON rainfall season with very distinct highs and lows in certain years. Buginyanya showed the biggest difference between the highest and lowest peaks of rainfall amounts for different years while Jinja showed the smallest difference. Then further analysis of IOD data during the SON rainfall season was also carried out and an increasing significant trend was observed in the SON temporal variability of IOD . The findings of the research showed that the IOD affects the SON rainfall patterns in some regions of Eastern Uganda while it may not have effects in some regions. The Tororo and Soroti regions showed insignificant correlation with IOD hence accepting the Null hypothesis, Ho while Jinja and Buginyanya showed significant correlation with IOD hence rejecting the Null hypothesis, Ho . The findings of this dissertation have Important implications for water resource management and agricultural planning in Eastern Uganda, for understanding the relationship between the IOD and rainfall patterns can help to improve predictions of seasonal rainfall anomalies and inform strategies for adapting to climate variability.