Assessing the impact of rainfall variability on areal coverage of Lake Kyoga in eastern Uganda

Abstract

Rainfall variability is a very important aspect that affects adverse sectors of the social-economic welfare particularly hydrological and agricultural sectors of any region especially in the tropical Uganda. Therefore, it is important to understand rainfall variability at all levels in order to deal with its associated effects. This study assessed the effects of rainfall variability on the area coverage of Lake Kyoga from 1990 to 2015. The study focused on trends of rainfall and surface aerial coverage of the lake, using the Mann–Kendall trend test and established the effects of rainfall variability on the area coverage of the lake using correlation analysis and simple linear regression analysis. A dataset containing 26 years monthly rainfall and ortho-rectified Landsat satellite images of 1990, 2002, and 2015 was used for this purpose. The major findings of this study include: (1) generally, the variability of annual rainfall shows a decreasing tendency, implying intensified frequency of the occurrence of dry; (2) most of the rainfall trends over months, and seasons have decreasing trends except for the months of the SON season, indicating the more frequent occurrence of drought events or wet extremes; (3) the variability of the rainfall over the lake significantly has an effect on the area coverage of the lake with a correlation value of 0.9838. Overall, these findings are highly meaningful from both theoretical and practical perspectives in providing critical information in managing water resource practices.