Moses David Tumusiime*, Lawrence Aribo, Benon Kalema and Exavery Kisesa Makula
Understanding rainfall distribution is crucial for sustainable water resource management and several economic activities. This study investigated seasonal and annual spatiotemporal variability and trends of rainfall in East Africa and their impacts on Lake Victoria water levels to update information that supports planning, management, and improvement of water dependent socioeconomic activities. Surface water observations for both the satellite (DAHITI altimetry) and ground based stations for 30 years were used in the study. The datasets were analyzed considering of the annual, and seasonal rainfall variability, trends of precipitation, variations of water levels, and the influence of rainfall on water level fluctuations of Lake Victoria the shared lake of East Africa. Study results showed an increase in water levels in Lake Victoria for the past 30 years. The rainfall trend showed a non-significant increase, as tested by Mann Kendall and the linear fit (Sen’s) test. Moreover, there was a noticeable variation in seasonal rainfall, with rainfall varying much more in the dry seasons of June to August (JJA) and December to February (DJF), than in rainy seasons, March to May (MAM) and October to December (OND). Significant correlations were observed between rainfall from Bunjumbura and Gisozi ground based rainfall stations and Lake Victoria water levels, although a weak relationship exists with other ground based stations around the Lake Victoria basin. The study concludes that rainfall influences the lake water levels to a lesser extent; hence, it is recommended to consider the analysis of other different water resources in the Lake Victoria catchment, especially Inlet Rivers and groundwater. The information obtained from this study could be used as input for decision makers to take appropriate adaptive measures in water resource management.
