TITLE:
Spatiotemporal Variability of Rainfall Trends and Influencing Factors in Tanzania
AUTHORS:
Jean de la Croix Musabyimana, Thadee Niyigena, Jean Claude Uwayezu, Gentil Samuel Ishimwe, Banda Noel
KEYWORDS:
Spatiotemporal Rainfall Variability, Rainfall Trends, Sea Surface Temperature, Climate Variability, Tanzania
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.4,
April
21,
2026
ABSTRACT: Rainfall variability strongly influences water availability, agriculture, and social and economic development in Tanzania, where most livelihoods depend on rain-fed farming. Understanding how rainfall varies across space and time and recognizing its driving factors are therefore essential for cultivating climate monitoring and resource management. This study examines the spatiotemporal variability of rainfall trends in Tanzania and their relationship with global sea surface temperature patterns during the period 1979-2024. Rainfall data were obtained from the European Centre for Medium-Range Weather Forecasts reanalysis dataset, while global sea surface temperature data were obtained from the National Oceanic and Atmospheric Administration. Several statistical methods were applied to evaluate rainfall variability and trends, including standardized anomaly analysis, the Mann-Kendall trend test with Sen’s slope estimator, empirical orthogonal function analysis, and correlation analysis. The results reveal pronounced spatial variability in rainfall across the country, with higher rainfall amounts occurring in the Lake Victoria basin and coastal regions and lower rainfall over the central plateau. Tanzania displays both bimodal rainfall patterns in northern and eastern regions and a unimodal rainfall regime in southern areas. Trend analysis indicates generally weak and spatially heterogeneous rainfall trends, with slight decreasing tendencies in parts of northwestern Tanzania. Temporal analysis highlights strong inter-annual variability, with wet years such as 1983, 1998, 2018, and 2023 and dry conditions during 1993, 2003, and 2005. The dominant spatial mode of rainfall variability explains about 42.5% of the variance during the long rains season and about 69.1% during the short rains season. Correlation analysis indicates that rainfall variability is influenced by sea surface temperature disparities in the tropical Pacific and Indian Oceans, suggesting the influence of large-scale ocean-atmosphere interactions. These findings provide insights that may support improved climate forecasting and sustainable management of water and agricultural resources in Tanzania.