Open Access

ARTICLE

Analysis of Annual Rainfall and Annual Number of Rainy Days in the Research for Indices of Climate Change in the Zambezian Phytogeographic Region

N’Landu Dikumbwa^1,*, Scott Tshibang Nawej², Gabriel Mutundo Teteka², Benjamin Mayaka Kibwila³, Jules Aloni Komanda³

1 Department of Geographic Engineering, Faculty of Natural Sciences, Agostinho Neto University, Luanda, Republic of Angola
2 Department of Geography and Environmental Sciences, Faculty of Sciences and Technology, University of Lubumbashi, Lubumbashi, Democratic Republic of the Congo
3 A Department of Geosciences, Faculty of Sciences and Technology, University of Kinshasa, Kinshasa, Democratic Republic of the Congo

* Corresponding Author: N’Landu Dikumbwa. Email:

Revue Internationale de Géomatique 2026, 35, 13-30. https://doi.org/10.32604/rig.2026.068019

Received 19 May 2025; Accepted 22 December 2025; Issue published 05 February 2026

Abstract

Rainfall data from four weather stations, quite far from each other, but located in the Zambezian phytogeographic region, were analysed for the research for indices of climate change. Two variables, rainfall and the annual number of rainy days, were considered. The rainfall data examined are 114 years for Luanda (1901–2014), 106 years for Lubumbashi (1916–2021), respectively, 54 and 41 years for Huambo (1961–2014) and Boma (1981–2021); 100 years (1921–2021) for the annual number of rainy days for only the Lubumbashi weather station. The results were a widespread decline in rainfall at all weather stations. Despite the general decrease in rainfall, the Mann Kendall trend test, except for Huambo only, within the space-time limits of the present study, does not confirm it in the other three weather stations, corroborating the conclusion of Nicholson’s work in the Congo Basin. The declines described in this study would therefore only be episodes in the current climate. Moreover, there would be no causal links between the decline in rainfall and in annual number of rainy days. Indeed, on the one hand, although the decrease in the annual number of rainy days, the annual rainfall totals recorded at weather stations remain very close to the usual annual averages. On the other hand, the association of these two parameters gives a correlation coefficient r = 0.45; that of determination r² = 0.2012. The decrease in the annual number of rainy days would therefore only explain 20% of the decrease in rainfall. In reality, the concomitant decreases in two parameters have harmful effects on exopercolation and endopercolation in the feeding of groundwater, water retention basins for electricity production and crop irrigation.

---

Keywords

---