TITLE:
Assessment of Climate Change Impacts on Drought in the Okpara Basin at Nanon (Benin)
AUTHORS:
Ezéchiel Obada, Halissou Yarou, Freddy Zinsè Hounnondaho, Iboukoun Eliézer Biao, Adéchina Eric Alamou
KEYWORDS:
Drought Characteristic, Climate Change, Climate Models, Climate Scenarios, Nanon Basin
JOURNAL NAME:
Atmospheric and Climate Sciences,
Vol.16 No.2,
February
11,
2026
ABSTRACT: Droughts are among the extreme weather events that generate serious social, economic, and environmental consequences. This study aims to characterize historical (1951-2020) and projected (2031-2100) droughts in the Nanon Basin. To this end, we used observed and simulated daily rainfall data from three climate models (AWI CM, EC Earth, INM CM4) from five rain gauge stations located around the basin. The standardized precipitation index was used to define drought episodes and assess their duration, severity, intensity, and extent. We calculated the marginal probability of precipitation from the empirical position on the Gringorten diagram and then transformed it into a standardized precipitation index using a standard normal distribution function. The results reveal that over the historical period (1951-2020), the number of droughts varied from 17 to 28 with an average length of 7 to 14 months. Droughts maximum length varied from 10 to 110 months while droughts intensity and severity varied respectively from −1.5 to −0.5 and −120 to −20. During the projected period, all climate models under SSP245 and SSP485 scenarios show increases in average drought durations (0 to 10 months), number of droughts (0 to 10 months), drought intensity (0 to 1), and drought severity (up to 10) compared to the reference period. It should be noted that these changes are not great compared to historical period. This situation could deteriorate the quality of natural resources in the Nanon Basin in the future if adaptation measures are not implemented.