TITLE:
Trend and Frequency Analysis of Long-Term Maximum Daily Rainfall in Benin
AUTHORS:
Ezéchiel Obada, Freddy Zinsè Hounnondaho, Halissou Yarou, Orou Moctar Ganni Mampo, Adéchina Eric Alamou
KEYWORDS:
Trend, Stationarity Breakpoint, Frequency Analysis, Maximum Daily Rainfall
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.13 No.12,
December
10,
2025
ABSTRACT: The objective of this study is to assess the trends and predict the maximum daily rainfall using Benin century rainfall gauges. The Pettitt, Buishand, and entropy breakpoint detection tests were employed to identify stationarity breaks, while the Mann-Kendall trend test was used to assess trends. Stationary and non-stationary Generalized Extreme Value (GEV) distributions are used to conduct the frequency analysis. From 1921-2020, a significant increasing trend is detected at Abomey and Adjohoun stations with a slope of 0.17 and 0.16 mm/year, respectively, while a significant decreasing trend is found at Allada, Cotonou, Natitingou, and Savè stations with a slope of −0.24, −0.20, −0.13, and −0.21, respectively. Other stations exhibit a non-significant trend over the entire period of study. However, some of these stations exhibit a significant increasing or decreasing trend before or after the breakpoint. The frequency analysis shows that the stationary GEV distribution provides a good fit for rainfall time series without a significant trend, while the non-stationary GEV model better fits the series exhibiting significant trends. The results also show that many stations have recorded the precipitation of a 150 - 200-year return period, indicating the level of exposure of the region to extreme events.