Trends and prediction of extreme precipitation indices in three cities of Burkina Faso using non-parametric statistics and the Holt-Winters smoothing method

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Résumé

Climate extremes have become an important issue in recent years, leading to renewed scientific interest in the topic. However, few studies have focused on the analysis of precipitation extremes in cities in Burkina Faso, a Sahelian country in West Africa. The aim of this study is to analyse the trends and future projections of extreme precipitation indices in three cities in Burkina Faso. To this end, precipitation data were collected from the National Meteorological Agency of Burkina Faso (ANMBF) over the period 1991-2020 on a daily time step. The stations selected were Boromo for the small town of Boromo, Saria for the medium-sized town of Koudougou and Bobo-Dioulasso for the town of Bobo-Dioulasso. The precipitation data were used to calculate the extreme precipitation indices described by ETCCDMI (Expert Team for Climate Change Detection Monitoring and Indices) using Rclimdex. Descriptive statistics, the Mann-Kendall test and trends from innovative models were used to analyse the extreme precipitation indices, and the Holt-Winter additive model was used to analyse future projections. The study shows that there is considerable variability and an increasing monotonic trend in extreme precipitation indices over the period 1991-2020. However, for the city of Koudougou, the trend is a non-monotonic increase. The study also shows that the forecast based on the Holt-Winter additive model shows that the extreme precipitation indices are subject to considerable variability, with an upward trend over the period 2020-2030. On the other hand, in the city of Koudougou, the duration indices will decrease more. This means that the city will be affected by the frequency and intensity of extreme precipitation.

Mots-clés

Innovative graphical trendadditive, Holt-Winters model, extreme precipitation indices, Burkina Faso