Trends and Temporal of Rainfall Erosion due Variability Rainfall in Nakambè Watershed

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Résumé

Understanding how rain erosion evolves and what determines it can contribute to the better management of soil re -sources. This study analyses the evolution of rain erosion in the Nakambè catchment in Burkina Faso between 1992 and2022. Monthly rainfall data for this period were extracted from NASA POWER. Erodibility indices were then employed toevaluate the extent of erosion. Precipitation variability was assessed using the coefficients of variation and the standardizedprecipitation index. The study shows that precipitation varied within the catchment area during this period. This variationis seasonal, as it fluctuates before, during and after the rainy season, with a coefficient of variation ranging from 18 dur-ing the rainy season to 556.18 after the rainy season. The catchment also multi-year fluctuations, long-term fluctuations orperennial variations (1992–2004 and 2004–2022). The study also shows that rain erosion also varies annually and season-ally. The Fournier, Arnoldus and rainfall concentration indices indicate variability in erosivity, with a significant increase inAugust. It also appears that rainfall trends and variability have an impact on erosion in the catchment. For example, erosionincreases with precipitation concentration and the standardized rainfall anomaly over the period 1992-2022. The cumula-tive effect of precipitation concentration, which translates into increased precipitation in July and August, and the wet phaseof the 1992–2022 period are therefore the determining factors for rain erosion in the catchment. It is therefore important toreduce the number of dams in the basin in order to prevent its continued deterioration

Mots-clés

Nakambé Watershed, Rainfall Variability, Erosion Index Trends, Burkina Faso