Trends and Temporal of Rainfall Erosion due Variability Rainfall in Nakambè Watershed, Burkina Faso

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