Spatial and temporal variability of the rainfall erosivity factor in Northern Algeria

Erosion, sediment transport, and deposition result in agricultural soil degradation, dam siltation, and significant and costly damage. In Algeria, despite a decrease in total rainfall, especially in the central and western parts of the country, dam siltation and erosion are on the rise according to recent studies by the National Agency of Dams and Transfers. Developing a map of the spatial variation of rainfall erosivity will provide a powerful tool for land and dam managers. Erosivity can be quantified using the R factor from the Universal Soil Loss Equation. The purpose of this work is to develop a model for estimating rain erosivity based on the modified Fournier index (MFI), longitude, altitude, and mean maximum daily rainfall, and then to produce a map of the spatial distribution of erosivity in Northern Algeria. The R factor reaches a maximum value of roughly 905 MJ mm ha−1 year−1 in the Jijel area of Mediterranean Eastern Algeria and a minimum value of 37 MJ mm ha−1 year−1 in the southern portion of the study area. The study of the temporal evolution of annual rainfall erosivity index (R) and Imax over 30 min showed that R recorded a negative trend and Imax recorded no trend.