Rainfall Erosivity Estimators for Application in Burundi

In this paper, following the results of previous studies and using the monthly rainfall data of 13 sites in Burundi, a comparison between two different estimators (modified Fournier index MFI and FF index) of the rainfall erosivity factor of the Universal Soil Loss Equation (USLE) was firstly developed. The theoretical relationships between MFI and the mean annual rainfall P and between FF and P were tested by the available rainfall data. The constants Km and K, linking MFI and FF with P, were used to assess hydrological similitude with other geographical regions. Then, in order to predict the erosion risk corresponding to a climatic condition of given return period, the applicability of the Extreme Value Type 1 (EV1) probability distribution to the annual values of the Fa,j index was tested by an at-site analysis. Finally, the descriptive ability of the EV1 distribution was investigated by a regional procedure.