Assessment of rainfall erosivity in Southwest Bulgaria using the Fournier index

Soil erosion is one of the most widespread environmental problems in Bulgaria, which often occurs together with other dangerous phenomena such as landslides, soil degradation, wind erosion, etc. The main factor for erosion is rainfall. Rainfall erosivity is an indicator of the potential of rainfall to generate erosion processes and is of fundamental importance in the analysis of the climate vulnerability of a given region. The purpose of the present study is to assess rainfall erosivity in one of the most populated regions of Bulgaria – the Southwest by comparing the results of two indices - the Fournier index (FI) and the modified Fournier index (MFI). The results show that, in general, the studied stations belong to a low class of erosivity. It is found that MFI has greater sensitivity and provides more detail, showing also years with high and even very high rainfall erosivity.