Erosivity Index and Characteristics of Erosive Rainfall from the Far Western Region of Santa Catarina, Brazil

The objective of this study was to determine the erosivity index and to characterize the erosive rainfalls with respect to the far western region of Santa Catarina. Four meteorological stations were used to determine the rainfall erosivity based on the index of the product of the maximum rain intensity during a 30 min period and the kinetic energy of the rain (${\mathrm{EI}}_{30}$), and the equations were adjusted to estimate the ${\mathrm{EI}}_{30}$ value from the rainfall coefficient. Erosive rainfalls were classified, according to the pattern of temporal distribution, as Advanced, Intermediate, and Late rainfall pattern. The erosive rainfalls represent, on average, 83–88% of the annual precipitation, and the value of ${\mathrm{EI}}_{30}$ varies from 6,072 to $\mathrm{10,478}\mathrm{MJ}\mathrm{mm}{\mathrm{ha}}^{-1}{\mathrm{h}}^{-1}{\mathrm{year}}^{-1}$. The adjusted equations can be used to estimate the rainfall erosivity in places with only pluviometric data. Erosive rainfalls presented an average distribution of 51, 31, and 18%, respectively, of the Advanced, Intermediate, and Late patterns. The maximum rainfall intensity of 30 min with 20% of frequency ranged from 21.8 to $33.6\mathrm{mm}{\mathrm{h}}^{-1}$. For larger frequency, no significant variation was observed between the time distribution patterns.