Erosivity index based on climatological norms from 1991 to 2020 for the state of Rio Grande do Sul

ABSTRACT Water erosion is one of the main cause of soil degradation and the pollution of water resources. The aim of the present study is to update and evaluate the seasonal variation of the erosivity index and the Modified Fournier Index as a tool to predict rain erosivity for the state of Rio Grande do Sul. A series of monthly average rainfall data was used from 112 rainfall stations based on the Climatological Norms of the period between 1991 and 2020. Based on 16 regression equations, the values of the Modified Fournier Index (MFI) and the EI30 index were estimated, assessing their spatial and seasonal variation. Results show a strong seasonal variation with greater erosivity in the months of April, October and December. The EI30 varied between 3500 and 12500 MJ, ha-1 h-1 year-1. A significant spatial variation could be observed, with an increase in values in the east-west direction.