Knowledge of the erosive potential of rainfall and its distribution throughout the year contribute to planning management and soil conservation practices that aim to reduce water erosion, decreasing soil loss and increasing crop yields. The goal of this study is to characterize rainfall in the region of Urussanga, SC, Brazil, in relation to its erosive potential, determining monthly and annual Erosivity Indices (EI30), thus establishing the R factor to use in the Universal Soil Loss Equation. In addition, the goal is to determine hydrological patterns, return period, and the probability of the occurrence of erosive rainfalls based on rainfall data from the daily pluviograph records from the Meteorological Station of Urussanga from October 1980 to March 2012. The rainfall amounts were converted into digital information in segments with constant intensity. In addition, a computer program was developed to read this data, identify the erosive rainfalls, calculate the erosivity, and classify the hydrological patterns of rainfalls. The average annual rainfall was around 1,781.8 mm, of which 1,502.6 mm were erosive rainfall and 279.1 mm non-erosive rainfall. There were an average of 184.9 rainfalls per year, of which 77.7 % were non-erosive and 22.3 % were erosive. The annual average value of the El30 index is 5,665.10 MJ mm ha-1 h-1, thus classifying the rainfalls as being of medium to strong erosivity. The period of greatest erosivity is from December to March. The R factor of the USLE for areas with similar characteristics neighboring Urussanga can be estimated from pluviometer data using the fitted linear equation.
erosivity; soil; erosive rainfall; soil loss
