Erosividade da chuva para a região do Planalto Serrano de Santa Catarina, Brasil

The objective of this work was to estimate the rainfall erosivity factor and evaluate the temporal distribution pattern of the erosive rains for the Planalto Serrano region of Santa Catarina, Brazil. The pluviograms of the meteorological stations of São Joaquim (from the period of 1970 to 2014) and of Lages (from 1969 to 2014) were analyzed. Rainfall erosivity was determined by the EI30 index. Based on the results obtained, the equations for estimating the EI30 index were adjusted according to the Modified Fournier Index (IFM). The equations recommended respectively for Lages and São Joaquim are EI30 =148.3 IFM0.584 and EI30 = 35.4 IFM + 49.1.The frequencies of erosive rains were also determined according to the temporal distribution pattern. Erosive rains represent 83.6% and 81.5% of the rainfall volume of São Joaquim and Lages, respectively. The adjusted equations allow estimating the erosivity factor for the places where only information measured in rain gauges exists. The estimated erosivity factor for São Joaquim is 7579.3 MJ mm ha-1 h-1, classified as High Erosivity, and for Lages the value was 5546.8 MJ mm ha-1 h-1, classified as Medium. In both stations the erosive rains of the Advanced pattern predominate, followed by Intermediate and Delayed.