Palavras-chave -Chuvas intensas. Erosão. Registros pluviográficos.
Abstract -In the Universal Equation ofSoil Loss (USLE), erosivity is the factor related to rain and express its potential to cause soil erosion, being necessary to know its kinetic energy and the maximum intensities of rain in duration of 30 min. Thus, the aim of this study was to verify and quantify the impact of the rain duration, considering 15 and 30 min, on the USLE erosivity factor. To achieve this, 863 rain gauge records were used, duiring the period of 1983 to 1998 in the city of Pelotas, RS, obtained from the Agrometeorological Station -Covenant EMBRAPA/UFPel, INMET (31 o 51´S; 52 o 21´O and altitude of 13,2 m). With the records, it was estimated the erosivity values from the maximum intensities of rain during the period evaluated. The average annual values of erosivity was 2551,3 MJ ha -1 h -1 ano -1 and 1406,1 MJ ha -1 h -1 ano -1 , for the average intensities of 6,40 mm h -1 and 3,74 mm h -1 , in durations of 15 and 30 min, respectively. The results of this study have shown that the percentage of erosive rainfalls in relation to the total precipitation was of 91.0%, and that the erosivity was influenced by the duration of the maximum intensity of rain.