Water/Hydro-erosion comes as a result of rain erosivity and soil erodibility. Knowledge on erosivity is therefore useful as a guide for recommendations on management practices and soil conservation which have the aim to reduce hydro- erosion. Objectives of this study were the factor identification and quantification of natural rain erosivity in Lages, Santa Catarina, as well as knowledge on its temporary distribution. The study was carried out in 2000, using data on rainfall and soil loss of the period from 1989 to 1998, in the Centro de Ciências Agroveterinárias of Lages (SC), at 27° 49' latitude south and 50° 20' longitude West, at an average height of 937 m in the southern plateau region of Santa Catarina. Several erosivity factors were examined in 437 erosive rainfalls out of a total of 966, making up an average annual volume of 1,301 mm erosive rainfalls in a total annual average of 1,549 mm rain, using the Wischmeier & Smith as well as the Wagner & Massambi methods. EI30 (factor R of the Universal Soil Loss Equation of -USLE) is the recommended erosivity factor, whose average annual value is 5,790 MJ mm ha-1 h-1, out of which 63 % occur during spring and summer, 76 % in the period from September to March, and, during the critical period of October, January and February, 41 % of the factor referred to. Considering number and volume of the rainfalls, 45 and 84 %, respectively, are erosive.
Factor R; factor EI30; kinetic energy; erosive rainfall; USLE