Knowledge on rainfall erosivity associated to occurrence probability and return periods can contribute to conservation planning in the medium and long term. With the objective of generating information for a better use of medium and long-term erosion models and erosion control, rainfall data of 30 pluviometric and pluviographic data sets from 25 cities ranging from 1933 to 2006 were studied in terms of adjustment of data sets, calculation of the probability of theoretical occurrence (P) and return period (T) of rainfall erosivity (EI30 and KE>25) for the State of Rio de Janeiro, as well as the spatialization of erosivity associated to return periods of 2, 5, 10, 20, 50, and 100 years for the whole state. Average annual erosivity (EI30), or "R" factor of USLE, for any location in the state of Rio de Janeiro, can on average be equaled or surpassed at least once in a 1.8-2.1 year period, at a theoretical occurrence probability of 48.5 to 54.9 %. The locations with highest erosivity rates associated to return periods are located in the Metropolitan mesoregions as well as in parts of the South and Center Mesoregions. It was possible to identify 8-12 homogeneous regions of spatial distribution of erosivity associated to the return periods of 2-100 years in the state of Rio de Janeiro. In general, the variation of spatial distribution of erosivity was highest in a return period ranging from two to five years.
soil conservation; USLE; erosivity return period
