Erosividade determinada por desagregação de chuva diária no lado brasileiro da Bacia da Lagoa Mirim.

Abstract

Erosivity, which is the rain’s potential to cause the soil’s erosion, constitutes a fundamental object of study for soil conservation planning. However, to obtain the rain’s erosivity it is necessary to know its intensity, which is normally derived through pluviographic records, but there is no such data in many places. In this sense, this study aimed to (i) validate the daily rain technique for the erosivity’s calculation, based on localities which pluviographic and pluviometric records are available; (ii) apply the disaggregation technique to obtain the erosivity at Lagoa Mirim Basin municipalities that do not have pluviographic records; (iii) determine the spatial distribution of rainfall erosivity at the Brazilian side of Lagoa Mirim Basin-RS; (iiii) to verify the existence of homogeneous erosivity regions within Lagoa Mirim Basin-RS. For this purpose pluviometric and pluviographic data from the municipality of Pelotas from a series of 17 years for the period of 1982 -1998 were used. The erosivity in 20 municipalities in the Brazilian side of Lagoa Mirim Basin was also derived by the same disaggregation method and this data was spatialized thus obtaining the erosivity map of the basin. The results show that the erosivity values obtained based on the disaggregation technique of daily rainfall using pluviometric data did not differ from those obtained by pluviographic records, therefore the disaggregation technique can be employed for the calculation of erosivity. We had an increase in information for the region studied with the availability of erosity data for 20 cities and the identification of two homogeneous erosivity regions.