Rain Erosivity in the Basin of the Araçuaí-MG River

Abstract

Soil erosion is one of the greatest environmental problems of our time. Every year millions of tons of arable land are lost through this process, contributing to the loss of soil fertility and to the decrease of crop productivity. Rain erosivity is described as an interaction between the kinetic energy of the raindrops and the soil surface, representing the potential of rainfall and flooding in soil erosion production, thus exerting a great influence on erosion, especially in tropical environments. In this context, the present work aims to determine the spatio-temporal variation of rainfall erosivity in the Araçuaí river basin - MG. Precipitation data of 14 rainfall stations distributed in the basin territory, containing uninterrupted historical series from 1996 to 2015, were selected. From the historical series, the Fournier Modified Index (MFI), the average monthly erosivity (EI30_m) and the Annual Average Erosivity (R-Factor) were calculated for each rainfall season. The data were interpolated for the entire basin by the inverse method of Distance (IDW). The results indicate an annual mean erosivity in the basin of 9125 MJ mm ha^-1 h^-1 year^-1. The spatial analysis indicated the existence of a decreasing gradient of erosivity in the South-North direction, with the highest values in the upper reaches of the basin. The temporal analysis showed that the highest values of erosivity occurred in the period from October to March, and the lowest values from April to September.