Influence of climate variability on erosivity in Belém (PA)

Abstract

The Universal Soil Loss Equation (USLE) is a model in which soil loss is the product of several indices, including rainfall erosivity (R). This factor identifies when the greatest risk of water erosion occurs. The objective of this study was to analyze the influence of ENOS (El Niño Southern Oscillation) and Atlantic Dipole on the R factor in Belém (PA). Erosivities from 1986 to 2015 were classified according to intensity. ENSO events were also classified to evaluate a possible influence of their amplitude. The Niño Oscillation Index (ION) was used to verify the occurrence of ENSO. In order to analyze the Atlantic Dipole, the TNA (Tropical Northern Atlantic) and TSA (Tropical Southern Atlantic) indices were used, because this phenomenon directly interferes in the region’s main atmospheric system, the Intertropical Convergence Zone (ZCIT). Pearson correlation analysis and linear regression were determined between R and climatic indexes. Thus, lower erosivities were observed in years of intense El Niño, obtaining higher correlation coefficients. Coincidence of intense La Niña with Negative Dipole also represented higher correlation coefficients, meaning the increase of erosivity. There was a weak correlation of erosivity during Positive Dipole.