Analysis of mathematical models to estimate erosivity

Abstract

The main cause of soil degradation in humid tropical and subtropical environments is water erosion, characterized by being the most important in Brazil. The main factors that determine soil losses by water erosion are erosivity, erodibility, topography, soil use and management and conservationist practices. Proper conservation planning requires knowledge of the factors that influence local erosion. The quantification of soil losses due to water erosion helps to define management techniques and conservation practices appropriate for each province. The municipality of Rio Largo - AL, is located in the metropolitan region of Maceió, within the physiographic region of the Coastal Tablelands. The objective of this work was to determine the erosivity of rainfall for the municipality of Rio Largo - AL, through rainfall data from 1963 to 2015. These data were tabulated to calculate rainfall, coefficient and its relationship with erosivity using six equations. The average annual rainfall calculated was 1800 mm for the observation period of 52 years, showing a wide variation in rainfall distribution, with the rainy season concentrated in the months of April to August. The computed average annual erosivity index was 3761 MJ mm ha-1 h-1 year-1, ranging from 312 to 7211 MJ mm ha-1 h-1 year-1. The months of May, June and July correspond to the most critical period in relation to the erosive potential of the rains and the months of October, November and December are the least critical.