Mapeamento e análise da erosividade da chuva na sub-bacia do Alto Paraíba.

Abstract

Among the various factors that contributed to soil erosion, described in the EUPS model, the Erosivity of the Rains (Factor R) stood out, which is one of the most important factors of soil loss, due to its ability to disaggregate, by the impact of the droplets and generate runoff carrying the soil particles. The EUPS estimates soil losses through laminar erosion, through the multiplication of six intrinsic factors: climatic characteristics, soil properties, terrain landscape, vegetation cover, agricultural management and conservation practices. The focus of the study was to analyze the erosivity of rain (EI30) in the Alto Paraíba sub-basin region, through geotechnologies, resulted in monthly and annual maps. The work used precipitation data provided by the water Management Executive Agency (AESA) with 103 years of abservation between 1911 and 2014. The data on erosivity, latitude and longitude were entered in an electronic spreadsheet with the coordinates of the posts of each municipality. The SURFER® 11 program was used to prepare the maps, in the Kriging method was used for the mapping, where the means, medians, maximum and minimum values, variance and standard deviation were obtained. When all factors, with the exception of rain, are kept constant, the loss of soil per unit area of an unprotected area of vegetation is directly proportional to the product of two characteristics of rain: kinetic energy multiplied by its maximum intensity in 30 minutes; this was the best correlation found to express the erosive potential of rain. Therefore, information generated in the work made it possible to analyze the erosivity of rain in the region of the Alto Paraíba sub-basin, thus, it was concluded that the use of geotechnologies allowed to predict and map the erosivity of the watershed basins under study quickly and agility. It was possible to prove that the average annual distribution of the rain erosivity factor was 3,477.57 mm.ha-¹.year-¹. And the standard deviation of the erosivity parameter The monthly average presented a value of 639.96 mm.ha-¹, and the coefficient of variation presented a value of 0.184.