Erosividade pluvial obtida com diferentes modelos matemáticos no Baixo Rio São Francisco no Estado de Sergipe.

Abstract

Obtaining monthly and annual erosivity indices for municipalities or watersheds, using mathematical models, is of great importance in calculating soil losses. Such indices can be safely used in order to increase the possibility of their use in conservation planning in activities such as agriculture, livestock, among others. The present work aimed to determine a mathematical model of erosivity for the municipality of Amparo de São Francisco, on the Lower São Francisco River, in the state of Sergipe. Monthly and annual rainfall data acquired from the Superintendência de Desenvolvimento do Nordeste (SUDENE) and the Empresa de Desenvolvimento Agropecuário de Sergipe (EMDAGRO) were used in the period 1963-2019, totaling 57 years. Monthly and annual rainfall classifications were carried out, using deviation intervals, in order to explain the interannual rainfall variability and thus also show its relationship with the aridity index (Ia). The calculation of the water balance was obtained by the Thornthwaite method, aiming to delimit the climate classification by the interannual aridity index (Ia) of the data series. To obtain monthly erosivity values, 4 equations were used based on different mathematical models, produced in different environments. According to the classification of the annual rainfall, there were, in general, wetter periods from 1963 to 1973 and very dry periods from 2017 to 2019. The monthly erosivity indices, for the studied models, showed erosivity classifications ranging from weak to moderate, with a predominance of weak. Monthly, the highest erosivity indices occurred from April to June, while annually, the highest erosive and rainfall indices were recorded in the years 1964, 1966 and 1972, and the lowest indices occurred in 1970 and 2018.