Zoneamento e avaliação da severidade das estiagens entre os anos de 1961 até 2019 na Bacia Hidrográfica do Rio São Francisco com base em valores do Índice de Precipitação Padronizado

Assessment of Drought Occurrence and Severity in the São Francisco River Basin between the years 1961 to 2019

Abstract

This research sought to determine the severity of droughts in the São Francisco River Basin, as well as to map the areas of drought, and to determine whether the areas with more severe droughts are distributed along the Basin or if they are concentrated in a single point. To determine the severity of droughts, the Standardized Precipitation Index (SPI) was used. Precipitation data from pluviometric stations, from the National Institute of Meteorology (INMET) database, were used. To perform the calculation of the drought index, a programming language software was used. The results of this research showed that although the Upper São Francisco region has high values ​​of accumulated precipitation, it stands out in terms of SPI3, short-term droughts, contrary to the Lower São Francisco, which showed lower incidences of short-term droughts. Thus, long-lasting droughts, related to SPI 12 and SPI24, were observed in the Sub-Medium and Middle São Francisco. Through Cluster Analysis, the existence of similarity between pluviometric stations allocated within different regions of the basin was verified when observed in the parameters of the drought variables.