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 de SPI

Abstract

Drought events, characterized according to their duration, severity and area, have become a global concern, when taking into account the recurring reports of this phenomenon in different territories, such as the European continent, Asia, Central America, America of the South and among others. Due to the recurrence of these events, determining the severity of droughts is necessary for the development of policies associated with controlling this phenomenon. In this way, this research sought to determine the severity of droughts in the São Francisco River Basin, as well as to map the drought areas, and determine whether the areas with the most severe droughts are distributed throughout the Basin or whether they are concentrated in one single point. The São Francisco River Basin is located in Brazil and covers most of the semi-arid Northeast. To determine the severity of droughts, the Standardized Precipitation Index (SPI) was used, in order to classify droughts as mild, moderate, severe and extreme. Precipitation data from rain gauge stations from the National Institute of Meteorology (INMET) database were used. To calculate the drought index, 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, in contrast to the Lower São Francisco, which showed lower incidences of short-term droughts. term. Therefore, long-term droughts related to SPI 12 and SPI24 were observed in the Sub-Middle and Middle São Francisco. Through Cluster Analysis, the existence of similarity between rainfall stations allocated within different regions of the basin was verified when observed in the parameters of the drought variables.