Homogeneity, Extreme Events and Climatic Causes: São Francisco River Basin

Abstract

The objective of this research is to identify climatologically homogeneous areas, to identify and quantify the extreme events that occurred in this Basin using the Standardized Precipitation Index (SPI), as well as to know its climatic causes. ANA precipitation data from 1912 to 2019 was used, and various statistical methods were used. Rainfall homogeneous areas are the Lower São Francisco/Middle São Francisco, Middle São Francisco and Upper São Francisco, with different rainy periods and active systems. MSF presented the most intense extremes and BSF presented the least intense events in the Basin. There were more episodes of moderate, severe or extreme rain in the entire São Francisco River region than of moderate, severe and extreme droughts, according to the SPI. Through Wave Analysis it was found that these indices fluctuate in various time scales: seasonal, half-yearly, inter-annual, that of ENSO, extended ENSO, that of the Atlantic Dipole, that of solar cycles and the Interdecadal Oscillation of the Pacific.

Keywords
SPI; cluster analysis; wavelet analysis