Análise de eventos extremos de precipitação e de estiagem na Região Nordeste do Rio Grande do Sul

Abstract

This assignment makes an analysis of extreme events of precipitation and drought in three municipalities of the northeast region of Rio Grande do Sul, Brazil: Bento Gonçalves, Caxias do Sul and Passo Fundo. Extreme weather events, such as droughts and floods, have adverse effects on several sectors of society, such as the economy, health and living conditions of the population. For this purpose, using precipitation data between 1961 and 2020 made available by BDMEP (Banco de Dados Meteorológicos para Ensino e Pesquisa) and ANA (Agência Nacional de Águas) an analysis of the relative frequency of intense rainfall with precipitation greater than 50 mm/day is presented for each of the three municipalities. In addition, a rhythmic analysis of a case of heavy rainfall is made to identify the meteorological phenomena responsible for the high rainfall recorded in this event. In addition, the Standardized Precipitation Index (SPI) is applied on different time scales for the identification of wet and dry periods recorded over the years analyzed. The influence of the ENSO (El-Niño South Oscillation) phenomenon on these periods indicated by the SPI is also discussed using the MEI.v2 (ENSO Multivariate Index) and SOI (South Oscillation Standardized Index) indexes. The comparison of the ENSO indexes with the periods indicated by the SPI showed that although it influences some events, the occurrence of the phenomena in the Pacific is not determinant to define a period as dry or rainy in the studied region. [resumo fornecido pelo autor]