Análise de tendências e padrões de variação das séries históricas de vazões do Operador Nacional do Sistema (ONS)

Abstract

This paper aims to evaluate possible trends in streamflow time series at the stations of the National System Operator (ONS) of Brazil. The analytical methods used were the classical methods (mobile mean and mobile median, local regression (LOWESS), linear regression and Mann-Kendall-Sen), the wavelet transform analyses and flood study. The results showed that there is a positive trend in flow series in the South, Southeast and Center-West of Brazil and a negative trend in flow series in the North and Northeast of Brazil. It was also found that there is a positive correlation between the PDO Index (Pacific Decadal Oscillation Index) an d change in levels of peak flow at most stations and that there is a negative correlation between the SOI (Southern Oscillation Index) and changes in levels of peak flows at most stations analyzed.