Statistical characterization of trends in annual series of hydro-climatic data in the state of Sao Paulo, Brazil/Caracterizacao estatistica de tendencias em series anuais de dados hidro-climaticos no estado de Sao Paulo

The aim of this research was to identify trends, in annual time series, of rainfall, average temperature and flow of rivers, registered in twelve localities that belong to some sub-basins of Sao Paulo state. The measurements used were made by the Instituto Agronomico de Campinas (IAC) and the Sistema de Informacoes para o Gerenciamento de Recursos Hidricos do Estado de Sao Paulo (SigRH), with temporal variability that depends on the series. For each series, linear regression analyses and nonparametric tests of Mann-Kendall and Pettitt, were conducted, aiming to identify the presence of a trend. The results confirm that five rivers accused instances of positive trends and for only one a negative trend was found. Only a locality presented increase in precipitation, while five have recorded positive trends for the temperature average. In other cities it has not been verified any evidence of trends of these climatic variables.