Análise de agrupamento e tendências de mudanças em séries temporais pluviométricas na bacia hidrográfica do Alto Jacuí, Rio Grande do Sul

Abstract

Climate studies in watersheds are very important for the water resources planning and management because they indicate climate extremes potentialities and risks. This paper aimed to identify homogeneous rainfall sectors associated with the evaluation of possible changes trends in rainfall series in the Alto Jacuí Watershed (AJW), Rio Grande do Sul State. Were used annual, monthly, and seasonal data from 27 rainfall with a historical series equivalent to 31 years, between the period from 1980 to 2010. The two main methodologies applied in this research corresponded to Cluster Analysis and the Mann-Kendall (MK) test to identify the spatial-temporal rainfall variability. The cluster analysis dendrogram was generated by the Statistica 7.0 software and the MK test and the climate extreme indicators of precipitation were obtained using the R software. Was verified that the orography conditions the rainfall spatial distribution in the AJW. Was identified the most significant trends were identified for the decrease in rainfall during autumn and winter and for the central-southern region of the study area. These results are important to AJW because they can warn to future water scarcity problems for study area.