Daily precipitation extremes and their variations in the Itajaí River Basin, Brazil

Abstract The south of Brazil is a territory where different weather systems act, contributing to a non-homogeneity of the rainfall distribution in the region. This paper presents a characterization of rainfall occurring in the Itajaí River Basin, Santa Catarina, located in the south of Brazil. Through the use of daily rainfall data, we propose a review of the rainfall analysis using 10 climatic indexes created by the ETCCDI (Expert Team, ET, On Climate Change Detection and Indexes). The time period data from 1983 to 2014, originated from 31 meteorological stations, were analysed after an intense quality control and accurate historical research. Cluster technical analysis was performed to identify climatic areas within the basin. The results indicate that three climatic regions were identified with similar total annual precipitation but different seasonal distribution in the studied area. The analysis performed by the climatic indices confirms that an increase in total precipitation was recorded in almost all stations analysed and extreme precipitation was the main contributor to such additions. In this sense, the significant increase in total annual precipitation is mainly related to values above 95‰, that is, higher rainfall rates, as well as higher precipitation events above 10 and 20 mm/day. The present article presented alarming results and the possibility of future studies and research on the effects of variability, climate change and assessment of the vulnerability of the Itajaí River Basin.