Homogeneity analysis of daily precipitation series in Paraná State, Southern Brazil

The analysis of extreme precipitation events plays a crucial role in the management of water resources, infrastructure, public water supply, agriculture, fire control, and public health. For an accurate characterization of precipitation events using historical series, the observed variations must be solely attributable to weather and climate conditions. This study aimed to identify homogeneous gauge stations in Paraná State, southern Brazil, based on four statistical tests (SNHT, Buishand, Pettitt, and Von Neumann) and conduct a homogeneity analysis of daily rainfall data. Missing values were imputed into the time series, and only stations with up to 25% of data gaps were included. Of the 482 stations analyzed in the state, 73.7% (n = 355) demonstrated homogeneity, 11.6% (n = 56) were considered doubtful, and 14.7% (n = 71) were deemed suspect. The highest number of homogeneity breaks was recorded from 1990 to 2005. The number of breaks during this period was estimated at 75 (59.1%) by SNHT, 86 (67.7%) by the Buishand test, and 89 (70.1%) by the Pettitt test. The year with the highest number of homogeneity breaks was 1998, with 81 breaks identified by the Pettitt test. These breaks may be related to El Niño and La Niña phenomena, given that a large sample of rainfall stations was analyzed in the study.