Extreme Rainfall Events on the Coastland of Paraná State (Paranaguá Bay)

Abstract

The occurrence of extreme precipitation events (EEP) of the coast of Paraná increases the erosivity potential of the rivers in this region, causing flooding among other occurrences. In this context, the objective of this study is to analyze the trends in intensity and frequency of daily EEP, as well as to analyze the extreme hourly cycle for the coastal region of Paraná and the synoptic conditions. Thus, precipitation data and divergence of moisture flow were collected. Daily precipitation above the 95th percentile (EEP95) was considered in this study. From the EEP95, linear trend analysis using the Mann-Kendall test, daily cycle analysis and the spatial distribution of the synoptic environment were studied. Although the study is limited to one locality, areas of maximum moisture convergence highlight the pattern of the Convergence Zone of moisture. The results show that the threshold for a daily EEP95 is 46.40 mm.dia⁻¹; only during the early morning and in the rainy season, the daily cycle of the EEP95 presented hourly rates that reached the 95th percentile. The period from January to March, concentrated around 50% EEP95, with the frequency of EEP95 decreasing in years of La Niña and increasing in years of El Niño and neutral.

Keywords:
Southern Brazil; coastal region; season wet; extreme events