Daily rainfall intensity and temporal trends in eastern Paraná state – Brazil

Abstract

The present study aims to analyze the intensity of daily extreme rainfall and trends for precipitation in Castro, Curitiba and Paranaguá stations, located in the state of Paraná, Brazil. Historical series of rainfall registered by the Brazilian National Institute of Meteorology were used considering the period from 1976 to 2015. The Mann-Kendall and Pettitt statistical tests were applied to identify trends and ruptures in historical rainfall series. Other indicators of trends in rainfall and temperature were calculated using the RClimDex software, developed by the Canadian Meteorological System. The classification of cumulative daily rainfall in 24 h with the application of the quantile technique was defined as a standard for percentiles. The months of January, February and December presented greater occurrence frequency of rainfall equal to or greater than 95% and 99% of the quantiles for all locations. The comparative analysis showed that Paranaguá station has the largest accumulated values of rainfall in 24 h during the rainiest months, between September and April, while Castro and Curitiba stations recorded the highest daily totals between May and August. Increasing daily precipitation totals were identified in all quantile's classes with statistical significance only in Curitiba and Paranaguá station, which is attributed to greater urban densities and its direct impacts over daily rainfall totals. Significant trends for increased rainfall were observed, especially in Curitiba, a condition that is associated with the expressive and also significant increase in climate indicators of air temperature.