The knowledge of intense rainfall magnitude is very important for the elaboration of hydraulic projects, management of hydric resources in engineering and structure dimensionality for the water erosion control on soil conservation. However, information about the rainfall intensity can only be obtained directly from pluviograms, which quite often are not available at the study site, where the presence of pluviometer data (rainfall of "one day") is more common. In this case, the disaggregation of daily rainfall into 24 hour periods and smaller durations can be used to estimate the correspondent intensity. The study was carried out at Santa Catarina State University (UDESC), in Lages (SC), during the first semester of 1996. Maximum rainfall of "one day" annual series, obtained from pluviometers located in Lages and Campos Novos (SC), during 30 consecutive years (1966-1995), were used. The Gumbel statistic distribution was applied to obtain the rainfall height in the following periods of return: 2, 5, 10, 15, 20, 25, 50 and 100 years. After that, the daily rainfall disaggregation model was applied to provide the expected maximum rainfall height for duration times varying between 24 hours and 5 minutes and their corresponding maximum average intensities. With the results obtained, it was possible to get the intensity-duration-frequency (I-D-F) curves for the selected periods of return as well as their mathematical relations. The I-D-F equations estimated for Lages and Campos Novos were: i = 2050Tr0.20 (t + 29.41)-0.89 and i = 2157Tr0.17 (t + 29.42)-0.89, respectively, where i stands for maximum average intensity (mm h-1), t for rainfall duration (minute) and Tr for rainfall return period (year).
extreme rainfall; intensity-duration-frequency curves; Gumbel distribution