Intensity-duration-frequency relationships of rainfall through the technique of disaggregation of daily rainfall/ Relacoes intensidade-duracao-frequencia da precipitacao mediante a tecnica da desagregacao da chuva diaria

Rainfall intensity-duration-frequency (IDF) relationships are a tool that can be used in modeling the transformation of rainfall to runoff, required for the design of hydraulic works. The objective of this study was to verify if there is a significant difference between the intensity-duration-frequency relationships generated using pluviographic records and those determined from pluviometric data. Maximum annual rainfall intensity values were obtained from the disaggregation of maximum daily rainfall and rainfall records in the durations of 5, 10, 15, 20, 30, 60, 120, 360, 720 and 1440 min and for the return periods of 2, 5, 10, 20, 25, 50 and 100 years, in the locality of Pelotas, Rio Grande do Sul state, Brazil (31[degrees]46' 34" S; 52[degrees]21' 34" W, altitude of 13.2 m). By Student's t-test, it was verified that there is no significant difference between the values of maximum rainfall intensity obtained from pluviographic records and those determined from pluviometric data. Key words: intense rains, pluviometric data, pluviographic records A relacao intensidade-duracao-frequencia de ocorrencia de precipitacao e uma tecnica que pode subsidiar estudos hidrologicos em modelos de transformacao chuva-vazao, muitas vezes, utilizada no dimensionamento de obras hidraulicas. Objetivou-se verificar se ha diferenca significativa entre as redoes, cujos valores de intensidades maximas anuais foram obtidos a partir da desagregacao da chuva maxima diaria e registros pluviograficos, nas duracoes de 5, 10, 15, 20, 30, 60, 120, 360, 720 e 1440 min e para os periodos de retorno de 2, 5, 10, 20, 25, 50 e 100 anos, na localidade de Pelotas/RS, Brasil (31[degrees]46' 34" S; 52[degrees]21' 34" O, altitude de 13,2 m). Pelo teste t de Student, constatou-se que nao ha diferenca significativa entre os valores de intensidades maximas obtidos a partir de registros pluviograficos e aqueles mediante a desagregacao de dados pluviometricos diarios. Palavras-chave: chuvas intensas, dados pluviometricos, registros pluviograficos