The use of rainfall disaggregation coefficients to obtain intensity-duration-frequency curves: estimation using pluviographic data versus national mean values

Abstract

The lack of sub-daily rainfall data to obtain intensity-duration-frequency (IDF) relationships at a local scale is a common limitation in many countries. This study determines rainfall disaggregation coefficients using pluviographic data from several meteorological stations to adjust IDF curves for Rio de Janeiro state, Brazil. The adjusted IDF curves using the coefficients obtained show satisfactory adjustment with Nash and Sutcliffe efficiency values above 0.99 compared to the mean values proposed by Cetesb (1979). The root mean square error (RMSE) of the estimated rainfall intensities using the adjusted IDF relationships for different return periods and rainfall durations varied between 2.55 at the Eletrobrás station and 42.49 at the São Bento station. The disaggregation coefficients obtained for Rio de Janeiro state differ from the values proposed in the literature, which confirms the need to adjust values locally and for hydrologically homogeneous regions. This local and regional scale approach provides more accurate IDF curves.