Heavy rain equations for Brazil

The IDF equation is widely used in several engineering areas to estimate rainfall intensities with a specific duration and frequency. These equations can be adjusted based on the series of pluviographic records or by the disaggregation of daily rain in shorter duration rains. In the present study, a survey of the IDF equations published in Brazil was carried out in 118 different types of publications. Until 2010, 634 IDF equations were registered, predominantly (61%) generated by pluviographic data. In the last decade, there was a large increase in the IDF equations, totaling 3096 IDF equations, 19% of which came from pluviographic data and 81% from the disaggregation of daily rain measured in pluviometers. The North region has a lower density of rainfall stations, reflecting the lower density of IDF equations. The rainfall intensities estimated with the IDF equations show variation above 100% in the Brazilian territory, with the highest values occurring mainly in the North and Midwest regions, and southwest of Rio Grande do Sul. The lowest values occurred in the Northeast and Southeast regions. However, even in these regions there are equations that generated high intensities rainfall, which demonstrates the need to update and obtain equations representative of the location.