Method for Establishing Heavy Rainfall Equations Based on Regional Characteristics: Transformation of Maximum Daily Precipitation

Modeling heavy rainfall patterns is essential for designing hydraulic structures, planning land use and water resources, and predicting disasters, among others. Usually, heavy rainfall is characterized by curves that relate the intensity, duration, and frequency (IDF), adjusted from the analysis of pluviograms. Alternatively, these equations can be adjusted using disaggregated daily rainfall data, whose reliability is currently questioned due to the use of common coefficients to disaggregate the maximum daily precipitation (hday) into rainfall associated with shorter durations. This study proposes the Transformation of Maximum Daily Precipitation method (TMDP) using the maximum daily precipitation of the station of interest and the curve of heavy rainfall of the nearest location, denoting the local characteristic, to transform the hday associated with a return period into rainfall intensities for shorter durations. The TMDP proved to be slightly superior to the most widely used rainfall disaggregation method in Brazil, particularly in regions with a higher density of data for the IDF equation. The TMDP is a potential tool for regions with low density of rainfall data, although it has limitations in regions where such data are scarce.