Depth Area Duration analysis of the rainfall event that caused the 2024 floods in Southern Brazil

Código

I-EBHE0160

Autores

Walter Collischonn

Tema

WG 1.10: Hydrologic Design - Solutions & Communication

Resumo

From end of April to the beginning of May 2024, intense rains caused extraordinary flooding in a large part of Rio Grande do Sul. The largest floods ever observed occurred along several rivers, such as Jacuí, Taquari, Forqueta, Pardinho, Caí, Sinos and Guaíba. Lagoa dos Patos itself, which receives water from all these rivers, also reached the highest levels ever recorded. Extreme rainfall, such as that of April and May 2024 in Southern Brazil, can be analyzed from a local and regional point of view. From a local point of view, it is possible to analyze extreme rainfall using data measured from a single rain gauge. From a regional point of view, it is necessary to analyze observed rainfall data from a set of gauges distributed over a given area. To analyze the characteristics of precipitation over large areas and long durations, an important analysis tool is the ?Depth Area Duration? (DAD) curve, usually applied in Probable Maximum Precipitation (PMP) studies. We prepared the DAD curve for the extreme rain event in RS in April and May 2024, and compared it to the envelope DAD curve for all the biggest rain events in Brazil, from 1980 to 2022, and show that, on certain scales of time and space, the 2024 Southern Brazil event is the largest rainfall event ever observed in central-southern Brazil from 1980 to 2024.