Early warning services for disaster risk reduction in Brazil: The experience of CEMADEN during the floods of Rio Grande do Sul of May 2024

Author(s)

Marengo, Jose A. ; Alcantara, Enner H. ; Moraes, Osvaldo L. ; Martinez, Rodney ; Seluchi, Marcelo ; Alvala, Regina C. ; Dolif, Giovanni ; Goncalves, Demerval

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF DISASTER RISK REDUCTION; v. 126, p. 13-pg., 2025-08-01.

Abstract

Floods are among the most expensive meteorological hazards globally and are the leading cause of disaster-related fatalities worldwide. They also result in severe health, social, and economic consequences. The unprecedented floods that occurred from April to May 2024 in the state of Rio Grande do Sul, southern Brazil, affected over 90 % of the state and resulted in 183 deaths. These floods were triggered by heavy rainfall exceeding 500 mm within five days, causing the water levels in Gua & iacute;ba Lake to reach 5.35 m on May 6, the highest level since the flood in 1941. This inundation severely affected vulnerable areas of the capital city, Porto Alegre. Prior to the major flooding event in Porto Alegre, rainfall forecasts and high-risk flood warnings were issued a few days in advance. In Brazil, the Early Warning System (EWS) operates through an intersectoral, multi-agency framework. Over the past fifteen years, the integration of climate information into disaster prevention, risk reduction, monitoring, and early warning has improved significantly. However, despite the National Center for Monitoring and Early Warning of Natural Disasters (CEMADEN) being the primary institution responsible for monitoring and issuing nationwide early warnings for floods, flash floods, and landslides, there is still a need for better integration of information. This improvement could enhance response actions and contribute to resilience building. This study provides a brief review of the climatological conditions that led to the floods in Rio Grande do Sul in April-May 2024. It also examines the role of EWS and Multi-Hazard Early Warning System (MHEWS) centers in Brazil during the disaster, as well as an evaluation of CEMADEN's prevention and early warning activities before and during the event. The aim is to understand the unique nature and impacts of this disaster to better prepare for similar events in the future. (AU)

• FAPESP's process: 14/50848-9 - INCT 2014: INCT for Climate Change
• Grantee: Jose Antonio Marengo Orsini
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants