The 2024 unprecedent flood in South Brazil in the context of climate change

Código

I-EBHE0195

Autores

Pedro Torres Miranda, Rodrigo Cauduro Dias de Paiva, Ingrid Petry, Walter Collischonn

Tema

WG 1.08: Deep Explanation & Evaluation for Practices in Hydrological Changes (DEEPHY)

Resumo

The disastrous flood that occurred in May 2024 caused unprecedent impacts in South Brazil. During the event, many rivers presented record flows. Among them, Guaíba and Taquari rivers stood out as they registered values near global maximum reference. Most of South Brazil stands as a hotspot of flood increase. This matches the signal of projected alteration due to climate change, possibly configuring an additional challenge in the future. Here, we evaluate May 2024 event in the context of past historical observations and projections of climate change impacts on flood flows based on IPCC CMIP6 climate data and continental scale simulations using a physically based hydrological model MGB. Last decades showed an increase in flood event occurrence compared to 20th century records. For instance, in the Guaíba river, a flood rich period occurred from 1930s to 1960s followed by a flood poor period until the 1990s. However, last decade presented floods high above any past variability, including the 1st, 3rd and 4th largest in record in the last 2 years. Projections of climate change impacts over Brazil show the south region as the one with marked increases of floods both in terms of magnitude (10-20%) and frequency. These results highlight the need for strategies for the adaptation to climate change for future planning in the context of flood risk management and also for current efforts for rebuilding the infrastructure.