Did the 2024 floods in Brazil threaten the world’s largest choked lagoon?

In 2024, exceptional rains caused catastrophic flooding in the Brazilian state of Rio Grande do Sul. These storms deeply affected Patos Lagoon, the largest choked lagoon on the planet. Using satellite images, researchers were able to observe the impact of these floods on this vital coastal ecosystem. The floodwaters carried an unprecedented amount of sediment into the lagoon, forming a plume covering up to 3,000 km², nearly 30% of its surface. This plume is estimated to have transported up to 5 million tons of suspended matter, severely disrupting water quality and ecosystem services such as fishing and navigation.

Patos Lagoon, 250 km long and shallow, plays a key role in biodiversity and local human activities. The surrounding rivers, including the Guaíba River, discharge their waters into it, influencing its hydrological dynamics. During the floods, the exceptional flow of the Guaíba injected massive amounts of sediment, creating record turbidity. Satellite data revealed that the concentration of suspended matter reached extreme levels, exceeding 350 mg per liter in some areas. This increased turbidity persisted for weeks, altering aquatic habitats and threatening local species.

Scientists emphasize that climate change could worsen these phenomena. Forecasts indicate an increase in precipitation in the region, which could multiply flooding and erosion events. Without continuous water quality monitoring, the consequences for the 2.4 million inhabitants living around the lagoon could worsen. The accumulated sediments also alter the seabed, complicating navigation and reducing the light available for aquatic life.

This study highlights the urgency of implementing adaptation strategies to protect this fragile ecosystem. Remote sensing tools prove essential for real-time monitoring of turbidity changes and anticipating future risks. The findings remind us that extreme events, amplified by global warming, require proactive management of water resources and coastal areas.

Source Mentions

Cited Publication

DOI: https://doi.org/10.1007/s12237-026-01701-w

Title: Earth Observation Records of Extreme Sediment Mobilization in the World’s Largest Choked Lagoon During the 2024 Southern Brazil Flood Catastrophe

Journal: Estuaries and Coasts

Publisher: Springer Science and Business Media LLC

Authors: Sergio M. M. Cárdenas; Juliana Tavora; María L. C. Rosa; Harriet L. Wilson; Elisa H. Fernandes; Jair Weschenfelder