Brazil Proposal for real-time rainfall monitoring of gravitational mass movements in Serra do Mar, SP

Landslides represent a significant risk in Brazil and worldwide, especially in mountainous areas prone to extreme precipitation. Despite advances in risk reduction policies over the past decades, Brazil still faces challenges in adopting effective measures for natural disaster prevention. In the context of global climate variability and the increase in extreme events that affect thousands of people each year, there is an urgent need to implement risk reduction policies focused on prevention. This article presents a prototype of a real-time precipitation monitoring system based on critical rainfall thresholds for the early issuance of landslide alerts. The system was applied in the municipalities of Cubatão and São Sebastião, both located in the Serra do Mar Mountain range in the state of São Paulo, which have a long history of disasters related to mass gravitational movements during two rainy seasons (2022–2023) and (2023–2024), with particular emphasis on the disaster that occurred in São Sebastião. The disaster recorded in São Sebastião on February 19, 2023, registered the highest 24-h precipitation in Brazil’s history (> 600 mm/24 h), resulting in 64 deaths and losses amounting to USD 122.4 million. This event highlighted the importance of implementing early monitoring systems focused on preventive actions. The system’s functionality proved highly promising, demonstrating that it was possible to estimate scenarios for advancing operational levels as accumulated precipitation progressed, always correlated with weather forecasts. It is concluded that this system fits well within the logic of preventive monitoring, which is essential in the context of climate change and the increasing frequency of extreme events in various parts of the world.