Meteorological conditions and social impacts associated with natural disaster landslides in the Baixada Santista region from March 2nd–3rd, 2020

Abstract

In Brazil, hydrometeorological disasters have been responsible for much damage, given extreme weather events ranging from 1991 to 2012. The most lethal events were floods and landslides. On March 2nd–3rd, 2020, cities in the Baixada Santista Metropolitan Region (São Vicente, Guarujá and Santos) were affected by a disaster after periods of intense rain. This study evaluated the geometeorological conditions leading to the event, and analyzed post-disaster socioeconomic aspects. The storm that caused the disaster was documented via satellite imagery, meteorological radar, pluviometric and geotechnical stations, and numerical weather forecasting models. The floods and landslides caused approximately US$ 40 million of damage, 680 thousand people were affected, and 44 deaths and 17 injuries were reported. The storm was formed from a combination of the convergence of low level humidity, a medium level cyclonic vortex, and a high level trough. Rainfall stations registered accumulated precipitation up to 300 mm day−1 between March 2nd–3rd. Soil saturation levels on the slopes were already above 40% on February 11th, which, when combined with extreme rain on March 2nd–3rd, resulted in a landslide. This shows the importance of improving more effective communication between institutions and citizens, along with improvements in monitoring and alert systems.