Rainfall episodes and local stability thresholds in Santos

Abstract

The temporal distribution of rain and its impacts on the municipality of Santos for the period 1980-2015 was evaluated, with emphasis on the correlation between rainfall events and mass movements, estimating the local stability thresholds for accumulated rain over 24, 48, and 72 h. Additionally, calculations at annual, seasonal and monthly level were carried out to evaluate the rainfall distribution. The rainfall distribution did not reveal a pattern of increase or decrease, and although higher amounts of precipitation have occurred below the average of the period since 2000, they tended to be more concentrated in recent years. Results also suggested that there is a probability of the occurrence of gravitational mass movements when the volume of rain reaches a value equal to or greater than 75.0 mm over a 2-day period. Besides to mass movements, flooding and property collapses were the recurring impacts recorded, which brought in turn a large number of displaced, homeless and deaths.