A report presented in December 2018 by the Technological Research Institute (IPT), linked to the Economic Development Secretariat of the State of São Paulo, showed that there were 161 homes in São Sebastião in high risk areas for landslides. The document also pointed out that 2,043 homes were in areas of medium or low risk for landslides in the municipality.
The IPT document did not list, in the area of Barra do Sahy, on the North coast, one of the places most affected by the storms that occurred last Sunday (19), any building in a situation of high or very high risk. This shows, according to the technical director of the IPT, Fabrício Mirandola, that there may have been an increase in irregular occupation since the publication of the report. He also points out that, according to the residents’ reports, the victims were hit by the mud when they left the residences.
“Some of the people who were affected were no longer inside the houses, they were on the streets and in the alleys, leaving, fleeing the houses. When we have this soil liquefaction process, this material tends to follow the path of the streets, because the street normally follows the natural path of the water”, he said.
Most recurring events
The director also points out that the 2018 report was based on historical average rainfall data in the area and did not predict the atypical occurrence of the rainfall that hit the region last Sunday. But, according to him, the recent episode may indicate a new trend.
“And then we end up having, less than 10 years later, an event that is almost five times bigger than this one. [de 2014]. We have really been experiencing changes in the climate”, she highlighted. “This may indicate, we cannot nail it but, from what we have been seeing from the histories, that extreme events like this will be more recurrent, and we need to be prepared”, he added.
He says that the report refers to a storm that occurred in 2014 in the region, which accumulated about 180mm of rain. By the model used in the document, the institute predicted that a new rain of this size could only occur again in 60 years, a forecast technically called return time.
natural process
For the professor at the São Paulo State University (Unesp) in Rio Claro, and director of the Brazilian Federation of Geologists, Fábio Augusto Reis, the event that took place on the north coast is a natural process in the region and should continue to happen in the future.
“Other events have already occurred, not of this magnitude, but extreme events in the history of Brazil, in Serra do Mar. This will continue to happen. Other extreme examples will occur, this is part of the natural process and Serra do Mar is a mountain range that has always had processes of landslides, landslides, and will continue to do so, ”he said.
He cites, as an example, the series of landslides that occurred in 1967 in the municipality of Caraguatatuba, also on the North coast, in which around 450 people died. “The ’67 event was much worse. But at that time, there were 15,000 people living in Caraguatatuba. If that same event had occurred today, we would be talking about thousands of people dead.”
“So that’s what we have to separate: the natural event will continue. Now, the big problem is the occupation, the disorderly occupation that takes place in these cities,” he added.
