21 February 2022
Landslide risk in the Brazilian city of Petrópolis
The recovery operations in the aftermath of the dreadful landslides in Petrópolis, Brazil continue. To date there are over 150- confirmed fatalities, with many more reported to be missing. There is no prospect of finding any further survivors.
Inevitably attention is now returning to the causes of the disaster. ABC News has an excellent article exploring the issues. The piece uses an excellent quote from Antônio Guerra, who is a professor of geography professor at the Federal University of Rio de Janeiro, and who has studied weather-related catastrophes in Petropolis for almost 30 years. He says:
“Rain is the great villain, but the main cause is poor land use. There’s a total lack of planning,”
This is exactly right. The Google Earth image of Petrópolis below shows a sprawling city built between and on steep slopes, with little or no planning and few attempts to make the slopes safe:-
The city has over 300,000 inhabitants, many of whom live in poorly planned housing on steep slopes. The ABC article notes that in 2017 about 20,000 households – 18% of the total – were located on slopes with high or very high risk. Climate change is of course elevating that risk, primarily because of increasing rainfall intensities.
That Petrópolis has high levels of landslide risk is not news. Almost 30 years ago Antônio Guerra published an article (Guerra 1995), available online, reviewing catastrophic events in the city between 1940 and 1990. The abstract of the article notes that:
“Petrópolis has suffered 1,161 catastrophic events (1940-1990 only) including landslides, mudslides, rockfalls and floods. Most events are caused by heavy rains…The number of deaths appears to be increasing and nearly 90% of the events occurred within urbanized areas. Currently the principal responses are reactive, rather than preventive.”
The management of landslide risk in cities in expensive and difficult, but Hong Kong has demonstrated that it is possible. Petrópolis will continue to suffer disasters, probably at an accelerating rate, unless action is taken.
Guerra, A. 1995. Catastrophic Events in Petrópolis City (Rio de Janeiro State), between 1940 and 1990. GeoJournal, 37 (3), 6 pp.