Consequences of the January 2011 Nova Friburgo flooding. Man looking for his family in the rubble of what was left over his house. A series of floods, landslides and mudslides took place in several towns of the Mountainous Region ( Regiao Serrana ), in the Brazilian state of Rio de Janeiro. According to the National Institute for Space Research, the precipitation was caused by a Humidity Convergence Zone, a lesser form of the South Atlantic Convergence Zone. Nova Friburgo was the city most heavily affected by the floods. It is considered one of the worst weather-related natural disaster in Brazilian history.