Risk assessment on landslides focused on the role of the water: examples from model regions (Rio de Janeiro State and Hong Kong)

Landslides are one of the most vital natural hazards on Earth. To satisfy the demand for protection against landslides, it is necessary to systematically assess and manage landslide hazards and risk. Landslide mechanisms related to hydrology are analyzed with focus in the major risks, and formal risk assessment methodologies are presented in the paper. Issues related to risk assessment are discussed and different steps are described. The management of accidents in slopes is discussed, with particular emphasis to Hong Kong and Rio de Janeiro in Brazil. Hong Kong is a region of China with a large population density and very mountainous. There is a history of tragic accidents in the slopes. The territory has a tradition of a high standard in the practice of slope engineering. The establishment of an efficient security system developed by Geotechnical Engineering Office was established in the territory. Also, specific aspects of slope instability in the state of Rio de Janeiro are discussed, and in Rio de Janeiro city, with focus on cases which occurred in the mountainous region of the State. The mega-disaster that occurred in 2011, with high number of deaths and significant economic losses, is studied with incidence in individual landslides.