Evolução temporal do risco a movimentos de massa incorporando a influência da ocupação antrópica e de obras de estabilização na comunidade da Rocinha RJ

Abstract

In urban areas, mass movements can cause serious damage to society, whether these materials or humans. In this context, the Rocinha community, currently known as a neighborhood, has been undergoing to mass movements events over the years, sometimes catastrophically. According to the 2010 IBGE Census, Rocinha has about 70 thousand inhabitants distributed in more than 25 thousand households, evidencing the need for an intensive risk management at this region. So, actions that the goals are to reduce materials and human s loss by the government turns out to be indispensable. Among these actions are: (i) delimitation of risky areas; (ii) definition of rain intensity thresholds capable of deflagrating mass movements; (iii) implementation of alerting systems in the counties so that the population can be protected. The definition of risky areas is based on observational criteria. In other words, whether engineers or geologists go through the slopes and establish the areas with high, medium and low potential for landslides. From this table, the high, medium and low risky areas are classified and mitigating actions are given a priority criterion. Despite intensive work, there is no research about the effectiveness of mitigating steps to effectively change the regional boundaries of risky areas. This work aims to study the temporal evolution of the risk mapping to landslides incorporating the influence of anthropic occupation and stabilization works in the community. To do so, the following relation was evaluated: risk reduction versus government investments through landslide susceptibility maps of GEO-RIO and the landslide probability maps of this research. With this data, it was compared its evolution with the containment works carried out in the place. The study also addressed the reports of occurrences in the community related to the landslides that occurred in the last 40 years and selecting those in which there was more detailed information about the events for the generation of new maps based on probabilistic studies that aim to reduce the subjectivities of the classification of levels of risk, giving rise to updated sliding probability maps. The general analysis of the maps presents a reduction of the risk profile found over the years, influenced by the stabilization works carried out, being slightly counterbalanced by the increasing anthropic occupation in the region.