Urban expansion on relief compartments susceptible to flooding: South Zone of the city of Porto Alegre, Rio Grande do Sul

Abstract

The southern area of Porto Alegre municipality (RS) has only recently experienced urban growth. This urban expansion causes changes in the environmental dynamics which can lead to situations of high risk to its occupants. Therefore, this article has aimed the elaboration of some environmental indicators for an appropriate spatial and environmental planning for the Arroio do Salso’s watershed, southern area of Porto Alegre. This article has the purpose to present the results from research guided by the following objectives: (1) to characterize the flooding susceptible areas in the watershed, (2) to analyze the dynamic of rain the city of Porto Alegre; and, (3) to analyze the vegetation cover, land use and socio-economic and infrastructure conditions of the resident population in the study area. For this purpose, we constructed a map of susceptibility to flooding and analyzed the forms of occupation and socioeconomic characteristics of the population and infrastructure in that area. Additionally, rainfall data were collected annually, monthly and daily and we collected sediment samples for granulometric analysis in different sectors susceptible to flooding. From the analysis, one can conclude that flood related events are quite common in various locations of the municipality. The effects of concentration and urban density, the inequality of infrastructure to the residents of urban space and urban irregularities in housing location increase the susceptibility to flooding processes in areas with natural potential to that event.