Inundações e escorregamento em Teófilo Otoni, Minas Gerais: uma situação de risco ambiental em continuada construção, segundo indicadores geomorfológicos

Abstract

The urbanization experienced by underdeveloped countries shows the occurrence of floods, overflows and landslides, reflecting the non-observance of potentialities and limitations of occupation sites in cities. Among other socioenvironmental hazards of brazilian urban environments, these are even more common in areas with a) concentrated rainfall in short rainy seasons; and b) relief characterized by high declivity slopes and covering slopes. Considering the large amount of people affected by floods, overflows and landslides, as well as damages caused to urban facilities, there are considerable efforts from geosciences to recognize and map areas at risk for the phenomena. This work, in addition to such efforts, aims to present proposals for mapping the risks to floods, overflows and landslides, based on geomorphological and socioeconomic indicators inherent to urban and periurban spaces in the city of Teófilo Otoni (MG). For so, analyzes were subsidized by interpretation of satellite images and field work, in which direct interventions in the fluvial channels and changes in the flood plains were evaluated, as well as soil and superficial formations present in slopes recesses in the investigated area. Morphometric parameters analyses mediated by geoprocessing tools were also employed, especially regarding the role of embankments and terrain slope classes related to susceptibility to landslides. These natural factors had their spatialities associated to a data collection related to rescue operations carried out by the Fire and Military Police Corps in Teófilo Otoni, as well as demographic information which includes housing density, population income and sanitary indicators, allowing to understand where, how and why floods, overflows and landslides occurred in the city, as well as determining the exposure degree of populations to phenomena. It was observed that densely built sectors, adjacent to the most downstream stretch of the main watercourse that drains the city, are affected by periodic floods, as well as portions highly affected by urbanization in their main tributaries, largely due to negligence during occupation of these areas and execution of drainage works that aggravate their occurrences, instead of minimizing them. Alloys are in intimate relationship with the slopes waterproofing in alveolar microbasins in the city interior, especially when drainage channels of these areas are channeled. It was also possible to conclude that most of the recesses with highest risk of landslides are located at the vicinity of urban area limits, not only due to specificities of the occupation site but also due to the socio-spatial segregation that characterizes the production of urban space in Teófilo Otoni (MG). This model of city expansion, adopted at least during the last four decades, disregards the geomorphological characteristics of the occupation site and perpetuates an already historical construction of risk in the investigated area, in time and space.