Impacto ambiental por ocupação em encostas urbanas: estudo de caso no bairro Gilberto Mestrinho Zona Leste de Manaus

Abstract

The studies that deal with the irregular occupations in slopes located in urban areas and the serious consequences of this process in the environment, have been widely discussed in various areas of knowledge. In this context, this work aims to present findings about environmental impacts on slopes, from a case study in Gilberto Mestrinho neighborhood, located in the East Zone of Manaus. The steps were the development of the research included: bibliographic research, surveys and field inspections, geocoding and mapping of the area, systematization, data integration based on information about the neighborhood. Among the techniques and methodological procedures used to obtain the results can be enunciated: the correlation indicators, the identification of geomorphological factors that exert control over erosive process, pedological composition and characterization of surface runoff. Generation of thematic maps and cartographic collection of temporal images of the Landsat series / TM 5 and 80 ADS- sensor provided by the Amazon Protection System and the creation of a database of the study area also composed phases of data collection. Carried out the phases of research and systematization of data, interpretations have provided the following results were found and mapped in the field, 10 points of occurrences of erosive incisions gullies type, following the landslide scars and areas susceptible to flooding in areas the foot of the slopes. With regard to this last aspect, it was taken as mapping condition the local drainage network with respect to 30m quota. The temporal analysis to recognize the process of occupation of the area was carried out by identifying the deforestation ahead of the points discussed in the ground surface. Thus, according to this parameter was shown that 74% of the study area, which is equivalent to 591.98 hectares were deforested in 2005. In 2010, this number rose to 619.13 ha, thus corresponding to 77% the deforested area. Continuing with the analysis, it was found by geoprocessadas information that in 2015, an increase of 634.71 ha corresponding to 80% range where the vegetation has been removed. These data are significant from a recent footprint. Regarding the characterization geomorphological, in toposequences the slopes, selected for particle size analysis, it was found that the soil type and textural composition associated with factors such as slope and shape of the slope, carrying paper control over erosion, and in some cases, on mass movements. These aspects were identified in AREA 1 predominantly clayey soil and therefore provides greater stability to the outbreak of erosion with steepness 27-47% considered high, has been hit by interventions and in the vicinity is occupied, degree of risk R3. In AREA 2, the predominance of sandy soils, slopes 9 to 16% are low to moderate and are affected by flooding processes which increases the risk occupations at the foot of the slopes, the degree of risk R4. AREA 3 in the sandy clay composition, slope 16-27% moderate risk level R3. As regards the steepness factor in the neighborhood Gilberto Mestrinho risk classes which have increased expression in the study area are 16 to 27% equivalent to an area of 255.37 km2 total of 705.61 km2 neighborhood area. Certifying that the areas are complex to occupation, with instabilities on the slopes and interference of various factors, and thus require government interventions and mitigating measures of competent organs to prevent future events.