Análise da vulnerabilidade ambiental à inundação na bacia hidrográfica do rio Grande, Baixada de Jacarepaguá (RJ)

Abstract

Since the 1970s, this watershed of the Rio Grande has undergone environmental changes due to the incorporation of the Baixada de Jacarepaguá into the municipal expansion zone. As a result, the disorderly occupation process has led to the deforestation of forests, the waterproofing of soils, interventions in river channels, the degradation of ecosystems and, above all, the growth of irregular occupations on the banks of rivers, which have a negative impact. and increase floods, making them potentially more dangerous to these populations. The objective of the present study is to analyze the environmental vulnerability to urban flooding in the Rio Grande hydrographic basin, making it possible to subsidize decision-making by the management bodies in order to provide adequate public policies in an attempt to reduce vulnerability and increase the population's resilience of the river basin resident. In the present work, the Multicriteria Analysis method capable of integration in a GIS environment called AHP (Analystic Hierarchy Process) was used, in which it was possible to compare different alternatives to define the degree of relevance of the variables (weights) and their respective classes (notes). For this, the methodology was divided into three parts: construction of the flood susceptibility map; elaboration of the social vulnerability map; and, finally, elaboration of the synthesis map of environmental vulnerability. From the result of the mapping of environmental vulnerability, the following spatial pattern can be identified in the distribution of classes in the Rio Grande Hydrographic Planning Unit (UHP): the class of very low environmental vulnerability is found in an area with the highest income population UHP or areas of demographic voids, whether in areas that are extremely susceptible or not to flooding; the class of low vulnerability is the population with one of the best social indicators, which largely occupy areas of medium to very high susceptibility; that of medium vulnerability is spread across the central portion of the ÚHP, where the land can be of medium to very high susceptibility; the classes of high and very high vulnerability have the worst social indicators and are found mainly in areas of high to very high susceptibility, with the exception of the slums that occupy the hillside areas. When assessing by neighborhood, he concluded that the neighborhood of Freguesia, Pechincha, Jacarepaguá and Taquara have the best levels of environmental vulnerability. The Cidade de Deus, Gardênia Azul, Tanque, Praça Seca, Realengo and Sulacap neighborhoods had the worst vulnerability rates.