Ocupação dos solos em terrenos marginais às lagoas costeiras: mudanças e perspectivas ambientais frente à expansão urbana - o caso da lagoa de Jacarepaguá (Rio de Janeiro)

Abstract

The aim of this paper is to analyse the lagoon of Jacarepaguá and the occupation of its outskirts throughout the multi-temporal, contributing for a better understanding of the current environmental conditions of the lowland of Jacarepaguá. The adopted methodology seeked to identify the physical changes of the environment from 1980 s on, through the elaboration, comparison and analysis of occupation maps and the usage of soils related to the years of 1984, 1992, 2001 and 2010, and the identification of the water quality of the Lagoon of Jacarepagua, of its depth conditions, the size of the water mirror and its relation to the local community. This way, it was possible to portray ways of integration between the natural and social processes in a given time-space, as well as to establish future tendencies of this environment. The results show that from time to time there is a refunctionalization of the space, which reflects not only in the conformation of the marginal swampy terrains, but also in the physical conditions of the Lagoon of Jacarepagua itself. The lagoon s water mirror has been confined by the means of occupation in the river basins and its marginal terrains (waterproofing, landfills and drainage work) creating a relative stability in its sandy dimension and also in its water volume. The lagoon presents some historical data of pollution through domestic sewer which has accelerated its natural conditions of silting up and compromised the quality of its waters. And even though there are some projects and sanitation works for the place, it is verified that there has been a pollution increase of the lagoon, mainly, in its western portion, as has shown the results of the accomplished analyses with the BOD (Biochemical Oxygen Demand) available data, phosphorus, nitrogen, DO (Dissolved Oxygen) and salinity. This can be explained by the current tendency of the urban expansion due to this direction. It is verified, despite the fact that, for a while, the types of terrain have conditioned its ways of occupation. Nowadays the process has inverted, being the inductorial occupation and reconditioning of the environment structuration. It is presented and characterized several forms and respective types of soil usage in the area. Thus, the environmental condition of the Lagoon of Jacarepagua and its future perspectives depends on, nowadays, more in the way in which the society want and intend to incorporate to its environment, than to the natural dynamic of the physical system to which it is belonged.