Dispersão urbana e apropriação do relevo na bacia do Ribeirão do Jerivá, Boituva - São Paulo

Abstract

The recognition of the landscape’s geomorphologic aspects may fundament a proposal of urban occupation that considers the hydrological dynamics of a given area, favors the maintenance of the infiltration and reduction of the superficial leakage, reducing erosive processes, floods, minimizing the environmental problems. This master is part of the research “Environmental planning and prioritization of conservation areas in Boituva/SP – Brasil” (FEHIDRO 10452). It it aims at evaluate the impacts of the urbanization process of Brazilian cities discussing, for such, the compatibility between the kinds of urban ocupations and the process of relief appropriation. The study was developed on the hidrographic basin of Ribeirão do Jerivá, at Boituva, city with 60k habitants and, despite the recente urban expansion, still shows conditions of actual planning and reduction of urbanization impacts. Methodologically, the study was Urban Geomorphology, Urban dispersion and Hidrographic Basin Management oriented. In order to understand such dinamics that holds occupation of the geomorphological compartiments, thematic maps were created, such as the relief units, declivities, sliding risk, mass movement and inundation, APP (Permanent Protection Areas) and Forest Fragments, Soil Usage and Hipsometric maps. Topographic profiles were elaborated for some key areas, with different stages of urbanization, aiming at a more specific analysis. Fieldworks were also made. As results, it was shown that Ribeirão do Jerivá basin, with 45,34 km², has an importante área of its spring occupied with urbanized areas or farming activities. Three relief units were identified at the basin, one with strong dissection of spring and river courses, at the high basin sector; a second unit with top interfluvuim more plain to softly convexizated, and the third unit of the fluvial plains, wider at the lower basin. The conclusions show that the processo of relief appropriation for urbanization alters in ways very often irreversible the energy entrance and exit systems of the hidrographic basins, changing the disposition of matters and its carriage along the rain waters, besides unbalancing the natural pedogenic processes.