Vulnerabilidade do Aquífero Taubaté na região urbana do município de Caçapava – SP

Abstract

The process of land occupation, both in urban and rural areas, grows exponentially in the state of São Paulo, linked to recent periods of drought, and decrease in the level of reservoirs. Taubaté’s Aquifer System is composed of granular aquifers of Tertium-Quaternary sediments, of fluvial and lacustrine origin, of the Taubaté’s Basin. The vulnerability of Taubaté’s Aquifer System has generated significant concern because it is a free aquifer and is just below a large urban, industrial, and rural center, potential sources of contamination. Moreover, it is an important source of water supply throughout the Vale do Rio Paraíba do Sul Metropolitan Region as much as for some cities in the São Paulo Metropolitan Region. In this paper, the vulnerability of the Taubaté Aquifer in the municipality of CaçapavaSP - SP was studied using the GOD method, a method already used in several regions, which has been shown to be very effective, especially in places where information on aquifers is scarce, such as in developing countries. This method has three parameters to be analyzed: G - degree of hydraulic confinement, O - occurrence of the lithological substrate, and D - aquifer depth. The multiplication of these parameters results in the ultimate vulnerability of the aquifer. The database used was the one available at SIAGAS (Sistema de Informações de Águas Subterrânias (PT) - Groundwater Information System), where 95 wells were located in the municipality of Caçapava, with 23 wells used for the elaboration of the vulnerability map. A bibliographic review and environmental studies of the municipality were carried out, which allowed the association of several important information both for the application of the method and for the identification of potentially polluting activities. For the map’s elaboration, the QGis Software was used, it's an accessible and free software with several vectors and raster tools. As a result, maps, and charts of each index of the GOD method, and the vulnerability map were generated, as well as a map with the location of possible sources of contamination. The flow direction map of the Taubaté Aquifer was also prepared with the help of the Surfer Software. Accomplishing the search, it was possible to observe that, in general, the vulnerability of the aquifer in the county is low, however, two portions were identified a significant vulnerability, ranging from medium to high. The results were considered satisfactory for the purposes of this paper, several thematic maps were prepared that can be used later for consultation, both for future searches in the region and as an aid for inspection in future projects or even for municipal planning.