Avaliação da vulnerabilidade natural à contaminação dos recursos hídricos subterrâneos na região cultural da Quarta Colônia de Imigração Italiana, RS

Abstract

The research developed search to contribute with the conservation of the groundwater hydrics resources, tends as objectives to accomplish a register of the wells of the Quarta Colônia de Imigração Italiana, Rio Grande do Sul, in the Central Area of the state, with area of 1.402 km², proceeding like this to the study of the natural vulnerability, to cartography represent the obtained information, besides relating the potential sources of contamination. The obtaining of the data felt through the consultation to the Sistema de Informações de Águas Subterrâneas (SIAGAS) and through field work. A database was elaborated with information regarding to 136 wells, of which 72 possessed the data for application of the Method "GOD" proposed by Foster and Hirata (1993) and Foster et al. (2003) for the study of the index of aquifer pollution vulnerability to the contamination of the groundwater hydric resources. The natural vulnerability and the parameters static level and potentiometric surface were cartography represented through the software Surfer 8.0. It was verified that in the area in analysis the 72 wells that possessed data on the static level possess depths of 0 more than 50 m the, divided in 4 strips in agreement with the Method "GOD", and in the strips of smaller depth the groundwater hydric resources are closer to the surface, and, for that, more vulnerable to the contamination. The main sense of the flow of the potentiometric surface of the 64 wells that possessed that registered information is towards the gutters of the Rivers Jacuí and Soturno, indicating a possible contribution of the groundwater hydric resources for the pereniall of the courses of water. Regarding the vulnerability, most of the wells are located in the negligible and low classes. In the class it exalts there are 6 wells, and in the proximities of the same ones a careful planning should be had, to avoid the installation of potential activities to the contamination. In what refers to the activities potentially pollutants investigated, it is had that the agricultural activities can come to contaminate the groundwater hydric resources in areas where the geology is formed by the Depósitos Aluvionares Atuais. The positions of distribution of fuels can alter the characteristics of the groundwater, through the drainage of the coming residues of the wash of vehicles for the sewerage system, that, for time, it contaminates the courses of water from where the pollutants can infiltrate, being excepted of that condition the municipal districts of Pinhal Grande and Silveira Martins, where the sewer receives another final destination. The cemeteries, in majority present holes cemented that don't constitute danger of contamination, saved some cases of older holes, where the burials happened directly in the soil. In the municipal districts of Ivorá and Nova Palma has probability of happening necrochorume infiltration if it happens burial directly in the soil, due to the geology. In this direction, is indispensable the adoption in new protection ways and conservation of the natural resources, and the developed research can serve as subsidy, seeking the maintainable use of the groundwater hydric resources.