Avaliação de impactos ambientais de projetos de grandes barragens: um estudo de caso

Abstract

The objective of this study was to know the environmental feasiability of the public project of the "Açude do Castanhão", through the analysis of the principal environmental impacts and socio-economics with results of its implementation and operation, The evaluation of the environmental impacts was conducted according to the method of ponderal evaluation of the environmental impacts developed by BIANCHI et alli, which resulted of the evolution of the matrix method by LEOPOLD. The technique used involves the attribuition of wights to the symbols of foreseen impacts, where the adoption with and without the measures of environmental protection recommended. The data used in this paper are from SIRAC - Serviços Integrados de Assessoria e Consultoria Ltda, which in that time of the elaboration of the Report of the Environmental Impact (REM) of the public dam "Castanhão" project developed a complete bibliographic information about the area of the project, and complemented with the realization of the field research, Before the evaluation of the environmental impact it o was realized one analysis of the project and one environmental diagnostic showing the characteristics of bio-geo-phisics and socio-economics of their physical and functional influence areas. Some tests were made in order to identify the possible impacts that will be generated during the implementation and the operation of the reservoir. Such impacts were distinguished and listed Jin the systematic way second it beneficial, adverse, or indefinite character in the level of the 'iabiotic, ibiotic íHieand antropic of the physical and functional influence areas of the undertakinge. After the identification of the waited impacts, they were recommended measures looking for a mitigation or absortion of the negative impacts and the advantage of the possibilities that will emerge with the implementation of the project. Such measures were presented in the form of plans, which in the future must be developed by specific projects level, The measurement of the impacts were made through the attribuition of the values by part of a multi-disciplinary team. Thus counted with the help of the specialists in environmental that have links with SIRAC, universities and local government offices. The global analysis of the undertaking, represented by the function of the results got in the physical and functional influence areas, demonstrated that, in its original version, the project represents an amount of ponderated benefits inferior to | the collection of the adversities and the indefinitions included, that characterizes like indefinite or poorly understood. The incorporation of the measures of environmental protection (MEP's), however, gets to revert this picture, conducting the characterization of the project to the area of the beneficial undertakinge As to setorial analysis, the evaluation of the set of physical influence area of the Pprogect showed that the inplementation and operation will be with injury either to the natural environment or to the antropic way , which is characteristic of the type of undertaking in some part. The application of the MEP's turns the project favorable to the natural environment, although does not make to the antropic way, due to the involution of the environmental questions. The evaluation of the functional influence area showed that the constrution and operation of the reservoir results in adversity to the natural ecosystem, being the situation reverted with the adoption of the MEP's. Even though to the antropic way, the results showed strongly favorables although without the MEP!'s, increasing with the adoption of such measures. In sum, the undertaking implementation and operation only can be adversable of the environment point of view with the incorporation of the MEP's., With the adoption of suck measures, however the project becomes enough advisable, with heavy benefict character to the antropic way, and one level of adversity tolerable very well in means to natural ecosystem.