The environmental impacts of the tucuri dam on the middle and lower tocantins river basin, Brazil

Abstract

AbstractAn attempt is made to appraise the present and likely future environmental impacts of the Tucuruí Dam upon the mid and lower Araguaia‐Tocantins Basin (Brazilian Amazonia). Information has been obtained by literature review and from field visits made by the author in 1981, 1983, and 1985. The problems of impoundment‐related environmental impact assessment in tropical developing countries are also discussed.Tucuruí is the world's fourth largest hydroelectric project and is the first large dam to be completed in an Amazonian rainforest environment. It is also the first of a number of large dams which Brazil plans to construct in the Araguaia‐Tocantins Basin and on other tributaries of the Amazon. The appraisal of problems associated with Tucuruí Dam should help planners minimize difficulties with future Amazonian hydroprojects.Like many developing country environmental impact assessments, that carried out at Tucuruí was begun after the construction site had been selected and construction had begun. Tucuruí impact studies have tended to concentrate on the environmental and socioeconomic impacts generated in the vicinity of the dam and reservoir; downstream impacts have received less attention but are already apparent. Major impacts identified include reservoir siltation, disruption of fisheries and agriculture (especially floodland cultivation) downstream, and human disease problems.