This paper contains an analysis of the mechanisms through which the authoritarian planning contributed to the worsening of social and environmental disarray in the Amazonian Region of Brazil. Recomposing the process of compulsory displacement and relocation of the populations, triggered when the reservoir of the Hidroelectric Plant of Tucuruí, in the State of Pará, was being filled, the author could observe that: a) the absence of a policy established through negotiations with legitimate social spokesmen has been a factor which only contributed to intensify the opposition of local populations towards the whole undertaking; b) casuistic solutions have proved to be incapable of responding to the social and juridical complexity of the physical space comprised by the program of relocation; c) the vagueness involving the limits of the area to be flooded has enlarged and diversified conflicts associated with the program of relocation; d) the lack of an attuning between the executive chronology fixed for the construction of the dam and the one foreseeing the filling up of the reservoir has given place to a socially damaging incompatibility between the indemnities and an effective relocation. By turning the populations affected by the changes into groups political1y disqualified and culturally deprived of their character, the authoritarian planning, when applied to hydroelectric projects, produces on local societies true "mercantile shocks", brought about by the lack of information and by uncertainty.Reconstituição do processo de relocação compulsória de populações por ocasião do enchimento do reservatório da Usina Hidrelétrica de Tucuruí. Planejamento autoritário aplicado aos empreendimentos hidrelétricos responsável pela desqualificação política e descaracterização cultural das populações atingidas. “Choques mercantis" regulados por desinformação e incerteza.