Guairá Falls were a series of immense waterfalls on the Paraná River along the border between Paraguay and Brazil. The falls ceased to exist in 1982 when they were inundated by the impoundment of the Itaipu Dam reservoir. While published figures vary, ranging from 13,000 m³ per second to 50,000 m³ per second, Guaíra's flow rate was among the greatest …Guairá Falls were a series of immense waterfalls on the Paraná River along the border between Paraguay and Brazil. The falls ceased to exist in 1982 when they were inundated by the impoundment of the Itaipu Dam reservoir. While published figures vary, ranging from 13,000 m³ per second to 50,000 m³ per second, Guaíra's flow rate was among the greatest of any then-existing falls on Earth.