<br><br>Parnaiba (port. Parnaíba) – the largest river in the north-east of Brazil. It flows from south to north along the border between the states of Piaui and Maranhao. The length is about 1400 km, and the basin area is 344 112 km².<br>Flow<br>It originates on the Brazilian Highlands, on the slopes of the Chapada das Mangabeiras mountains. In the upper and middle reaches, it has a rapids, in the lower, it crosses the hollow of the same name, where it becomes suitable for navigation (from the town of Terezina). At the mouth of the Parnaiba, it forms a vast delta, the territory of which in 1996 became a landscape.<br><br>Like most other basins in the region, influenced by the Kaatinga, this biome is characterized by low rainfall and high evaporation rates. Low-water period from June to October, large floods occur in January and February. Parnaiba has 143 tributaries from the state of Piaui and 74 tributaries from the state of .<br><br>North of the city of Guadalupi, the river is dammed by a hydroelectric power plant that supplies the state of Piauí with electricity.<br><br>In addition to the river delta, there is another nature conservation area in the basin – the Serra das Confucions National Park.<br>Flora and fauna<br>The Parnaiba river basin occupies 3.6% of the territory of Brazil and in some places is still poorly understood. A recent study of the ichthyofauna of the river found that about 140 species of fish are found in it, 40% of them are endemic, and some of them were met by for the first time. One of these types – Potamotrygon signata… Approximately 70% of fish are characiniform and catfish.<br><br>Two species of turtles are also endemic to the region – one of the varieties of freshwater turtles Trachemys adiutrix and the piauya side-necked turtle Mesoclemmys perplexa, opened quite recently, in 2005.<br><br>The river delta is a key bird area, with 119 bird species that settle and nest in mangroves; in particular, the red ibis lives here.<br>