Paraná

Abstract

The Paraná River Basin has an area of 2.6 million km2. The river has a mean annual discharge of 19,700 m3/s, the third largest in South America after the Amazonas and the Orinoco. It contains huge areas of wetlands (e.g., the Pantanal) and large floodplains along its entire course. The main river runs for 3965 km from the headwaters of the Rio Grande in the humid highlands of the Serra do Mar and Serra da Mantiqueira, crossing several ecoregions like the Atlantic Forest, Cerrado, Chacoan forests, Pampean plains, and the Paraná flooded savanna, finally flowing into one of the largest estuaries in the world: the Río de la Plata. In this chapter, we describe the geology, hydrology, biodiversity, and environmental problems of seven rivers of this large basin: Upper Paraná, Middle and Lower Paraná, Paranaíba, Grande, Tietê, Paranapanema, and Iguaçu rivers; the Paraguay and the Andean tributaries are discussed in other chapters. Since the 1970s the upper basin has experienced a vertiginous hydropower development with almost 800 dams constructed until today, which generate strong environmental impacts. The lower basin is still unregulated and with the Paraguay River it forms a 3500-km free-flowing riverine axis with intact floodplains that is still the habitat of many migratory fish species that sustain highly productive fisheries.