Parnaíba

Parnaíba (pərnīē`bə), river c.800 mi (1,290 km) long, rising in the highlands of NE Brazil. It flows generally north, forming the boundary between Maranhão and Piauí states, and enters the Atlantic Ocean through a delta near the town of Parnaíba, which is the shipping center for the valley; Teresina is the chief upstream city. Much of the river is navigable, although it is filled with rapids.

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Parnaíba 

a river in northeastern Brazil. It is about 1,450 km or, according to other sources, 1,700 km long. It drains an area of about 350,000 sq km. It rises in the Brazilian Highlands, on the slopes of the Serra de Tabatinga. There are rapids in the upper and middle course. The lower course crosses the Parnaíba depression, where the river becomes navigable at the city of Teresina. The river regularly floods. The average annual flow of water is about 2,400 cu m per sec. The Boa Esperança hydroengineering complex (a complex consisting of power plants, reservoirs, canals, and the like) has been under construction since 1964. In 1970 the first phase of a hydroelectric power station with a 164-megawatt capacity was completed. The cities of Floriano, Teresina, and Parnaíba are situated on the Parnaíba.