Paraná River

Course

The course is formed at the confluence of the Paranaiba and Rio Grande rivers in southern Brazil. From the confluence the river flows in a generally southwestern direction for about 619 km (385 mi) before encountering the city of Saltos del Guaira, Paraguay. This was once the location of the Guaíra Falls (Sete Quedas waterfalls, where the Paraná fell over a series of seven cascades. This natural feature was said to rival the world-famous Iguazu Falls to the south. The falls were flooded, however, by the construction of the Itaipu Dam, which began operating in 1984. For approximately the next 200 km (120 mi), the Paraná flows southward and forms a natural boundary between Paraguay and Brazil until the confluence with the Iguazu River. Further upstream from this confluence, however, the river is dammed by the Itaipu Dam, the third largest hydroelectric power plant in the world (following the Three Gorges Dam and the Baihetan Dam, both in the People's Republic of China), creating a massive, shallow reservoir behind it.

After merging with the Iguazu, the Paraná becomes the natural border between Paraguay and Argentina. Overlooking the Paraná River from Encarnación, Paraguay, across the river, is downtown Posadas, Argentina. The river continues its general southward course for about 468 km (291 mi) before making a gradual turn to the west for another 820 km (510 mi), and then encounters the Paraguay River, the largest tributary along the course of the river. Before this confluence, the river passes through a second major hydroelectric project, the Yacyretá Dam, a joint project between Paraguay and Argentina. The massive reservoir formed by the project has been the source of a number of problems for people living along the river, most notably the poorer merchants and residents in the low-lying areas of Encarnación, a major city on the southern border of Paraguay. River levels rose dramatically upon completion of the dam, flooding out large sections of the city's lower areas.

From the confluence with the Paraguay River, the Paraná again turns to the south for another approximately 820 km (510 mi) through Argentina, making a slow turn back to the east near the city of Rosario for the final stretch of less than 500 km (310 mi) before merging with the Uruguay River to form the Río de la Plata. This flows into the Atlantic Ocean. During the part of its course downstream from the city of Diamante, Entre Ríos, it splits into several arms and it forms the Paraná Delta.

Tributaries

The main tributaries from the mouth:

^*Period: 1971–2000

Uses

Together with its tributaries, the Rio Paraná forms a massive drainage basin that encompasses much of the south-central part of South America, essentially including all of Paraguay, much of southern Brazil, northern Argentina, and the south-eastern part of Bolivia. If the Uruguay River is counted as a tributary to the Paraná, this watershed extends to cover most of Uruguay as well. The volume of water flowing into the Atlantic Ocean through the Río de la Plata roughly equals the volume at the Mississippi River delta. This watershed contains a number of large cities, including São Paulo, Buenos Aires, Rosario, Asunción, Brasília, and La Plata.

The Paraná and its tributaries provide a source of income and daily sustenance for fishermen who live along its banks. Some of the species of fish (such as the surubí and the sábalo) are commercially important, and they are exploited for heavy internal consumption or for export. The Paraná River delta ranks as one of the world's greatest bird-watching destinations.

Much of the length of the Paraná is navigable, as part of the Paraná–Paraguay Waterway and the Tietê–Paraná Waterway. The river serves as an important waterway linking inland cities in Argentina and Paraguay with the ocean, providing deepwater ports in some of these cities. The construction of enormous hydroelectric dams along the river's length has blocked its use as a shipping corridor to cities further upstream, but the economic impact of those dams offsets this. The Yacyretá Dam and the Itaipu Dam on the Paraguay border have made the small, largely undeveloped nation of Paraguay the world's largest exporter of hydroelectric power.

Due to its use for oceangoing ships, measurements of the water tables extend back to 1904. The data correlates with the Sun's solar cycle.

Navigation rights

The immediate background to the 1966 dispute over navigation rights included the fact that Argentina wanted to build a bridge across the Paraná River, either near Asunción or at some point further south. Paraguay were not in favour and would do nothing to facilitate it unless the navigation issue was resolved. Argentina was also actively seeking an agreement to develop a major hydroelectric facility at the Apipé Rapids. Paraguay, meanwhile, had already implemented the Acaray Dam project, whose output was sufficient to meet Paraguay's energy requirements for the next ten to fifteen years, with a surplus available for export to Brazil and Argentina. The bilateral agreement between Argentina and Paraguay for the construction of a bridge over the river was signed in October 1964.

In late 1965, Paraguay had offered a draft treaty to Argentina. According to the US ambassador of the time, Wiliam P Snow, the Paraguayan proposal, although short on detail, would be well received by Argentina who would be pleased to see Paraguay directing its aggression mainly towards Brazil as a result.

The agreement on navigation rights, endorsing free navigation on the river and requiring that each nation treat the other's vessels as its own, was signed in January 1973. Construction began on the Itaipú Dam in 1973.

Links across the Paraná

The course of the Paraná is crossed by the following bridges, beginning upstream: