The Pilcomayo River is a river in central South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. At 1100 kilometres (683.5 mi) long, it is the longest western tributary of the Paraguay River

Paraguay River

The Paraguay River is a major river in south central South America, running through Brazil, Bolivia, Paraguay, and Argentina...

. Its drainage basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 is 270000 square kilometres (104,247.6 sq mi) in area, and its mean discharge

Discharge (hydrology)

In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...

 is 200 m3/s.

Along its course the Pilcomayo silts up and splits into two main branches, North and South. After some distance these branches rejoin to form the Lower Pilcomayo.

The Pilcomayo rises in the foothills of the Andes

Andes

The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 cordillera

Cordillera

A cordillera is an extensive chain of mountains or mountain ranges, that runs along a coastline . It comes from the Spanish word cordilla, which is a diminutive of cuerda, or "cord"...

, between the Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

n departments of Potosí

Potosí Department

Potosí Department is a department in southwestern Bolivia. It comprises 118,218 km² with 709,013 inhabitants . The capital is the city of Potosí....

 and Oruro

Oruro Department

Oruro is a department in Bolivia, with an area of 53,588 km². Its capital is the city of Oruro. At the time of census 2001 it had a population of 391,870.- Provinces of Oruro :...

, east of Poopó Lake. From there it flows in a southeasterly direction through Chuquisaca

Chuquisaca Department

Chuquisaca is a department of Bolivia located in the center south. It borders on the departments of Cochabamba, Tarija, Potosí, and Santa Cruz. The departmental capital is Sucre, which is also the constitutional capital of Bolivia.-Geography:...

 and Tarija

Tarija Department

Tarija is a department in Bolivia. It is located in south-eastern Bolivia bordering Argentina to the south and Paraguay to the east. According to the 2001 census, it has a population of 391,226 inhabitants. It has an area of 37.623 km²...

 departments, passes through the Argentine

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 province of Formosa

Formosa Province

Formosa Province is in northeastern Argentina, part of the Gran Chaco Region. Its northeast end touches Asunción, Paraguay, and borders the provinces of Chaco and Salta to its south and west, respectively...

 and the Gran Chaco

Gran Chaco

The Gran Chaco is a sparsely populated, hot and semi-arid lowland region of the Río de la Plata basin, divided among eastern Bolivia, Paraguay, northern Argentina and a portion of the Brazilian states of Mato Grosso and Mato Grosso do Sul, where it is connected with the Pantanal region...

 plains of Paraguay

Paraguay

Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...

, forming the border between these two countries before it joins the Paraguay River near Asunción. The Río Pilcomayo National Park

Río Pilcomayo National Park

The Río Pilcomayo National Park is a national park located in the northeastern part of the Argentine province of Formosa, on the border with Paraguay...

 is located on the Argentine side of the border. It also forms a short part of the boundary between Argentina and Bolivia, just prior to the Argentina–Bolivia–Paraguay tripoint

Tripoint

A tripoint, or trijunction , is a geographical point at which the borders of three countries or subnational entities meet....

.

The river basin is home to approximately 1.5 million people: one million in Bolivia, 300,000 in Argentina, and 200,000 in Paraguay.

The Nakotoi Indian Tribe resides in the southern region of the Pilcomayo, a region located along the Río Pilcomayo in central Paraguay (Kerr, 116). The aboriginies of this tribe are descendants of the highly renowned Redskin Tribe (Kerr, 116). The Natokoi treated all neighbors as enemies, but none more so than the Tobas Tribe and the Nimká Tribe, their respective neighbors to the southwest and northeast (Kerr, 116). Guerilla warfare has long existed between the tribes, isolating the tribe from direct intercourse with the European settlers in the late 19th century (Kerr, 116). Men of this tribe are generally tall and skinny, built like hunters or warriors, whereas women are short in size (Kerr, 117). The Natokoi dress in a rug, fastened around the waist-line (Kerr, 117).

Sources

• Kerr, Graham. A Naturalist in the Gran Chaco. Cambridge: Cambridge UP, 1950.
• Pilcomayo River. (2010). In Encyclopædia Britannica. Retrieved January 18, 2010, from Encyclopædia Britannica Online: http://www.britannica.com/EBchecked/topic/460371/Pilcomayo-River
• W. H. Strosnider, F. Llanos, R.W. Nairn: LEGACY OF NEARLY 500 YEARS OF MINING IN POTOSÍ, BOLIVIA: STREAM WATER QUALITY (pdf) - conference paper at the 2008 National Meeting of the American Society of Mining and Reclamation. New Opportunities to Apply Our Science, June 14–19, Richmond, VA.