URUGUAY RIVER: HISTORY, CHARACTERISTICS, TRIBUTARIES, FLORA, FAUNA - GEOGRAPHY - 2025

The Uruguay River is located in the central region of South America. It is part of the Plata Basin, the second largest in the continent only behind the Amazon Basin. Due to its route it is recognized as an international river, since in its course it crosses the territory of three countries: Brazil, Argentina and Uruguay, even serving as a geographical landmark to demarcate territorial borders.

It is constituted as a waterway for the transport of merchandise and travelers from the region, especially in its lower section (between Salto and Nueva Palmira), due to the fact that the construction of reservoirs such as that of the Salto Grande dam interrupt the movement of vessels.

The Uruguay River runs through various types of relief and geographical features that modify its behavior. Photo: Luis Esnal on Flickr.

Due to its beauty and the diversity of the biome, the Uruguay basin is considered a jewel for tourism in the region. Its flow bathes the territory of parks and natural monuments that invite exploration and enjoyment.

Birth

Uruguay River in La Plata basin. Kmusser

It is born from the meeting of the Pelotas and Canoas rivers at a height of 2,050 meters above sea level, in the Sierra del Mar between the states of Rio Grande do Sul and Santa Catarina, on the Brazilian plateau.

Since its origin and in its journey through the territory of Brazil, Uruguay passes through the Atlantic forest, a biome declared in 1992 by Unesco a biosphere reserve due to the diversity of fauna and flora that it shelters.

Its discovery appears documented (being confused with the San Cristóbal River) on a world map that shows the results of the exploration of the Spanish kingdom around 1525.

It is accepted that its name comes from the Guaraní, however there is disagreement regarding its meaning. The most accepted hypotheses relate it to elements of the fauna, two examples of this are: agua del urú (a bird present in the region) and river of the snails.

Route and mouth

Course and basin of the Uruguay river. Kmusser

It flows from north to south describing a curve in its course. It bathes an area of ​​370,000 km² in a 1,800 km route through Brazil, Argentina and Uruguay.

It empties into the Río de la Plata, right on the border of Argentina and Uruguay in a place known as Punta Gorda. It is divided into three sections for study: upper, middle and lower.

Upper Uruguay River

It ranges from its source in Sierra del Mar to the mouth of the Piratiní River. This section is entirely in the territory of Brazil and is 816 km long. The presence of hydrological dams in this section prevents its continuous navigation although there is river traffic of smaller boats.

Middle Uruguay River

It goes from the mouth of the Piratiní River (Brazil) to the town of Salto (Uruguay) with an extension of 606 km. The lake formed by the Salto Grande dam is one of the main tourist attractions that develop around the river in this section.

Lower Uruguay River

This section goes from Salto (Uruguay) to Punta Gorda (Argentina / Uruguay), with an extension of 348 km. It is the route with the greatest fluvial development thanks to the interconnectivity represented by the ports and access to the sea.

History

Uruguay is a river rich in beauty, biological diversity and history. Since its discovery in January 1520 by the maritime expedition of Fernando Magellan, it has been a participant in the socio-political development of the region.

Thus, on March 11, 1641, the waters of the Uruguay River were the scene of the first naval battle in South America. Flag bearers sent from Sao Paulo in the service of the Portuguese colonizers and Jesuit monks who sought to protect the indigenous population from slavery faced it.

Around 1810, José Artigas, Uruguayan hero of the independence of Latin America, took advantage of the strategic position of Artigas Island to defend his center of operations.

In response to the advances of the independence forces, the royalists occupied Martín García Island in May 1810 and turned it into a place of seclusion for soldiers who refused to follow orders. The history of this island is full of conflicts and invasions. Finally in 1852 it was returned to the Argentine Confederation.

In 2002, the most recent conflict involving the Uruguay River began, confronting the governments of Uruguay and Argentina. The friction occurs with the installation of two cellulose pulp plants by the Uruguayan government.

Due to citizen pressure and environmental groups, the Argentine government asks for explanations and rejects the project due to the environmental impact it generates in the region. The conflict has moved to the international stage with litigation in The Hague and Mercosur that are still in process.

characteristics

The international river Uruguay has a flow of 5,500 m3 / s (cubic meters per second). In the upper section it reaches 12 kilometers per hour, descending to 2 kilometers per hour in the lower section.

River islands

In the course from its source to its mouth, Uruguay has more than 100 islands that add up to an approximate area of ​​20,000 hectares. Most of them owe their formation to the accumulation of sediments carried by the current. To a lesser extent they are due to the breakdown of the continental terrain.

Brazil, Argentina and Uruguay distribute the jurisdiction of the territories of the islands with international treaties. However, there are disputes for the control of some territories, this is the case of the Brazilian Island and Rincón de Artigas, in dispute between Brazil and Uruguay since 1940.

Another case of dispute weighs on the Martín García and Timoteo Domínguez islands, this time between the governments of Uruguay and Argentina. The islands were united due to sedimentation, making necessary the demarcation of the first land border between both countries.

Growing

The Uruguay River has two growing periods of irregular regime, the first occurs in January and then again in August. This happens thanks to the 2,000 mm per year of rain that it receives throughout its basin.

During these seasons, the authorities are alert to the behavior of the flow to make early forecasts for the benefit of the population.

Diversity of behaviors

On its way it passes through various types of relief and geographical features that modify its behavior. Rapids and jumps abound in the upper section. In the middle section, the presence of waterfalls alternates with the reservoir of the dam, which modified the natural behavior of the flow as an effect of its construction.

In the lower section the channel widens due to the coastal nature of the area, losing up to 80% of its speed.

Hydroelectric engine of the region

A total of four dams are installed on the flow of the Uruguay River that take advantage of the potential of the water to produce electricity, destined to supply the needs of the population. There are also various proposals to install new plants in other areas.

The use of the hydroelectric potential of the Uruguay flow has led to the development of the region and has dramatically changed the landscape. An example of this is the heartfelt disappearance of the Salto Grande waterfall (Uruguay) due to the filling, in 1979, of the lake with the homonymous dam.

Environmental alerts

The development of human activity on the banks of the river has had a profound impact on the biodiversity of the region.

The economic activities that take place along the riverbed have endangered the lives of animals that disappear from their natural habitat. The activities with the greatest impact are agricultural exploitation, logging, the development of dams and roads. Hunting and species smuggling are added to these regulated activities.

Being a significant percentage of endogenous native species, the destruction of their habitat places them at risk of extinction. Only in its upper section are around its channel 383 of the 633 species considered in danger of extinction in the territory of Brazil.

In June 2019, within the framework of the visit of Brazilian President Jair Bolsonaro to Argentina, the construction of a hydroelectric complex with two dams (Garabí and Panambí) on the waters of the Uruguay River was a topic on the negotiating agenda.

A group of Brazilian environmentalists stopped the project of the Panambí dam with an amparo appeal for the Turvo National Park and the Moconá Falls. For its part, the construction of the Garabí dam has generated rejection among some of the citizens of the communities near the project due to its impact on the ecosystem, biodiversity and cultural heritage of the region.

Main tributaries

From its source in Sierra del Mar to its mouth in the Río de la Plata, Uruguay is fed by more than twenty tributaries that deserve the classification of rivers.

Among these are, in addition to the Pelotas and the Canoas, the Peixe, Chapecó, Pepirí Guazú, Passo Fundo, Várzea, Ijuí, Piratiní, Icamaquã, Ibicuí, Aguapey, Miriñay, Mocoretá, Gualeguaychú, Cuareim, Arapey, Daymán, Queguay, rivers, Negro and San Salvador.

Through the Uruguay River, economic activities of various kinds are developed, national and international, among them the transport of passengers and goods.

Flora

The flora that surrounds the Uruguay River is very diverse because its basin runs through three ecological regions: Paraná jungles and fields, Mesopotamian savannas and humid pampas grasslands.

200 native trees and more than 2,000 vascular plant species have been identified, many of which are endemic.

In the jungle areas the presence of Paraná pines predominates, also known as Missionary pine or Brazil pine. In addition to laurel, cedars, bamboos, palm hearts and ferns. In these areas the vegetation is closed with trees that reach 40 meters in height crowned with lianas and intricate herbaceous.

In the savannah, xerophilous species, shrubs, grasses and palm trees dominate, distributed in forests and marginal jungles. The most distinctive tree in the ñandubay. In areas that are flooded proliferate: reeds, straw and reed. Woody species such as carob and ñandubay as well as grasses abound in the pasture.

Fauna

As it passes through the Atlantic forest and other rich biomes, different stretches of the river are home to an enormous diversity of mammals, birds and fish, as well as reptiles, amphibians and insects.

Mammals

More than 264 species of mammals have been identified in the area, such as the matero deer, the jaguarundí or Moorish cat and the ounce. It highlights the presence of endemic mammals such as the three-toed sloth and the nagging short-tailed opossum.

In addition, 26 primates live in the region, including endemic species: the golden lion tamarin, the black-faced lion tamarin and the woolly spider monkeys.

Birds

436 species of birds have been described, including the red-tailed amazon, the alagoas paujil, the blue-breasted parakeet, the woodpecker, the yacutinga and the harpies.

In the province of Misiones (Argentina) social projects are developed for the observation of bird species in the region. With this they seek to promote the protection of wild areas and their fauna.

Fishes

Specialists have described more than 350 species of fish that inhabit the Uruguay River, among them the curimbatá, the boga, the armed catfish, the blind catfish, the paiva, the dorado and the patí.

Recreational fishing is a popular activity in the waters of the Uruguay River. The diversity and beauty of its landscape, together with the clarity of its waters, make it a very attractive tourism activity.

Reptiles, amphibians and insects

The richness of this ecosystem is manifested at all levels. Among the reptiles present in the area, the alligator overo and the Brazilian snake neck turtle stand out.

Likewise, there is a whole family of frogs that are only found in the region and more than 1,000 species of butterflies have been registered in different areas.

References

1. “They set the first land border with Uruguay”, article in the newspaper El Litoral de Argentina, published online on April 27, 2019, ellitoral.com/index.php/diarios/2019/04/27/politica/POLI-05. html.
2. "Compilation and analysis of issues related to transportation infrastructure and cargo movement between the countries of the La Plata Basin", report of the X Meeting of Foreign Ministers of the La Plata Basin Countries in 1978, taken from oas. org / usde / publications / Unit / oea18s / ch05.htm # TopOfPage.
3. Uruguay River basin in Argentina, report of the Ministry of the Interior Government of Argentina, November 2005, taken from mininterior.gov.ar/obras-publicas/pdf/39_nueva.pdf.
4. Brief review on the Uruguay River, article in the annual publication of the Technological Laboratory of Uruguay, taken from ojs.latu.org.uy.
5. The lower Uruguay river: two nations, one territory ?, Article of the open access portal to knowledge of the Polytechnic University of Catalonia, taken from upcommons.upc.edu