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Uruguay - Geography

Uruguay is located in the eastern part of South America between latitudes 30° and 35° South. It is in a zone of humid subtropical to temperate climate. The country is characterized ecologically and physiographically by native grasslands (savannah) and topography ranging from plains to rolling hills with elevations up to 500 meters.

It is bounded on the west by Argentina, on the north and northeast by Brazil, and on the southeast by the Atlantic Ocean. To the south, it fronts the Rio de la Plata, a broad estuary that opens out into the South Atlantic. Montevideo, the capital and major port, sits on the banks of the Rio de la Plata and is on approximately the same latitude as Capetown and Sydney. Uruguay is the smallest Spanish-speaking nation in South America with a land area of 176,220 square kilometers, slightly smaller than North Dakota.

The country is easily penetrable in every part. There are no mountain ridges or dense forests to interrupt travel, and most of the rivers are easily fordable. On the west, the broad flood of the Uruguay River gives easy communication to the ocean, while it affords protection against sudden invasions from the Argentine province of Entre Rios. The low and sandy foreshore of the Atlantic has no harbours, but after rounding Cape Santa Maria and entering the estuary of the Plate, there are several bays which afford some shelter for shipping.

The coastal area presents a succession of sandy beaches divided by rock outcrops. There are also slopes and cliffs. The storms affecting the coastal areas, when associated to SE winds, are characterized by increments in the height and frequency of the waves and by a rise in the sea level. The variability of the Uruguayan coast determines the presence of a great diversity of species and sea resources. On the coast, there are several human settlings as well as economic developments (tourism, fishing, etc.). Most of the fishing is done in the River Plate and in the Atlantic Ocean.

Most of Uruguay is a gently rolling plain that represents a transition from the almost featureless Argentine pampas to the hilly uplands of southern Brazil. The country itself has flat plains on its eastern, southern, and western edges. The narrow Atlantic coastal plain is sandy and marshy, occasionally broken by shallow lagoons. The littorals of the Rio de la Plata and the Rio Uruguay are somewhat broader and merge more gradually into the hilly interior.

The remaining three-quarters of the country is a rolling plateau marked by ranges of low hills that become more prominent in the north as they merge into the highlands of southern Brazil. Even these hilly areas are remarkably featureless, however, and elevations seldom exceed 200 meters. Uruguay is a water-rich land. Prominent bodies of water mark its limits on the east, south, and west, and even most of the boundary with Brazil follows small rivers. Lakes and lagoons are numerous, and a high water table makes digging wells easy.

Three systems of rivers drain the land: rivers flow westward to the Rio Uruguay, eastward to the Atlantic or tidal lagoons bordering the ocean, and south to the Rio de la Plata. The Rio Uruguay, which forms the border with Argentina, is flanked by low banks, and disastrous floods sometimes inundate large areas. The longest and most important of the rivers draining westward is the Rio Negro, which crosses the entire country from northeast to west before emptying into the Rio Uruguay. A dam on the Rio Negro at Paso de los Toros has created a reservoir—the Embalse del Rio Negro—that is the largest artificial lake in South America. The Rio Negro's principal tributary and the country's second most important river is the Rio Yi.

The rivers flowing east to the Atlantic are generally shallower and have more variable flow than the other rivers. Many empty into lagoons in the coastal plain. The largest coastal lagoon, Laguna Merin, forms part of the border with Brazil. A half-dozen smaller lagoons, some freshwater and some brackish, line the coast farther south.

About 85% of Uruguay’s land mass (176,000 km2) is in pasture/agriculture, the highest percentage in the world. Historically, most of the grasslands have been used for livestock grazing while some of the better soils have been used for row crop farming. Only about 3.3% of the land remains as native forest.

Uruguay’s forest industry began with the Forestry Act of 1988. In 1989, the Uruguayan government instituted financial incentives for the establishment of tree plantations in an effort to diversify the rural economy. In response, national and multinational timber corporations have purchased land and planted trees (primarily eucalyptus, loblolly pine, and slash pine) over significant portions of the landscape.

Approximately 600,000 ha of grasslands were planted to trees between 1990 and 2003. Due to the magnitude of these land use changes, local stakeholders have expressed concerns regarding the impact of converting grasslands to tree plantations on water resources. Of particular concern are the effects of the tree plantations on water yield and downstream water supply, as well as the impact on base flows in the receiving streams and rivers.