The Upper Paraguay Basin
The Paraguay-Paraná System, also known as the Sub-Andean Depression, surrounds the Pantanal and includes the wetlands of the middle and lower Paraguay River, the alluvial valley of the middle, and lower Paraná River to the mouth of the La Plata River. This region forms one of the longest wetland corridors on the planet integrating areas in Argentina, Brazil, Bolivia, Paraguay, and Uruguay. The Upper Paraguay Basin (UPB) brings together the Paraguay-Paraná system and encompasses Brazil, Bolivia, and Paraguay.
With approximately 600,000 km², the Upper Paraguay Basin can be divided into an upper region, called the Plateau (217,000 km²), where the springs of the rivers that form this immense hydrographic basin can be found and a lower, flat region, called the Pantanal (160,000 km²), that is temporarily and partially flooded by the Paraguay River and its main affluents every year. This region is cross-border and covers areas in Bolivia, Brazil, and Paraguay.
The springs of the main rivers of the UPB are in the Cerrado, in Chapada dos Parecis, in Mato Grosso. These plateau areas, which can reach up to 1,400 meters high, are fundamental for the existence of biodiversity and balance of the plain, since the relationship between the springs in the highlands (plateau) and the rivers in the depression areas (plain) is responsible for the ecological and cultural characteristics of the entire region, creating a flood pulse that dictates the rhythm of life in the Basin.
The so-called Spring Arch surrounds the water divisors of the Basin and is present in an extensive area that goes from Rondonópolis (MT) to Chapada dos Guimarães (MT), Diamantino (MT), and Cárceres (MT), in Brazil. This region where there are the springs of the rivers Paraguay, Sepotuba, Cabaçal, Jauru, Cuiabá, São Lourenço, Manso, Rio dos Bugres, Coxim, and Taquari is responsible for supplying 70% of the water that flows into the Pantanal.
The relief conditions and the nature of the soil provide a natural fragility that is one of the greatest threats to the integrity of the UPB. Another great treat is the removal of the original vegetation cover in a generalized manner, including riparian forests and spring vegetation, due to the expansion of human activities since the 1970s, with agriculture and livestock.
As it is one of the most biodiverse places on the planet, the Constitution of 1988 declared Pantanal a National Heritage, and Sítio Ramsar, in 1993. Unesco declared Pantanal a Natural Heritage of Humanity and Biosphere Reserve in 2000.