The UN World Water Assessment Programme - Dialogue Paper - Confronting the Challenges of Climate Variability and Change through an Integrated Strategy for the Sustainable Management of the La Plata River Basin

The La Plata River Basin is one of the largest river basins in the world and drains approximately one-fifth of the South American continent, including the southern part of Brazil, the south-eastern part of Bolivia, a large part of Uruguay, the whole of Paraguay, and an extensive portion of the central and northern parts of Argentina. Water and nutrients from the central regions of South America discharge through the La Plata River to the South Atlantic Ocean, creating in its maritime front one of the richest and most diverse marine ecosystems in the world. The La Plata River Basin is comprised of three large river systems: the Paraná River, the Paraguay River, and the Uruguay River. The Paraguay River has an average annual flow of 3,800 m3/s (at Pilcomayo Harbour); the Parana River has an average annual flow of 17,100 m3/s (at Corrientes); and the Uruguay River has an average annual flow of 4,500 m3/s. These last two rivers converge to form the La Plata River, which drains into the Atlantic Ocean, with an average output of 25,000 m3/s. A large wetland corridor links the Pantanal (in the headwaters of the Paraguay River) with the Delta del Parana, at its outlet to the La Plata River. This system of interconnected wetlands is essential to the existence of extensive area of biological diversity and productivity. Important groundwater systems include the Guaraní Aquifer System, one of the largest aquifers in the world comprised of confined deep groundwater bodies and the Yrenda-Toba-Tarijeño Aquifer System (SAYTT), entirely contained within the La Plata Basin in the semi-arid Chaco of Argentina, Bolivia and Paraguay. Climate change scenarios show an increasing process of desertification within this region, which, when combined with high poverty index values and the presence of indigenous communities, make the SAYTT a top priority for integrated surface-groundwater management.

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