Rivers draining the Southern Gran Chaco

Abstract

The Grán Chaco is a semiarid and hot area roughly between East Andes and the Paraguay river and from Bolivia to Argentina. The Southern Chaco is drained by four major rivers. The Pilcomayo and Bermejo rivers run almost parallel from their headwaters in the Andes (3700–4600 m a.s.l.) and after about 1300 km, reach their mouths in the Paraguay River. The Salado flows from the Cordillera Oriental (∼5400 m a.s.l.) and after ∼2200 km, reaches the Paraná River. The endorheic Salí-Dulce originates at ∼2000 m a.s.l. mainly in the Pampean hills (adjacent to the Andes) and flows into the “Mar Chiquita” (14,000 km3). The combined basin of these rivers covers a surface approximately the size of France. The rivers cross different ecoregions, from High Andes and Puna to humid heterogeneous mountain (Yungas jungle), high valleys, and the Gran Chaco plain. They have similar and rich fauna and flora but also unique characteristics due to the different geological units they traverse. These rivers have great importance for the pre-Columbian cultures that persist to the present, as they are the main watercourses in this economically important region shared by three different countries.