https://www.researchgate.net/profile/Alain-Chambrier/publication/273678149/figure/fig2/AS:614126632046596@1523430607036/Map-of-South-America-with-two-principal-

https://www.researchgate.net/profile/Alain-Chambrier/publication/273678149/figure/fig2/AS:614126632046596@1523430607036/Map-of-South-America-with-two-principal-river-basins-Amazon-and-Parana-Rivers.png https://www.researchgate.net/profile/Alain-Chambrier/publica... It seems plausible that Amazon rainforest will affect the North tributaries. And the Parana state with its deforestation is about midway of the river.