I wonder what the breakdown in sources for the disparity is. I can think of three potential differences, that are all likely contributors: - Rainfall levels i

I wonder what the breakdown in sources for the disparity is. I can think of three potential differences, that are all likely contributors: - Rainfall levels in the drainage area - Evaporation over the course of the river - Diversion for human use I have to think the third is a substantial factor with the Nile vs the Amazon, considering that the Nile is essentially the only water source for two high-population countries (agriculture in Brazil is ostensibly supported by rainfall as well as by the river).