That may seem like a good thing, but it could also grow more variable, by 50%.
In other words, there would be more (and worse) floods and droughts.
There is, of course, uncertainty in the projections, not least because differing global climate models give different numbers.
But the idea that the flow of the Nile is likely to become more variable is lent credibility, the authors argue, by the fact that trends over decades seem to agree with them, and by consideration of the effects of El Ninos.
These colossal climatic oscillations, driven by changes in the temperature of the Pacific, are correlated with the Nile's flow, and climate-change studies suggesting more extreme El Ni?os in years to come thus bolster the idea of a more variable Nile.
More storage capacity will be needed to smooth out the Nile's flow.
But unlike Egypt's large Aswan Dam, which was built with storage in mind, the new Ethiopian one is designed for electricity production.
Once water starts gushing through its turbines, it is expected to produce over 6,000 megawatts of power.
It is unclear, though, if the structure has the necessary flexibility to meet downstream demands in periods of prolonged drought.
The talks between the three countries seem to be glossing over the potential effects of climate change.
The filling of the reservoir is being negotiated in terms of years, but nature may not co-operate with their timeline.
The countries would be better off focusing on how much water is needed downstream, which will vary in wet and dry years, say experts.
Similar considerations will need be taken into account when running the dam.
“Nowhere in the world are two such large dams on the same river operated without close co-ordination,” says another study from MIT.
But so far co-operation is in short supply.
The latest round of talks has been postponed.
Even the methodology of impact studies is cause for wrangling.
Once the dam is up and running, the Nile's variability will be controllable for some 60 years, say Messrs Siam and Eltahir.
That assumes the dam is flexible enough and that the countries work together.
Even then, storage would have to be increased by about 45% to keep things steady for the next 60 years.
So the countries have time to build new dams; but that will need even greater co-operation.