It's come up a few times because all are interesting projects, but for a long while, there's been ideas and proposals to make lakes in North Africa for the sake of hydropower, chemicals, and salt. The Sahara Sea is probably the most famous, in that at the fullest extent it would cut a deep bay/canal into North Africa from Tunisia to eastern Algeria a bit south of the mountains. The Qattara Sea is also noted, because by flooding the Qattara Sea from the Mediterranean, you'd make a lake you could mine for chemicals as well as make a ton of hydropower. There are also smaller dry lake beds in Libya, fairly close to the sea unlike those in Tunisia, that can be flooded for similar purposes.
So let's say all these get constructed. I'm not so much worried about the economic effect as I am about the climate effects of putting these salt lakes in the desert. Some say the increased evaporation would create a slight increase in moisture for North Africa. I've heard it wouldn't be as much as is commonly touted, but if makes a few wadis anywhere in North Africa become permanent rivers, then their job is done. I've heard it would also reduce evaporation in Egypt, allowing Egypt to have more water through indirect effects. There's also a potential cooling effect they might have on the climate. Am I correct in all this? How much might agriculture in North Africa benefit from these lakes, even if you can't irrigate crops with them?
Finally, since some of these lakes would be huge, what might their effect on climate outside of North Africa be? And could these lakes have any noticable impact on global climate change?