[3ncryptabl3_lick]

In theory there are allot of ideas that work, but practically speaking, not allot of them do.

Filling lakes in deserts with ocean water makes for hypersaline lakes that are useless for life or power and does nothing about rising sea levels, in fact it would only exacerbate that situation as you would be introducing higher water tables to an otherwise dryer area.

Desalination and pumping stations to create freshwater from ocean water is cost prohibitive. Nevermind the amount of thjat very same water that would be needed to pump as hydroelectric energy. (which would need to be refreshed at least twice as fast as it is being used) Coupled with plans to use that same water for human use?

Take a look at some of those number in those links. They're big.

I'm not suggesting wells would turn the land fertile. I'm saying that if they want water, there are aquifers available.

Also, you can't really generalize in something like this as 'they' and 'desert' is arbitrary. Without knowing the specific area, sea level, environmental specifics and likely a whole other host of details, nobody can say with a definitve 'yes' that this will work. It's barely theory. Speculation at best.