There are lots of ideas around for desert greening; see the linked article for a list. Canals are unlikely to work well, but seawater farming is kind of close

There are lots of ideas around for desert greening; see the linked article for a list. Canals are unlikely to work well, but seawater farming is kind of close to your proposal. It requires greenhouses to be built though, so I don’t know how well it scales. Years ago I read about a system that seemed successful. Ridges were built up at the desert’s edge, and salt-tolerant trees and shrubs were planted on hem to keep the ground stable. This change in microclimate promoted more greening in the valleys between, which increased overall moisture levels. Once this is established, more ridges can be constructed further out to repeat the process. It’s not an easy thing to search the web for, and I don’t recall how long it takes for one ridge to be productive, but I recall thinking it was shorter than I expected (still on the order of years, of course). https://en.m.wikipedia.org/wiki/Desert_greening https://en.m.wikipedia.org/wiki/Desert_greening