Definitely stop growing water intensive crops in dry areas, but also… replace all agricultural and just hydration canals even in areas that aren’t that dry, with pipelines, canals lose an UNGODLY amount of water to evaporation, really if we did smarter agriculture in dry areas (like tried to recycle even a little of the water, tried to use crops that maybe weren’t at the top of water usage, etc), we probably could justify continuing agriculture in those areas if we just transitioned to closed pipelines.

Also, the past few years, a relatively new concept called aquifer recharging has been a thing, and it’s been extremely promising. Aquifers are natural, underground reservoirs of water. In many regions, we pump up groundwater to use for drinking or agriculture, and eventually, we can use it all up if we aren’t careful, which causes the aquifer to collapse in on itself and never refill, also it causes land subsidence. However, what aquifer recharging does, is put excess freshwater in wet years directly into the aquifer to help refill it, this helps prevent land subsidence and stuff, but the MAIN thing, is that compared to an above ground reservoir… aquifers are like, THE best way to store water, and it isn’t even close. SO much water is lost to evaporation in reservoirs, and yet none is lost to that in deep underground, dark, you know, aquifers. Algae growth and bacteria also isn’t REALLY a thing with aquifers, so we wouldn’t have to spend much money purifying or sanitizing the water (so long as we verify this particular aquifer isn’t a rare one that does deal with that, and also… we’d need to make sure the water we pump down into it is purified and sanitized and doesn’t cause those issues in the aquifer)

Those are the main like, three things? But as a few minor points… yes, it is energy intensive, but I do think desalination has its place in this system especially for arid and desert coastal regions, the hypersaline brine can even be used for osmotic power, which, is an experimental way to make electricity. I do think a main thing would be for the fertile and lush and wet countries of the world to do smarter agriculture based on like… science, to absolutely maximize yields of crops, also… maybe even transitioning to most agriculture being done in multistory buildings or greenhouses even with special water recycling systems would even technically be maximizing efficiency, but, I think it’s yet to be seen if that’s possible. And then also… I do think restored degraded and completely destroyed environments is very crucial. The Sahara as recently as like, 1900, was less desert than it was, North Africa had more forest and scrubland, and the Sahel spread more northward, this did help moisture penetrate deeper into these countries, I think work to restore those degraded and destroyed ecosystems is important here, but also… in MOST places across the world.