Green Legend Ran (1992) IMDb
Aliens have sucked up the Earth’s water, turning the planet into a desert, and they now manipulate the remaining humans by means of gigantic mutants given religious functions. Ships travel through the great sands as though through water. Rebels attempt to restore the Earth, among them two children.
Post-apocalyptic SF. Lots of plot holes, but some interesting concepts.
References here: Now and Then, Here and There (1999).