I've been thinking about this one for ages. The water table theory keeps coming back around every few years and honestly it makes more sense to me than "landing strips for aliens" even though that's the fun answer.
The thing that gets me is the sheer scale of them. You don't carve lines that long and precise just for decoration, surely? There had to be some practical element, even if we're not 100% sure what it was. Johan Reinhard's work linking them to mountain water sources is worth looking into if you haven't already - he mapped out how several of the lines point toward peaks where rainfall would originate.
That said I don't think irrigation map fully explains the animal and bird figures. Those feel like something else entirely, maybe ritual, maybe astronomical.
What does everyone else make of it? Anyone been out to Nazca and seen them up close? I'd love to hear from people who've actually stood on the plateau.