Interesting thread but I'd want to see the actual research before getting too excited. The irrigation hypothesis has been floated before - the subterranean aqueducts nearby (the puquios) are genuinely impressive engineering and there's a reasonable geographic case for a connection. But the lines themselves being functional conduits rather than ceremonial markers is a bigger claim than it sounds.
My issue with a lot of ancient mysteries research is that people see a correlation and immediately jump to causation. The Nazca people clearly had sophisticated water management knowledge, thats documented. Whether the lines were part of that system or completely separate ritual landscape markings is another matter entirely.
What's the source on this old research? Is it the Reinhard stuff or something more recent? Would genuinely change my thinking if there's solid hydrological data behind it rather than just geometric patterns lining up on a map. Post the link if you have it.