Irrigation's one theory but I've never fully bought it. The scale is just too massive for practical agricultural use, you'd get far more efficient results with smaller localised channels.
What keeps pulling me back is the astronomical alignment angle. A lot of the lines point directly at solstice and equinox positions on the horizon, which fits better with a ritual or calendrical function than water management. The Nasca people weren't stupid, they likely understood seasonal flooding patterns and built around them rather than trying to map them on a 50km canvas.
That said I'd genuinely love to see your evidence. What kind of weird is we talking? Geological surveys, water table data, or more the photographic anomaly type stuff? Because if theres a correlation between the lines and ancient aquifer positions that would be significant and worth digging into properly.
Been studying these for about 15 years and the honest answer is they probably served multiple purposes depending on which group or period created them. Different lines, different functions.
