[battousai]

I thought the prevailing theory was already that the Nasca lines were related to water, but more indirectly as a plea to their gods for water as their region settled into a drought.

If these are actually maps to sources of water, then why did the people not survive, there are many line drawings which should mean many underground sources, yet they did not survive the extended drought.

[Deaf Smith]

I thought that the bigger mystery is that the Nasca lines are on top of a carved off mountain.

[SunkenCiv]

/bingo