Also, what's this reservoir stuff? If the water table drops you dig a small hole down to it don't you, not a huge one? It'll never run dry no matter how much water you take out of it.[/quote]

Yeah I take your point it is strange why such a large area was needed but as we know, nothing then was for purely practical reasons but at least this theory proposes a motive. I'm not saying this is definitely what happened but compared to other theories it seems credible.