GIANT BOULEVARD just to the top of the picture with
While I realize / expect you were just kidding, the same thought occurred to me at first.
Then I appreciated that the intent wasn't to hide the entire airfield; that wouldn't have been remotely feasible. Instead they were just trying to divert attacks away from the most important and/or vulnerable parts. With the camouflage in place, bombers (at least if in possession with less-than-perfect maps of the site) would look down, see the runway but not see the real plant, rather would be fooled into thinking that the uncamouflaged and (presumably) lower-priority warehouses, or whatever they are, just to the right were their intended target. Thus those buildings would be bombed instead. Still annoying, to be sure, but nowhere near as devastating as if the important stuff were destroyed.
It may even be that the latter buildings were an explicit part of the ruse, and were left entirely empty?
Anyway, that's my take on it. This approach would also help mitigate the issues cited by the taphilo.com article quoted by infinite monkey...