Hmmm, a very long tunnel out into the desert ~ sounds like an irrigation tunnel very similar to those found throughout the Andes, Afghanistan, Persia, various places in Central Asia, and so on.
The idea with these tunnels is to reduce evaporation of the water.
The discovery of such a tunnel leading from Jerusalem, a source of water, to the Judean desert, really wouldn't be a surprise.
Hmmm, just read about these while doing some research for a novel. They are called Qanats in the Persion regions. Check out
this link and go down about a third of the page and look for Qanat. It's pretty cool.
While you're at it, also check out the section entitled "Ship Railroad of Corinth". It is really amazing. Explains why Corinth was known as a wealthy city.
Will do. I recalled the irrigation tunnel technique immediately because they had a "travel" show on the other night showing how extensive they were in the high plateau country in Peru. A guy was found crawling through a small one clearing roots ~ the tunnel was over 1,000 years old and was still being maintained by a local farmer.
The tunnels in Afghanistan were a big concern during the period of combat. Earlier they caused the Soviets all sorts of problems because the Afghan mujahadeen could move vast distances without detection in those systems.