[Tagging] Aqueducts?

[Steve Bennett]

  On 7/01/2011 9:19 AM, M∡rtin Koppenhoefer wrote:
> What do you think about waterway=aqueduct ?
> Around here there are quite some historical aqueducts (e.g. [1]). Most
> are ruins, but they are still impressive. I tag them
> waterway=aqueduct, ruin=yes
> Some are bridge-like (arches), but others are solid underneath.
Hmm. It could get increasingly difficult to objectively distinguish 
between all the different types of man-made water channel: canal, drain, 
aqueduct. (Incidentally, taginfo shows 40,000 uses of 
"waterway=artificial" - anyone know what that is?)

I guess the difference in the above is the purpose: transport, 
stormwater, and drinking water respectively. How is one supposed to tag 
an irrigation channel?

Steve