[Tagging] mapping qanats
michal at salaban.info
Fri Sep 27 11:19:54 UTC 2013
On Fri, Sep 27, 2013 at 1:00 PM, John Sturdy <jcg.sturdy at gmail.com> wrote:
>> Also, wouldn't we be able to use waterway=canal, tunnel=yes (or whatever tag
>> we use for underground waterways)? Possibly combined with qanat=yes?
> Or perhaps waterway=canal, tunnel=yes, canal=qanat?
This makes sense. It also leaves possibility for mapping open qanats,
which go on the surface. This happens sometimes in the end sections,
before the water gets divided among recipients.
> Or man_made=pipeline, location=underground, type=water?
> I think I'd call it a pipeline if the water fills it to the roof of
> the tunnel, and a canal if there's air above the water (which seems to
> be the case, as Wikipedia mentions air from the tunnels being used for
Qanats are not pipelines, there's usually plenty of space above the
water. Some of them would collapse when filled, as the upper part is
not protected against water.
> If anyone's going to map to that level of detail, will "depth" refer
> to the draught of the water channel (depth from bottom to top of the
> water), or depth of the whole thing below the ground surface?
I think it should mean the depth of the bottom of the qanat relative
to the ground surface. The depth of water is variable with seasons and
of less importance.
How do we map the shafts then? It is similar to manhole=* in some way,
but also serves for ventilation purposes.
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