[Tagging] How to tag small canals?

Martin Koppenhoefer dieterdreist at gmail.com
Thu Aug 16 13:15:23 UTC 2018



sent from a phone

> On 16. Aug 2018, at 09:49, SelfishSeahorse <selfishseahorse at gmail.com> wrote:
> 
> It seems to me that waterway=ditch +
> usage=headrace/tailrace/irrigation fits best, but the wiki defines
> waterway=ditch as 'a small man-made draining waterway, often found
> along roads'.


yes, waterway tagging is not very clear in general, some refining would be seriously appreciated.

Based on the established waterway tags, there are currently only 2 classes for natural waterways:
stream (sufficiently narrow that an adult can jump over it) and river (bigger), formerly established „wadi“ is now discouraged AFAIK,
and 3 for artificial waterways:
ditch, drain, canal

plus additional attributes (width, intermittent, seasonal, usage, ...).

Apparently (that’s what the wiki says at the moment) the artificial waterways are to be classified according to their function and type of construction (canal for navigable waterways and big drains, drain for draining waterways lined with concrete or similar (storm water and grey water is explicitly mentioned) and ditch for „simple“ waterways not lined with concrete.

I’m probably not the only one who thinks this is not a good system. Why would we require „concrete“, this is clearly context specific, you can have artificial waterways without any concrete. At least once we could mention „steel“.

As there is already a „usage“ property, the usage shouldn’t matter for the class (let’s not intermingle orthogonal properties, this will work in some setting and fail in others).

IMHO we should see the waterway tags as a network hierarchy, similar to roads (and I assumed we did this, but looking at how the wiki evolved it is apparently not a thought shared with everybody).
If you have to drain vast areas you will build small ditches which discharge into bigger artificial waterways, which again might be collected prior to flow into a natural waterway. And all that without any „storm water“ or „industrial discharge“.

There isn’t a universal definition of river, but locally people usually know whether a waterway is considered a river or not (in my home area, a 3-5 m waterway is usually not considered a river, but you cannot jump over it either). There’s a huge difference between a stream of 0,5-1m and one of 5m.

Following the wiki by the word, we have no waterway type for irrigation, because all waterways that are mentioned and defined are for „draining“ or navigating. Likely the result of having central and north europeans writing the definitions, where abundance of water is the standard.

Cheers,
Martin 


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