[Tagging] Drain vs ditch

[François Lacombe]

During the RFC of waterways for power generation proposal several
discussion raised because of some waterways values. Drain and ditches were
ones of them.
https://wiki.openstreetmap.org/wiki/Proposed_features/Hydropower_water_supplies

Currently, both canal and drain refer to structure and usage also.
Canal is designed for useful water while drain is intended for waste water.
usage=* comes to give more information of what canal is intended for.

Regarding ditch, it regards both useful and waste water.

If we choose to be consistent in waterway=* values, waterway=drain should
be abandonned in favor of canal + appropriate usage=* values.
Then we'll obtain waterway=canal for artificial waterways whatever their
usage and waterway=river, stream and ditch for natural or not-lined
watercourses.

It's long time changes, see the table here :
https://wiki.openstreetmap.org/wiki/Key:waterway#Values

All the best

François

Le ven. 11 janv. 2019 à 20:05, Tod Fitch <tod at fitchdesign.com> a écrit :

> Most of what I’d call a drain around here would be large underground pipes
> designed to carry storm water. Empty most of the time except perhaps for a
> trickle of water from various urban/suburban watering overflow. Used most
> of the time by raccoons, possums and rats as away to navigate through or
> shelter in an area without having to worry about being attacked by
> neighborhood dogs, though the larger ones could be attractive for
> adventuresome teenage boys to explore.
>
> I’d call the open air, usually concrete lined, versions “storm channels”
> though that might be a local colloquial. Many/most of those follow
> reasonably close to the alignment of the original natural waterways and
> often carry the same name as the original (e.g. “Santa Ana River”, “Los
> Angele River”, etc.). Again “river” would be a historic term as they are
> often dry except during or immediately after a storm.
>
> Cheers!
>
> On Jan 11, 2019, at 10:18 AM, Eugene Podshivalov <yaugenka at gmail.com>
> wrote:
>
> Tod, what would be definition of "drain"?
>
> Eugene
>
> пт, 11 янв. 2019 г. в 21:10, Tod Fitch <tod at fitchdesign.com>:
>
>>
>> > On Jan 11, 2019, at 8:36 AM, ael <law_ence.dev at ntlworld.com> wrote:
>> >
>> > As a native speaker, I do not recognise "canal" as appropriate for
>> > irrigation. That is not to say that some canals may also be used
>> > partly for irrigation.
>> >
>> > But the phrase "irrigation ditch" is common and understood.  Bear in
>> > mind that the UK is mainly a fairly wet place, so the need for
>> > substantial irrigation is not high except in some special cases.  The
>> > unqualified word "ditch" would normally be understood as an artificial
>> > unlined and usually small watercourse. But also, in certain contexts,
>> > for a historic trench acting as a defense or fence, not necessarily
>> > containing water.
>> >
>> > That seems to accord with a the sub tag irrigation=yes on ditches -
>> > and maybe on other waterways if that is one of the uses/functions.
>> >
>> > ael
>> >
>>
>> +1
>>
>> In the desert where I was raised the cotton fields were surrounded with
>> “irrigation ditches”, or “ditches” for short. The fields were watered from
>> the ditches by either syphon hoses or sluice gates.
>>
>> Later, when working on road projects, I found that the low areas on the
>> sides of roads (often used as “side borrow” areas during construction of
>> the roadway) were formally called “drainage ditches” or just “ditches” for
>> short.
>>
>> So to me a ditch is simply a channel dug to move water.
>>
>> But I am an American and our terms diverge somewhat from UK usage. So I
>> looked it up in my older paper version of the OED to find the first two
>> definition are “1. An excavation narrow in proportion to its length; the
>> trench or fosse of a fortification, etc.”. “2. Such a hollow dug out to
>> receive or conduct water, esp. to carry off the surface drainage of a road
>> or field, etc.”
>>
>> Based on the second, I can see the reason why some would conflate
>> “drainage ditch” with simply “ditch”. But I don’t see from this where even
>> in UK usage a ditch has to be for drainage. It is simply a long narrow
>> excavation and, in the waterway sense, dug to conduct water from one place
>> to another.
>>
>>
>> Cheers!
>> tf
>>
>>
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