[Tagging] Irrigation: ditches, canals and drains

[Joseph Eisenberg]

> Not sure about small rock-cut waterways  with massive impermeable sides, are these ditches or canals or drains?

We don't have these in the western USA, but generally our ditches are
dug out of the soil, so I would be surprised to see a feature tagged
as waterway=ditch if it were cut from bedrock or lined with stone.

I'd think waterway=canal would be appropriate for these if they are
large enough.

One tag that's already used is canal=qanat for "a gently sloping
underground channel or tunnel constructed to lead water from the
interior of a hill to a village below", found in the Middle East

If there are small irrigation waterways that area lined with stone (or
concrete etc), we probably need a new tag, since waterway=drain is
pretty strongly associated with drainage, not irrigation, and
waterway=canal probably has a minimum width?


On 5/29/19, Martin Koppenhoefer <dieterdreist at gmail.com> wrote:
>
>
> sent from a phone
>
>> On 29. May 2019, at 03:37, Joseph Eisenberg <joseph.eisenberg at gmail.com>
>> wrote:
>>
>> What, then, should be the distinguishing characteristic between
>> waterway=canal and waterway=ditch or =drain? Width or importance or
>> navigability, or should we still mention the usage as the main
>> difference?
>
>
> IIRR ditches were seen without construction like steel or concrete, just a
> man made depression to channel water, while drains are required to have
> their borders (and maybe base) constructed.
>
> Not sure about small rock-cut waterways  with massive impermeable sides, are
> these ditches or canals or drains?
>
> Stating the usage explicitly might help interpretation of the data, or while
> we’re still mapping fragments of an incomplete network, although I would
> have guessed with a more mature mapping this could already be seen from
> looking at the network structure and flow directions?
>
> What about the practical, human scale distinction we use for natural
> waterways (can be jumped over), wouldn’t it be equally interesting for man
> made waterways?
> Is a canal you can jump over still a canal, or does size somehow come into
> the equation? Can there be draining canals, or are these always drains?
>
> Cheers, Martin
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