[Tagging] Drain vs ditch

Eugene Podshivalov yaugenka at gmail.com
Fri Jan 11 11:11:30 UTC 2019

How about the following definitions?
drain - an artificial free flow waterway typically lined with concrete or
similar used for carrying storm water or industrial discharge
ditch - an artificial free flow waterway used for draining or irrigating


пт, 11 янв. 2019 г. в 12:02, Hufkratzer <hufkratzer at gmail.com>:

> https://wiki.openstreetmap.org/wiki/DE:Key:waterway says:
> - drain is for rain or industrial water ("Abwassergraben") -> may be
> wastewater
> - ditch is just for rain water ("Entwässerungsgraben") -> no wastewater
> Am 11.1.2019 07:35, schrieb John Willis:
> On Jan 11, 2019, at 3:00 PM, Marc Gemis <marc.gemis at gmail.com> wrote:
>  was always under the impression that the ones I encounter between
> farmland and meadows, which typically are surrounded by dirt, ground,
> plants are ditches. That drains are constructed with concrete or
> similar material and that there are normally no plants on the bedding
> of the drain.
> TL;DR - the connotation of “drain” is a problem. it is not “draining away”
> unwanted water, it is merely moving it around, and this connotation causes
> mapping issues.
> ~~~~
> I like this summary too. I think the issue is that “drain” has a
> connotation of moving water “away” from some spot where it is no longer
> needed or has been used - which is confusing for a lot of irrigation uses.
> In places like southern California, which only have large (5x5m) open-air
> aqueduct systems to move usable water, and further distribution handled
> almost 100% by pipe for irrigation or drinking. sewer is also piped and
> handled by treatment plants, and “storm drains" merely channel the
> occasional rain to the ocean.
> This makes mapping “drains” and "ditches” is super easy, because almost
> all drains/ditches are moving unwanted rainwater to a waterway/ocean.
> but in my area of Japan, each neighborhood has several *Kilometers* of
> tiny concrete roadside “drains” (covered and uncovered) that have little
> doors or valves that farmers can open to flood ditches that flood rice
> fields. there are side channels, small storage ponds (3x3m), and other very
> detailed and intricate water management systems that make a Californian
> like me marvel at the rain management system they have created.  The drains
> act merely as storm drains the rest of the year, and integrate “streams”
> and other natural channels sometimes. but the rain they move is useful for
> irrigation; rain “drained” away from my area is actually irrigation water
> for people further downstream.
> the other issue is scale. some concrete drains are very tiny measure less
> than 20cm2, though most are 30cm2 or 50cm2 . most ditches are also roughly
> 30cm2.
> if we go by construction, and try to remove connotation of wastewater,
> then I think it is easy to map.
> Javbw
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