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 land
Eugene пт, 11 янв. 2019 г. в 12:02, Hufkratzer <hufkrat...@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.ge...@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 > > > _______________________________________________ > Tagging mailing > listTagging@openstreetmap.orghttps://lists.openstreetmap.org/listinfo/tagging > > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging >
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