On Sat, 23 Feb 2019 at 17:19, Hufkratzer <hufkrat...@gmail.com> wrote:
> > Irrigate with drains? This was the original question of the whole ditch > vs. drain discussion (see > ( > https://lists.openstreetmap.org/pipermail/tagging/2019-January/042047.html). > > It seems to be a contradiction to what wikipedia explains (and therefore > is difficult to remember): > As I see it, ditches are unlined. They're essentially trenches that are intended to have water in them. In areas with a lot of rain (like mine) they allow for the drainage of fields where the water table is close to the surface. In dry countries they can serve the purpose of irrigation (in which case they tend to be interwoven with fields rather than at the edges). We don't have words for "big ditches" or "very big ditches", they're just ditches. As I see it, drains are lined. They're intended to transport water from A to B either for the purposes of drainage or irrigation. Which is a little counter-intuitive, until you think of a drain connecting a reservoir of water higher than a field to one or more ditches around or in that field. You build a drain rather than a ditch in that case because you don't want the water seeping away between the reservoir and the irrigation ditches. But it's still a drain because it's draining the reservoir (that's the bit that's counter-intuitive until you think about what is being drained). If it's a big drain then it might be better tagged as a canal (that's a different endless discussion we can have in another thread). Trying to call big ditches drains is, in my opinion, a bad move. Ditches are permeable and drains are not. Ditches allow the seepage of water to or from the ditch and the land surrounding it; drains prevent such seepage. Lined/unlined (alternatively seepage/no seepage) are the key distinctions. Maybe we need a way of specifying the width to avoid people tagging a ditch as a drain, or vice versa, to achieve different rendering. -- Paul
_______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
