Talk:Tag:waterway=ditch

ditch vs. drain

How do I decide between the two? The picture and descriptions look very similar

While these features are similar, a waterway=drain is lined with concrete or another hard, impermeable surface, while a ditch is lined with soil. --Jeisenbe (talk) 13:20, 28 May 2019 (UTC)

When you talk about surface, subtags like surface=* or material=* come to mind. To base the selection of the main tag on such a property does not seem right. There is waterway=drain and waterway=ditch, and the definition of waterway=ditch says "Use waterway=ditch for ... waterways ... used to drain...". Isn't that counter-intuitive, to put it mildly? Unbelievable that these 2 tags have existed for 1½ decades and been used millions of times and there is still no reasonable distinction. I have mapped thousands myself based on earlier versions of the definitions and on the meaning of the word drain: If swampy land is drained to lower the ground water level and enable agriculture, I use waterway=drain. If a ditch is only used to carry excessive surface rain water, I use waterway=ditch. --Fkv (talk) 04:50, 11 August 2022 (UTC)

I have used waterway=ditch where "swampy land is drained to lower the ground water level and enable agriculture", and I wouldn't find it more intuitive/helpful to base the distinction between the tags on the difference between "drainage to lower the ground water level" and "carrying excessive surface rain water". I can't see any difference there. But in general, if you have ideas for improving the wiki page(s), why not? There was an extended discussion about this topic in Jan/Feb 2019 on the tagging mailing list. --Hufkratzer (talk) 07:55, 11 August 2022 (UTC)

You find it intuitive to use a value other than waterway=drain when something is used to drain? That almost leaves me speechless. Would you also find it intuitive to tag meadows as landuse=forest and forests as landuse=meadow? When I was a kid, our teacher told us a story about a man who started to create his own language in which he called a chair a table and a table a chair and so on. The story ended with nobody else being able to understand what he said.

I've now read the mailing list discussion and everyone agreed that the distinction on whether they are lined is not backed by any dictionary definition.

That discussion also made it clear that such a distinction wasn't backed by tag usage in OSM (example: Belorussia).

In my opinion, the wiki should not make such a distinction that is neither based on dictionary definitions nor on actual tag usage. The wiki should rather just document that the two tags overlap and that tag definitions and usage in OSM are a mess. --Fkv (talk) 12:05, 11 August 2022 (UTC)

I don't tag meadows as landuse=forest and forests as landuse=meadow. What I tag as waterway=ditch looks like: ditch, so it don't think I have crated my own language here. --Hufkratzer (talk) 12:15, 11 August 2022 (UTC)

Direction

As I see this page included in Category:Way Direction Dependent category, should I assume that the way must be draw so that the direction of the way is downstream?. If so is it better to add, as in page Tag:waterway=stream, the following sentence?

Direction of the way should be downstream.

AnyFile (talk) 15:14, 11 March 2013 (UTC)

Barrier

I disagree with the fact that every waterway=ditch implies barrier=ditch, however the reverse is true (a ditch barrier implies a ditch). Can we change it? Teuxe (talk) 17:16, 17 December 2014 (UTC)

• In my opinion neither implies the other one (there may be small ditch that is not a barrier, there may be a dry ditch that is a barrier but not a waterway) Mateusz Konieczny (talk) 08:31, 18 December 2014 (UTC)
• Both are distinctive. A waterway=ditch is for draining, a barrier=ditch for denying access. Neither implies the other. Perhaps barrier=ditch should be man_made=ditch/trench? --Jojo4u (talk) 20:40, 25 March 2015 (UTC)
• Me too. Obviously it's a mistake. It should be removed the word "Implies barrier=ditch". Sergio (talk) 23:05, 8 September 2017 (UTC)

For drainage and irrigation

In Asian countries, ditches are commonly used as minor irrigation channels from a larger canal or pond. How do we differentiate a ditch used for drainage from that used for irrigation? --Planemad/Talk 07:15, 13 April 2016 (UTC)

I could find some uses ([1]) and discussions ([2] [3] [4]) on irrigation=yes, so I'd recommend this.--Jojo4u (talk) 22:09, 17 April 2016 (UTC)

The alternative tag is usage=irrigation - this is the tag used with waterway=canal irrigation canals. Some mappers also think that even small irrigation ditches should be mapped waterway=canal with width=*, though I have trouble imagining this for ditches <1 meter in width. Or a new waterway value could be created? --Jeisenbe (talk) 13:33, 28 May 2019 (UTC)

Use on relations

Hi @Maro21:, you've recently edited the page to say the tag shouldn't be used on relations. I didn't see an edit comment. Did this change follow a discussion? I am asking because the tag is used on about 20,000 relations (Overpass) and is also documented on Relation:waterway, so the Wiki is inconsistent now. Osmuser63783 (talk) 07:03, 1 October 2024 (UTC)

On 3662 relations. I didn't see any mention of use on relations in the article, which is why I marked it as such. You're right, it can be used on relations. maro21 20:40, 1 October 2024 (UTC)

Your number is of course right, not sure where I got the 20,000 from. Thanks for correcting the article. Osmuser63783 (talk) 22:55, 1 October 2024 (UTC)

Swales

This page is a redirect from waterway=swale. A swale can be an artificial depression used for holding water, rather than (as here) a waterway for carrying water. (These are a requirement of planning consent in the UK: https://www.openstreetmap.org/way/1321825858/history )

There seems to be a need for this tag: could we have a tag (and page) for swales of that sort?

eteb3 (talk) 12:29, 7 October 2024 (UTC)