RfC: Deprecate use of "waterway=pressurised" on anything not artificially built

General talk Tagging general discussion
61

Personally, I would prefer natural=cave over tunnel=cave

+1 to natural=cave

62

In the case the cave is not completely flooded, you can barely tag the waterway with natural=cave or tunnel=cave anyway.
Look at this drawing from the cave here

Unfortunately the course of the river is not on this drawing, but it flows through the blue areas.
Should we go indoor micro-mapping on this, there would be a natural = cave area, a river, lakes, siphons, some paths, steps, bridges, man_made tunnels, lit=yes on some, etc…
The question remains, how to tag the river?
I’d go for waterway=underground_river or waterway=subterranean_river, news values for which the wiki definitions would emphasise the natural aspect.

63

I am still at a loss, if there is any actual use to deprecate at all. Are there people that consider waterway=pressurised correct for mapping underground rivers in caves?

@InfosReseaux The waterwaymap.org issue turned out a misunderstanding?

64

I did not find any uses of waterway=pressurised applied to underground rivers in caves in an informal survey. But I did not look at every instance where the tag was used.

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65

Further reduced result set overpass turbo – Looking at returned data found me this Way: ‪Movran‬ (‪1286897875‬) | OpenStreetMap

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66

PS: The feature is quite a bit interesting, Movran - Wikipedia – The fine article talks about a siphon, but from looking at videos, I cant believe that. The pressurised waterways are copied from bing imagery.

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67

The challenge with Movran or any of these subterranean waterways is finding enough information to be able to map them. Often we just have the inlet and outlet and little to no information about the nature or location of the waterway.

It would be very interesting to find a scientific paper that describes the supposed siphon at Movran. But without a verifiable source, we would just be guessing.

68

You’re absolutely right when you say we often don’t know what happens down there.
However we used to map forests from landsat, so we know we can deal with some generalization.

69

For an extra-complicated, naturally subterranean but artificially dammed, piped and redirected waterflow, see Trebišnjica, in the same karst region as Movran.

I gave up making the heads and tails of that.

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70

I’m certainly guilty of connecting the inlet and outlet of an underground stream with a straight line. In the absence of more detailed source data, it’s better than nothing.

71

I analysed recent OSM data, and if I include waterway=pressurized then there are only 22 more loops than with the current approach of ignoring them. There are ~16,100 waterway loops in OSM now. So +22 isn’t a lot. This shows that OSMers aren’t causing many

Here’s a GeoJSON of the “new loops” when you include =pressurized.

In comparison, someone recently asked for waterway=ditch to be included. Although the wiki says ditches should be mapped how the water flows, there are 28,000 loops in waterway=ditch alone!

Based on this, I will probably put =pressurized back into WWM’s “flowing water” category.