[Tagging] Is waterway=riverbank an 'Old scheme' ?

Kevin Kenny kevin.b.kenny at gmail.com
Fri Sep 7 13:51:31 UTC 2018

On Thu, Sep 6, 2018 at 6:38 PM Fran├žois Lacombe
<fl.infosreseaux at gmail.com> wrote:
> To me, waterway=* should only get values to map linear water courses for the routable hydrographic network.
> Newer tagging with natural=water sounds ok, except for artificial water features.
> I'm not so keen of natural=water over a man made irrigation canal, unless there is no artificial water, even in artificial man made structures

natural=* is a lost cause, and  part of the issue there is that there
are a good many natural=* tags that don't have neutral equivalents.
There does need to be some way to say, "this land is covered by water
perennially" without asserting who put it there. It's much worse when
it's 'this land is covered by trees.' There is no non-controversial
tag to assert that simple fact. As soon as we start in with the idea
that a reservoir is 'unnatural' water, we give trouble for initial
mapping. I can't necessarily see on aerials whether the pond that I
see has a dam at its outlet, or whether the dam was put there by
humans or beavers, or whether the dam is creating a new impoundment or
merely inducing an insignificant rise in the water level of an
already-existing waterbody.

If a mapper can't say, 'there's water here', 'there are trees here',
'there is grass here' without doing research on human intent and
purpose for the landcover, navigability of the waterways, there's
something wrong with the data model. Those are the bones that
everything else fleshes out. In some of the places I map, there are
still broad expanses of blank areas on the map, where the road network
is hallucinatory, even fairly major watercourses are missing, and
geomorphology is virtually nonexistent. I need a way to sketch in
broad strokes without either telling lies or having to do research
before I even start.

The idea that  waterway=* must be routable is, frankly, a new one to
me.  How is a mapper supposed to tag a non-navigable river? Water
routing sounds like an intriguing idea, but at least so far, tagging
doesn't appear to support it.

To be more specific:

I don't want to stand in the way of that sort of project by mismapping
things, but I frankly don't know how to get it right. I recently
mapped my first river multipolygon (needed it for a large-scale map
that I was rendering), It is most emphatically NOT navigable, but I
added the polygons because it's fairly wide and I wouldn't fancy
fording it in a season of high water. I'll plead guilty to stopping
at, 'induces no warnings in JOSM, and renders correctly on OSM and in
my custom rendering.' I used waterway=riverbank and a multipolygon,
because that appears to be what others used nearby, and I did indeed
try to approximate the Thalweg with waterway=river.

In any case, it would be a very quick thing to change that particular
multipolygon to natural=water water=river. How *ought* the Thalweg be

That particular river drains into a reservoir. At least *some* of its
land area is 'natural' water; there are drowned ponds under there
(whose shorelines could be researched; I have maps from a 1903
survey). But recovering their shorelines hardly seems urgent to me.
Can we agree on some sort of tagging for, 'this is a waterbody'?
That's more observable than, 'this is something Mother Nature put
here' as opposed to 'this is something crafted by the hand of

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