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I am mapping rivers nearly from the source, where the waterway is very narrow and almost indistinct at 500 ft zoom, to the ocean.

Should the entire line be tagged as waterway=river? Or should I break it and tag the narrow, upper reaches as waterway=stream and the wider, lower part as waterway=river?

I'm concerned "rivers" will appear too extensive when the final result is rendered.


asked 12 Sep '14, 10:28

stweb's gravatar image

accept rate: 0%

I think that is a good method. The Wiki loosely defines a river as being wider than a stream so it's up to you. If you want to measure the stream and tag it strictly in accordance with the Wiki, that's fine. We break highways into segments all the time for various reasons: a speed limit change, more or fewer lanes, etc. The same reasoning would apply to streams that become rivers. In any case the renderings are not very different in most of the maps I've seen. Adding riverbanks to either feature will make them appear wider and in most cases this is the appropriate way to handle bigger rivers.

(12 Sep '14, 10:42) AlaskaDave

In Dutch it is just to other way around, a "stroom" ends in the ocean, a "rivier" ends in a "stroom" or another "rivier" So it's easy to mess things up.

(12 Sep '14, 15:17) escada

I got corrected, the above is only true in Flemish, in Dutch stroom=stream, rivier=river. So even more complicated for mappers over here

(12 Sep '14, 16:55) escada

You have to break (split) the line(s) and tag the stream section as a "waterway=stream" and the river section as a "waterway=river". Keep the name on both sections (if they really have the same name since rivers have often more than one source/spring).
You can create a relation of type "waterway" to collect all sections in one OSM entity.

You shouldn't care too much about the "rendering" which is something to treat separately (sometimes, rendering process generates its own errors). It is important that the OSM data reflects the reality : tag the stream as a stream and the river as a river.
The limit between a stream and a river is not clearly specified today in OSM but some national geographic agencies have their own definition (like based on the width or volumetric flow)

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answered 12 Sep '14, 10:45

Pieren's gravatar image

accept rate: 15%


It might make sense to make the switch tags from river to stream where another stream enters it. Not directly related, but the Strahler Stream Order number could be another factor you could use in deciding where to switch:

(12 Sep '14, 15:02) neuhausr

Hi stweb, if you can not jump over the stream, it could roughly be a river. Read this as well,

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answered 12 Sep '14, 12:11

Hendrikklaas's gravatar image

accept rate: 5%

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question asked: 12 Sep '14, 10:28

question was seen: 4,607 times

last updated: 12 Sep '14, 16:55

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum